Columbia Thermostat Fund (CTFAX) N-CSR Certified annual shareholder report (management investment company)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number			811-01829
Columbia Acorn Trust
(Exact name of registrant as specified in charter)
One Financial Center, Boston, Massachusetts					02111
(Address of principal executive offices)					(Zip code)
Scott R. Plummer 5228 Ameriprise Financial Center Minneapolis, MN 55474
(Name and address of agent for service)
Registrant’s telephone number, including area code:				1-612-671-1947
Date of fiscal year end:	December 31
Date of reporting period:		December 31, 2010

Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

Item 1. Reports to Stockholders.

Q4 2010

Columbia Acorn Family of Funds

Class Z Shares

Managed by Columbia Wanger Asset Management, LLC

Annual Report

December 31, 2010

n  Columbia^SM
Acorn® Fund

n  Columbia^SM
Acorn International®

n  Columbia^SM
Acorn USA®

n  Columbia^SM
Acorn International Select^SM

n  Columbia^SM
Acorn Select^SM

n  Columbia^SM
Thermostat Fund^SM

Not FDIC insured • No bank guarantee • May lose value

Columbia Acorn Family of Funds

The views expressed in the "Squirrel Chatter II" and "In a Nutshell" commentaries reflect the current views of the respective authors. These views are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult to predict so actual outcomes and results may differ significantly from the views expressed. These views are subject to change at any time based upon economic, market or other conditions and the respective authors disclaim any responsibility to update such views. These views may not be relied upon as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied upon as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific company's securities should not be construed as a recommendation or investment advice and there can be no assurance that as of the date of publication of this report, the securities mentioned in each Fund's portfolio are still held or that the securities sold have not been repurchased.

Letter to Shareholders from the
Columbia Acorn Board of Trustees

40 Years of Vision, Stability and Growth

Fellow Shareholders:

This has been an eventful year for the Columbia Acorn Funds. Early in the year, the Board negotiated new management and administrative agreements with the Funds' adviser, Columbia Wanger Asset Management ("CWAM"), following its acquisition by Ameriprise Financial, Inc. These new agreements were crafted with the objective of preserving CWAM's autonomy and culture and ensuring that the terms of these agreements were in Fund shareholders' best interests. Finally, I am especially pleased to report that the CWAM investment team remains in place following the ownership transition. Together with Ameriprise's expressed commitment to support and maintain the unique culture of CWAM and the Acorn Funds, your trustees are optimistic that the necessary foundation has been laid to perpetuate a vibrant and successful investment organization.

Last year's letter spoke of change and continuity in the governance of your Funds. That process has continued with the retirement of two long-serving trustees, David Kleinman and Jack Wing, and the selection of three new trustees, David Small, John Heaton and David Rudis. Mr. Small is a senior partner at Grosvenor Capital Management, a successful manager of investment partnerships. Mr. Rudis was formerly the president of LaSalle Bank, a major Chicago bank until its sale a few years ago, and Mr. Heaton is a distinguished professor of finance at the University of Chicago. Our new trustees collectively bring extensive business, investment and financial expertise to the job of overseeing your Funds, and we are glad to have them on board. At the same time, we will miss David and Jack, each of whom served shareholders faithfully and well for many years.

The markets continued to recover in 2010, and all the Funds delivered strong absolute returns during the year. While these results are important, your trustees—each a shareholder—focus especially on long-term performance. To this end, we salute present and past members of the investment team at CWAM for the remarkable record that they have created for the Acorn Fund. Since the Fund's inception 40 years ago, the original Class Z shares have enjoyed average annual total returns in excess of the S&P 500, as have the Fund's other classes of shares, which were instituted in 2000. As a result of this performance, the Acorn Fund was ranked the number one U.S.-based mutual fund over its lifetime, ahead of 149 other U.S.-based funds in existence during the period.* This is an extraordinary legacy, which your trustees will work to see perpetuated.

Thank you for your confidence in the Acorn Funds, and best wishes for the new year.

James A. Star
Independent Chairman of the Board of Trustees
Columbia Acorn Trust

*  According to Morningstar, Columbia Acorn Fund Class Z ranked #1 of 149 U.S.-based mutual funds in existence since June 10, 1970. These rankings are based on returns for Z Class shares for the period June 10, 1970, the inception date of the Fund, to December 31, 2010. Please refer to Page 1 for complete performance data.

	From Inception to 12/31/10		10 years		5 years		1 year
Acorn Fund compound return		15.01%		9.40%		5.91%		26.00%
Morningstar ranking		1 of 149		10 of 167		24 of 169		14 of 169

Source: ©2011 Morningstar, Inc. All rights reserved. Morningstar rankings are based on annualized total returns and do not reflect sales charges. Criteria: Open-ended mutual funds; inception date on or before Columbia Acorn Fund; oldest share class only; USD-based currency.

Columbia Acorn Family of Funds

Table of Contents

Performance At A Glance	1
Description of Indexes	2
Squirrel Chatter II: The Keys to Prosperity	3
Understanding Your Expenses	6
Columbia Acorn Fund
In a Nutshell	8
At a Glance	9
Major Portfolio Changes	20
Statement of Investments	23
Columbia Acorn International
In a Nutshell	10
At a Glance	11
Major Portfolio Changes	37
Statement of Investments	39
Portfolio Diversification	48
Columbia Acorn USA
In a Nutshell	12
At a Glance	13
Major Portfolio Changes	49
Statement of Investments	50
Columbia Acorn International Select
In a Nutshell	14
At a Glance	15
Major Portfolio Changes	58
Statement of Investments	59
Portfolio Diversification	63

Columbia Acorn Select
In a Nutshell	16
At a Glance	17
Major Portfolio Changes	64
Statement of Investments	65
Columbia Thermostat Fund
In a Nutshell	18
At a Glance	19
Statement of Investments	70
Columbia Acorn Family of Funds
Statements of Assets and Liabilities	72
Statements of Operations	73
Statements of Changes in Net Assets	74
Financial Highlights	78
Notes to Financial Statements	81
Report of Independent Registered Public Accounting Firm	91
Federal Income Tax Information	92
Board of Trustees and Management of Columbia Acorn Funds	93
Columbia Acorn Family of Funds Information	96

2010 Year-End Distributions

The following table details the year-end distributions for the Columbia Acorn Funds. Except for Columbia Thermostat Fund, the record date was December 14, 2010, the ex-dividend date was December 15, 2010, and the payable date was December 16, 2010. For Columbia Thermostat Fund, the record date was December 21, 2010, the ex-dividend date was December 22, 2010, and the payable date was December 23, 2010.

	Short-term Capital Gains		Long-term Capital Gains		Ordinary Income		Reinvestment Price
Columbia Acorn Fund		None	$	0.8374	$	0.0140	$	29.55
Columbia Acorn International		None		None	$	0.3276	$	39.79
Columbia Acorn USA		None		None		None		NA
Columbia Acorn International Select		None		None		None		NA
Columbia Acorn Select		None		None		None		NA
Columbia Thermostat Fund		None		None	$	0.0678	$	12.39

Columbia Acorn Family of Funds

Performance At A Glance Class Z Average Annual Total Returns through 12/31/10

	NAV on 12/31/10		4th quarter*			1 year			3 years			5 years			10 years			Life of Fund
Columbia Acorn Fund (ACRNX) (6/10/70)	$	30.19		14.57	%		26.00	%		2.64	%		5.91	%		9.40	%		15.01	%
Russell 2500 Index				14.86	%		26.71	%		2.48	%		4.86	%		6.98	%		NA
S&P 500 Index**				10.76	%		15.06	%		-2.86	%		2.29	%		1.41	%		10.65	%
Lipper Small-Cap Core Funds Index				15.40	%		25.71	%		2.88	%		4.76	%		6.96	%		NA
Lipper Mid-Cap Growth Funds Index				13.93	%		25.66	%		0.11	%		6.22	%		2.59	%		NA
Columbia Acorn International (ACINX) (9/23/92)	$	40.92		8.57	%		22.70	%		0.08	%		9.60	%		9.33	%		12.17	%
S&P Global Ex-U.S. Between $500M and $5B Index				10.58	%		24.36	%		0.28	%		8.19	%		11.75	%		9.45	%
S&P Global Ex-U.S. SmallCap Index				10.65	%		22.96	%		-1.11	%		7.29	%		10.69	%		8.64	%
MSCI EAFE Index				6.61	%		7.75	%		-7.02	%		2.46	%		3.50	%		6.24	%
Lipper International Small/ Mid Growth Funds Index				11.64	%		23.77	%		-1.96	%		6.34	%		7.63	%		NA
Columbia Acorn USA (AUSAX) (9/4/96)	$	28.56		16.43	%		23.16	%		1.93	%		3.48	%		8.74	%		10.57	%
Russell 2000 Index				16.25	%		26.85	%		2.22	%		4.47	%		6.33	%		7.55	%
Russell 2500 Index				14.86	%		26.71	%		2.48	%		4.86	%		6.98	%		9.14	%
S&P 500 Index**				10.76	%		15.06	%		-2.86	%		2.29	%		1.41	%		6.53	%
Lipper Small-Cap Growth Funds Index				15.57	%		26.08	%		-0.04	%		3.92	%		2.58	%		5.84	%
Columbia Acorn Int'l Select (ACFFX) (11/23/98)	$	28.33		8.09	%		21.89	%		-2.45	%		9.04	%		6.63	%		10.33	%
S&P Developed Ex-U.S. Between $2B and $10B Index				9.75	%		20.16	%		-3.22	%		4.95	%		8.22	%		8.36	%
MSCI EAFE Index				6.61	%		7.75	%		-7.02	%		2.46	%		3.50	%		3.96	%
Lipper International Small/ Mid Growth Funds Index				11.64	%		23.77	%		-1.96	%		6.34	%		7.63	%		11.35	%
Columbia Acorn Select (ACTWX) (11/23/98)	$	28.73		14.05	%		22.88	%		1.24	%		6.28	%		8.79	%		11.14	%
S&P MidCap 400 Index				13.50	%		26.64	%		3.52	%		5.74	%		7.16	%		9.47	%
S&P 500 Index**				10.76	%		15.06	%		-2.86	%		2.29	%		1.41	%		2.44	%
Lipper Mid-Cap Growth Funds Index				13.93	%		25.66	%		0.11	%		6.22	%		2.59	%		6.50	%
Columbia Thermostat Fund (COTZX) (9/25/02)†		$12.44		7.37%			17.58%			2.62%			5.38%			—			7.84%
S&P 500 Index				10.76	%		15.06	%		-2.86	%		2.29	%		—			7.44	%
Barclays Capital U.S. Aggregate Bond Index				-1.30	%		6.54	%		5.90	%		5.80	%		—			5.03	%
Lipper Flexible Portfolio Funds Index				7.29	%		12.91	%		0.68	%		4.75	%		—			8.15	%
50/50 Blended Benchmark††				4.65	%		11.29	%		2.04	%		4.44	%		—			6.57	%

*Not annualized.

**Although the Fund typically invests in small- and mid-sized companies, the comparison to the S&P 500 Index is presented to show performance against a widely recognized market index over the life of the Fund.

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end updates.

Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC). If they were included, returns would have been lower. Class Z shares are sold only at NAV with no distribution and service (Rule 12b-1) fees. Only eligible investors may purchase Class Z shares of the Funds, directly or by exchange. Please see each Fund's prospectus for eligibility and other details. Class Z shares have limited eligibility and the investment minimum requirement may vary.

Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers or expense reimbursement arrangements, performance results would have been lower.

†A "fund of funds" bears its allocable share of the costs and expenses of the underlying funds in which it invests. Such funds are thus subject to two levels of fees and potentially higher expense ratios than would be associated with an investment in a fund that invests and trades directly in financial instruments under the direction of a single manager.

††The 50/50 Blended Benchmark is a custom supplemental benchmark established by the adviser.

All results shown assume reinvestment of distributions and do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption of fund shares.

Unlike mutual funds, indexes are not actively managed and do not incur fees or expenses. It is not possible to invest directly in an index. For index definitions, see Page 2.

1

Columbia Acorn Family of Funds

Descriptions of Indexes Included in this Report

•50/50 Blended Benchmark, established by the Fund's adviser, is an equally weighted custom composite of Columbia Thermostat Fund's primary equity and primary debt benchmarks, the S&P 500 Index and the Barclays Capital U.S. Aggregate Bond Index, respectively. The percentage of the Fund's assets allocated to underlying stock and bond portfolio funds will vary, and accordingly the composition of the Fund's portfolio will not always reflect the composition of the 50/50 Blended Benchmark.

•Barclays Capital U.S. Aggregate Bond Index is a market value-weighted index that tracks the daily price, coupon, pay-downs and total return performance of fixed-rate, publicly placed, dollar-denominated and non-convertible investment grade debt issues with at least $250 million par amount outstanding and with at least one year to final maturity.

•Lipper Indexes include the largest funds tracked by Lipper, Inc. in the named category. Lipper Small-Cap Core Funds Index, 30 largest small-cap core funds; Lipper Mid-Cap Growth Funds Index, 30 largest mid-cap growth funds, including Columbia Acorn Fund and Columbia Acorn Select; Lipper International Small/Mid Growth Funds Index, 10 largest non-U.S. small/mid growth funds, including Columbia Acorn International; Lipper Small-Cap Growth Funds Index, 30 largest small-cap growth funds, including Columbia Acorn USA; Lipper International Funds Index, 30 largest non-U.S. funds, excluding non-U.S. small-cap funds; Lipper Flexible Portfolio Funds Index, an equal-weighted index of the 30 largest mutual funds within the Flexible Portfolio fund classification, as defined by Lipper.

•Morgan Stanley Capital International Europe, Australasia, Far East (MSCI EAFE) Index is a capitalization-weighted index that tracks the total return of common stocks in 22 developed-market countries within Europe, Australasia and the Far East. The returns of the MSCI EAFE Index are presented net of taxes.

•Russell 2000 Index measures the performance of the 2,000 smallest companies in the Russell 3000 Index, which represents approximately 8% of the total market capitalization of the Russell 3000 Index.

•Russell 2500 Index measures the performance of the 2,500 smallest companies in the Russell 3000 Index, which represents approximately 17% of the total market capitalization of the Russell 3000 Index.

•Standard & Poor's (S&P) 500 Index tracks the performance of 500 widely held, large-capitalization U.S. stocks.

•Standard & Poor's (S&P) MidCap 400 Index is a market value-weighted index that tracks the performance of 400 mid-cap U.S. companies.

•S&P Developed Ex-U.S. Between $2B and $10B Index is a subset of the broad market selected by the index sponsor representing the mid-cap developed market, excluding the United States.

•S&P Global Ex-U.S. SmallCap Index consists of the bottom 20% of institutionally investable capital of developed and emerging countries, outside the United States. The performance of the S&P Global Ex-U.S. SmallCap Index is provided to show how Columbia Acorn International's performance compares to foreign market performance with a similar geographic distribution and wider market cap range than the Fund's primary benchmark.

•S&P Global Ex-U.S. Between $500M and $5B Index is a subset of the broad market selected by the index sponsor representing the mid- and small-cap developed and emerging markets, excluding the United States.

Unlike mutual funds, indexes are not managed and do not incur fees or expenses. It is not possible to invest directly in an index.

2

Squirrel Chatter II: The Keys to Prosperity

In 1651, Thomas Hobbes described human life as "poor, nasty, brutish and short." Today, 360 years later, humanity has achieved record levels of prosperity, safety and longevity. The United Nations estimates that poverty was reduced more in the last 50 years than the previous 500.¹ In the developing world, life expectancy rose from 44 years to 64 years from 1950 to 1999, while in the developed world, life expectancy rose from 66 years to 78 years.²

Hobbes's perspective was accurate for his time. There was very little growth in worldwide per capita GDP until about 1820; income in Europe had dropped for centuries following the decline and collapse of the Roman Empire.³ England and much of Europe were caught in a Malthusian trap, with population gyrating up and down largely due to plagues, famines and wars. But sometime around 1820, economic growth accelerated, and per capita GDP growth has averaged over 2% yearly since then, compounding into excellent gains in living standards.⁴ Why?

Four Conditions for Growth

William Bernstein's The Birth of Plenty, How Prosperity in the Modern World was Created is a fascinating history of worldwide economic circumstances. He discusses reasons for the successes and failures of many empires and countries. Bernstein believes that four institutional conditions are necessary for sustained growth: property rights and civil liberties, scientific rationalism, efficient capital markets, and fast and cheap transportation and communications. He notes that these four factors existed temporarily in sixteenth century Holland, then firmly in the English speaking countries, and in the last 50 years, increasingly over much of the world.⁵

Physical and intellectual property rights plus civil liberties create incentives and intellectual freedom to work hard, innovate and create wealth. In empires, totalitarian states and feudalistic societies, incentives to produce beyond immediate needs are nil, because governments or lords tend to impose confiscatory taxes and arbitrarily seize property. Bernstein believes that Rome fell, in part, due to excessive taxation on farmers. He also thinks that an independent judiciary is necessary to enforce property rights and civil liberties.

Scientific rationalism is needed for technological progress and innovation. Throughout history, various regimes run by church and state ossified due to the rejection of scientific observations in favor of dogma or preconceived beliefs. During medieval times, for example, astronomers who concluded the earth revolved around the sun were tortured. Bernstein cites the trial of Galileo as a turning point toward scientific rationalism. Early inventors then tended to be tinkerers rather than scientists, but science became increasingly important. For example, by the nineteenth century the steel industry had initiated the use of modern science laboratories staffed by full-time researchers.⁶

Efficient capital markets enable entrepreneurs and enterprises to raise capital at reasonable costs. I remember Jesse Jackson citing a lack of capital as a cause for inner city poverty: "Capitalism without capital is just plain ism."⁷ Bernstein notes that entrepreneurs once had huge downside risk from failures, namely debtors prisons in recent centuries and enslavement by creditors in ancient times. The creation of limited liability corporations during the nineteenth century in Britain and the United States was a breakthrough in reducing downside risks for capitalists.

Fast and cheap transportation and communication are also needed for prosperity. Bernstein explains that before railroads and the telegraph, transportation and communication were horribly expensive and slow. Rarely could bulk goods be transported over land more than 20 miles a day, and theft was rampant. Local crop failures often caused starvation. Mass markets did not exist. The reach of rail and telegraph grew incredibly rapidly during their first decades, spurring economic growth.

Bernstein provides plenty of case studies of regimes and countries that stagnated or failed due to the lack of one or more conditions, ranging from ancient societies and Japan under the samurai to Communist countries of the twentieth century. He states, "Institutions, not the bounty of nature or freedom from imperialist domination, separate the winners from the losers in the global economy."⁸

3

Trade Drives Prosperity

Matt Ridley's The Rational Optimist, How Prosperity Evolves adds substantial perspective to Bernstein's work and provides comforting thoughts about the future. Though Ridley does not mention Bernstein by name, it is clear that he agrees with Bernstein's basic contentions. Ridley sees property rights as the primary key to prosperity. He quotes a study by MIT economist Daron Acemoglu, which compared measures of property rights to economic growth across countries and determined that three-quarters of the variation of economic growth is explained by property rights.⁹ Ridley adds, "In a sample of 127 countries, the sixty-three with higher economic freedom had more than four times the income per capita and twice the growth rate of the countries that did not."¹⁰

Ridley's emphasis is on trade, which he believes allows increasing specialization, expertise, productivity and innovation. Humans seem to be hard-wired for trade. Archaeological evidence indicates that some 100,000 years ago humans began to barter.¹¹ People traded things and also absorbed ideas. Human intelligence became collective and cumulative. Ridley states that, more recently, the history of the modern world is a history of ideas meeting, mixing, mating and mutating.¹² Innovation results from an exchange of ideas. I think of the iPhone. Steve Jobs utilizes technologies and resources developed over centuries and components originated in many countries to make an incredibly inno vative and useful device.

Ridley notes that societies that halted trade regressed. After ocean levels rose 10,000 years ago and cut off Tasmania from Australia, people there gradually lost the ability to fish and make tools out of bones. European mariners discovered Tasmanians wearing nothing but wallaby pelts and seal-fat grease.¹³ As another example of a closed-off society, Ridley writes, "China went from a state of economic and technological exuberance in around AD 1000 to one of dense population, agrarian backwardness and desperate poverty in 1950;" per capita income there was about flat in those 950 years.¹⁴

Ridley takes a libertarian view, highly skeptical of government. He states, "...governments generally tend to be good things at first and bad things the longer they last. First they improve society's ability to flourish by providing central services and removing impediments to trade and specialization... But...governments gradually employ more and more ambitious elites who... give themselves more and more rules to enforce, until they kill the goose that lays the golden eggs. ... Because it is a monopoly, government brings inefficiency and stagnation to most things it runs..."¹⁵

Ridley asserts that African governments have largely caused economic problems in Africa. He writes that famines in Darfur and Zimbabwe were the result of government policies. Setting up a company in Tanzania takes 379 days and $5,500, a huge sum there. Botswana has done substantially better, growing per capita GDP nearly 8% annually since its independence in 1966. That growth exceeded China's, and is largely due to secure property rights, Ridley says. Ridley is optimistic for much of Africa, however. Cell phones are spreading rapidly, providing both communication and micro-finance (two of Bernstein's conditions for prosperity). Ridley cites wonderful examples of products and labor reaching optimal markets and payments being made over cell phones.¹⁶

Ridley has comforting thoughts about the future, debunking naysayers. He notes that (oddly enough) over time humans have temporarily exhausted or driven to extinction renewable resources like forests and certain animal species, while non-renewable resources have lasted much longer than many expected. In 1865, an economist said Britain's coal was running out, and as early as 1914 the U.S. Bureau of Mines wrote that American oil reserves would last 10 years.¹⁷

Ridley believes supplies of oil, coal and gas "will last decades, perhaps centuries, and people will find alternatives long before they run out."¹⁸ He states that prices of conventional fuels need to rise and prices of alternatives need to fall, and both will occur as conventional supplies run down and efficiencies of alternatives rise. Ridley notes that wind, solar and biomass alternatives envelop enormous quantities of land. He denounces organic farming, noting that if farm yields fell back to 1961 levels, 82% of the land area of the earth would be needed for farming, up from 38%. "The Dark Ages were a massive experiment in back-to-the-land hippy lifestyle (without the trust fund)," he says.¹⁹

4

Ridley largely dismisses climate change fears. The scenario that calls for significant climate change by the year 2100 is a scenario of dramatic economic growth. He believes the world, and especially developing countries, will be much, much richer and better able to adapt to and mitigate climate change. In the meantime, carbon intensity²⁰ of the worldwide economy is rapidly dropping, as wood, dung and coal become relatively less important and natural gas and nuclear power gain share, in an environment of substantially more efficient lighting, heating, transportation and manufacturing.

While some of Ridley's arguments seem a bit over the top, I think they generally appear coherent and largely believable. As to the climate change issue, I advocate taking reasonable steps to mitigate global warming. Most of my family's road miles are in a hybrid vehicle and both my home and Columbia Wanger Asset Management have adopted compact florescent lighting. Several years ago we calculated that replacing over 100 incandescent bulbs at the office saved enough electricity to power three average-sized homes.

I agree that prosperity is driven by the factors named by Bernstein and Ridley and, though there are imbalances in world economics, I think things will be okay. The Great Recession has ended, growth has resumed and the keys to prosperity remain in place. Many parts of the developing world are booming and we have invested accordingly. About 22% of Columbia Acorn International is invested in the developing world and many Fund investments in non-emerging market companies have some business tied to developing markets. Other Columbia Acorn Funds also own some stocks that benefit directly or indirectly from developing markets.

Charles P. McQuaid

President and Chief Investment Officer
Columbia Wanger Asset Management, LLC

The information and data provided in this analysis are derived from sources that we deem to be reliable and accurate. These views are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult to predict so actual outcomes and results may differ significantly from the views expressed. The views/opinions expressed in Squirrel Chatter II are those of the author and not of the Columbia Acorn Trust Board, are subject to change at any time based upon economic, market or other conditions, may differ from views expressed by other Columbia Management associates and the respective parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund.

The information included on Pages 3, 4 and 5 of this report is unaudited.

¹  Ridley, Matt, The Rational Optimist, How Prosperity Evolves, (New York, New York, HarperCollins 2010), p. 15.

²  Bernstein, William J., The Birth of Plenty, How the Prosperity of the Modern World was Created, (New York, New York, McGraw-Hill 2004), p. 10.

³  Ibid, p. 3.

⁴  Ibid, p. 12, 23.

⁵  Ibid, p. 15-17.

⁶  Ibid, p. 123.

⁷  Rev. Jesse Jackson quoted in an article that appeared in Ebony magazine, August 1967, titled "Apostles of Economics," p. 84.

⁸  Bernstein, William J., op. cit, p. 293.

⁹  Ridley, Matt, op. cit, p. 321.

¹⁰  Ibid, p. 117.

¹¹  Ibid, p. 350.

¹²  Ibid, p. 272.

¹³  Ibid, p. 78.

¹⁴  Ibid, p. 180.

¹⁵  Ibid, p. 182.

¹⁶  Ibid, p. 320-326.

¹⁷  Ibid, p. 237.

¹⁸  Ibid, p. 238.

¹⁹  Ibid, p. 144, 175.

²⁰  Carbon intensity is defined as the amount of CO_² produced divided by worldwide GDP.

5

Understanding Your Expenses

As a Fund shareholder, you incur two types of costs. There are transaction costs, which generally include sales charges on purchases and may include redemption or exchange fees. There are also ongoing costs, which generally include investment advisory fees and other Fund expenses. The following information is intended to help you understand your ongoing costs of investing in the Columbia Acorn Funds and to compare these costs with the ongoing costs of investing in other mutual funds.

Analyzing Your Fund's Expenses

To illustrate these ongoing costs, we have provided examples and calculated the expenses paid by investors in the Class Z shares of the Columbia Acorn Funds for the last six months. The information in the following table is based on an initial investment of $1,000, which is invested at the beginning of the reporting period and held for the entire period. Expense information is calculated two ways and each method provides you with different information. The amount listed in the "Actual" column is calculated using each Fund's actual operating expenses and total return for the period. The amount listed in the "Hypothetical" column assumes that the return each year is 5% before expenses and then applies each Fund's actual expense ratio for the period to the hypothetical return. You should not use the hypothetical account values and expenses to estimate either your actual account balance at the end of the period or the expenses you paid during the reporting period. See the "Compare With Other Funds" information for details on using the hypothetical data.

July 1, 2010 – December 31, 2010

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during the period ($)				Fund's annualized expense ratio (%)*
	Actual		Hypothetical		Actual		Hypothetical		Actual		Hypothetical		Actual
Class Z Shares
Columbia Acorn Fund		1,000.00		1,000.00		1,301.20		1,021.37		4.41		3.87		0.76
Columbia Acorn International		1,000.00		1,000.00		1,284.10		1,020.21		5.70		5.04		0.99
Columbia Acorn USA		1,000.00		1,000.00		1,313.70		1,020.06		5.95		5.19		1.02
Columbia Acorn International Select		1,000.00		1,000.00		1,265.90		1,019.31		6.68		5.96		1.17
Columbia Acorn Select		1,000.00		1,000.00		1,290.10		1,020.27		5.66		4.99		0.98
Columbia Thermostat Fund**		1,000.00		1,000.00		1,198.10		1,023.95		1.39		1.28		0.25

It is important to note that the expense amounts shown in the table are meant to highlight only ongoing costs of investing in the Funds and do not reflect any transaction costs, such as sales charges, redemption or exchange fees. Therefore, the hypothetical examples provided may not help you determine the relative total costs of owning different funds. If these transaction costs were included, your costs would have been higher.

*Expenses paid during the period are equal to each Fund's annualized expense ratio, multiplied by the average account value over the period and then multiplied by the number of days in the Fund's most recent fiscal half-year and divided by 365.

**Columbia Thermostat Fund's expenses do not include fees and expenses incurred by the Fund from the underlying portfolio funds in which it invests. Had the investment adviser and/or any of its affiliates not waived fees or reimbursed a portion of expenses, account value at the end of the period would have been reduced.

Compare With Other Funds

Since all mutual funds are required to include the same hypothetical calculations about expenses in shareholder reports, you can use this information to compare the ongoing cost of investing in the Funds with other funds. To do so, compare the 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of other funds. As you compare hypothetical examples of other funds, it is important to note that hypothetical examples are meant to highlight the continuing costs of investing in a fund and do not reflect any transaction costs, such as sales charges, or redemption or exchange fees.

6

Estimating Your Actual Expenses

To estimate the expenses that you actually paid over the period, first you will need your account balance at the end of the period:

•  For shareholders who receive their account statements from Columbia Management Investment Services Corp., your account balance is available online at columbiafunds.com or by calling Shareholder Services at (800) 922-6769.

•  For shareholders who receive their account statements from their brokerage firm, contact your brokerage firm to obtain your account balance.

1.  Divide your ending account balance by $1,000. For example, if an account balance was $8,600 at the end of the period, the result would be 8.6.

2.  In the section of the table titled "Expenses paid during the period," locate the amount for your Fund. You will find this number is in the column labeled "Actual." Multiply this number by the result from step 1. Your answer is an estimate of the expenses you paid on your account during the period.

7

Columbia Acorn Fund

In a Nutshell

Charles P. McQuaid	Robert A. Mohn
Lead Portfolio Manager	Co-Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

lululemon athletica	1.5	%
FMC Technologies	1.5	%
Ametek	1.5	%
Donaldson	1.4	%
Fugro	1.2	%
Pacific Rubiales Energy	0.9	%
Abercrombie & Fitch	0.9	%
Coach	0.6	%
Silver Wheaton	0.5	%
Southwestern Energy	0.4	%
Talbots	0.2	%

Columbia Acorn Fund rose an even 26.00% in 2010, building on its 39.65% gain achieved in 2009. We are happy to say that at year end 2010, the Fund, adjusted for distributions, was within 0.2% of its all-time high, which was achieved in October 2007, prior to the Great Recession. As shown on Page 1, Columbia Acorn Fund's gains for 2010 were a bit below its primary benchmark, the Russell 2500 Index, a bit above peer funds as represented by Lipper, and well above the large-cap S&P 500 Index. During the fourth quarter of 2010, the Fund rose 14.57%, approximately matching its benchmark and again beating the S&P 500.

Active apparel company lululemon athletica was up 125% during the year and 53% in the quarter and was the Fund's top dollar winner in both periods. Handbag designer and retailer Coach also did well, rising 53% for the year and 29% for the quarter. Both companies had excellent product offerings and fine earnings growth.

Other retail stocks held in the Fund had mixed results. Teen apparel retailer Abercrombie & Fitch jumped 68% in the year and 47% in the quarter, as it became more price-competitive and gained market share. Women's specialty apparel retailer Charming Shoppes and branded multi-channel retailer J Crew Group had disappointing results for the year, sinking 45% and 30% respectively, while Talbots, a women's retailer, was the biggest dollar loser in the quarter, dropping 35%. We sold the Fund's positions in Charming Shoppes and J Crew. We weighted consumer stocks correctly, as lululemon's dollar gains were five-times that of the largest consumer stock loser in the Fund and Abercrombie & Fitch's gains were more than twice that of the biggest loser.

Industrial stocks provided fine upside. Aerospace and industrial instrument maker Ametek measured a 55% gain during the year and 23% in the quarter, ranking in the Fund's top five dollar contributors for both periods. Filter maker Donaldson rose 39% in the year and 24% in the quarter. Both companies reported excellent earnings gains. Industrial stocks made up 18.5% of the Fund at year end.

Oil production and service stocks did very well. Oil and gas wellhead manufacturer FMC Technologies was the Fund's second largest dollar winner during the year, rising 54%, and Colombian oil producer Pacific Rubiales Energy nailed third place, gaining 130%. During the quarter, these stocks were up 30% and 21%, respectively. Holland-based sub-sea oilfield services provider Fugro jumped 48% in the year and 25% in the quarter. Natural gas related stocks, in contrast, fizzled. Oil and gas producer Southwestern Energy was off 22% during the year and was the Fund's largest dollar loser, surrendering less than one-third of FMC's gains. Believing that oil prices are likely to stay high relative to natural gas prices, we shifted some investments accordingly.

The portion of Columbia Acorn Fund's portfolio invested in foreign stocks was up 41.24% in the year and accounted for 12.6% of Fund assets at year end.* In addition to the strong international energy names mentioned above, Canada's Silver Wheaton, a company that invests in mines in exchange for favorable purchases of silver by-product, glistened with a 160% gain in the year and a 46% gain in the quarter.

Small- and mid-cap stocks outperformed larger caps in both 2009 and 2010 and are currently valued somewhat higher than large caps. Takeovers of small- and mid-cap companies are accelerating, and we believe that large companies and private capital groups have buying power and increasing confidence in the economy. Columbia Acorn Fund had 13 stocks subject to new or increased takeover offers during the year, mostly in the fourth quarter. Small- and mid-cap earnings growth was greater than large-cap earnings growth in 2010. We believe that, should takeovers and faster earnings growth continue, small- and mid-cap stocks could continue to outperform large caps.

*These returns are not comparable to mutual fund returns, as they are gross of fees and other expenses and do not portray the cash effects incurred by actual mutual funds. Columbia Acorn Fund's foreign stockholdings were not purchased as a balanced, stand-alone portfolio.

Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies. International investing involves special risks, including foreign taxation, currency risks, risks associated with possible differences in financial standards and other risks associated with future political and economic developments.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

8

Columbia Acorn Fund (ACRNX)

At a Glance

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Class Z)

through December 31, 2010

Inception 6/10/70	1 year			5 years			10 years
Returns before taxes		26.00	%		5.91	%		9.40	%
Returns after taxes on distributions		25.44			5.24			8.84
Returns after taxes on distributions and sale of fund shares		17.60			5.04			8.26
Russell 2500 Index (pretax)*		26.71			4.86			6.98

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class Z shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Columbia Acorn Fund Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn Fund Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	Crown Castle International Communications Towers	1.5	%
2.	lululemon athletica Premium Active Apparel Retailer	1.5	%
3.	FMC Technologies Oil & Gas Wellhead Manufacturer	1.5	%
4.	Ametek Aerospace/Industrial Instruments	1.5	%
5.	Donaldson Industrial Air Filtration	1.4	%
6.	Mettler Toledo Laboratory Equipment	1.3	%
7.	Informatica Enterprise Data Integration Software	1.3	%
8.	Fugro (Netherlands) Sub-sea Oilfield Services	1.2	%
9.	Amphenol Electronic Connectors	1.1	%
10.	Expeditors International of Washington International Freight Forwarder	1.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn Fund (Class Z)

June 10, 1970 through December 31, 2010

This graph compares the results of $10,000 invested in Columbia Acorn Fund at inception on June 10, 1970 to the S&P 500 Index and to an initial $31,777 investment in the Russell 2500 Index on the index's December 31, 1978 inception date. Although the indexes are provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the indexes. The indexes are unmanaged and returns for both the indexes and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder would pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $18.1 billion

*  A $10,000 investment in Columbia Acorn Fund at inception appreciated to $31,777 on December 31, 1978, the inception date of the Russell 2500 Index. For comparison with the Russell 2500 Index, we assigned the index the same value as the Fund at index inception.

**Although the Fund typically invests in small- and mid-sized companies, the comparison to the S&P 500 Index is presented to show performance against a widely recognized market index over the life of the Fund.

9

Columbia Acorn International

In a Nutshell

P. Zachary Egan	Louis J. Mendes III
Co-Portfolio Manager	Co-Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund's Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

Zhaojin Mining Industry	1.1	%
Mr. Price	0.8	%
Shandong Weigao	0.6	%
Shriram Transport Finance	0.5	%
Intralot	0.4	%
CIR	0.3	%

Columbia Acorn International finished the year up 22.70%, underperforming the 24.36% return of the S&P Global Ex-U.S. Between $500M and $5B Index, the Fund's primary benchmark. The Fund's 2010 fourth quarter return was 8.57%, versus a benchmark return of 10.58%. Smaller international stocks continued to outperform their larger-cap counterparts for the second consecutive year, and for four out of the last five years. The large-cap MSCI EAFE Index returned 7.75% in the year.

Emerging market demand continues to explain much of the ongoing rebound from 2008 in corporate earnings and stock returns around the world. While the U.S. grapples with rising budget deficits and Europeans ponder the possibility of default among one or more euro zone members, formerly troubled economies such as Thailand and Brazil now enjoy strong economic growth and corporate earnings and comparatively good public balance sheets. Indeed, as reported in the Financial Times, the World Bank calculates that domestic demand in developing economies contributed fully 46% of global growth in 2010.*

We believe this represents a significant opportunity for investors, although a highly differentiated one, as valuation and other intervening variables often stand between GDP growth and stock returns. While China, for example, continued to post high growth in 2010, its stock market (as measured by the Hang Seng China Enterprises Index) rose less than 2%. Emerging market stocks represented, in the course of the year, almost one quarter of Columbia Acorn International's assets. However, emerging market demand for goods and services provided by companies domiciled elsewhere remains a core component of the Fund's strategy, so implicit emerging market exposure is higher. With these companies we seek to access growth at either a more reasonable price or with less risk.

Unsurprisingly, emerging market stocks were among the largest contributors to positive returns in 2010. South African apparel, household and sporting goods retailer Mr. Price rose over 100% as improved merchandising and working capital levels bolstered the company's already strong fundamentals. Zhaojin Mining Industry, a Chinese gold miner, posted a similar return on the back of rising gold prices, value-accretive acquisitions, exploration on current properties, and rising production. Also in China, Shandong Weigao, a manufacturer of vertically integrated hospital consumables, rose over 70% on strong demand for medical consumables and improving results from its joint venture with Medtronic. In India, Shriram Transport Finance also increased over 70% on high growth and low defaults in its core used truck finance business.

Disappointments in 2010 included Greek lottery company Intralot, which declined nearly 40% on adverse tax developments in Bulgaria and Greece and start-up costs in the United States and Italy. A weak currency in Bulgaria further impacted earnings. Japanese retailer Point fell 30% on weak same-store sales and heavy upfront investments. We no longer hold this name in the Fund. Italian holding company CIR fell 29% as gas prices squeezed its electricity generation business.

It is notable that the U.S. dollar has fallen over 30% versus the yen, 28% versus the Swiss franc, and over 55% versus gold over the last five years. As managers, we take an agnostic view on currency, notwithstanding volatile movements and long-term uncertainties about the creditworthiness of certain countries. Instead, we consider carefully how currency movements might impact competitiveness and profitability within individual companies. And we seek to hedge out some of the risk relative to our benchmark caused by overweighting or underweighting countries or regions. Particularly in the present context of "quantitative easing" (printing money) and competitive devaluation, however, we take comfort as managers and investors in the Fund, knowing that equities confer claims on real businesses. Among the attractions of an internationally diversified equity portfolio is the possibility it offers of retaining purchasing power through economic cyc les and bouts of monetary experimentation. We believe it may prove to be an important component of a capital preservation strategy.

*Beattie, Alan, "World Bank backs efforts to counter rapid inflows," Financial Times, January 13, 2011, p. 4.

International investing involves special risks, including foreign taxation, currency risks, risks associated with possible differences in financial standards and other risks associated with future political and economic developments. Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies. Investing in emerging markets may involve greater risks than investing in more developed countries. In addition, concentration of investments in a single region may result in greater volatility.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

10

Columbia Acorn International (ACINX)

At a Glance

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Class Z)

through December 31, 2010

Inception 9/23/92	1 year			5 years			10 years
Returns before taxes		22.70	%		9.60	%		9.33	%
Returns after taxes on distributions		22.40			8.84			8.81
Returns after taxes on distributions and sale of fund shares		15.42			8.31			8.24
S&P Global Ex-U.S. Between $500M and $5B Index (pretax)*		24.36			8.19			11.75

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class Z shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Columbia Acorn International Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn International Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	Naspers (South Africa) Media in Africa, China, Russia & Other Emerging Markets	1.6	%
2.	Hexagon (Sweden) Measurement Equipment & Software	1.5	%
3.	Olam International (Singapore) Agriculture Supply Chain Manager	1.4	%
4.	Localiza Rent A Car (Brazil) Car Rental	1.2	%
5.	Kansai Paint (Japan) Paint Producer in Japan, India, China & Southeast Asia	1.2	%
6.	Imtech (Netherlands) Electromechanical & Information & Communications Technologies Installation & Maintenance	1.2	%
7.	Zhaojin Mining Industry (China) Gold Mining & Refining in China	1.1	%
8.	Fugro (Netherlands) Sub-sea Oilfield Services	1.0	%
9.	NHN (South Korea) South Korea's Largest Online Search Engine	1.0	%
10.	Advance Residence Investment (Japan) Residential REIT	1.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn International (Class Z)

September 23, 1992 through December 31, 2010

This graph compares the results of $10,000 invested in Columbia Acorn International at inception on September 23, 1992 to the S&P Global Ex-U.S. Between $500M and $5B Index. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. The index is unmanaged and returns for both the index and Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder would pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $6.1 billion

11

Columbia Acorn USA

In a Nutshell

Robert A. Mohn

Co-Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

FMC Technologies	2.6	%
Informatica	2.6	%
Ametek	2.2	%
Nordson	2.0	%
tw telecom	1.6	%
lululemon athletica	1.6	%
Atmel	1.4	%
Abercrombie & Fitch	1.4	%
Finisar	1.3	%
ITT Educational Services	0.6	%
Global Payments	0.5	%
Monolithic Power Systems	0.3	%
Talbots	0.2	%
Equinix	0.2	%

*The Lehman Brothers bankruptcy was announced on Monday, September 15, 2008. On Friday, September 12, 2008, Columbia Acorn USA's net asset value (NAV) was $24.16. On December 31, 2010, the Fund's NAV was $28.56. In 2008, the Fund's peak NAV was $28.22. As of December 31, 2010, the Fund was just 2.28% below its dividend-adjusted, all-time high, which it reached on June 4, 2007.

Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

Columbia Acorn USA ended the fourth quarter of 2010 up 16.43%, which compares to a 16.25% gain for its primary benchmark, the Russell 2000 Index. Small-cap stocks were very strong in 2010. For the annual period, the Fund was up 23.16% while its benchmark gained 26.85%. The Fund's relative annual return was hurt by poor performance of some of the Fund's positions in women's apparel stocks and small-cap semiconductor names, as well as the Fund's overweight position in the lagging telecom sector.

Several stocks in the retail, technology and industrial sectors were among the Fund's winners for the quarter and the year. lululemon athletica, a retailer of premium activewear, enjoyed blistering sales growth of 56% over the prior year, driving the Fund's investment up 53% in the fourth quarter and more than 125% for the year. Teen apparel retailer Abercrombie & Fitch grew same-store sales by 15% in December, outpacing competitors, most of whom posted negative year-over-year sales for this important retail month. The stock was up 47% in the fourth quarter and had an annual gain of 70% in the Fund.

Technology winners included Atmel, a leader in touchscreen microcontrollers, radio frequency and memory semiconductors. Its business has benefited from surging sales of smart phones and tablet computers. Atmel gained 55% in the fourth quarter and was up 130% for the Fund during the year. Finisar provides optical sub-systems and components for communications networks. The Fund's investment rose 67% in the quarter and 169% for the year as the company benefited from a surge in demand for data transmission and storage. Informatica, a data integration software provider that helps companies manage their disparate data streams, has also enjoyed strong revenue growth and Fund gains in the stock were 15% in the quarter and 70% for the year.

Two niche industrial companies rounded out the list of top contributors. Ametek, a manufacturer of aerospace and industrial instruments, gained 23% in the fourth quarter and was up 55% for the Fund during the year. Nordson, a maker of dispensing systems for adhesives and coatings, was up 25% in the quarter and 52% for the year in Columbia Acorn USA. Both companies have benefited from strong revenue growth and productivity improvements through wise expense control.

Outside these winning sectors, FMC Technologies, the largest position in the Fund at the end of 2010, was the top contributor to performance in the fourth quarter and ranked second for the year. Order flow at this oil and gas wellhead manufacturer climbed dramatically, nearly reaching pre-recession peaks. The stock was up 30% for the quarter and 54% for the year.

Laggards for the quarter included fiber optic telephone and data services provider tw telecom. Its stock fell 8% on underwhelming sales growth. Women's specialty retailer Talbots fell 35% in the quarter on declining sales. Equinix, a provider of offsite data centers for larger companies, suffered from price cutting in its sector and difficulties in integrating a recent acquisition. The stock fell 21% in the fourth quarter.

For the annual period, ITT Educational Services, a provider of post-secondary degree education, suffered as new regulatory requirements dogged the for-profit education sector, leading to declines in new enrollment. The stock was down 33% in the Fund for the year. Credit card processor Global Payments fell 14% during the annual period as a pricing war in its Canadian credit and debit processing business drove down margins. Monolithic Power Systems, a manufacturer of high performance analog and mixed-signal integrated circuits, fell 31% for the year due to pricing pressure and management's reduction of company profit margin targets.

Here are some fun facts for long-term stock investors: at the end of 2010, the S&P 500 large-cap index was higher than it was that fateful day before Lehman Brothers went bankrupt in September 2008, and so was Acorn USA; the Russell 2000 small-cap index was trading higher than at any point during the entire year of 2008, and so was Acorn USA; and the S&P 400 mid-cap index ended 2010 a mere 2% below its all-time high! And so did Acorn USA.* A stock market Rip Van Winkle waking up from his stress-free, two-year nap would find the market just as he left it. Turns out, buy and HOLD actually works quite well.

12

Columbia Acorn USA (AUSAX)

At a Glance

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Class Z)

through December 31, 2010

Inception 9/4/96	1 year			5 years			10 years
Returns before taxes		23.16	%		3.48	%		8.74	%
Returns after taxes on distributions		23.16			3.12			8.42
Returns after taxes on distributions and sale of fund shares		15.05			2.96			7.72
Russell 2000 Index (pretax)*		26.85			4.47			6.33

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class Z shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Columbia Acorn USA Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn USA Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	FMC Technologies Oil & Gas Wellhead Manufacturer	2.6	%
2.	Informatica Enterprise Data Integration Software	2.6	%
3.	Ametek Aerospace/Industrial Instruments	2.2	%
4.	Nordson Dispensing Systems for Adhesives & Coatings	2.0	%
5.	Micros Systems Information Systems for Hotels, Restaurants & Retailers	1.8	%
6.	Atwood Oceanics Offshore Drilling Contractor	1.7	%
7.	tw telecom Fiber Optic Telephone/Data Services	1.6	%
8.	Mettler Toledo Laboratory Equipment	1.6	%
9.	lululemon athletica Premium Active Apparel Retailer	1.6	%
10.	Gaylord Entertainment Convention Hotels	1.6	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn USA (Class Z)

September 4, 1996 through December 31, 2010

This graph compares the results of $10,000 invested in Columbia Acorn USA at inception on September 4, 1996 to the Russell 2000 Index. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. The index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder would pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $1.7 billion

13

Columbia Acorn International Select

In a Nutshell

Christopher J. Olson

Lead Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund's Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

Serco	4.1	%
Hexagon	4.0	%
Pacific Rubiales Energy	3.9	%
Naspers	3.5	%
Fugro	3.2	%
Pan American Silver	2.6	%
Zhaojin Mining Industry	2.6	%
United Drug	2.0	%
Cobham	1.6	%
Micro Focus	0.7	%

Columbia Acorn International Select ended the fourth quarter of 2010 up 8.09%, underperforming its primary benchmark, the S&P Developed Ex-U.S. Between $2B and $10B Index, which gained 9.75%. For the annual period, the Fund's 21.89% return topped the benchmark's 20.16% gain in what turned out to be a very strong year for the global equity markets.

Top contributors to Fund performance in the quarter and year included two names in the energy sector. Pacific Rubiales Energy, a Colombian oil exploration and development company, benefited from new oilfield discoveries. The stock was up 20% for the fourth quarter and 129% for the year in the Fund. In the Netherlands, sub-sea oilfield services provider Fugro had a 25% gain in the fourth quarter and ended the year up 48% as customers confirmed their commitment to deep water drilling and higher oil prices led to a recovery in oil industry exploration spending.

Two mining companies were among the top contributors. China's Zhaojin Mining Industry had another strong quarter, gaining 34% and ending the year up 113%. The company continued to benefit from strong production and exploration profiles and rising gold prices. In Canada, Pan American Silver, a silver miner, was up 36% for the quarter and 55% for the year. Silver prices rose 83% over the year and the company continued to move forward on two large exploration projects.

The Fund's investment in Swedish measurement equipment manufacturer Hexagon gained 15% in the quarter and ended the year up 70%. The company has been enjoying strong sales growth both in Europe and emerging markets. Naspers, a media company with assets in South Africa, China and other emerging markets, was up 20% for the quarter and 48% for the year. Results in the company's underlying businesses remained strong, driven by increasing levels of Internet usage throughout its emerging market Internet holdings.

Underperformers in the quarter included UK facilities management company Serco, down 11% on concerns the government austerity program in the United Kingdom would reduce its sales growth. Irish pharmaceutical wholesaler United Drug was off 15% in the quarter on Irish budgetary concerns and worries over the impact cuts could have on the domestic economy. Cobham, a UK manufacturer of aerospace components, was down 10% in the quarter and also ranked among the worst performers for the year, with an annual decline of 17%, as the uncertainty regarding U.S. and UK defense budget cuts delayed sales. Other laggards for the year included MegaStudy, a South Korean provider of online education services that fell 33% after the government moved to subsidize its publicly run competitors. We sold the Fund's position in MegaStudy in the second quarter of 2010. Micro Focus, a UK legacy software provider, had an annual loss of 26% on news of the departure of t he company's CFO and a revenue growth downgrade.

International investing involves special risks, including foreign taxation, currency risks, risks associated with possible differences in financial standards and other risks associated with future political and economic developments. Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies. Investing in emerging markets may involve greater risks than investing in more developed countries.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

14

Columbia Acorn International Select (ACFFX)

At a Glance

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Class Z)

through December 31, 2010

Inception 11/23/98	1 year			5 years			10 years
Returns before taxes		21.89	%		9.04	%		6.63	%
Returns after taxes on distributions		21.70			8.72			6.47
Returns after taxes on distributions and sale of fund shares		14.62			7.89			5.87
S&P Developed Ex-U.S. Between $2B and $10B Index (pretax)*		20.16			4.95			8.22

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class Z shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Columbia Acorn International Select Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn International Select Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	Kansai Paint (Japan) Paint Producer in Japan, India, China & Southeast Asia	4.1	%
2.	Serco (United Kingdom) Facilities Management	4.1	%
3.	Hexagon (Sweden) Measurement Equipment & Software	4.0	%
4.	Pacific Rubiales Energy (Colombia) Oil Production & Exploration in Colombia	3.9	%
5.	NHN (South Korea) South Korea's Largest Online Search Engine	3.9	%
6.	Ascendas REIT (Singapore) Singapore Industrial Property Landlord	3.8	%
7.	Jiangsu Expressway (China) Chinese Toll Road Operator	3.7	%
8.	Naspers (South Africa) Media in Africa, China, Russia & Other Emerging Markets	3.5	%
9.	Fugro (Netherlands) Sub-sea Oilfield Services	3.2	%
10.	UGL (Australia) Engineering & Facilities Management	3.1	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn International Select (Class Z)

November 23, 1998 through December 31, 2010

This graph compares the results of $10,000 invested in Columbia Acorn International Select at inception on November 23, 1998 to the S&P Developed Ex-U.S. Between $2B and $10B Index. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. The index and Fund returns include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder would pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $452.7 million

15

Columbia Acorn Select

In a Nutshell

Ben Andrews

Lead Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund's Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

Pacific Rubiales Energy	6.8	%
ITT Educational Services	2.8	%
Canacol Energy	2.5	%
ShaMaran Petroleum	2.2	%
Canadian Solar	1.7	%
Career Education	1.7	%
Union Agriculture Group	0.9	%
Kirkland Lake Gold	0.7	%

Columbia Acorn Select gained 14.05% in the fourth quarter of 2010. This exceeded the 13.50% rise in the Fund's primary benchmark, the S&P MidCap 400 Index. For the year, the Fund was up 22.88%, underperforming the 26.64% gain of its benchmark, as we were not able to completely offset the relative lag from earlier in the year. The Fund handily beat the large-cap S&P 500 Index's 10.76% fourth quarter gain and its 15.06% return for the full year.

Our investments in the oil industry helped the portfolio greatly, not so much because the price of oil went up 15% a barrel in 2010, but because the oil companies we owned were successful at finding oil, which was our thesis for making the investments. Over the past three years, we've focused on Colombia and the area known as Kurdistan in northern Iraq. Fund investments in Colombia have been a multi-year success for the portfolio, with Pacific Rubiales Energy, an oil exploration and development company, and Canacol Energy, an oil production company, together adding 8.80% to performance in 2010. The improved security provided by government forces has allowed small petroleum companies in Colombia to look more broadly for oil for the first time in more than 20 years. The fall of Saddam Hussein in Iraq allowed the Kurds to open up their semi-autonomous region within Iraq to outside investment. ShaMaran Petroleum, a company that cobbled together several exploration blocks in Kurdistan, found oil this year and its stock added 1.90% to our portfolio for the year.

On the downside, Fund investments in for-profit, post-secondary education companies ITT Educational Services and Career Education hurt returns. We've been investors in for-profit education stocks for a long time. We are believers in this industry as its student placement rates, and the career earnings of its graduates, have always been consistent and strong. We believe that many of these schools will continue to provide the same benefits for their students and make a solid profit, even if proposed "gainful employment standards" are implemented by the U.S. Department of Education. We did decrease the Fund's exposure to this sector upon realizing the negative impact that this proposed legislation could have. We intend to watch the for-profit education industry to see whether solid student and earnings growth return under the new standards and to evaluate the Fund's investments in the industry.

Canadian Solar, a solar cell and module manufacturer based in China, cost the portfolio 2.02% for the year. Solar panel pricing has been erratic as the industry is often in over supply or under supply due to its reliance on government subsidies. We invested in one of the low-cost producers of solar panels, believing that the industry is close to standing on its own two feet without big subsidies, which should fuel growth. While Canadian Solar is becoming one of the main players in the solar industry, the sector needs to improve for its stock to benefit.

During the fourth quarter of 2010, we sold out of seven companies and purchased eight new names. We made our first investments in the precious metals and farmland industries. We purchased Kirkland Lake Gold, a Canadian gold mining company that is expanding existing operations to increase production, and Union Agriculture Group, a farmland operator in Uruguay.

I'm relieved that the expiring income tax cuts were extended for another two years and I believe that the 2% cut in payroll taxes is another positive. My hope is that consumers continue to repair their balance sheets and the government starts to cut spending! Overall, I'm optimistic as a slow economic recovery is evident, but stock market valuations are not cheap, so caution is in order.

Risks include stock market fluctuations due to economic and business developments. The Fund also has potentially greater price volatility due to the Fund's concentration in a limited number of stocks of mid-size companies. The Fund is a non-diversified fund and may, therefore, have a greater risk of loss from a few issuers than a similar fund that invests more broadly. The Fund may not operate as a non-diversified fund at all times. International investments involve greater potential risks, including less regulation, currency fluctuations, economic instability and political developments.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

16

Columbia Acorn Select (ACTWX)

At a Glance

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Class Z)

through December 31, 2010

Inception 11/23/98	1 year			5 years			10 years
Returns before taxes		22.88	%		6.28	%		8.79	%
Returns after taxes on distributions		22.88			6.05			8.57
Returns after taxes on distributions and sale of fund shares		14.87			5.41			7.78
S&P MidCap 400 Index (pretax)*		26.64			5.74			7.16

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class Z shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Columbia Acorn Select Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn Select Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	Pacific Rubiales Energy (Colombia) Oil Production & Exploration in Colombia	6.8	%
2.	Hertz Largest U.S. Rental Car Operator	5.5	%
3.	Discover Financial Services Credit Card Company	4.2	%
4.	Abercrombie & Fitch Teen Apparel Retailer	4.0	%
5.	Safeway Supermarkets	3.7	%
6.	CNO Financial Group Life, Long-term Care & Medical Supplement Insurance	3.7	%
7.	Sanmina-SCI Electronic Manufacturing Services	3.6	%
8.	Ametek Aerospace/Industrial Instruments	3.2	%
9.	Crown Castle International Communications Towers	3.0	%
10.	ITT Educational Services Post-secondary Degree Services	2.8	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn Select (Class Z)

November 23, 1998 through December 31, 2010

This graph compares the results of $10,000 invested in Columbia Acorn Select at inception on November 23, 1998 to the S&P MidCap 400 Index. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings differ significantly from those in the index. The index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder would pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $2.3 billion

17

Columbia Thermostat Fund

In a Nutshell

Charles P. McQuaid

Lead Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

A "fund of fund" bears its allocable share of the costs and expenses of the underlying funds in which it invests. Such funds are thus subject to two levels of fees and potentially higher expense ratios than would be associated with a fund that invests and trades directly in financial instruments under the direction of a single manager.

Columbia Thermostat Fund gained 7.37% in the fourth quarter of 2010, compared to a 10.76% gain of its primary equity benchmark, the S&P 500 Index, and a 1.30% drop of the Fund's primary debt benchmark, the Barclays Capital U.S. Aggregate Bond Index. For the annual period, the Fund's 17.58% gain beat a 15.06% return for the large-cap S&P 500 and the 6.54% gain of the Barclays index.

Selling stock funds on the strength of the equity markets, we made three reallocations during the fourth quarter into bond funds. At the end of the period, the Fund had a 60% exposure to its underlying stock funds and 40% exposure to its underlying bond funds.

The Fund's equity positions had returns ranging from 14.57% (Columbia Acorn Fund) to 8.39% (Columbia Dividend Income Fund) in the quarter. Similarly, for the annual period, Columbia Acorn Fund's 26.00% gain was at the top while Columbia Dividend Income Fund's 13.02% was the lowest.

On the bond side, Columbia Conservative High Yield Fund posted the only gain among the underlying bond funds for the fourth quarter, up 2.14%. For the annual period, the weighted average income return was 8.28%, less than half that of the equity portion, which had a 19.18% weighted average annual gain.

Given its structure and investment objective, one would expect Columbia Thermostat Fund's returns to fall between its debt and equity benchmarks. That was not the case in 2010 as Fund performance topped both benchmarks. We attribute this to good selection of underlying funds and to the stock market trading in a range that was optimal for the Fund's rebalancing points during much of the year. As you may recall, we added to the Fund's international equity exposure earlier this year while reducing large-cap domestic equity weights. Our domestic mid-cap and international emphasis boosted the Fund's performance.

Results of the Funds Owned in Columbia Thermostat Fund as of December 31, 2010

Stock Funds	Weightings			4th
Fund	in category			quarter			1 year
Columbia Acorn International		20	%		8.57	%		22.70	%
Columbia Dividend Income Fund		20	%		8.39	%		13.02	%
Columbia Acorn Fund		15	%		14.57	%		26.00	%
Columbia Marsico Growth Fund		15	%		13.93	%		19.74	%
Columbia Acorn Select		10	%		14.05	%		22.88	%
Columbia Contrarian Core Fund		10	%		13.56	%		16.21	%
Columbia Large Cap Enhanced Core Fund		10	%		9.89	%		13.32	%
Weighted Average Equity Return		100	%		11.42	%		19.18	%
Bond Funds	Weightings			4th
Fund	in category			quarter			1 year
Columbia Intermediate Bond Fund		50	%		-0.57	%		7.91	%
Columbia U.S. Treasury Index Fund		30	%		-2.56	%		5.67	%
Columbia Conservative High Yield Fund		20	%		2.14	%		13.00	%
Weighted Average Income Return/Loss		100	%		-0.61	%		8.28	%

Columbia Thermostat Fund
Rebalancing in the Fourth Quarter

October 6, 2010	70% stocks, 30% bonds
November 5, 2010	65% stocks, 35% bonds
December 22, 2010	60% stocks, 40% bonds

The value of an investment in the Fund is based primarily on the performance of the underlying portfolio funds and the allocation of the Fund's assets among them. An investment in the underlying portfolio funds may present certain risks, including stock market fluctuations that occur in response to economic and business developments; and a greater degree of social, political and economic volatility associated with international investing. Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies. Value stocks may also be subject to specific business risks that have caused the stocks to be out of favor. Lower-rated and medium quality debt securities are more speculative and incur more risk. International investing involves special risks, including foreign taxation, currency risks, risks associated with possible differences in fin ancial standards and other risks associated with future political and economic developments. Changes in interest rates and changes in the financial strength of issuers of lower-rated bonds may also affect underlying fund performance. The Fund is also subject to the risk that the investment adviser's decisions regarding asset classes and underlying portfolio funds will not anticipate market trends successfully, resulting in a failure to preserve capital or lower total return. In addition, the Fund may buy and sell shares of the portfolio funds frequently. This may result in higher transaction costs and additional tax liability. This is not an offer of the shares of any other mutual fund mentioned herein.

18

Columbia Thermostat Fund (COTZX)

At a Glance

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Class Z)

through December 31, 2010

Inception 9/25/02	1 year			5 year			Life of fund
Returns before taxes		17.58	%		5.38	%		7.84	%
Returns after taxes on distributions		17.22			4.04			6.57
Returns after taxes on distributions and sale of fund shares		11.82			4.01			6.26
S&P 500 Index (pretax)*		15.06			2.29			7.44
Barclays Capital U.S. Aggregate Bond Index (pretax)*		6.54			5.80			5.03
Lipper Flexible Portfolio Funds Index (pretax)		12.91			4.75			8.15

All results shown assume reinvestment of distributions.

*The Fund's primary stock and bond benchmarks, respectively.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class Z shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Columbia Thermostat Fund Asset Allocation

as a percentage of net assets, as of 12/31/10

Columbia Thermostat Fund Portfolio Weightings

as a percentage of assets in each investment category, as of 12/31/10

Stock Mutual Funds

Columbia Acorn International, Class I	20	%
Columbia Dividend Income Fund, Class I	20	%
Columbia Acorn Fund, Class I	15	%
Columbia Marsico Growth Fund, Class I	15	%
Columbia Acorn Select, Class I	10	%
Columbia Contrarian Core Fund, Class I	10	%
Columbia Large Cap Enhanced Core Fund, Class I	10	%

Bond Mutual Funds

Columbia Intermediate Bond Fund, Class I	50	%
Columbia U.S. Treasury Index Fund, Class I	30	%
Columbia Conservative High Yield Fund, Class Z	20	%

The Growth of a $10,000 Investment in Columbia Thermostat Fund (Class Z)

September 25, 2002 through December 31, 2010

This graph compares the results of $10,000 invested in Columbia Thermostat Fund at inception on September 25, 2002 to the S&P 500 Index, the Barclays Capital U.S. Aggregate Bond Index and the Lipper Flexible Portfolio Funds Index. Although the indexes are provided for use in assessing the Fund's performance, the Fund's holdings differ significantly from those in the indexes. The Indexes are unmanaged and returns for the indexes and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder would pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $131.3 million

19

Columbia Acorn Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Information
AboveNet		1,100,000		1,200,000
Applied Micro Circuits		0		1,650,000
Ariba		0		500,000
Concur Technologies		1,035,000		1,480,000
IMAX (Canada)		0		800,000
Infinera		800,000		1,925,000
IPG Photonics		2,600,000		2,710,000
Ixia		681,003		1,470,000
Mail.ru - GDR (Russia)		0		464,305
Microsemi		2,085,000		2,345,000
Netgear		1,100,000		1,200,000
Plexus		1,677,807		1,790,000
Polycom		1,745,000		1,955,000
SPS Commerce		0		856,429
Trimble Navigation		1,545,000		1,935,000
Verisk Analytics		0		450,000
WMS Industries		790,000		1,050,000
Industrial Goods & Services
Albany International		1,000,000		1,100,000
Arcadis (Netherlands)		261,990		626,524
FMC Corp.		0		300,000
GrafTech International		1,980,000		2,340,000
Marel (Iceland)		0		10,000,000
Neopost (France)		205,000		280,000
Oshkosh		2,608,607		3,650,000
St. Joe		0		500,000
Ushio (Japan)		1,000,000		1,134,100
Consumer Goods & Services
Bravo Brio Restaurant Group		0		367,900
Career Education		2,600,000		2,800,000
Cheesecake Factory		330,000		450,000
Crocs		800,000		1,400,000
Deckers Outdoor		0		1,120,000
Diamond Foods		810,000		1,300,000
DSW		403,700		525,000
Guess?		0		1,550,000
Hanesbrands		250,000		700,000
Lance		0		240,000
Lifetime Fitness		1,960,000		2,190,000
Localiza Rent A Car (Brazil)		1,100,000		2,000,000
Melco Crown Entertainment - ADR (Hong Kong)		0		3,000,000
Phillips-Van Heusen		500,000		1,055,000
Shutterfly		1,531,492		1,700,000
Steven Madden		0		400,000
Tesla Motors		294,000		400,000
The Fresh Market		0		66,000
Warnaco Group		612,972		2,190,000

	Number of Shares
	09/30/10		12/31/10
Energy & Minerals
Alange Energy (Colombia)		12,100,000		17,100,000
Augusta Resource		0		800,000
Canadian Overseas Petroleum (United Kingdom)		0		2,520,000
Canadian Overseas Petroleum - Subscription Receipts (United Kingdom)		0		5,880,000
Duluth Metals (Canada)		2,800,000		3,154,000
Mongolian Mining (Hong Kong)		0		5,215,500
Oil States International		0		200,000
Petroamerica (Colombia)		13,000,000		30,275,000
STR Holdings		400,000		500,000
Swift Energy		0		275,000
Union Agriculture Group (Argentina)		0		6,818,182
Finance
Alliance Data Systems		0		140,000
Associated Banc-Corp		5,063,800		5,413,800
Brown & Brown		0		900,000
First Busey		1,614,507		3,299,507
Hanover Insurance Group		1,230,000		1,320,000
Tower Group		900,000		1,225,000
TriCo Bancshares		1,136,175		1,350,000
Whitney Holding		2,200,000		4,000,000
Health Care
Akorn		759,718		2,659,068
Alimera Sciences		0		361,450
Allos Therapeutics		5,981,889		7,035,000
BioMarin Pharmaceutical		3,205,000		3,920,421
Chelsea Therapeutics		2,649,300		3,449,900
Community Health Systems		0		1,300,000
Health Management Associates		0		2,650,000
Idenix Pharmaceuticals		2,800,000		3,340,255
InterMune		0		1,088,500
Isis Pharmaceuticals		2,350,000		4,500,000
Micromet		3,500,000		5,500,000
Nabi Biopharmaceuticals		0		1,383,454
Neogen		0		77,602
Onyx Pharmaceuticals		900,000		1,200,000
Pacific Biosciences of California		0		932,768
Patterson Companies		0		1,100,000
Seattle Genetics		4,114,900		4,180,918
Sirona Dental Systems		1,500,000		1,800,000
United Therapeutics		860,000		1,110,000
Other Industries
Associated Estates Realty		1,500,000		2,200,000
Dupont Fabros Technology		1,300,000		1,935,579

See accompanying notes to financial statements.

20

	Number of Shares
	09/30/10		12/31/10
Purchases (continued)
Other Industries—continued
Federal Realty Investment Trust		480,000		641,165
Mapletree Logistics Trust (Singapore)		40,000,000		43,201,999
Post Properties		0		367,240
Rush Enterprises, Class A		2,500,000		2,800,000
Rush Enterprises, Class B		500,000		550,000

	Number of Shares
	09/30/10		12/31/10
Sales
Information
Actuate		3,700,000		1,500,000
Akamai		440,000		0
Avid Technology		700,000		0
Cogent Communications		3,400,000		2,800,000
CommScope		1,045,000		0
Finisar		1,875,000		1,725,000
Hong Kong Exchanges and Clearing (Hong Kong)		1,790,000		750,000
iGate		5,000,000		2,913,065
Mediacom Communications		3,000,000		0
Singapore Exchange (Singapore)		8,000,000		5,000,000
SRA International		1,780,893		1,655,000
Industrial Goods & Services
Mine Safety Appliances		1,687,699		1,525,000
Republic Services		1,500,000		1,000,000
Ritchie Brothers Auctioneers		687,500		0
Serco (United Kingdom)		2,900,000		2,559,000
Watsco		250,000		100,000
Consumer Goods & Services
Charming Shoppes		5,717,981		0
Chico's FAS		4,762,000		2,562,000
Coldwater Creek		4,773,374		1,384,597
Dress Barn		1,175,000		0
Expedia		4,500,000		3,900,000
Express		1,345,000		0
Flowers Foods		819,000		0
G-III Apparel Group		260,260		0
J Crew Group		1,784,000		0
Jones Apparel Group		2,025,000		0
lululemon athletica		4,135,000		4,035,000
P.F. Chang's China Bistro		370,000		300,000
Penn National Gaming		1,750,000		1,590,000
Pier 1 Imports		5,700,000		5,600,000
Pinnacle Entertainment		4,050,000		3,400,000
Princeton Review		2,970,000		2,000,000
Rue21		517,696		0
Smart Balance		2,000,000		0
Talbots		4,900,000		4,150,000
True Religion Apparel		2,397,000		2,047,000
Urban Outfitters		2,009,700		1,180,000
Vail Resorts		1,450,000		1,250,000
Wet Seal		4,815,600		0
Energy & Minerals
Core Laboratories (Netherlands)		696,000		641,000
Horizon North Logistics (Canada)		2,953,900		2,890,900
Oceaneering International		275,000		0

See accompanying notes to financial statements.

21

Columbia Acorn Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited), continued

	Number of Shares
	09/30/10		12/31/10
Sales (continued)
Energy & Minerals—continued
Silver Wheaton (Canada)		2,450,000		2,250,000
Southwestern Energy		2,160,000		1,800,000
Finance
Aspen Insurance		1,000,000		390,919
Assurant		700,000		121,342
Delphi Financial Group		1,450,000		1,000,000
H&E Equipment Services		3,033,300		3,000,000
Housing Development Finance (India)		1,625,000		1,300,000
Markel		100,000		0
Health Care
Acorda Therapeutics		1,550,000		900,000
Alexion Pharmaceuticals		2,800,000		2,100,000
Amylin Pharmaceuticals		1,550,000		0
Cepheid		3,350,000		2,415,000
Human Genome Sciences		1,100,000		0
ICU Medical		850,000		42,278
Illumina		1,100,000		506,000
Nanosphere		1,500,000		1,480,056
Nektar Therapeutics		3,300,000		2,700,000
Owens & Minor		600,000		200,000
PSS World Medical		3,300,000		0
QIAGEN (Netherlands)		1,435,000		0
Vermillion		694,849		0
Other Industries
American Commercial Lines		602,000		0
JB Hunt Transport Services		1,980,000		1,850,000
Macerich		752,161		530,000
Terna (Italy)		5,833,000		3,333,000

See accompanying notes to financial statements.

22

Columbia Acorn Fund

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 97.2%
Information 26.9%
		> Business Software 6.2%
	5,200,000	Informatica (a)(b)	$	228,956
		Enterprise Data Integration Software
	2,700,000	Micros Systems (a)		118,422
		Information Systems for Hotels, Restaurants & Retailers
	2,100,000	ANSYS (a)		109,347
		Simulation Software for Engineers & Designers
	1,480,000	Concur Technologies (a)		76,856
		Web Enabled Cost & Expense Management Software
	1,100,000	Quality Systems (c)		76,802
		IT Systems for Medical Groups & Ambulatory Care Centers
	12,500,000	Novell (a)		74,000
		Directory, Operating System & Identity Management Software
	2,250,000	Blackbaud (b)		58,275
		Software & Services for Non-profits
	9,000,000	Art Technology Group (a)(b)		53,820
		Software & Tools to Optimize Websites for E-Commerce
	1,800,000	NetSuite (a)		45,000
		End to End IT Systems Solutions Delivered Over the Web
	2,025,000	Kenexa (a)(b)		44,125
		Recruiting & Workforce Management Solutions
	1,400,000	Constant Contact (a)(c)		43,386
		E-mail & Other Marketing Campaign Management Systems Delivered Over the Web
	2,000,000	Tyler Technologies (a)(b)		41,520
		Financial, Tax, Court & Document Management Systems for Local Governments
	850,000	Red Hat (a)		38,803
		Maintenance & Support for Open Source & Middleware
	700,000	Blackboard (a)(c)		28,910
		Education Software
	920,000	Jack Henry & Associates		26,818
		Systems Financial Institutions
	345,000	Advent Software (a)(c)		19,982
		Asset Management & Trading Systems
	856,429	SPS Commerce (a)(b)		13,532
		Supply Chain Management Software Delivered via the Web
	500,000	Ariba (a)		11,745
		Cost Management Software
	1,500,000	Actuate (a)		8,550
		Information Delivery Software & Solutions
	1,000,000	InContact (a)		3,300
		Call Center Systems Delivered via the Web & Telecommunications Services
				1,122,149

Number of Shares			Value (000)
		> Instrumentation 3.3%
	1,600,000	Mettler Toledo (a)	$	241,936
		Laboratory Equipment
	5,915,000	Hexagon (Sweden) (c)		126,861
		Measurement Equipment & Software
	2,710,000	IPG Photonics (a)(b)		85,690
		Fiber Lasers
	1,935,000	Trimble Navigation (a)		77,265
		GPS-based Instruments
	300,000	Dionex (a)		35,403
		Ion & Liquid Chromatography
	600,000	FLIR Systems (a)		17,850
		Infrared Cameras
	400,000	Hamamatsu Photonics (Japan)		14,612
		Optical Sensors for Medical & Industrial Applications
				599,617
		> Computer Hardware & Related Equipment 2.9%
	3,750,000	Amphenol		197,925
		Electronic Connectors
	2,225,000	II-VI (a)(b)		103,151
		Laser Optics & Specialty Materials
	1,140,000	Dolby Laboratories (a)		76,038
		Audio Technology for Consumer Electronics
	1,605,000	Zebra Technologies (a)		60,974
		Bar Code Printers
	1,200,000	Netgear (a)		40,416
		Networking Products for Small Business & Home
	800,000	Nice Systems - ADR (Israel) (a)		27,920
		Audio & Video Recording Solutions
	605,000	Stratasys (a)(c)		19,747
		Rapid Prototyping Systems
				526,171
		> Mobile Communications 2.3%
	6,300,000	Crown Castle International (a)		276,129
		Communications Towers
	3,150,000	SBA Communications (a)		128,961
		Communications Towers
	1,000,000	MetroPCS Communications (a)		12,630
		Discount Cellular Telephone Services
	1,500,000	Globalstar (a)(c)		2,175
		Satellite Mobile Voice & Data Carrier
				419,895
		> Telecommunications Equipment 1.9%
	1,045,000	F5 Networks (a)		136,017
		Internet Traffic Management Equipment
	1,955,000	Polycom (a)		76,206
		Video Conferencing Equipment
	1,725,000	Finisar (a)		51,215
		Optical Sub-systems & Components
	1,260,000	Blue Coat Systems (a)		37,636
		WAN Acceleration & Network Security
	1,470,000	Ixia (a)		24,667
		Telecom Network Test Equipment
	1,925,000	Infinera (a)		19,885
		Optical Networking Equipment
				345,626

See accompanying notes to financial statements.

23

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Semiconductors & Related Equipment 1.9%
	7,470,000	Atmel (a)	$	92,030
		Microcontrollers, Radio Frequency & Memory Semiconductors
	2,345,000	Microsemi (a)		53,701
		Analog/Mixed-signal Semiconductors
	3,440,000	ON Semiconductor (a)		33,987
		Mixed-signal & Power Management Semiconductors
	4,500,000	Entegris (a)		33,615
		Semiconductor Materials Management Products
	1,035,000	Supertex (a)(b)		25,026
		Analog/Mixed-signal Semiconductors
	500,000	Littelfuse		23,530
		Little Fuses
	1,900,000	IXYS (a)(b)		22,078
		Power Semiconductors
	1,765,000	Pericom Semiconductor (a)(b)		19,380
		Interface Integrated Circuits (ICs) & Frequency Control Products
	1,650,000	Applied Micro Circuits (a)		17,622
		Communications Semiconductors
	800,000	Monolithic Power Systems (a)		13,216
		High Performance Analog & Mixed-signal Integrated Circuits (ICs)
				334,185
		> Telephone and Data Services 1.8%
	9,500,000	tw telecom (a)(b)		161,975
		Fiber Optic Telephone/Data Services
	1,200,000	AboveNet		70,152
		Metropolitan Fiber Communications Services
	2,800,000	Cogent Communications (a)(b)		39,592
		Internet Data Pipelines
	9,600,000	PAETEC Holding (a)(b)		35,904
		Telephone/Data Services for Business
	2,000,000	General Communications (a)		25,320
		Commercial Communications & Consumer CATV, Web & Phone in Alaska
				332,943
		> Gaming Equipment & Services 1.1%
	3,725,000	Bally Technologies (a)(b)		157,158
		Slot Machines & Software
	1,050,000	WMS Industries (a)		47,502
		Slot Machine Provider
				204,660
		> Computer Services 1.1%
	2,913,065	iGate (b)		57,416
		IT & BPO (Business Process Outsourcing) Services
	1,655,000	SRA International (a)		33,845
		Government IT Services
	2,000,000	Virtusa (a)(b)		32,720
		Offshore IT Outsourcing
	1,560,000	Acxiom (a)		26,754
		Database Marketing Services
	1,045,000	ExlService Holdings (a)		22,447
		BPO (Business Process Outsourcing)

Number of Shares			Value (000)
	4,500,000	Hackett Group (a)(b)	$	15,795
		IT Integration & Best Practice Research
	1,000,000	WNS - ADR (India) (a)		11,570
		Offshore BPO (Business Process Outsourcing) Services
				200,547
		> CATV 1.0%
	3,000,000	Discovery Communications, Series C (a)		110,070
		Cable TV Programming
	1,250,000	Liberty Global, Series A (a)(c)		44,225
		Cable TV Franchises Outside the USA
	17,770	Jupiter Telecommunications (Japan)		18,691
		Largest Cable Service Provider in Japan
				172,986
		> Financial Processors 0.9%
	2,429,000	Global Payments		112,244
		Credit Card Processor
	5,000,000	Singapore Exchange (Singapore)		32,805
		Singapore Equity & Derivatives Market Operator
	750,000	Hong Kong Exchanges and Clearing (Hong Kong)		17,011
		Hong Kong Equity & Derivatives Market Operator
				162,060
		> Internet Related 0.6%
	188,000	NHN (South Korea) (a)		37,514
		South Korea's Largest Online Search Engine
	435,000	Equinix (a)		35,348
		Network Neutral Data Centers
	464,305	Mail.ru - GDR (Russia) (a)(d)		16,715
		Internet Social Networking & Games for Russian Speakers
	1,000,000	Terremark Worldwide (a)		12,950
		Data Center Colocation & IT Managed Services Provider
	1,000,000	TheStreet.com		2,670
		Financial Information Websites
				105,197
		> Electronics Distribution 0.6%
	3,125,000	Avnet (a)		103,219
		Electronic Components Distribution
				103,219
		> Contract Manufacturing 0.5%
	1,790,000	Plexus (a)		55,383
		Electronic Manufacturing Services
	2,800,000	Sanmina-SCI (a)		32,144
		Electronic Manufacturing Services
				87,527
		> Business Information & Marketing Services 0.4%
	900,000	FTI Consulting (a)		33,552
		Financial Consulting Firm
	3,100,000	Navigant Consulting (a)(b)		28,520
		Financial Consulting Firm
	450,000	Verisk Analytics (a)		15,336
		Risk & Decision Analytics
				77,408

See accompanying notes to financial statements.

24

Number of Shares			Value (000)
		> Entertainment Programming 0.1%
	800,000	IMAX (Canada) (a)	$	22,440
		IMAX Movies, Theatre Equipment & Theatre Joint Ventures
				22,440
		> Consumer Software 0.1%
	3,567,000	THQ (a)(b)		21,616
		Entertainment Software
				21,616
		> Radio 0.1%
	1,541,000	Salem Communications (b)		4,885
		Radio Stations for Religious Programming
	164,991	Saga Communications (a)		4,343
		Radio Stations in Small & Mid-sized Cities
	2,400,000	Spanish Broadcasting System (a)(b)		1,699
		Spanish Language Radio Stations
				10,927
		> TV Broadcasting 0.1%
	2,500,000	Entravision Communications (a)		6,425
		Spanish Language TV & Radio Stations
	1,750,000	Gray Television (a)		3,272
		Mid-market Affiliated TV Stations
				9,697
		> Advertising —%
	1,500,000	VisionChina Media - ADR (China) (a)(c)		6,960
		Advertising on Digital Screens in China's Mass Transit System
				6,960
Information: Total				4,865,830
Industrial Goods & Services 18.5%
		> Machinery 9.6%
	6,750,000	Ametek		264,937
		Aerospace/Industrial Instruments
	4,200,000	Donaldson (b)		244,776
		Industrial Air Filtration
	1,500,000	Nordson		137,820
		Dispensing Systems for Adhesives & Coatings
	3,650,000	Oshkosh (a)		128,626
		Specialty Truck Manufacturer
	3,100,000	Pentair		113,181
		Pumps & Water Treatment
	2,565,000	Clarcor (b)		110,013
		Mobile & Industrial Filters
	2,375,000	Kennametal		93,718
		Consumable Cutting Tools
	1,800,000	Pall		89,244
		Filtration & Fluids Clarification
	2,200,000	ESCO Technologies (b)		83,248
		Automatic Electric Meter Readers
	1,820,000	MOOG (a)		72,436
		Motion Control Products for Aerospace, Defense & Industrial Markets
	1,150,000	WABCO Holdings (a)		70,070
		Truck & Bus Component Supplier

Number of Shares			Value (000)
	1,700,000	HEICO	$	63,444
		FAA Approved Aircraft Replacement Parts
	1,300,000	Kaydon		52,936
		Specialized Friction & Motion Control Products
	805,000	Toro		49,620
		Turf Maintenance Equipment
	1,525,000	Mine Safety Appliances		47,473
		Safety Equipment
	600,000	Wabtec		31,734
		Freight & Transit Component Supplier
	1,600,000	Generac (a)		25,872
		Stand-by Power Generators
	280,000	Neopost (France)		24,395
		Postage Meter Machines
	3,500,000	Jain Irrigation Systems (India)		16,484
		Agricultural Micro-irrigation Systems & Food Processing
	10,000,000	Marel (Iceland) (a)		8,713
		Largest Manufacturer of Poultry & Fish Processing Equipment
	1,250,000	Spartan Motors		7,613
		Specialty Truck & Chassis Manufacturer
				1,736,353
		> Industrial Materials & Specialty Chemicals 2.7%
	1,750,000	Sociedad Quimica y Minera de Chile - ADR (Chile)		102,235
		Producer of Specialty Fertilizers, Lithium & Iodine
	1,530,000	Albemarle		85,343
		Refinery Catalysts & Other Specialty Chemicals
	1,800,000	Nalco Holding Company		57,492
		Provider of Water Treatment & Process Chemicals & Services
	340,000	Novozymes (Denmark)		47,377
		Industrial Enzymes
	753,000	Mersen (France)		34,514
		Advanced Industrial Materials
	1,260,000	Drew Industries (b)		28,627
		RV & Manufactured Home Components
	1,100,000	Albany International		26,059
		Paper Machine Clothing & Advanced Textiles
	300,000	FMC Corp.		23,967
		Niche Specialty Chemicals
	350,000	Greif		21,665
		Industrial Packaging
	2,200,000	Kansai Paint (Japan)		21,286
		Paint Producer in Japan, India, China & Southeast Asia
	9,000	Sika (Switzerland)		19,752
		Chemicals for Construction & Industrial Applications
	400,000	Silgan Holdings		14,324
		Metal & Plastic Packaging
				482,641

See accompanying notes to financial statements.

25

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Other Industrial Services 2.1%
	3,200,000	Expeditors International of Washington	$	174,720
		International Freight Forwarder
	1,850,000	Imtech (Netherlands)		70,184
		Electromechanical & Information & Communications Technologies Installation & Maintenance
	1,300,000	Forward Air		36,894
		Freight Transportation Between Airports
	1,600,000	Mobile Mini (a)		31,504
		Portable Storage Units Leasing
	1,000,000	UTI Worldwide		21,200
		Freight Forwarding & Logistics
	1,050,000	TrueBlue (a)		18,890
		Temporary Manual Labor
	626,524	Arcadis (Netherlands)		14,580
		Engineering Consultants
	900,000	American Reprographics (a)		6,831
		Document Management & Logistics
				374,803
		> Industrial Distribution 1.0%
	900,000	WW Grainger		124,299
		Industrial Distribution
	2,600,000	Interline Brands (a)(b)		59,202
		Industrial Distribution
	100,000	Watsco		6,308
		HVAC Distribution
				189,809
		> Electrical Components 0.8%
	1,440,000	Acuity Brands		83,045
		Commercial Lighting Fixtures
	1,134,100	Ushio (Japan)		21,604
		Industrial Light Sources
	600,000	Ibiden (Japan)		18,907
		Electronic Parts & Ceramics
	351,000	Saft (France)		12,922
		Niche Battery Manufacturer
				136,478
		> Construction 0.6%
	66,000	NVR (a)		45,607
		D.C. Homebuilder
	1,800,000	Mills Estruturas e Serviços de Engenharia (Brazil)		22,337
		Civil Engineering & Construction
	700,000	Simpson Manufacturing		21,637
		Wall Joint Maker
	700,000	Lumber Liquidators (a)(c)		17,437
		Hardwood Flooring Retailer
	500,000	St. Joe (a)(c)		10,925
		Florida Panhandle Landowner
				117,943
		> Outsourcing Services 0.6%
	1,950,000	Quanta Services (a)		38,844
		Electrical & Telecom Construction Services
	1,210,000	Administaff		35,453
		Professional Employer Organization
	2,559,000	Serco (United Kingdom)		22,163
		Facilities Management

Number of Shares			Value (000)
	600,000	GP Strategies (a)	$	6,144
		Training Programs
				102,604
		> Waste Management 0.5%
	1,672,500	Waste Connections		46,044
		Solid Waste Management
	1,000,000	Republic Services		29,860
		Solid Waste Management
	280,000	Clean Harbors (a)		23,542
		Hazardous Waste Services & Disposal
				99,446
		> Conglomerates 0.3%
	2,225,287	Aalberts Industries (Netherlands)		46,909
		Flow Control & Heat Treatment
				46,909
		> Steel 0.3%
	2,340,000	GrafTech International (a)		46,426
		Industrial Graphite Materials Producer
				46,426
		> Water —%
	1,750,000	Mueller Water Products		7,298
		Fire Hydrants, Valves & Ductile Iron Pipes
				7,298
Industrial Goods & Services: Total				3,340,710
Consumer Goods & Services 16.8%
		> Retail 4.2%
	4,035,000	lululemon athletica (a)(b)(c)		276,075
		Premium Active Apparel Retailer
	2,835,000	Abercrombie & Fitch		163,381
		Teen Apparel Retailer
	1,700,000	Shutterfly (a)(b)		59,551
		Internet Photo-centric Retailer
	5,600,000	Pier 1 Imports (a)		58,800
		Home Furnishing Retailer
	5,225,000	Saks (a)(c)		55,907
		Luxury Department Store Retailer
	1,180,000	Urban Outfitters (a)		42,256
		Apparel & Home Specialty Retailer
	4,150,000	Talbots (a)(b)		35,358
		Women's Specialty Retailer
	2,562,000	Chico's FAS		30,821
		Women's Specialty Retailer
	525,000	DSW (a)		20,527
		Branded Footwear Retailer
	1,371,366	Gaiam (b)		10,560
		Healthy Living Catalogs & E-Commerce
	1,384,597	Coldwater Creek (a)		4,389
		Women's Apparel Retailer
	66,000	The Fresh Market (a)		2,719
		Specialty Food Retailer
				760,344
		> Apparel 3.2%
	2,190,000	Warnaco Group (a)		120,603
		Global Branded Apparel Manufacturer

See accompanying notes to financial statements.

26

Number of Shares			Value (000)
		> Apparel—continued
	2,100,000	Coach	$	116,151
		Designer & Retailer of Branded Leather Accessories
	1,120,000	Deckers Outdoor (a)		89,309
		Fashion Footwear Wholesaler
	1,550,000	Guess?		73,346
		Branded Apparel, Accessories & Licensor
	1,055,000	Phillips-Van Heusen		66,476
		Apparel Wholesaler & Retailer
	2,047,000	True Religion Apparel (a)(b)		45,566
		Premium Denim
	1,400,000	Crocs (a)		23,968
		Branded Footwear Wholesaler & Retailer
	700,000	Hanesbrands (a)		17,780
		Apparel Wholesaler
	400,000	Steven Madden (a)		16,688
		Wholesaler/Retailer of Fashion Footwear
				569,887
		> Travel 2.7%
	3,850,000	Gaylord Entertainment (a)(b)		138,369
		Convention Hotels
	3,900,000	Expedia		97,851
		Online Travel Services Company
	4,600,000	Avis Budget Group (a)		71,576
		Second Largest Car Rental Company
	1,250,000	Vail Resorts (a)		65,050
		Ski Resort Operator & Developer
	3,000,000	Hertz (a)		43,470
		Largest U.S. Rental Car Operator
	970,000	Choice Hotels		37,122
		Franchisor of Budget Hotel Brands
	2,000,000	Localiza Rent A Car (Brazil)		32,417
		Car Rental
				485,855
		> Food & Beverage 1.6%
	2,200,000	Hansen Natural (a)		115,016
		Alternative Beverages
	37,000,000	Olam International (Singapore)		90,529
		Agriculture Supply Chain Manager
	1,300,000	Diamond Foods (b)(c)		69,134
		Culinary Ingredients & Snack Foods
	1,200,000	GLG Life Tech (Canada) (a)		12,888
		Produce an All-natural Sweetener Extracted from the Stevia Plant
	240,000	Lance		5,625
		Snack Foods
	22,800	Sodastream (a)		720
		Home Beverage Carbonation System
				293,912
		> Educational Services 1.0%
	1,080,000	ITT Educational Services (a)(c)		68,785
		Post-secondary Degree Services
	2,800,000	Career Education (a)		58,044
		Post-secondary Education
	1,700,000	Universal Technical Institute (b)		37,434
		Vocational Training

Number of Shares			Value (000)
	200,000	New Oriental Education & Technology - ADR (China) (a)	$	21,046
		China's Largest Private Education Service Provider
	2,000,000	Princeton Review (a)		2,360
		College Preparation Courses
	2,000,000	Voyager Learning, Contingent Value Rights (a)(d)		262
		Education Services for the K-12 Market
				187,931
		> Furniture & Textiles 0.8%
	2,800,000	Herman Miller		70,840
		Office Furniture
	4,000,000	Knoll (b)		66,920
		Office Furniture
	1,000,000	Interface		15,650
		Modular & Broadloom Carpet
				153,410
		> Other Consumer Services 0.7%
	2,190,000	Lifetime Fitness (a)(b)		89,768
		Sport & Fitness Club Operator
	14,000,000	Lifestyle International (Hong Kong)		34,402
		Mid- to High-end Department Store Operator in Hong Kong & China
	1,325,000	IFM Investments (Century 21
		China RE) - ADR (China) (a)		6,625
		Provides Real Estate Services in China
				130,795
		> Casinos & Gaming 0.7%
	1,590,000	Penn National Gaming (a)		55,888
		Regional Casino Operator
	3,400,000	Pinnacle Entertainment (a)(b)		47,668
		Regional Casino Operator
	3,000,000	Melco Crown Entertainment - ADR (Hong Kong) (a)(c)		19,080
		Macau Casino Operator
				122,636
		> Nondurables 0.5%
	1,600,000	Helen of Troy (a)(b)		47,584
		Hair Dryers & Curling Irons
	550,000	Energizer Holdings (a)		40,095
		Household & Personal Care Products
				87,679
		> Other Durable Goods 0.4%
	1,720,000	Jarden		53,097
		Branded Household Products
	400,000	Tesla Motors (a)(c)		10,652
		Design, Manufacture & Sell High Performance Electric Vehicles
	180,000	Cavco Industries (a)		8,404
		Manufactured Homes
				72,153
		> Restaurants 0.4%
	2,000,000	AFC Enterprises (a)(b)		27,800
		Popeye's Restaurants
	300,000	P.F. Chang's China Bistro (c)		14,538
		Mandarin Style Restaurants

See accompanying notes to financial statements.

27

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Restaurants—continued
	450,000	Cheesecake Factory (a)	$	13,797
		Casual Dining Restaurants
	367,900	Bravo Brio Restaurant Group (a)		7,053
		Upscale Casual Italian Restaurants
				63,188
		> Consumer Goods Distribution 0.3%
	2,100,000	Pool		47,334
		Distributor of Swimming Pool Supplies & Equipment
				47,334
		> Leisure Products 0.2%
	1,190,000	Thor Industries		40,412
		RV & Bus Manufacturer
				40,412
		> Other Entertainment 0.1%
	370,000	CTS Eventim (Germany)		22,848
		Event Ticket Sales
				22,848
Consumer Goods & Services: Total				3,038,384
Energy & Minerals 10.8%
		> Oil Services 4.2%
	3,100,000	FMC Technologies (a)		275,621
		Oil & Gas Wellhead Manufacturer
	2,570,626	Fugro (Netherlands)		211,260
		Sub-sea Oilfield Services
	3,200,000	Atwood Oceanics (a)		119,584
		Offshore Drilling Contractor
	1,670,000	ShawCor (Canada)		55,611
		Oil & Gas Pipeline Products
	1,750,000	Tesco (a)		27,790
		Developing New Well Drilling Technologies
	375,000	Bristow (a)		17,756
		Largest Provider of Helicopter Services to Offshore Oil & Gas Producers
	10,719,200	Tuscany International Drilling (Colombia) (a)(b)(d)		14,791
	2,600,000	Tuscany International Drilling - Warrants (Colombia) (a)(b)(d)		333
		South America-based Drilling Rig Contractor
	200,000	Oil States International (a)		12,818
		Diversified North American Oil Service Provider
	375,000	Gulfmark Offshore (a)		11,400
		Operator of Offshore Supply Vessels
	500,000	Black Diamond Group (Canada)		10,817
		Provides Accommodations/Equipment for Oil Sands Exploitation
	2,890,900	Horizon North Logistics (Canada) (a)		8,635
		Provides Diversified Oil Service Offering in Northern Canada
				766,416
		> Oil & Gas Producers 4.2%
	4,910,550	Pacific Rubiales Energy (Colombia)		166,681
		Oil Production & Exploration in Colombia
	1,800,000	Southwestern Energy (a)		67,374
		Oil & Gas Producer

Number of Shares			Value (000)
	2,700,000	Denbury Resources (a)	$	51,543
		Oil Producer Using Co2 Injection
	2,400,000	Tullow Oil (United Kingdom)		47,185
		Oil & Gas Producer
	910,000	Ultra Petroleum (a)		43,471
		Oil & Gas Producer
	715,000	SM Energy		42,135
		Oil & Gas Producer
	695,000	Range Resources		31,261
		Oil & Gas Producer
	650,000	Baytex (Canada)		30,470
		Oil & Gas Producer in Canada
	22,000,000	ShaMaran Petroleum (Iraq) (a)		30,091
		Oil Exploration in Kurdistan
	779,000	Rosetta Resources (a)		29,322
		Oil & Gas Producer Exploring in South Texas & Montana
	24,000,000	Petrodorado (Colombia) (a)(b)(d)		16,795
	24,000,000	Petrodorado - Warrants (Colombia) (a)(b)(d)		10,138
		Oil & Gas Exploration & Production in Colombia, Peru & Paraguay
	850,000	Northern Oil & Gas (a)		23,128
		Small E&P Company in North Dakota Bakken
	1,200,000	Houston American Energy (c)		21,708
		Oil & Gas Exploration & Production in Colombia
	583,000	Carrizo Oil & Gas (a)		20,108
		Oil & Gas Producer
	30,275,000	Petroamerica (Colombia) (a)(b)		18,574
		Oil Exploration & Production in Colombia
	37,500,000	Petromanas (Canada) (a)(b)(d)		14,599
	18,750,000	Petromanas - Warrants (Canada) (a)(b)(d)		2,218
		Exploring for Oil in Albania
	1,400,000	Gran Tierra Energy (Colombia) (a)		11,391
		Oil Exploration & Production in Colombia, Peru & Argentina
	275,000	Swift Energy (a)		10,766
		Oil & Gas Exploration & Production Co.
	6,300,000	Canacol Energy (Colombia) (a)(d)		9,749
		Oil Producer in South America
	250,000	Cabot Oil & Gas		9,462
		Large Natural Gas Producer in Appalachia & Gulf Coast
	17,100,000	Alange Energy (Colombia) (a)(c)		9,287
		Oil & Gas Exploration/Production in Colombia
	8,000,000	Petrolifera Petroleum (Colombia) (a)(b)(d)		4,889
	5,950,000	Petrolifera Petroleum (Colombia) (a)(b)		3,710
		Oil & Gas Exploration & Production in South America
	1,198,100	Pan Orient (Canada) (a)		8,013
		Growth Oriented & Return Focused Asian Explorer
	5,880,000	Canadian Overseas Petroleum - Subscription Receipts (United Kingdom) (a)(d)		4,926
	2,520,000	Canadian Overseas Petroleum (United Kingdom) (a)(d)		1,813
	1,260,000	Canadian Overseas Petroleum - Warrants (United Kingdom) (a)(d)		298
		Oil & Gas Exploration & Production in the North Sea

See accompanying notes to financial statements.

28

Number of Shares			Value (000)
		> Oil & Gas Producers—continued
	228,200	Oasis Petroleum (a)	$	6,189
		Oil Producer in North Dakota
	750,000	Vaalco Energy (a)		5,370
		Oil & Gas Producer
				752,664
		> Mining 1.9%
	2,250,000	Silver Wheaton (Canada) (a)		87,840
		Silver Mining Royalty Company
	641,000	Core Laboratories (Netherlands) (c)		57,081
		Oil & Gas Reservoir Consulting
	880,000	Pan American Silver (Canada)		36,265
		Silver Mining
	7,500,000	Zhaojin Mining Industry (China)		30,684
		Gold Mining & Refining in China
	10,000,000	Orko Silver (Canada) (a)(b)		28,160
		Silver Exploration & Development
	1,000,000	Ivanhoe Mines (Canada) (a)		23,132
	1,000,000	Ivanhoe Mines - Rights (Canada) (a)		1,348
		Copper Mine Project in Mongolia
	3,250,000	Northam Platinum (South Africa)		22,349
		Platinum Mining in South Africa
	400,000	Royal Gold		21,852
		Precious Metals Mining Royalty Company
	2,400,000	Alexco Resource (a)		19,656
		Mining, Exploration & Environmental Services
	3,154,000	Duluth Metals (Canada) (a)		9,199
		Copper & Nickel Miner
	5,215,500	Mongolian Mining (Hong Kong) (a)		6,086
		Coking Coal Mining in Mongolia
	236,400	Tahoe Resources (Canada) (a)(d)		3,425
		Silver Project in Guatemala
	800,000	Augusta Resource (a)(c)		3,048
		U.S. Copper/Molybdenum Mine
				350,125
		> Alternative Energy 0.2%
	3,000,000	GT Solar International (a)(c)		27,360
		Largest Manufacturer of Furnaces & Reactors to Produce & Cast Polysilicon
	500,000	STR Holdings (a)(c)		10,000
		Makes Encapsulant for Solar Power Modules/Provides Quality Assurance
	1,800,000	Synthesis Energy Systems (China) (a)		2,106
		Owner/Operator of Gasification Plants
				39,466
		> Oil Refining, Marketing & Distribution 0.2%
	600,000	Vopak (Netherlands)		28,343
		World's Largest Operator of Petroleum & Chemical Storage Terminals
				28,343
		> Agricultural Commodities 0.1%
	6,818,182	Union Agriculture Group (Argentina) (a)(d)		15,000
		Farmland Operator in Uruguay
				15,000
Energy & Minerals: Total				1,952,014

Number of Shares			Value (000)
Finance 10.0%
		> Banks 4.1%
	2,800,000	BOK Financial	$	149,520
		Tulsa-based Southwest Bank
	6,004,115	Valley National Bancorp		85,859
		New Jersey/New York Bank
	5,413,800	Associated Banc-Corp		82,019
		Midwest Bank
	1,260,000	SVB Financial Group (a)		66,843
		Bank to Venture Capitalists
	1,045,000	City National		64,121
		Bank & Asset Manager
	4,150,000	TCF Financial		61,461
		Great Lakes Bank
	4,000,000	Whitney Holding		56,600
		Gulf Coast Bank
	2,860,000	MB Financial (b)		49,535
		Chicago Bank
	3,640,000	CVB Financial (c)		31,559
		Inland Empire Business Bank
	1,350,000	TriCo Bancshares (b)		21,803
		California Central Valley Bank
	1,121,188	Sandy Spring Bancorp		20,663
		Baltimore/D.C. Bank
	772,632	Hudson Valley		19,130
		Metro New York City Bank
	3,299,507	First Busey		15,508
		Illinois Bank
	2,640,000	Wilmington Trust		11,458
		Delaware Trust Bank
	706,559	Eagle Bancorp (a)		10,196
		Metro D.C. Bank
	246,505	Pacific Continental		2,480
		Pacific Northwest Bank
	583,872	Green Bankshares (a)(c)		1,868
		Tennessee Bank
				750,623
		> Insurance 2.3%
	2,820,000	Leucadia National		82,288
		Insurance Holding Company
	9,400,000	CNO Financial Group (a)		63,732
		Life, Long-term Care & Medical Supplement Insurance
	1,320,000	Hanover Insurance Group		61,670
		Personal & Commercial Lines Insurance
	1,200,000	HCC Insurance Holdings		34,728
		Specialty Insurance
	1,225,000	Tower Group		31,336
		Commercial & Personal Lines Insurance
	1,000,000	Delphi Financial Group		28,840
		Workers Compensation & Group Employee Benefit Products & Services
	832,000	Willis Group (Ireland)		28,812
		Insurance Broker
	1,420,000	Selective Insurance Group		25,773
		Commercial & Personal Lines Insurance
	1,600,000	Symetra Financial		21,920
		Life Insurance

See accompanying notes to financial statements.

29

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Insurance—continued
	900,000	Brown & Brown	$	21,546
		Insurance Broker
	390,919	Aspen Insurance		11,188
		Commercial Lines Insurance/Reinsurance
	121,342	Assurant		4,674
		Specialty Insurance
				416,507
		> Finance Companies 1.8%
	1,505,202	World Acceptance (a)(b)		79,475
		Personal Loans
	2,350,000	McGrath Rentcorp (b)		61,617
		Temporary Space & IT Rentals
	1,480,000	GATX		52,214
		Rail Car Lessor
	2,532,500	Aaron Rents		51,638
		Rent to Own
	3,000,000	H&E Equipment Services (a)(b)		34,710
		Heavy Equipment Leasing
	1,650,000	CAI International (a)(b)		32,340
		International Container Leasing
	1,091,000	Marlin Business Services (a)(b)		13,801
		Small Equipment Leasing
	78,500	Textainer Group Holdings		2,237
		Top International Container Leasor
				328,032
		> Brokerage & Money Management 1.5%
	6,198,000	SEI Investments		147,450
		Mutual Fund Administration & Investment Management
	3,391,000	Eaton Vance		102,510
		Specialty Mutual Funds
	700,000	Investment Technology Group (a)		11,459
		Electronic Trading
	452,146	Kaiser Federal Financial Group		5,236
		Los Angeles Savings & Loan
				266,655
		> Savings & Loans 0.2%
	1,300,000	Housing Development Finance (India)		21,135
		Indian Mortgage Lender
	1,024,069	ViewPoint Financial		11,971
		Texas Thrift
	1,010,000	Provident New York Bancorp		10,595
		New York State Thrift
	65,991	Berkshire Hills Bancorp		1,458
		Northeast Thrift
				45,159
		> Credit Cards 0.1%
	140,000	Alliance Data Systems (a)		9,944
		Diversified Credit Card Provider
				9,944
Finance: Total				1,816,920
Health Care 9.1%
		> Biotechnology & Drug Delivery 3.4%
	3,920,421	BioMarin Pharmaceutical (a)		105,577
		Biotech Focused on Orphan Diseases

Number of Shares			Value (000)
	1,110,000	United Therapeutics (a)	$	70,174
		Biotech Focused on Rare Diseases
	4,180,918	Seattle Genetics (a)		62,505
		Antibody-based Therapies for Cancer
	4,500,000	Isis Pharmaceuticals (a)		45,540
		Biotech Pioneer in Anti-sense Drugs
	5,500,000	Micromet (a)(b)		44,660
		Next-generation Antibody Technology
	1,200,000	Onyx Pharmaceuticals (a)		44,244
		Commercial-stage Biotech Focused on Cancer
	1,088,500	InterMune (a)		39,621
		Drugs for Pulmonary Fibrosis & Hepatitis C
	2,700,000	Nektar Therapeutics (a)		34,695
		Drug Delivery Technologies
	7,035,000	Allos Therapeutics (a)(b)		32,431
		Cancer Drug Development
	3,449,900	Chelsea Therapeutics (a)(b)		25,874
		Biotech Focused on Rare Diseases
	1,200,000	Auxilium Pharmaceuticals (a)(c)		25,320
		Biotech Focused on Niche Disease Areas
	3,200,000	NPS Pharmaceuticals (a)		25,280
		Orphan Drugs & Healthy Royalties
	900,000	Acorda Therapeutics (a)		24,534
		Biopharma Company Focused on Nervous Disorder Drugs
	3,340,255	Idenix Pharmaceuticals (a)		16,835
		Developer of Drugs for Infectious Diseases
	3,500,000	Array Biopharma (a)(b)		10,465
		Drugs for Cancer & Inflammatory Diseases
	1,383,454	Nabi Biopharmaceuticals (a)		8,010
		Biotech Focused on Vaccines
	1,450,000	Anthera Pharmaceuticals (a)		7,076
		Biotech Focused on Cardiovascular, Cancer & Immunology
	359,944	MicroDose Technologies (a)(d)		94
		Drug Inhaler Development
	94,715	Locus Pharmaceuticals (a)(d)		9
		High Throughput Rational Drug Design
				622,944
		> Medical Equipment & Devices 3.4%
	2,100,000	Alexion Pharmaceuticals (a)		169,155
		Biotech Focused on Orphan Diseases
	1,000,000	Edwards Lifesciences (a)		80,840
		Heart Valves
	1,800,000	Sirona Dental Systems (a)		75,204
		Manufacturer of Dental Equipment
	1,065,000	Haemonetics (a)		67,287
		Blood & Plasma Collection Equipment
	3,150,000	American Medical Systems (a)		59,409
		Medical Devices to Treat Urological Conditions
	750,000	Gen-Probe (a)		43,762
		Molecular In-vitro Diagnostics
	500,000	Idexx Laboratories (a)(c)		34,610
		Diagnostic Equipment & Services for Veterinarians
	1,150,000	Orthofix International (a)(b)		33,350
		Bone Fixation & Stimulation Devices
	506,000	Illumina (a)		32,050
		Leading Tools & Service Provider for Genetic Analysis

See accompanying notes to financial statements.

30

Number of Shares			Value (000)
		> Medical Equipment & Devices—continued
	932,768	Pacific Biosciences of California (a)(c)	$	14,840
		Genome Sequencing
	1,480,056	Nanosphere (a)(b)		6,453
		Molecular Diagnostics Company with Best of Breed Platform
				616,960
		> Health Care Services 1.4%
	1,250,000	Mednax (a)		84,112
		Physician Management for Pediatric & Anesthesia Practices
	1,300,000	Community Health Systems (a)		48,581
		Non-urban Hospitals
	4,250,000	eResearch Technology (a)(b)		31,238
		Clinical Research Services
	400,000	HMS Holdings (a)		25,908
		Cost Containment Services
	2,650,000	Health Management Associates (a)		25,281
		Non-urban Hospitals
	500,000	AthenaHealth (a)(c)		20,490
		Revenue Cycle Management for Physician Offices
	700,000	Allscripts Healthcare Solutions (a)		13,489
		IT for Physician Offices & Hospitals
				249,099
		> Medical Supplies 0.8%
	2,415,000	Cepheid (a)		54,941
		Molecular Diagnostics
	650,000	Henry Schein (a)		39,904
		Largest Distributor of Healthcare Products
	1,100,000	Patterson Companies		33,693
		Dental, Veterinarian & Medical Distributor
	200,000	Owens & Minor		5,886
		Distribution of Medical Supplies
	77,602	Neogen (a)		3,184
		Food & Animal Safety Products
	42,278	ICU Medical (a)		1,543
		Intravenous Therapy Products
				139,151
		> Pharmaceuticals 0.1%
	2,659,068	Akorn (a)		16,141
		Develops, Manufactures & Sells Specialty Generic Drugs
	2,272,582	United Drug (Ireland)		6,377
		Irish Pharmaceutical Wholesaler & Outsourcer
	361,450	Alimera Sciences (a)(c)		3,752
		Ophthalmogy-focused Pharmaceutical Company
				26,270
Health Care: Total				1,654,424
Other Industries 5.1%
		> Real Estate 3.0%
	4,000,000	BioMed Realty Trust		74,600
		Life Science-focused Office Buildings
	641,165	Federal Realty Investment Trust		49,966
		Shopping Centers
	1,935,579	Dupont Fabros Technology (c)		41,170
		Technology-focused Office Buildings

Number of Shares			Value (000)
	1,120,000	Kilroy Realty	$	40,846
		Southern California Office & Industrial Properties
	720,000	Digital Realty Trust (c)		37,109
		Technology-focused Office Buildings
	2,200,000	Associated Estates Realty (b)		33,638
		Multi-family Properties
	43,201,999	Mapletree Logistics Trust (Singapore)		32,485
		Asian Logistics Landlord
	1,850,000	Extra Space Storage		32,190
		Self Storage Facilities
	900,000	Corporate Office Properties		31,455
		Office Buildings
	530,000	Macerich		25,106
		Regional Shopping Malls
	15,000,000	Ascendas REIT (Singapore)		24,194
		Singapore Industrial Property Landlord
	3,000,000	Education Realty Trust (b)		23,310
		Student Housing
	700,000	Washington REIT		21,693
		Washington D.C. Diversified Properties
	3,750,000	DCT Industrial Trust		19,912
		Industrial Properties
	2,800	Orix JREIT (Japan)		18,204
		Diversified REIT
	3,050,000	Kite Realty Group		16,501
		Community Shopping Centers
	367,240	Post Properties		13,331
		Multi-family Properties
	37,407	Security Capital European Realty (Luxembourg) (a)(d)(e)		—
		Self Storage Properties
				535,710
		> Transportation 1.2%
	1,850,000	JB Hunt Transport Services		75,498
		Truck & Intermodal Carrier
	2,800,000	Rush Enterprises, Class A (a)(b)		57,232
	550,000	Rush Enterprises, Class B (a)(b)		9,889
		Truck Sales & Services
	2,730,000	Heartland Express		43,735
		Regional Trucker
	1,110,000	World Fuel Services		40,138
		Global Fuel Broker
				226,492
		> Regulated Utilities 0.9%
	2,000,000	Northeast Utilities		63,760
		Regulated Electric Utility
	900,000	Wisconsin Energy		52,974
		Wisconsin Utility
	500,000	ALLETE		18,630
		Regulated Electric Utility in Minnesota
	333,000	Red Eléctrica de España (Spain)		15,657
		Spanish Power Transmission
	3,333,000	Terna (Italy)		14,079
		Italian Power Transmission
				165,100
Other Industries: Total				927,302
Total Equities: 97.2% (Cost: $11,026,459)				17,595,584

See accompanying notes to financial statements.

31

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares or Principal Amount (000)			Value (000)
Securities Lending Collateral – 2.1%
	375,541,061	Dreyfus Government Cash Management Fund (f) (7 day yield of 0.01%)	$	375,541
Total Securities Lending Collateral: (Cost: $375,541)				375,541
Short-Term Obligations: 2.9%
		>Repurchase Agreement 2.5%
$	453,434	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by U.S. Government Agency obligations with various maturities to 9/08/14, market value $462,507 (repurchase proceeds $453,440)		453,434
				453,434
		>Commercial Paper 0.4%
	50,000	Toyota Motor Credit 0.20% Due 1/21/11		49,995
	25,000	ConocoPhillips (g) 0.25% Due 1/07/11		24,999
				74,994
Total Short-Term Obligations: (Amortized Cost: $528,428)				528,428
Total Investments: 102.2% (Cost: $11,930,428)(h)(i)				18,499,553
Obligation to Return Collateral for Securities Loaned: (2.1)%				(375,541	)
Cash and Other Assets Less Liabilities: (0.1)%				(25,300	)
Total Net Assets: 100.0%			$	18,098,712

ADR = American Depositary Receipts

GDR = Global Depository Receipts

See accompanying notes to financial statements.

32

> Notes to Statement of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  An affiliated person of the Fund may include any company in which the Fund owns five percent or more of its outstanding voting shares. Holdings and transactions in these affiliated companies during the year ended December 31, 2010, are as follows:

Affiliates	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
Abercrombie & Fitch*		4,500,000		-		1,665,000		2,835,000	$	163,381	$	2,031
Actuate*		3,700,000		-		2,200,000		1,500,000		8,550		-
Administaff*		1,428,224		-		218,224		1,210,000		35,453		629
AFC Enterprises		2,000,000		-		-		2,000,000		27,800		-
Allos Therapeutics		2,800,000		4,235,000		-		7,035,000		32,431		-
AMAG Pharmaceuticals*		600,000		650,000		1,250,000		-		-		-
AmeriCredit*		7,235,000		250,000		7,485,000		-		-		-
AnnTaylor Stores*		3,500,000		-		3,500,000		-		-		-
Anthera Pharmaceuticals*		-		1,450,000		-		1,450,000		7,076		-
Array Biopharma		-		3,500,000		-		3,500,000		10,465		-
Art Technology Group		2,594,654		6,405,346		-		9,000,000		53,820		-
Associated Estates Realty		-		2,200,000		-		2,200,000		33,638		255
Bally Technologies		4,025,000		-		300,000		3,725,000		157,158		-
Blackbaud		1,800,000		450,000		-		2,250,000		58,275		990
CAI International		1,650,000		-		-		1,650,000		32,340		-
Cepheid*		2,500,000		1,065,000		1,150,000		2,415,000		54,941		-
Charming Shoppes*		7,500,000		2,300,000		9,800,000		-		-		-
Chattem*		1,010,000		-		1,010,000		-		-		-
Chelsea Therapeutics		-		3,449,900		-		3,449,900		25,874		-
Clarcor		2,627,500		-		62,500		2,565,000		110,013		1,020
Cogent Communications		4,200,000		-		1,400,000		2,800,000		39,592		-
Coldwater Creek*		-		4,950,442		3,565,845		1,384,597		4,389		-
Diamond Foods		550,475		749,525		-		1,300,000		69,134		143
Donaldson		4,200,000		-		-		4,200,000		244,776		2,079
Drew Industries		1,600,000		-		340,000		1,260,000		28,627		1,890
Education Realty Trust		-		3,000,000		-		3,000,000		23,310		370
eResearch Technology		4,250,000		-		-		4,250,000		31,238		-
ESCO Technologies		2,200,000		-		-		2,200,000		83,248		528
Gaiam		1,371,366		-		-		1,371,366		10,560		411
Gaylord Entertainment		3,700,000		1,189,500		1,039,500		3,850,000		138,369		-
H&E Equipment Services		3,300,000		-		300,000		3,000,000		34,710		-
Hackett Group		4,500,000		-		-		4,500,000		15,795		-
HEICO**		1,225,000		475,000		-		1,700,000		63,444		165
Helen of Troy		1,700,000		-		100,000		1,600,000		47,584		-
Herman Miller*		2,800,000		-		-		2,800,000		70,840		246
ICU Medical*		850,000		200,000		1,007,722		42,278		1,543		-
iGate		5,000,000		-		2,086,935		2,913,065		57,416		1,075
II-VI		2,400,000		-		175,000		2,225,000		103,151		-
Informatica		7,000,000		-		1,800,000		5,200,000		228,956		-
Interline Brands		2,600,000		-		-		2,600,000		59,202		-
IPG Photonics		2,750,000		435,000		475,000		2,710,000		85,690		-
IXYS		1,900,000		-		-		1,900,000		22,078		-
Kenexa		2,425,000		-		400,000		2,025,000		44,125		-
Knoll		4,000,000		-		-		4,000,000		66,920		480
Lifetime Fitness		2,150,000		230,000		190,000		2,190,000		89,768		-
lululemon athletica		4,200,000		485,000		650,000		4,035,000		276,075		-
Marlin Business Services		1,091,000		-		-		1,091,000		13,801		-
MB Financial		2,305,600		554,400		-		2,860,000		49,535		107
McGrath Rentcorp		2,350,000		-		-		2,350,000		61,617		2,103
Mediacom Communications*		4,000,000		-		4,000,000		-		-		-
Micromet		1,400,000		4,100,000		-		5,500,000		44,660		-
Mine Safety Appliances*		1,975,000		-		450,000		1,525,000		47,473		1,705
Nanosphere		1,232,900		267,100		19,944		1,480,056		6,453		-
Navigant Consulting		2,500,000		600,000		-		3,100,000		28,520		-
NPS Pharmaceuticals*		2,700,000		500,000		-		3,200,000		25,280		-
Orko Silver		10,000,000		-		-		10,000,000		28,160		-
Orthofix International		1,000,000		150,000		-		1,150,000		33,350		-
PAETEC Holding		9,600,000		-		-		9,600,000		35,904		-

See accompanying notes to financial statements.

33

Columbia Acorn Fund

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

Affiliates	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
Pericom Semiconductor		1,765,000		-		-		1,765,000	$	19,380	$	-
Petroamerica		-		30,275,000		-		30,275,000		18,574		-
Petrodorado***		48,000,000		-		-		48,000,000		26,933		-
Petrolifera Petroleum		264,000		13,686,000		-		13,950,000		8,599		-
Petromanas***		-		56,250,000		-		56,250,000		16,817		-
Pinnacle Entertainment		4,050,000		-		650,000		3,400,000		47,668		-
Princeton Review*		3,000,000		-		1,000,000		2,000,000		2,360		-
PSS World Medical*		2,750,000		550,000		3,300,000		-		-		-
Rush Enterprises		3,000,000		350,000		-		3,350,000		67,121		-
Salem Communications		1,541,000		-		-		1,541,000		4,885		308
Shutterfly		-		1,700,000		-		1,700,000		59,551		-
SkillSoft - ADR*		9,500,000		-		9,500,000		-		-		-
Spanish Broadcasting System		2,400,000		-		-		2,400,000		1,699		-
SPS Commerce		-		856,429		-		856,429		13,532		-
Supertex		1,035,000		-		-		1,035,000		25,026		-
Switch & Data Facilities*		2,500,000		-		2,500,000		-		-		-
Talbots		4,250,000		650,000		750,000		4,150,000		35,358		-
THQ		3,200,000		600,000		233,000		3,567,000		21,616		-
TriCo Bancshares		1,200,000		250,000		100,000		1,350,000		21,803		476
True Religion Apparel		1,500,000		975,000		428,000		2,047,000		45,566		-
Tuscany International Drilling***		-		28,048,000		14,728,800		13,319,200		15,124		-
tw telecom		9,500,000		-		-		9,500,000		161,975		-
Tyler Technologies		1,134,260		1,315,740		450,000		2,000,000		41,520		-
Universal Technical Institute		1,750,301		-		50,301		1,700,000		37,434		2,550
Vail Resorts*		1,950,000		-		700,000		1,250,000		65,050		-
Vermillion*		-		694,849		694,849		-		-		-
Virtusa		1,800,000		200,000		-		2,000,000		32,720		-
World Acceptance		1,545,000		-		39,798		1,505,202		79,475		-
Xenoport*		-		2,100,000		2,100,000		-		-		-
Total of Affiliated Transactions		268,131,280		182,342,231		131,865,418		366,608,093	$	3,996,294	$	19,561

*  At December 31, 2010, the Fund owned less than five percent of the company's outstanding voting shares.

**  Includes the effects of a 2:1 stock split.

***  Includes the effects of a corporate action.

  The aggregate cost and value of these affiliated companies at December 31, 2010, were $2,324,758 and $3,446,513, respectively. Investments in affiliated companies represented 19.0% of the Fund's total net assets at December 31, 2010.

(c)  All or a portion of this security was on loan at December 31, 2010. The total market value of Fund securities on loan at December 31, 2010 was $363,573.

(d)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the market value of these securities amounted to $116,054, which represented 0.64% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Petrodorado	11/20/09		24,000,000	$	5,049	$	16,795
Mail.ru - GDR	11/5/10-12/31/10		464,305		16,518		16,715
Union Agriculture Group	12/08/10		6,818,182		15,000		15,000
Tuscany International Drilling	2/12/10-3/23/10		10,719,200		12,997		14,791
Petromanas	5/20/10		37,500,000		13,032		14,599
Petrodorado - Warrants	11/20/09		24,000,000		2,965		10,138
Canacol Energy	4/15/10		6,300,000		4,667		9,749
Canadian Overseas Petroleum - Subscription Receipts	11/24/10		5,880,000		2,882		4,926
Petrolifera Petroleum	4/06/10		8,000,000		6,768		4,889
Tahoe Resources	5/28/10		236,400		1,350		3,425
Petromanas - Warrants	5/20/10		18,750,000		1,086		2,218
Canadian Overseas Petroleum	11/24/10		2,520,000		1,116		1,813
Tuscany International Drilling - Warrants	2/12/10		2,600,000		322		333
Canadian Overseas Petroleum - Warrants	11/24/10		1,260,000		119		298
Voyager Learning, Contingent Value Rights	12/24/09		2,000,000		-		262

See accompanying notes to financial statements.

34

> Notes to Statement of Investments (dollar values in thousands)

Security	Acquisition Dates	Shares		Cost		Value
MicroDose Technologies	11/24/00		359,944	$	2,005	$	94
Locus Pharmaceuticals	9/05/01-2/08/07		94,715		7,780		9
Security Capital European Realty	8/20/98-7/20/99		37,407		205		-
				$	93,861	$	116,054

(e)  Security has no value.

(f)  Investment made with cash collateral received from securities lending activity.

(g)  Security exempt from registration under Section 4(2) of the Securities Act of 1933. This security may only be resold in exempt transactions to qualified buyers. Private resales of this security to qualified institutional buyers are also exempt from registration pursuant to Rule 144A under the Securities Act of 1933. At December 31, 2010, this security had an aggregate value of $24,999, which represented 0.1% of total net assets.

(h)  At December 31, 2010, for federal income tax purposes, the cost of investments was $12,029,556 and net unrealized appreciation was $6,469,997, consisting of gross unrealized appreciation of $7,237,867 and gross unrealized depreciation of $767,870.

(i)  On December 31, 2010, the market value of foreign securities represented 12.61% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percentage of Net Assets
Netherlands	$	428,357		2.37
Canada		355,060		1.96
Colombia		266,338		1.47
Singapore		180,013		1.00
Sweden		126,861		0.70
Japan		113,304		0.63
Chile		102,235		0.57
Hong Kong		76,579		0.42
United Kingdom		76,385		0.42
France		71,831		0.40
China		67,421		0.37
Brazil		54,754		0.30
India		49,189		0.27
Denmark		47,377		0.26
	Value		Percentage of Net Assets
South Korea	$	37,514		0.21
Ireland		35,189		0.19
Iraq		30,091		0.17
Israel		27,920		0.15
Germany		22,848		0.13
South Africa		22,349		0.12
Switzerland		19,752		0.11
Russia		16,715		0.09
Spain		15,657		0.09
Argentina		15,000		0.08
Italy		14,079		0.08
Iceland		8,713		0.05
Luxembourg		-		-
Total Foreign Portfolio	$	2,281,531		12.61

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Information	$	4,618,335	$	247,495	$	-	$	4,865,830
Industrial Goods & Services		2,938,582		402,128		-		3,340,710
Consumer Goods & Services		2,857,927		180,195		262		3,038,384
Energy & Minerals		1,507,133		429,881		15,000		1,952,014
Finance		1,795,785		21,135		-		1,816,920
Health Care		1,647,944		6,377		103		1,654,424
Other Industries		822,683		104,619		-		927,302
Total Equities		16,188,389		1,391,830		15,365		17,595,584
Total Securities Lending Collateral		375,541		-		-		375,541
Total Short-Term Obligations		-		528,428		-		528,428
Total Investments	$	16,563,930	$	1,920,258	$	15,365	$	18,499,553

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sales price on the foreign exchange or market on which they trade. The Fund may use a systematic fair valuation model provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements. Securities acquired via private placement that have a holding period or an extended settlement period are valued at a discount to the same shares that are trading freely on the m arket. These discounts are determined by the adviser's experience with similar securities or situations. Factors may include, but are not limited to, trade volume, shares outstanding and stock price. Warrants which do not trade are valued as a percentage of the actively trading common stock using a model based on Black Scholes.

See accompanying notes to financial statements.

35

Columbia Acorn Fund

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities acquired via private placement that are not yet trading are valued using a market approach for which management has determined that the original transaction price is the best representation of fair value. The original cost may be adjusted for the market movement in an index, ETF or similar security during the period it does not trade. Securities for which no market exists are valued based upon a market approach using some unobservable inputs which may include, but are not limited to, projected earnings, available cash, line of business, multiples, and consideration of th e prioritization of the equity in a company's capital structure.

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

  The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Equities
Consumer Goods & Services	$	336	$	-	$	(74	)	$	-	$	-	$	-	$	-	$	262
Energy & Minerals		-		-		-			15,000		-		-		-		15,000
Health Care		176		-		(73	)		-		-		-		-		103
	$	512	$	-	$	(147	)	$	15,000	$	-	$	-	$	-	$	15,365

  The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  The change in unrealized depreciation attributed to securities owned at December 31, 2010, which were valued using significant unobservable inputs (Level 3) amounted to $147. This amount is included in net change in unrealized appreciation on the Statement of Changes in Net Assets.

  For more information on valuation inputs, and their aggregation into the levels used in the table above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

36

Columbia Acorn International

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Asia
> Japan
Asahi Diamond Industrial		511,700		1,000,000
Daiseki		787,200		1,181,200
Kansai Paint		7,140,000		7,556,000
Nippon Sheet Glass		1,860,000		7,174,000
Pigeon		397,500		439,800
Ushio		950,000		1,041,800
> China
51job - ADR		0		247,000
China Communication Services		30,000,000		45,000,000
China Xiniya Fashion - ADR		0		1,766,700
Noah Holdings - ADR		0		223,100
Zhaojin Mining Industry		13,930,000		16,138,000
> Singapore
Goodpack		9,540,600		11,000,000
> India
Infrastructure Development Finance		3,785,000		4,730,000
Jain Irrigation Systems		1,280,000		6,400,000
Manappuram General Finance		0		3,115,000
REI Agro		23,000,000		30,575,000
S. Kumars Nationwide		7,702,000		9,600,000
> Hong Kong
L'Occitane International		8,336,150		10,500,000
Melco Crown Entertainment - ADR		5,000,000		7,000,000
Mongolian Mining		0		23,335,500
Sa Sa International		0		23,470,900
> South Korea
NHN		280,000		304,000
Woongjin Coway		909,000		1,157,000
> Thailand
Home Product Center		0		31,101,200
Europe
> United Kingdom
Archipelago Resources		20,823,776		24,346,593
Chemring		890,000		964,000
FlyBe		0		1,731,900
JLT Group		0		1,426,274
Petropavlovsk		1,768,000		1,976,000
SKIL Ports & Logistics		0		1,650,000
Sterling Resources		0		1,549,500
Sterling Resources		0		1,050,500
Workspace Group		54,275,000		60,304,000
> Netherlands
Aalberts Industries		1,968,060		2,258,060

	Number of Shares
	09/30/10		12/31/10
Arcadis		1,120,284		1,164,669
USG People		916,600		1,264,600
> France
Gemalto		383,000		460,000
Neopost		470,000		590,000
Norbert Dentressangle		201,101		213,724
Toreador Resources		0		372,000
> Germany
Rheinmetall		0		365,000
> Sweden
Orc Software		0		708,342
> Italy
Tod's		340,000		452,200
> Portugal
Banco Comercial Português		16,574,000		21,618,000
> Iceland
Marel		34,999,999		35,369,999
> Russia
Mail.ru		0		833,742
Other Countries
> Canada
DeeThree Exploration		0		1,042,877
Ivanhoe Mines		0		744,000
Ivanhoe Mines - Rights		0		850,000
> United States
BioMarin Pharmaceutical		725,000		1,010,534
Onex Capital		0		187,600
> South Africa
Northam Platinum		4,541,900		5,780,900
> Senegal
Sonatel		33,000		43,000
> Egypt
Paints & Chemical Industries (Pachin)		96,872		220,342
Latin America
> Brazil
MRV Engenharia		3,000,000		3,300,000
Suzano		5,375,000		5,937,000
> Mexico
Grupo Aeroportuario del Sureste - ADR		533,400		550,000
> Argentia
Madalena Ventures		0		5,400,000
Union Agriculture Group		0		6,818,182

See accompanying notes to financial statements.

37

Columbia Acorn International

Major Portfolio Changes in the Fourth Quarter (Unaudited), continued

	Number of Shares
	09/30/10		12/31/10
Sales
Asia
> Japan
Point		406,030		0
Zenrin		294,100		0
> China
Shandong Weigao		13,626,200		12,277,200
> Singapore
CDL Hospitality Trust		24,136,100		23,000,000
Olam International		37,000,000		35,000,000
Singapore Exchange		5,000,000		4,000,000
> India
Educomp Solutions		1,148,000		0
Shriram Transport Finance		2,700,000		1,835,000
> Hong Kong
Hong Kong Exchanges and Clearing		1,900,000		750,000
> South Korea
MegaStudy		172,000		121,132
Mirae Asset Securities		376,000		0
Taewoong		179,000		64,008
> Taiwan
Everlight Electronics		14,000,000		7,206,000
Yuanta Financial Holdings		27,000,000		0
Europe
> United Kingdom
Micro Focus		4,025,000		2,195,200
N Brown Group		2,266,644		0
> Netherlands
QIAGEN		650,000		0
> Germany
Tognum		390,355		0
Wincor Nixdorf		145,321		0
> Italy
Terna		7,674,000		4,111,000
> Ireland
Paddy Power		575,000		431,000
Other Countries
> Canada
Horizon North Logistics		2,262,100		2,214,100
> United States
Alexion Pharmaceuticals		625,000		411,000
Hewlett Packard Co.		26,300,000		0
Oceaneering International		192,000		0
Ritchie Brothers Auctioneers		679,000		0

	Number of Shares
	09/30/10		12/31/10
> Australia
Billabong International		2,200,000		0
Hastie Group		11,236,457		6,152,918
Latin America
> Brazil
Localiza Rent A Car		4,900,000		4,600,000
> Mexico
Urbi Desarrollos Urbanos		6,837,700		0

See accompanying notes to financial statements.

38

Columbia Acorn International

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 93.7%
Asia 37.8%
		>Japan 16.4%
	7,556,000	Kansai Paint	$	73,107
		Paint Producer in Japan, India, China & Southeast Asia
	27,000	Advance Residence Investment (a)		60,432
		Residential REIT
	21,000	Seven Bank		44,459
		ATM Processing Services
	6,400	Orix JREIT		41,608
		Diversified REIT
	1,846,000	Aeon Delight		36,341
		Facility Maintenance & Management
	20,900	Wacom		33,205
		Computer Graphic Illustration Devices
	8,071	Start Today		32,246
		Online Japanese Apparel Retailer
	274,000	Nakanishi		29,012
		Dental Tools & Machinery
	3,283,000	Kamigumi		27,557
		Port Cargo Handling & Logistics
	3,400	Fukuoka		26,632
		Diversified REIT in Fukuoka
	710,000	Hamamatsu Photonics		25,937
		Optical Sensors for Medical & Industrial Applications
	5,100	Osaka Securities Exchange		25,714
		Osaka Securities Exchange
	789,000	Tsumura		25,539
		Traditional Chinese/Japanese Herbal Rx Drugs (Kampo)
	24,022	Jupiter Telecommunications		25,267
		Largest Cable Service Provider in Japan
	707,000	Ain Pharmaciez		24,862
		Dispensing Pharmacy/Drugstore Operator
	1,343,000	Hoshizaki Electric		24,858
		Commercial Kitchen Equipment
	868,000	Kintetsu World Express		24,814
		Airfreight Logistics
	1,181,200	Daiseki (b)		24,634
		Waste Disposal & Recycling
	1,905,500	Asics		24,479
		Footwear & Apparel
	906,000	Aeon Mall		24,310
		Suburban Shopping Mall Developer, Owner & Operator
	800,000	Olympus		24,191
		Medical Equipment (Endoscopes) & Cameras
	977,000	Glory		24,047
		Currency Handling Systems & Related Equipment
	711,000	Ibiden		22,405
		Electronic Parts & Ceramics
	509,000	Makita		20,810
		Power Tools
	972,500	Torishima Pump Manufacturing		20,511
		Industrial Pump for Power Generation & Water Supply Systems

Number of Shares			Value (000)
	1,595,000	Gree	$	20,277
		Mobile Social Networking Game Developer/ Platform
	1,041,800	Ushio		19,845
		Industrial Light Sources
	942,000	Tamron		19,606
		Camera Lens Maker
	7,174,000	Nippon Sheet Glass		19,346
		Sheet Glass for Building & Automotive Use
	1,000,000	Asahi Diamond Industrial		18,989
		Consumable Diamond Tools
	408,700	Benesse		18,821
		Education Service Provider
	675,780	Icom		18,514
		Two Way Radio Communication Equipment
	1,501,000	Rohto Pharmaceutical		17,539
		Health & Beauty Products
	2,870	Kakaku.com		17,067
		Online Price Comparison Services for Consumers
	1,750,000	Suruga Bank		16,286
		Regional Bank
	587,800	Miura		15,686
		Industrial Boiler Manufacturer
	1,000,000	Japan Airport Terminal		15,424
		Airport Terminal Operator at Haneda
	439,800	Pigeon		14,950
		Baby Care Products
	1,986	Mori Hills		7,680
		Tokyo Centric Diversified REIT
				1,007,007
		>China 6.4%
	16,138,000	Zhaojin Mining Industry		66,024
		Gold Mining & Refining in China
	36,700,000	Jiangsu Expressway		42,117
		Chinese Toll Road Operator
	12,199,600	China Yurun Food		40,337
		Meat Processor in China
	12,277,200	Shandong Weigao		34,749
		Vertically Integrated Hospital Consumable Manufacturing
	33,160,400	China Green		32,423
		Chinese Fruit & Vegetable Grower & Processor
	1,110,000	Mindray - ADR (b)		29,304
		Medical Device Manufacturer
	278,315	New Oriental Education & Technology - ADR (a)		29,287
		China's Largest Private Education Service Provider
	45,000,000	China Communication Services		26,805
		China's Telecom Infrastructure Service Provider
	240,000,000	RexLot Holdings		25,319
		Lottery Equipment Supplier in China
	29,425,300	Wasion Group		19,458
		Electronic Power Meter Total Solution Provider
	1,766,700	China Xiniya Fashion - ADR (a)(b)		16,183
		Men's Apparel Provider in China

See accompanying notes to financial statements.

39

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		>China—continued
	18,910,000	Sino Ocean Land	$	12,383
		Property Developer in China
	247,000	51job - ADR (a)		12,165
		Integrated Human Resources Service Provider
	223,100	Noah Holdings - ADR (a)(b)		4,361
		Wealth Management Product Distributor in China
	83,200	XueDa Education Group - ADR (a)		938
		Chinese Tutoring
	15,300,000	Fu Ji Food & Catering Services (a)(c)		79
		Food Catering Service Provider in China
				391,932
		>Singapore 4.6%
	35,000,000	Olam International		85,635
		Agriculture Supply Chain Manager
	66,000,000	Mapletree Logistics Trust		49,628
		Asian Logistics Landlord
	23,000,000	CDL Hospitality Trust		37,278
		Hotel Owner/Operator
	20,000,000	Ascendas REIT		32,259
		Singapore Industrial Property Landlord
	37,010,000	Mapletree Industrial Trust (a)		31,434
		Singapore Industrial REIT
	4,000,000	Singapore Exchange		26,244
		Singapore Equity & Derivatives Market Operator
	11,000,000	Goodpack		17,571
		International Bulk Container Leasing
				280,049
		>India 3.5%
	565,000	Asian Paints		36,454
		India's Largest Paint Company
	1,835,000	Shriram Transport Finance		32,215
		Truck Financing in India
	6,400,000	Jain Irrigation Systems		30,143
		Agricultural Micro-irrigation Systems & Food Processing
	4,730,000	Infrastructure Development Finance		19,363
		Infrastructure Finance in India
	30,575,000	REI Agro		18,633
		Basmati Rice Processing
	9,600,000	S. Kumars Nationwide (a)		18,582
		Textiles, Clothing & Retail
	1,100,000	Housing Development Finance		17,883
		Indian Mortgage Lender
	4,800,000	Mundra Port & Special Economic Zone		15,431
		Indian West Coast Shipping Port
	2,125,000	Patel Engineering		14,494
		Civil Engineering & Construction
	3,115,000	Manappuram General Finance		10,380
		Short-term Lending Collateralized by Household Gold
				213,578
		>Hong Kong 3.1%
	22,154,200	Lifestyle International		54,439
		Mid- to High-end Department Store Operator in Hong Kong & China

Number of Shares			Value (000)
	7,000,000	Melco Crown Entertainment - ADR (a)(b)	$	44,520
		Macau Casino Operator
	10,500,000	L'Occitane International (a)		29,044
		Skin Care & Cosmetics Producer
	23,335,500	Mongolian Mining (a)		27,230
		Coking Coal Mining in Mongolia
	750,000	Hong Kong Exchanges and Clearing		17,011
		Hong Kong Equity & Derivatives Market Operator
	23,470,900	Sa Sa International		14,615
		Chinese Discount Cosmetics Retailer
				186,859
		>South Korea 2.0%
	304,000	NHN (a)		60,662
		South Korea's Largest Online Search Engine
	1,157,000	Woongjin Coway		41,054
		South Korean Household Appliance Rental Service Provider
	121,132	MegaStudy (a)		18,805
		Online Education Service Provider
	64,008	Taewoong (a)		2,648
		Niche Custom Forging
				123,169
		>Taiwan 1.7%
	7,200,000	Simplo Technology		52,352
		World's Largest Notebook Battery Pack Supplier
	1,599,620	Formosa International Hotels		28,310
		Hotel, Food & Beverage Operation & Hospitality Management Services
	7,206,000	Everlight Electronics		20,859
		LED Packager
				101,521
		>Thailand 0.1%
	31,101,200	Home Product Center		9,079
		DIY Home Improvement Retailer
				9,079
Asia: Total				2,313,194
Europe 35.5%
		>United Kingdom 6.8%
	6,700,000	Serco		58,027
		Facilities Management
	2,000,000	Intertek Group		55,348
		Testing, Inspection & Certification Services
	964,000	Chemring		43,646
		Defense Manufacturer of Countermeasures & Energetics
	1,976,000	Petropavlovsk		35,244
		Gold & Iron Ore Mining in Russia
	8,873,000	Cobham		28,152
		Aerospace Components
	24,346,593	Archipelago Resources (a)		23,155
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
	60,304,000	Workspace Group (d)		22,095
		United Kingdom Real Estate

See accompanying notes to financial statements.

40

Number of Shares			Value (000)
		>United Kingdom—continued
	682,000	Rotork	$	19,437
		Valve Actuators for Oil & Water Pipelines
	4,600,000	RPS Group		16,524
		Environmental Consulting & Planning
	3,262,210	Abcam		16,276
		Online Sales of Antibodies
	1,426,274	JLT Group		13,987
		International Business Insurance Broker
	690,000	Tullow Oil		13,566
		Oil & Gas Producer
	2,195,200	Micro Focus		13,303
		United Kingdom Legacy Software Provider
	1,250,000	Smith & Nephew		13,184
		Medical Equipment & Supplies
	304,000	Premier Oil (a)		9,242
		Oil & Gas Producer in Europe, Pakistan & Asia
	3,500,000	PureCircle (a)(b)		9,031
		Natural Sweeteners
	1,731,900	FlyBe (a)		8,573
		Largest European Regional Airline
	1,650,000	SKIL Ports & Logistics (a)		6,316
		Indian Container Port Project
	1,549,500	Sterling Resources (a)		5,377
	1,050,500	Sterling Resources (a)(e)		3,572
		Oil & Gas Exploration - Europe
				414,055
		>Netherlands 6.5%
	1,922,517	Imtech		72,936
		Electromechanical & Information & Communications Technologies Installation & Maintenance
	763,202	Fugro		62,722
		Sub-sea Oilfield Services
	1,040,200	Vopak		49,137
		World's Largest Operator of Petroleum & Chemical Storage Terminals
	1,476,800	Unit 4 Agresso (d)		47,807
		Business Software Development
	2,258,060	Aalberts Industries		47,600
		Flow Control & Heat Treatment
	1,240,557	Koninklijke TenCate		46,417
		Advanced Textiles & Industrial Fabrics
	1,164,669	Arcadis		27,104
		Engineering Consultants
	1,264,600	USG People (a)		25,686
		Temporary Staffing Services
	206,000	Core Laboratories		18,344
		Oil & Gas Reservoir Consulting
				397,753
		>France 4.7%
	590,000	Neopost		51,405
		Postage Meter Machines
	599,200	Eurofins Scientific		43,158
		Food, Pharmaceuticals & Materials Screening & Testing
	900,000	Saft		33,134
		Niche Battery Manufacturer

Number of Shares			Value (000)
	274,100	Rubis (b)	$	31,921
		Tank Storage & Liquefied Petroleum Gas Distribution
	322,200	Pierre & Vacances		25,997
		Vacation Apartment Lets
	539,000	Mersen		24,705
		Advanced Industrial Materials
	669,000	Teleperformance		22,573
		Call Center Operator
	460,000	Gemalto		19,575
		Smart Card Products & Solutions
	213,724	Norbert Dentressangle		18,935
		Leading European Logistics & Transport Group
	1,671,100	Hi-Media (a)(b)		7,816
		Online Advertiser in Europe
	372,000	Toreador Resources (a)(b)		5,774
		Drilling for Oil in France's Paris Basin
				284,993
		>Germany 3.5%
	305,000	Vossloh		38,949
		Rail Infrastructure & Diesel Locomotives
	610,000	CTS Eventim		37,668
		Event Ticket Sales
	365,000	Rheinmetall		29,355
		Defense & Automotive
	2,120,000	Wirecard (b)		29,041
		Online Payment Processing & Risk Management
	1,250,000	Rhoen-Klinikum		27,517
		Health Care Services
	110,000	Rational		24,282
		Commercial Ovens
	515,000	Elringklinger		18,226
		Automobile Components
	312,500	Deutsche Beteiligungs		8,769
		Private Equity Investment Management
				213,807
		>Switzerland 3.1%
	325,000	Kuehne & Nagel		45,152
		Freight Forwarding/Logistics
	185,000	Geberit		42,778
		Plumbing Supplies
	185,000	Partners Group		35,110
		Private Markets Asset Management
	15,500	Sika		34,017
		Chemicals for Construction & Industrial Applications
	720,000	Bank Sarasin & Cie		32,809
		Private Banking
				189,866
		>Sweden 2.5%
	4,382,000	Hexagon		93,982
		Measurement Equipment & Software
	3,887,000	Sweco		33,663
		Engineering Consultants
	1,078,000	East Capital Explorer (a)		13,587
		Sweden-based Russia/Central Eastern Europe Investment Fund

See accompanying notes to financial statements.

41

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		>Sweden—continued
	708,342	Orc Software (b)	$	13,457
		Software for Securities Trading, Analysis & Risk Management
				154,689
		>Italy 2.2%
	452,200	Tod's		44,693
		Leather Shoes & Bags
	2,083,000	Ansaldo STS		29,826
		Railway Systems Integrator
	4,311,600	Credito Emiliano		26,677
		Italian Regional Bank
	9,796,000	CIR (a)		17,998
		Italian Holding Company
	4,111,000	Terna		17,365
		Italian Power Transmission
				136,559
		>Ireland 1.1%
	12,110,000	United Drug (d)		33,983
		Irish Pharmaceutical Wholesaler & Outsourcer
	431,000	Paddy Power		17,682
		Irish Betting Services
	297,000	Aryzta (a)		13,887
		Baked Goods
				65,552
		>Finland 0.9%
	967,777	Stockmann (b)		36,603
		Department Store & Fashion Retailer in Scandinavia & Russia
	1,756,000	Poyry		21,468
		Engineering Consultants
				58,071
		>Denmark 0.9%
	306,000	Novozymes		42,639
		Industrial Enzymes
	74,296	SimCorp		11,920
		Software for Investment Managers
				54,559
		>Portugal 0.7%
	7,235,000	Redes Energéticas Nacionais		24,944
		Portuguese Power Transmission & Gas Transportation
	21,618,000	Banco Comercial Português		16,813
		Largest Portuguese Banking Franchise
				41,757
		>Iceland 0.5%
	35,369,999	Marel (a)		30,817
		Largest Manufacturer of Poultry & Fish Processing Equipment
				30,817
		>Russia 0.5%
	833,742	Mail.ru - GDR (a)(e)		30,015
		Internet Social Networking & Games for Russian Speakers
				30,015

Number of Shares			Value (000)
		>Czech Republic 0.5%
	121,268	Komercni Banka	$	28,697
		Leading Czech Republic Universal Bank
				28,697
		>Spain 0.4%
	579,000	Red Eléctrica de España		27,223
		Spanish Power Transmission
				27,223
		>Greece 0.3%
	6,475,300	Intralot		21,546
		Lottery & Gaming Systems & Services
				21,546
		>Poland 0.3%
	893,900	Central European Distribution (a)		20,470
		Largest Spirits Company in Central & Eastern Europe
				20,470
		>Norway 0.1%
	340,964	Atea		3,431
		Leading Nordic IT Hardware/Software Re-seller & Installation Company
				3,431
Europe: Total				2,173,860
Other Countries 14.5%
		>Canada 4.8%
	1,710,000	ShawCor		56,943
		Oil & Gas Pipeline Products
	850,000	Ivanhoe Mines (a)		19,662
	744,000	Ivanhoe Mines (a)(b)(f)		17,052
	850,000	Ivanhoe Mines - Rights (a)		1,146
	744,000	Ivanhoe Mines - Rights (a)(f)		1,042
		Copper Mine Project in Mongolia
	1,301,612	CCL Industries		38,775
		Leading Global Label Manufacturer
	735,000	Baytex		34,455
		Oil & Gas Producer in Canada
	540,000	AG Growth		27,193
		Leading Manufacturer of Augers & Grain Handling Equipment
	1,355,000	Guyana Goldfields (a)(e)		14,509
		Gold Mining Projects in Guyana
	753,000	Eldorado Gold		14,010
		Gold Miner in Turkey, Greece, China & Brazil
	872,700	Tahoe Resources (a)(e)		12,644
		Silver Project in Guatemala
	530,000	Black Diamond Group		11,466
		Provides Accommodations/Equipment for Oil Sands Exploitation
	1,350,000	DeeThree Exploration (a)(d)(e)		5,721
	1,042,877	DeeThree Exploration (a)(d)		4,510
		Canadian Oil & Gas Producer
	1,480,610	Pan Orient (a)		9,902
		Growth Oriented & Return Focused Asian Explorer
	12,500,000	Eacom Timber (a)(e)		8,008
		Canadian Lumber Producer

See accompanying notes to financial statements.

42

Number of Shares			Value (000)
		>Canada—continued
	2,214,100	Horizon North Logistics (a)	$	6,614
		Provides Diversified Oil Service Offering in Northern Canada
	12,500,000	Petromanas (a)(e)		4,866
	6,250,000	Petromanas - Warrants (a)(e)		739
		Exploring for Oil in Albania
	3,730,000	Bowood Energy (a)(e)		2,206
		Small E&P Targeting Alberta Bakken
	49,900	WestFire Energy (a)		346
		Oil Producer in Alberta & Saskatchewan
				291,809
		>United States 3.6%
	1,340,000	Atwood Oceanics (a)		50,076
		Offshore Drilling Contractor
	918,000	World Fuel Services		33,195
		Global Fuel Broker
	411,000	Alexion Pharmaceuticals (a)		33,106
		Biotech Focused on Orphan Diseases
	329,000	FMC Technologies (a)		29,251
		Oil & Gas Wellhead Manufacturer
	1,010,534	BioMarin Pharmaceutical (a)		27,214
		Biotech Focused on Orphan Diseases
	391,000	Bristow (a)		18,514
		Largest Provider of Helicopter Services to Offshore Oil & Gas Producers
	568,000	Textainer Group Holdings		16,182
		Top International Container Leasor
	187,600	Onex Capital		5,704
		Private Equity Firm
	324,000	Tesco (a)		5,145
		Developing New Well Drilling Technologies
	15,600	Sodastream (a)		492
		Home Beverage Carbonation System
				218,879
		>South Africa 3.0%
	1,644,000	Naspers		96,818
		Media in Africa, China, Russia & Other Emerging Markets
	4,600,000	Mr. Price		46,437
		South African Retailer of Apparel, Household & Sporting Goods
	5,780,900	Northam Platinum		39,753
		Platinum Mining in South Africa
				183,008
		>Australia 1.8%
	2,482,000	UGL		36,632
		Engineering & Facilities Management
	7,189,283	SAI Global		35,883
		Publishing, Certification & Compliance Services
	319,000	Cochlear		26,236
		Cochlear Implants
	6,152,918	Hastie Group		6,010
		Mechanical, Electrical & Hydraulic (MEH) Engineering
	731,000	Seek		4,957
		Online Job Listing & Education
				109,718

Number of Shares			Value (000)
		>Israel 0.8%
	2,890,000	Israel Chemicals	$	49,562
		Producer of Potash, Phosphates, Bromine & Specialty Chemicals
				49,562
		>Kazakhstan 0.3%
	1,770,000	Halyk Savings Bank of Kazakhstan - GDR (a)		17,789
		Largest Retail Bank & Insurer in Kazakhstan
				17,789
		>Senegal 0.2%
	43,000	Sonatel		13,490
		Leading Telecoms Operator in Western Africa
				13,490
		>Egypt —%
	220,342	Paints & Chemical Industries (Pachin)		2,050
		Paints & Inks in Egypt
				2,050
Other Countries: Total				886,305
Latin America 5.9%
		>Brazil 4.3%
	4,600,000	Localiza Rent A Car		74,558
		Car Rental
	5,937,000	Suzano		52,859
		Brazilian Pulp & Paper Producer
	1,300,000	Natura		37,358
		Direct Retailer of Cosmetics
	3,000,000	Mills Estruturas e Serviços de Engenharia		37,228
		Civil Engineering & Construction
	3,300,000	MRV Engenharia		31,046
		Brazilian Low-income Property Developer
	5,000,000	PDG Realty		30,614
		Brazilian Low-income Property Developer
				263,663
		>Chile 0.8%
	862,000	Sociedad Quimica y Minera de Chile - ADR		50,358
		Producer of Specialty Fertilizers, Lithium & Iodine
				50,358
		>Mexico 0.5%
	550,000	Grupo Aeroportuario del Sureste - ADR		31,048
		Mexican Airport Operator
				31,048
		>Argentina 0.3%
	6,818,182	Union Agriculture Group (a)(e)		15,000
		Farmland Operator in Uruguay
	5,400,000	Madalena Ventures (a)(e)		4,364
		Oil & Gas Exploration in Argentina
				19,364
Latin America: Total				364,433
Total Equities: 93.7% (Cost: $3,933,559)				5,737,792

See accompanying notes to financial statements.

43

Columbia Acorn International

Statement of Investments, continued

Number of Shares or Principal Amount (000)			Value (000)
Securities Lending Collateral: 0.9%
	53,018,320	Dreyfus Government Cash Management Fund (g) (7 day yield of 0.01%)	$	53,018
Total Securities Lending Collateral: (Cost: $53,018)				53,018
Short-Term Obligations: 5.2%
		>Repurchase Agreement 4.4%
$	270,852	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by U.S. Government Agency obligations with various maturities to 4/28/14, market value $276,271 (repurchase proceeds $270,856)		270,852
				270,852
		>Commercial Paper 0.8%
	29,300	Toyota Motor Credit 0.20% due 1/21/11		29,297
	20,500	ConocoPhillips (h) 0.24% due 1/18/11		20,498
				49,795
Total Short-Term Obligations: (Amortized Cost: $320,647)				320,647
Total Investments: 99.8% (Cost: $4,307,224)(i)(j)				6,111,457
Obligation to Return Collateral for Securities Loaned: (0.9)%				(53,018	)
Cash and Other Assets Less Liabilities: 1.1%				66,624
Total Net Assets: 100.0%			$	6,125,063

ADR = American Depositary Receipts

GDR = Global Depositary Receipts

See accompanying notes to financial statements.

44

> Notes to Statements of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  All or a portion of this security was on loan at December 31, 2010. The total market value of Fund securities on loan at December 31, 2010 was $51,194.

(c)  Illiquid security.

(d)  An affiliated person of the Fund may include any company in which the Fund owns five percent or more of its outstanding voting shares.

  Holdings and transactions in these affiliated companies during the year ended December 31, 2010, are as follows:

Affiliates	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
DeeThree Exploration		-		2,392,877		-		2,392,877	$	10,231	$	-
Koninklijke TenCate*		1,372,989		40,382		172,814		1,240,557		46,417		1,119
Nippon Residential Investment*		12,500		-		12,500		-		-		1,155
Unit 4 Aggresso		1,385,000		91,800		-		1,476,800		47,807		296
United Drug		8,100,000		4,010,000		-		12,110,000		33,983		-
Workspace Group		-		60,304,000		-		60,304,000		22,095		-
Total of Affiliated Transactions		10,870,489		66,839,059		185,314		77,524,234	$	160,533	$	2,570

*  At December 31, 2010, the Fund owned less than five percent of the company's outstanding voting shares.

  The aggregate cost and value of these affiliated companies at December 31, 2010, was $97,243 and $114,116, respectively. Investments in affiliated companies represented 1.9% of total net assets at December 31, 2010.

(e)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the market value of these securities amounted to $101,644, which represented 1.66% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Mail.ru - GDR	11/05/10-12/31/10		833,742	$	28,667	$	30,015
Union Agriculture Group	12/08/10		6,818,182		15,000		15,000
Guyana Goldfields	1/19/10		1,355,000		9,134		14,509
Tahoe Resources	5/28/10		872,700		4,984		12,644
Eacom Timber	3/17/10		12,500,000		6,188		8,008
DeeThree Exploration	9/07/10		1,350,000		3,525		5,721
Petromanas	5/20/10		12,500,000		4,344		4,866
Madalena Ventures	10/21/10		5,400,000		3,422		4,364
Sterling Resources	12/02/10		1,050,500		3,135		3,572
Bowood Energy	9/17/10		3,730,000		907		2,206
Petromanas - Warrants	5/20/10		6,250,000		362		739
				$	79,668	$	101,644

(f)  Security is traded on a U.S. exchange.

(g)  Investment made with cash collateral received from securities lending activity.

(h)  Security exempt from registration under Section 4(2) of the Securities Act of 1933. This security may only be resold in exempt transactions to qualified buyers. Private resales of this security to qualified institutional buyers are also exempt from registration pursuant to Rule 144A under the Securities Act of 1933. At December 31, 2010, this security had an aggregate value of $20,498, which represented 0.3% of total net assets.

(i)  At December 31, 2010, for federal income tax purposes, the cost of investments was $4,448,614 and net unrealized apppreciation was $1,662,843, consisting of gross unrealized appreciation of $1,863,992 and gross unrealized depreciation of $201,149.

(j)  On December 31, 2010, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Euro	$	1,223,144		20.0
Japanese Yen		1,007,007		16.6
U.S. Dollar		930,489		15.2
Hong Kong Dollar		442,033		7.2
British Pound		405,106		6.6
Other currencies less than 5% of total net assets		2,103,678		34.2
	$	6,111,457		99.8

See accompanying notes to financial statements.

45

Columbia Acorn International

Statement of Investments, continued

> Notes to Statements of Investments (dollar values in thousands)

  At December 31, 2010, the Fund had entered into the following forward foreign currency exchange contracts:

Forward Foreign Currency Exchange Contracts to Buy	Forward Foreign Currency Exchange Contracts to Sell	Principal Amount in Foreign Currency		Principal Amount in U.S. Dollar		Settlement Date	Unrealized Appreciation
AUD	USD		27,790	$	27,300	1/14/11	$	1,092
AUD	USD		9,746		9,700	1/14/11		257
AUD	USD		27,911		27,300	2/15/11		1,103
AUD	USD		9,785		9,700	2/15/11		257
AUD	USD		37,457		37,000	3/15/11		981
CAD	USD		28,726		28,500	1/14/11		385
CAD	USD		7,555		7,500	1/14/11		96
CAD	USD		28,839		28,500	2/15/11		480
CAD	USD		7,560		7,500	2/15/11		97
CAD	USD		36,310		36,000	3/15/11		462
USD	EUR		49,199		69,100	1/14/11		3,356
USD	EUR		15,632		20,900	1/14/11		11
USD	EUR		50,409		69,100	2/15/11		1,746
USD	EUR		15,634		20,900	2/15/11		10
USD	EUR		67,339		90,000	3/15/11		37
JPY	USD		1,082,620		13,300	1/14/11		36
JPY	USD		308,887		3,700	1/14/11		105
JPY	USD		1,094,723		13,300	2/15/11		189
JPY	USD		308,780		3,700	2/15/11		105
JPY	USD		1,418,327		17,000	3/15/11		482
				$	540,000		$	11,287

The counterparty for all forward foreign currency exchange contracts is State Street Bank and Trust Company.

AUD = Australian Dollar

CAD = Canadian Dollar

EUR = Euro

JPY = Japanese Yen

USD = United States Dollar

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Asia	$	136,758	$	2,176,357	$	79	$	2,313,194
Europe		79,980		2,093,880		-		2,173,860
Other Countries		461,995		424,310		-		886,305
Latin America		81,406		268,027		15,000		364,433
Total Equities		760,139		4,962,574		15,079		5,737,792
Total Securities Lending Collateral		53,018		-		-		53,018
Total Short-Term Obligations		-		320,647		-		320,647
Total Investments	$	813,157	$	5,283,221	$	15,079	$	6,111,457
Unrealized Appreciation on Forward Foreign Currency Exchange Contracts		-		11,287		-		11,287
Total	$	813,157	$	5,294,508	$	15,079	$	6,122,744

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sales price on the foreign exchange or market on which they trade. The Fund may use a systematic fair valuation model provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements. Forward foreign currency exchange contracts are valued at the prevailing forward exchange rate of the underlying currencies. Securities acquired via private placement that have a holding period or an extended settlement period are valued at a discount to the same shares that are trading freely on the market. These discounts are determined by the adviser's experience with similar securities or situations. Factors may include, but are not limited to, trade volume, shares outstanding and stock price.

See accompanying notes to financial statements.

46

> Notes to Statements of Investments (dollar values in thousands)

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities for which no market exists are valued based upon a market approach using some unobservable inputs which may include, but are not limited to, projected earnings, available cash, line of business, multiples, and consideration of the prioritization of the equity in a company's capital structure. Securities acquired via private placement that are not yet trading are valued using a market approach for which management has determined that the original transaction price is the best representation of fair value. The original cost may be adjusted for the market movement in an ind ex, ETF or similar security during the period it does not trade.

  The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Equities
Asia	$	158	$	-	$	(79	)	$	-	$	-	$	-	$	-	$	79
Latin America		-		-		-			15,000		-		-		-		15,000
	$	158	$	-	$	(79	)	$	15,000	$	-	$	-	$	-	$	15,079

  The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  The change in unrealized depreciation attributed to securities owned at December 31, 2010, which were valued using significant unobservable inputs (Level 3) amounted to $79. This amount is included in net change in unrealized appreciation (depreciation) on the Statements of Changes in Net Assets.

  The following table shows transfers between Level 1 and Level 2 of the fair value hierarchy.

Transfers In				Transfers Out
Level 1		Level 2		Level 1		Level 2
$	152,770	$	-	$	-	$	152,770

  Financial assets were transferred from Level 2 to Level 1 as they resumed trading during the period.

  For more information on valuation inputs, and their aggregation into the levels used in the tables above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

47

Columbia Acorn International

Portfolio Diversification

At December 31, 2010, the Fund's portfolio investments as a percent of net assets were diversified as follows:

	Value (000)		Percentage of Net Assets
> Industrial Goods & Services
Other Industrial Services	$	514,717		8.4
Machinery		398,588		6.5
Industrial Materials & Specialty Chemicals		396,880		6.5
Electrical Components		147,183		2.4
Construction		94,501		1.5
Outsourcing Services		83,714		1.4
Conglomerates		65,598		1.1
Industrial Distribution		17,571		0.3
		1,718,752		28.1
> Consumer Goods & Services
Food & Beverage		220,988		3.6
Nondurables		182,357		2.9
Retail		151,549		2.5
Travel		109,128		1.8
Casinos & Gaming		109,066		1.8
Other Consumer Services		107,658		1.8
Apparel		95,846		1.6
Educational Services		67,851		1.1
Other Entertainment		65,977		1.1
Consumer Electronics		19,606		0.3
		1,130,026		18.5
> Energy & Minerals
Mining		289,815		4.7
Oil Services		240,730		3.9
Oil & Gas Producers		104,641		1.7
Oil Refining, Marketing & Distribution		81,059		1.4
Agricultural Commodities		75,867		1.2
		792,112		12.9
> Information
Internet Related		209,518		3.4
Instrumentation		119,919		2.0
Computer Hardware & Related Equipment		105,132		1.7
Business Software		73,030		1.2
Financial Processors		72,296		1.2
Telephone and Data Services		36,063		0.6
Telecommunications Equipment		26,805		0.5
CATV		25,267		0.4
Semiconductors & Related Equipment		20,859		0.3
Gaming Equipment & Services		20,277		0.3
Mobile Communications		18,514		0.3
Computer Services		16,888		0.3
Business Information & Marketing Services		16,524		0.3
Advertising		7,816		0.1
		768,908		12.6

	Value (000)			Percentage of Net Assets
> Other Industries
Real Estate	$	383,090			6.2
Regulated Utilities		69,532			1.1
Transportation		168,276			2.8
		620,898			10.1
> Finance
Banks		170,084			2.8
Finance Companies		94,556			1.5
Brokerage & Money Management		90,275			1.5
Savings & Loans		17,883			0.3
Insurance		13,987			0.2
		386,785			6.3
> Health Care
Medical Equipment & Devices		189,782			3.1
Pharmaceuticals		59,522			1.0
Health Care Services		27,517			0.4
Biotechnology & Drug Delivery		27,214			0.4
Medical Supplies		16,276			0.3
		320,311			5.2
Total Equities:		5,737,792			93.7
Securities Lending Collateral:		53,018			0.9
Short-Term Obligations:		320,647			5.2
Total Investments:		6,111,457			99.8
Obligation to Return Collateral for Securities Loaned:		(53,018	)		(0.9	)
Cash and Other Assets Less Liabilities:		66,624			1.1
Net Assets:	$	6,125,063			100.0

See accompanying notes to financial statements.

48

Columbia Acorn USA

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Information
Applied Micro Circuits		0		448,000
Ariba		0		278,000
Concur Technologies		142,000		171,000
ExlService Holdings		310,000		372,800
Finisar		526,000		732,000
Infinera		114,000		402,000
Ixia		199,200		234,000
SPS Commerce		0		322,000
WMS Industries		73,000		150,000
Consumer Goods & Services
Avis Budget Group		717,950		1,175,950
Deckers Outdoor		0		40,000
Diamond Foods		162,000		197,000
Pier 1 Imports		540,000		805,000
Shutterfly		145,600		254,000
Warnaco Group		60,000		192,000
Industrial Goods & Services
Forward Air		66,350		109,000
HEICO		217,732		308,732
St. Joe		0		284,000
Finance
Associated Banc-Corp		453,400		692,400
First Busey		678,200		1,478,200
Textainer Group Holdings		0		165,000
Tower Group		120,000		222,000
Energy & Minerals
Houston American Energy		0		260,438
Swift Energy		0		84,000
Health Care
Akorn		137,682		481,782
BioMarin Pharmaceutical		266,000		344,394
Chelsea Therapeutics		460,728		600,000
Health Management Associates		0		653,900
Idenix Pharmaceuticals		450,000		530,282
InterMune		0		92,400
Isis Pharmaceuticals		437,000		626,000
Micromet		540,000		810,000
Nabi Biopharmaceuticals		0		191,040
Onyx Pharmaceuticals		117,000		190,000
Pacific Biosciences of California		0		95,200
Sirona Dental Systems		80,000		184,000
United Therapeutics		100,000		137,000
Other Industries
Associated Estates Realty		186,000		405,000
Rush Enterprises, Class A		180,000		210,091

	Number of Shares
	09/30/10		12/31/10
Sales
Information
Actuate		230,000		0
Art Technology Group		959,000		0
Avid Technology		100,000		0
Crown Castle International		383,000		250,000
Entegris		750,000		675,000
Equinix		79,188		44,000
Consumer Goods & Services
Charming Shoppes		670,861		0
Coldwater Creek		455,956		145,376
Dress Barn		90,000		0
J Crew Group		241,000		0
Jones Apparel Group		281,000		0
Finance
Delphi Financial Group		110,000		0
Green Bankshares		264,703		247,500
H&E Equipment Services		542,600		201,000
Health Care
Acorda Therapeutics		196,000		122,900
Amylin Pharmaceuticals		145,000		0
Human Genome Sciences		59,000		0
Nektar Therapeutics		431,000		363,000
Orthofix International		165,000		0
PSS World Medical		467,300		0
Other Industries
Macerich		212,619		98,619
SL Green Realty		359,000		0

See accompanying notes to financial statements.

49

Columbia Acorn USA

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 99.6%
Information 33.5%
		> Business Software 8.7%
	985,000	Informatica (a)	$	43,370
		Enterprise Data Integration Software
	698,000	Micros Systems (a)		30,614
		Information Systems for Hotels, Restaurants & Retailers
	375,000	ANSYS (a)		19,526
		Simulation Software for Engineers & Designers
	370,000	Blackbaud		9,583
		Software & Services for Non-profits
	171,000	Concur Technologies (a)		8,880
		Web Enabled Cost & Expense Management Software
	278,000	Ariba (a)		6,530
		Cost Management Software
	110,000	Advent Software (a)		6,371
		Asset Management & Trading Systems
	135,000	Blackboard (a)(b)		5,575
		Education Software
	322,000	SPS Commerce (a)		5,088
		Supply Chain Management Software Delivered via the Web
	157,000	Jack Henry & Associates		4,577
	��	Systems Financial Institutions
	132,000	Constant Contact (a)		4,091
		E-mail & Other Marketing Campaign Management Systems Delivered Over the Web
	52,000	Quality Systems		3,631
		IT Systems for Medical Groups & Ambulatory Care Centers
				147,836
		> Semiconductors & Related Equipment 4.7%
	1,958,000	Atmel (a)		24,123
		Microcontrollers, Radio Frequency & Memory Semiconductors
	760,000	Microsemi (a)		17,404
		Analog/Mixed-signal Semiconductors
	1,061,750	ON Semiconductor (a)		10,490
		Mixed-signal & Power Management Semiconductors
	287,000	Supertex (a)		6,940
		Analog/Mixed-signal Semiconductors
	346,000	Monolithic Power Systems (a)		5,716
		High Performance Analog & Mixed-signal Integrated Circuits (ICs)
	675,000	Entegris (a)		5,042
		Semiconductor Materials Management Products
	448,000	Applied Micro Circuits (a)		4,785
		Communications Semiconductors
	430,000	Pericom Semiconductor (a)		4,721
		Interface Integrated Circuits (ICs) & Frequency Control Products
				79,221
		> Computer Hardware & Related Equipment 4.1%
	549,000	II-VI (a)		25,452
		Laser Optics & Specialty Materials

Number of Shares			Value (000)
	285,600	Amphenol	$	15,074
		Electronic Connectors
	324,000	Zebra Technologies (a)		12,309
		Bar Code Printers
	280,000	Nice Systems - ADR (Israel) (a)		9,772
		Audio & Video Recording Solutions
	196,000	Netgear (a)		6,601
		Networking Products for Small Business & Home
				69,208
		> Instrumentation 3.3%
	180,000	Mettler Toledo (a)		27,218
		Laboratory Equipment
	575,000	IPG Photonics (a)		18,181
		Fiber Lasers
	168,000	Trimble Navigation (a)		6,708
		GPS-based Instruments
	130,000	FLIR Systems (a)		3,868
		Infrared Cameras
				55,975
		> Telecommunications Equipment 3.0%
	732,000	Finisar (a)		21,733
		Optical Sub-systems & Components
	386,000	Polycom (a)		15,046
		Video Conferencing Equipment
	197,000	Blue Coat Systems (a)		5,884
		WAN Acceleration & Network Security
	402,000	Infinera (a)		4,153
		Optical Networking Equipment
	234,000	Ixia (a)		3,927
		Telecom Network Test Equipment
				50,743
		> Telephone and Data Services 2.7%
	1,617,000	tw telecom (a)		27,570
		Fiber Optic Telephone/Data Services
	177,000	AboveNet		10,347
		Metropolitan Fiber Communications Services
	2,030,000	PAETEC Holding (a)		7,592
		Telephone/Data Services for Business
				45,509
		> Mobile Communications 2.1%
	595,000	SBA Communications (a)		24,359
		Communications Towers
	250,000	Crown Castle International (a)		10,957
		Communications Towers
	88,000	Globalstar (a)		128
		Satellite Mobile Voice & Data Carrier
				35,444
		> Gaming Equipment & Services 1.8%
	570,000	Bally Technologies (a)		24,048
		Slot Machines & Software
	150,000	WMS Industries (a)		6,786
		Slot Machine Provider
				30,834
		> Computer Services 1.6%
	372,800	ExlService Holdings (a)		8,008
		BPO (Business Process Outsourcing)

See accompanying notes to financial statements.

50

Number of Shares			Value (000)
		> Computer Services—continued
	261,000	SRA International (a)	$	5,338
		Government IT Services
	235,000	iGate		4,632
		IT & BPO (Business Process Outsourcing) Services
	1,005,500	Hackett Group (a)		3,529
		IT Integration & Best Practice Research
	710,000	RCM Technologies (a)(c)		3,294
		Technology & Engineering Services
	172,000	Acxiom (a)		2,950
		Database Marketing Services
				27,751
		> Financial Processors 0.5%
	188,000	Global Payments		8,687
		Credit Card Processor
				8,687
		> Contract Manufacturing 0.5%
	261,000	Plexus (a)		8,075
		Electronic Manufacturing Services
				8,075
		> Internet Related 0.3%
	44,000	Equinix (a)		3,575
		Network Neutral Data Centers
	343,000	TheStreet.com		916
		Financial Information Websites
				4,491
		> Radio 0.1%
	511,100	Salem Communications		1,620
		Radio Stations for Religious Programming
	705,500	Spanish Broadcasting System (a)		499
		Spanish Language Radio Stations
	18,750	Saga Communications (a)		494
		Radio Stations in Small & Mid-sized Cities
				2,613
		> TV Broadcasting 0.1%
	975,000	Entravision Communications (a)		2,506
		Spanish Language TV & Radio Stations
				2,506
Information: Total				568,893
Consumer Goods & Services 17.5%
		> Retail 5.9%
	390,000	lululemon athletica (a)(b)		26,684
		Premium Active Apparel Retailer
	401,000	Abercrombie & Fitch		23,110
		Teen Apparel Retailer
	875,000	Saks (a)		9,362
		Luxury Department Store Retailer
	254,000	Shutterfly (a)		8,898
		Internet Photo-centric Retailer
	805,000	Pier 1 Imports (a)		8,452
		Home Furnishing Retailer
	614,000	Chico's FAS		7,386
		Women's Specialty Retailer

Number of Shares			Value (000)
	205,000	Urban Outfitters (a)	$	7,341
		Apparel & Home Specialty Retailer
	480,000	Talbots (a)		4,090
		Women's Specialty Retailer
	620,000	Wet Seal (a)		2,294
		Specialty Apparel Retailer
	104,508	Express		1,965
		Dual Gender Fashion Retailer
	145,376	Coldwater Creek (a)		461
		Women's Apparel Retailer
	9,000	The Fresh Market (a)		371
		Specialty Food Retailer
				100,414
		> Travel 3.8%
	739,700	Gaylord Entertainment (a)		26,585
		Convention Hotels
	1,175,950	Avis Budget Group (a)		18,298
		Second Largest Car Rental Company
	750,000	Hertz (a)		10,867
		Largest U.S. Rental Car Operator
	150,000	Vail Resorts (a)		7,806
		Ski Resort Operator & Developer
				63,556
		> Furniture & Textiles 1.9%
	980,000	Knoll		16,395
		Office Furniture
	540,000	Interface		8,451
		Modular & Broadloom Carpet
	260,000	Herman Miller		6,578
		Office Furniture
				31,424
		> Casinos & Gaming 1.2%
	372,000	Penn National Gaming (a)		13,076
		Regional Casino Operator
	455,000	Pinnacle Entertainment (a)		6,379
		Regional Casino Operator
				19,455
		> Apparel 1.1%
	192,000	Warnaco Group (a)		10,573
		Global Branded Apparel Manufacturer
	241,530	True Religion Apparel (a)		5,377
		Premium Denim
	40,000	Deckers Outdoor (a)		3,190
		Fashion Footwear Wholesaler
				19,140
		> Educational Services 0.8%
	153,700	ITT Educational Services (a)		9,789
		Post-secondary Degree Services
	165,000	Universal Technical Institute		3,633
		Vocational Training
				13,422
		> Other Durable Goods 0.7%
	161,000	Cavco Industries (a)		7,517
		Manufactured Homes
	140,000	Jarden		4,322
		Branded Household Products
				11,839

See accompanying notes to financial statements.

51

Columbia Acorn USA

Statement of Investments, continued

Number of Shares			Value (000)
		> Consumer Goods Distribution 0.6%
	472,000	Pool	$	10,639
		Distributor of Swimming Pool Supplies & Equipment
				10,639
		> Other Consumer Services 0.6%
	259,000	Lifetime Fitness (a)		10,616
		Sport & Fitness Club Operator
				10,616
		> Food & Beverage 0.6%
	197,000	Diamond Foods		10,476
		Culinary Ingredients & Snack Foods
				10,476
		> Leisure Products 0.3%
	162,000	Thor Industries		5,502
		RV & Bus Manufacturer
				5,502
		> Restaurants —%
	26,600	Bravo Brio Restaurant Group (a)		510
		Upscale Casual Italian Restaurants
				510
Consumer Goods & Services: Total				296,993
Industrial Goods & Services 15.2%
		> Machinery 10.9%
	941,250	Ametek		36,944
		Aerospace/Industrial Instruments
	373,600	Nordson		34,326
		Dispensing Systems for Adhesives & Coatings
	445,000	Donaldson		25,935
		Industrial Air Filtration
	587,000	ESCO Technologies		22,212
		Automatic Electric Meter Readers
	585,000	Pentair		21,358
		Pumps & Water Treatment
	308,732	HEICO		11,522
		FAA Approved Aircraft Replacement Parts
	195,000	MOOG (a)		7,761
		Motion Control Products for Aerospace, Defense & Industrial Markets
	177,000	Kennametal		6,985
		Consumable Cutting Tools
	111,000	WABCO Holdings (a)		6,763
		Truck & Bus Component Supplier
	162,000	Oshkosh (a)		5,709
		Specialty Truck Manufacturer
	71,800	Toro		4,426
		Turf Maintenance Equipment
	50,000	Kaydon		2,036
		Specialized Friction & Motion Control Products
				185,977
		> Electrical Components 1.0%
	280,000	Acuity Brands		16,148
		Commercial Lighting Fixtures
				16,148

Number of Shares			Value (000)
		> Industrial Materials & Specialty Chemicals 0.8%
	326,000	Drew Industries	$	7,407
		RV & Manufactured Home Components
	135,000	Albany International		3,198
		Paper Machine Clothing & Advanced Textiles
	54,000	Albemarle		3,012
		Refinery Catalysts & Other Specialty Chemicals
				13,617
		> Other Industrial Services 0.6%
	265,000	TrueBlue (a)		4,767
		Temporary Manual Labor
	109,000	Forward Air		3,093
		Freight Transportation Between Airports
	396,000	American Reprographics (a)		3,006
		Document Management & Logistics
				10,866
		> Steel 0.6%
	486,000	GrafTech International (a)		9,642
		Industrial Graphite Materials Producer
				9,642
		> Industrial Distribution 0.5%
	350,000	Interline Brands (a)		7,970
		Industrial Distribution
				7,970
		> Construction 0.4%
	284,000	St. Joe (a)(b)		6,205
		Florida Panhandle Landowner
				6,205
		> Waste Management 0.3%
	195,000	Waste Connections		5,368
		Solid Waste Management
				5,368
		> Water 0.1%
	550,000	Mueller Water Products		2,294
		Fire Hydrants, Valves & Ductile Iron Pipes
				2,294
Industrial Goods & Services: Total				258,087
Finance 11.0%
		> Banks 5.6%
	981,941	Valley National Bancorp		14,042
		New Jersey/New York Bank
	692,400	Associated Banc-Corp		10,490
		Midwest Bank
	659,800	TCF Financial		9,772
		Great Lakes Bank
	431,597	Lakeland Financial		9,262
		Indiana Bank
	532,000	MB Financial		9,214
		Chicago Bank
	170,000	SVB Financial Group (a)		9,018
		Bank to Venture Capitalists
	571,000	Whitney Holding		8,080
		Gulf Coast Bank

See accompanying notes to financial statements.

52

Number of Shares			Value (000)
		> Banks—continued
	1,478,200	First Busey	$	6,948
		Illinois Bank
	527,700	Pacific Continental		5,309
		Pacific Northwest Bank
	269,600	Eagle Bancorp (a)		3,890
		Metro D.C. Bank
	178,826	Sandy Spring Bancorp		3,296
		Baltimore/D.C. Bank
	210,000	CVB Financial (b)		1,821
		Inland Empire Business Bank
	90,000	TriCo Bancshares		1,453
		California Central Valley Bank
	851,247	Guaranty Bancorp (a)		1,200
		Colorado Bank
	245,000	Wilmington Trust		1,063
		Delaware Trust Bank
	247,500	Green Bankshares (a)(b)		792
		Tennessee Bank
				95,650
		> Finance Companies 3.3%
	345,000	World Acceptance (a)		18,216
		Personal Loans
	335,418	McGrath Rentcorp		8,795
		Temporary Space & IT Rentals
	240,000	GATX		8,467
		Rail Car Lessor
	412,500	Aaron Rents		8,411
		Rent to Own
	165,000	Textainer Group Holdings		4,701
		Top International Container Leasor
	230,000	CAI International (a)		4,508
		International Container Leasing
	201,000	H&E Equipment Services (a)		2,325
		Heavy Equipment Leasing
	99,200	Marlin Business Services (a)		1,255
		Small Equipment Leasing
				56,678
		> Brokerage & Money Management 1.0%
	209,500	Eaton Vance		6,333
		Specialty Mutual Funds
	675,000	MF Global (a)		5,643
		Futures Broker
	140,000	Investment Technology Group (a)		2,292
		Electronic Trading
	173,073	Kaiser Federal Financial Group		2,004
		Los Angeles Savings & Loan
				16,272
		> Savings & Loans 0.8%
	756,000	ViewPoint Financial		8,838
		Texas Thrift
	215,000	Berkshire Hills Bancorp		4,751
		Northeast Thrift
				13,589

Number of Shares			Value (000)
		> Insurance 0.3%
	222,000	Tower Group	$	5,679
		Commercial & Personal Lines Insurance
				5,679
Finance: Total				187,868
Energy & Minerals 8.5%
		> Oil Services 4.8%
	500,000	FMC Technologies (a)		44,455
		Oil & Gas Wellhead Manufacturer
	755,000	Atwood Oceanics (a)		28,215
		Offshore Drilling Contractor
	95,000	Bristow (a)		4,498
		Largest Provider of Helicopter Services to Offshore Oil & Gas Producers
	104,000	Exterran Holdings (a)		2,491
		Natural Gas Compressor Rental & Fabrication
	106,000	Tesco (a)		1,683
		Developing New Well Drilling Technologies
				81,342
		> Oil & Gas Producers 2.9%
	1,135,000	Quicksilver Resources (a)		16,730
		Natural Gas & Coal Steam Gas Producer
	133,000	SM Energy		7,838
		Oil & Gas Producer
	230,000	Northern Oil & Gas (a)		6,258
		Small E&P Company in North Dakota Bakken
	162,000	Carrizo Oil & Gas (a)		5,587
		Oil & Gas Producer
	129,000	Rosetta Resources (a)		4,856
		Oil & Gas Producer Exploring in South Texas & Montana
	260,438	Houston American Energy (b)		4,711
		Oil & Gas Exploration & Production in Colombia
	84,000	Swift Energy (a)		3,289
		Oil & Gas Exploration & Production Co.
	22,800	Oasis Petroleum (a)		618
		Oil Producer in North Dakota
				49,887
		> Mining 0.8%
	100,000	Core Laboratories (Netherlands)		8,905
		Oil & Gas Reservoir Consulting
	393,000	Alexco Resource (a)		3,218
		Mining, Exploration & Environmental Services
	180,000	Augusta Resource (a)		686
		U.S. Copper/Molybdenum Mine
				12,809
Energy & Minerals: Total				144,038
Health Care 8.1%
		> Biotechnology & Drug Delivery 4.8%
	344,394	BioMarin Pharmaceutical (a)		9,275
		Biotech Focused on Orphan Diseases
	137,000	United Therapeutics (a)		8,661
		Biotech Focused on Rare Diseases
	491,882	Seattle Genetics (a)		7,354
		Antibody-based Therapies for Cancer

See accompanying notes to financial statements.

53

Columbia Acorn USA

Statement of Investments, continued

Number of Shares			Value (000)
		> Biotechnology & Drug Delivery—continued
	190,000	Onyx Pharmaceuticals (a)	$	7,005
		Commercial-stage Biotech Focused on Cancer
	810,000	Micromet (a)		6,577
		Next-generation Antibody Technology
	626,000	Isis Pharmaceuticals (a)		6,335
		Biotech Pioneer in Anti-sense Drugs
	1,055,000	Allos Therapeutics (a)		4,864
		Cancer Drug Development
	600,000	NPS Pharmaceuticals (a)		4,740
		Orphan Drugs & Healthy Royalties
	363,000	Nektar Therapeutics (a)		4,665
		Drug Delivery Technologies
	600,000	Chelsea Therapeutics (a)		4,500
		Biotech Focused on Rare Diseases
	205,000	Auxilium Pharmaceuticals (a)(b)		4,325
		Biotech Focused on Niche Disease Areas
	92,400	InterMune (a)		3,363
		Drugs for Pulmonary Fibrosis & Hepatitis C
	122,900	Acorda Therapeutics (a)		3,350
		Biopharma Company Focused on Nervous Disorder Drugs
	530,282	Idenix Pharmaceuticals (a)		2,673
		Developer of Drugs for Infectious Diseases
	450,000	Array Biopharma (a)		1,345
		Drugs for Cancer & Inflammatory Diseases
	191,040	Nabi Biopharmaceuticals (a)		1,106
		Biotech Focused on Vaccines
	220,000	Anthera Pharmaceuticals (a)		1,074
		Biotech Focused on Cardiovascular, Cancer & Immunology
	18,181	Metabolex, Series A-1 (a)(d)		18
		Diabetes Drug Development
	738,060	Medicure - Warrants (a)(d)		2
		Cardiovascular Biotech Company
	37,500	Locus Pharmaceuticals, Series A-1, Pfd. (a)(d)		1
	19,329	Locus Pharmaceuticals, Series B-1, Pfd. (a)(d)		1
		High Throughput Rational Drug Design
	100,000	IsoRay - Warrants (a)(d)		1
		Radiology Cancer Company
				81,235
		> Medical Equipment & Devices 2.1%
	185,000	Alexion Pharmaceuticals (a)		14,902
		Biotech Focused on Orphan Diseases
	184,000	Sirona Dental Systems (a)		7,687
		Manufacturer of Dental Equipment
	76,000	Gen-Probe (a)		4,435
		Molecular In-vitro Diagnostics
	53,000	Idexx Laboratories (a)		3,669
		Diagnostic Equipment & Services for Veterinarians
	25,000	Illumina (a)		1,583
		Leading Tools & Service Provider for Genetic Analysis
	95,200	Pacific Biosciences of California (a)		1,515
		Genome Sequencing

Number of Shares			Value (000)
	72,000	American Medical Systems (a)	$	1,358
		Medical Devices to Treat Urological Conditions
	246,834	Nanosphere (a)		1,076
		Molecular Diagnostics Company with Best of Breed Platform
				36,225
		> Health Care Services 0.6%
	653,900	Health Management Associates (a)		6,238
		Non-urban Hospitals
	45,000	Mednax (a)		3,028
		Physician Management for Pediatric & Anesthesia Practices
				9,266
		> Medical Supplies 0.4%
	295,600	Cepheid (a)		6,725
		Molecular Diagnostics
	11,800	Neogen (a)		484
		Food & Animal Safety Products
				7,209
		> Pharmaceuticals 0.2%
	481,782	Akorn (a)		2,924
		Develops, Manufactures & Sells Specialty Generic Drugs
	54,800	Alimera Sciences (a)		569
		Ophthalmogy-focused Pharmaceutical Company
				3,493
Health Care: Total				137,428
Other Industries 5.8%
		> Real Estate 4.8%
	995,200	BioMed Realty Trust		18,560
		Life Science-focused Office Buildings
	915,000	Extra Space Storage		15,921
		Self Storage Facilities
	246,000	Corporate Office Properties		8,598
		Office Buildings
	1,450,000	Kite Realty Group		7,845
		Community Shopping Centers
	177,000	Kilroy Realty		6,455
		Southern California Office & Industrial Properties
	405,000	Associated Estates Realty		6,192
		Multi-family Properties
	1,058,000	DCT Industrial Trust		5,618
		Industrial Properties
	98,619	Macerich		4,672
		Regional Shopping Malls
	191,000	Dupont Fabros Technology		4,063
		Technology-focused Office Buildings
	400,000	Education Realty Trust		3,108
		Student Housing
				81,032
		> Transportation 1.0%
	210,091	Rush Enterprises, Class A (a)		4,294
	115,000	Rush Enterprises, Class B (a)		2,068
		Truck Sales & Services

See accompanying notes to financial statements.

54

Number of Shares or Principal Amount (000)			Value (000)
		> Transportation—continued
	156,000	World Fuel Services	$	5,641
		Global Fuel Broker
	310,000	Heartland Express		4,966
		Regional Trucker
				16,969
Other Industries: Total				98,001
Total Equities: 99.6% (Cost: $1,177,142)				1,691,308
Securities Lending Collateral: 0.9%
	15,767,797	Dreyfus Government Cash Management Fund (e) (7 day yield of 0.01%)		15,768
Total Securities Lending Collateral: (Cost: $15,768)				15,768
Short-Term Obligation: 1.1%
		> Repurchase Agreement: 1.1%
$	18,498	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by a U.S. Government Agency obligation maturing 4/28/14, market value $18,869 (repurchase proceeds $18,498)		18,498
Total Short Term Obligation: (Cost: $18,498)				18,498
Total Investments: 101.6% (Cost: $1,211,408)(f)				1,725,574
Obligation to Return Collateral for Securities Loaned: (0.9)%				(15,768	)
Cash and Other Assets Less Liabilities: (0.7)%				(11,260	)
Total Net Assets: 100.0%			$	1,698,546

ADR = American Depositary Receipts.

See accompanying notes to financial statements.

55

Columbia Acorn USA

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  All or a portion of this security was on loan at December 31, 2010. The total market value of Fund securities on loan at December 31, 2010 was $15,262.

(c)  An affiliated person of the Fund may include any company in which the Fund owns five percent or more of its outstanding voting shares.

  Holdings and transactions in these affiliated companies during the year ended December 31, 2010, are as follows:

Affiliate	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
Cavco Industries*		327,900		-		166,900		161,000	$	7,517	$	-
RCM Technologies		786,000		-		76,000		710,000		3,294		-
Total of Affiliated Transactions		1,113,900		-		242,900		871,000	$	10,811	$	-

*   At December 31, 2010, the Fund owned less than five percent of the company's outstanding voting shares.

  The aggregate cost and value of this affiliated company at December 31, 2010, were $4,479 and $3,294, respectively. Investments in the affiliated company represented 0.2% of total net assets at December 31, 2010.

(d)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the market value of these securities amounted to $23, which represented less than 0.01% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Metabolex, Series A-1	2/11/00		18,181	$	2,000	$	18
Medicure - Warrants	12/22/06		738,060		-		2
IsoRay - Warrants	3/21/07		100,000		-		1
Locus Pharmaceuticals, Series A-1 Pfd.	9/05/01		37,500		1,500		1
Locus Pharmaceuticals, Series B-1 Pfd.	2/08/07		19,329		56		1
				$	3,556	$	23

(e)  Investment made with cash collateral received from securities lending activity.

(f)  At December 31, 2010, for federal income tax purposes, the cost of investments was $1,211,741 and net unrealized appreciation was $513,833, consisting of gross unrealized appreciation of $618,098 and gross unrealized depreciation of $104,265.

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Information	$	568,893	$	-	$	-	$	568,893
Consumer Goods & Services		296,993		-		-		296,993
Industrial Goods & Services		258,087		-		-		258,087
Finance		187,868		-		-		187,868
Energy & Minerals		144,038		-		-		144,038
Health Care		137,405		3		20		137,428
Other Industries		98,001		-		-		98,001
Total Equities		1,691,285		3		20		1,691,308
Total Securities Lending Collateral		15,768		-		-		15,768
Total Short-Term Obligation		-		18,498		-		18,498
Total Investments	$	1,707,053	$	18,501	$	20	$	1,725,574

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Warrants which do not trade are valued as a percentage of the actively trading common stock using a model based on Black Scholes.

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

See accompanying notes to financial statements.

56

> Notes to Statement of Investments (dollar values in thousands)

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities for which no market exists are valued based upon a market approach using some unobservable inputs which may include, but are not limited to, projected earnings, available cash, line of business, multiples, and consideration of the prioritization of the equity in a company's capital structure.

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

  The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sells		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Equities
Health Care	$	25	$	-	$	(5	)	$	-	$	-	$	-	$	-	$	20
	$	25	$	-	$	(5	)	$	-	$	-	$	-	$	-	$	20

  The information in the above reconciliation represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  The change in unrealized depreciation attributed to securities owned at December 31, 2010, which were valued using significant unobservable inputs (Level 3) amounted to $5. This amount is included in net change in unrealized appreciation on the Statement of Changes in Net Assets.

  For more information on valuation inputs, and their aggregation into the levels used in the tables above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

57

Columbia Acorn International Select

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Europe
> United Kingdom
Archipelago Resources		0		422,600
Chemring		207,000		286,000
JLT Group		0		360,308
> Netherlands
Aalberts Industries		0		238,000
AkzoNobel		0		74,000
> Germany
Rheinmetall		0		67,000
> France
Neopost		101,355		126,000
> Ireland
United Drug		2,860,000		3,213,000
> Iceland
Marel		0		4,800,000
> Russia
Mail.ru - GDR		0		107,000
Asia
> Japan
Asahi Diamond Industrial		140,100		241,000
Gree		265,000		396,000
Kansai Paint		1,879,000		1,932,000
> Hong Kong
Mongolian Mining		0		1,555,500
Latin America
> Argentina
Union Agriculture Group		0		1,000,000

	Number of Shares
	09/30/10		12/31/10
Sales
Europe
> United Kingdom
Cobham		3,145,000		2,287,000
Intertek Group		530,000		412,000
Micro Focus		1,280,000		553,600
Serco		2,300,000		2,139,000
> Netherlands
Core Laboratories		82,000		51,000
> Spain
Red Eléctrica de España		127,000		93,000
Asia
> Japan
Ain Pharmaciez		164,000		110,000
Kamigumi		242,400		0
Rohto Pharmaceutical		343,300		0
> China
Jiangsu Expressway		17,450,000		14,649,000
Zhaojin Mining Industry		5,515,200		2,876,700
> Singapore
Olam International		4,100,000		3,750,000
Other Countries
> Canada
Eldorado Gold		243,250		0
Pan American Silver		548,000		287,000
> South Africa
Naspers		287,000		271,000
Latin America
> Columbia
Pacific Rubiales Energy		615,000		525,000

See accompanying notes to financial statements.

58

Columbia Acorn International Select

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 94.8%
Europe 43.7%
		> United Kingdom 16.0%
	2,139,000	Serco	$	18,525
		Facilities Management
	286,000	Chemring		12,949
		Defense Manufacturer of Countermeasures & Energetics
	412,000	Intertek Group		11,402
		Testing, Inspection & Certification Services
	568,000	Petropavlovsk		10,131
		Gold & Iron Ore Mining in Russia
	2,287,000	Cobham		7,256
		Aerospace Components
	13,467,511	Workspace Group		4,934
		United Kingdom Real Estate
	360,308	JLT Group		3,534
		International Business Insurance Broker
	553,600	Micro Focus		3,355
		United Kingdom Legacy Software Provider
	422,600	Archipelago Resources (a)		402
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
				72,488
		> Netherlands 8.5%
	175,427	Fugro		14,417
		Sub-sea Oilfield Services
	258,904	Imtech		9,822
		Electromechanical & Information & Communications Technologies Installation & Maintenance
	238,000	Aalberts Industries		5,017
		Flow Control & Heat Treatment
	74,000	AkzoNobel		4,597
		Largest Global Supplier of Protective Paints & Coatings
	51,000	Core Laboratories		4,542
		Oil & Gas Reservoir Consulting
				38,395
		> Germany 4.2%
	672,000	Wirecard		9,205
		Online Payment Processing & Risk Management
	67,000	Rheinmetall		5,389
		Defense & Automotive
	200,000	Rhoen-Klinikum		4,403
		Health Care Services
				18,997
		> Sweden 4.0%
	836,666	Hexagon		17,944
		Measurement Equipment & Software
				17,944
		> Switzerland 2.9%
	51,000	Kuehne & Nagel		7,085
		Freight Forwarding/Logistics
	135,900	Bank Sarasin & Cie		6,193
		Private Banking
				13,278

Number of Shares			Value (000)
		> France 2.4%
	126,000	Neopost	$	10,978
		Postage Meter Machines
				10,978
		> Ireland 2.0%
	3,213,000	United Drug		9,016
		Irish Pharmaceutical Wholesaler & Outsourcer
				9,016
		> Spain 1.0%
	93,000	Red Eléctrica de España		4,373
		Spanish Power Transmission
				4,373
		> Iceland 0.9%
	4,800,000	Marel (a)		4,182
		Largest Manufacturer of Poultry & Fish Processing Equipment
				4,182
		> Denmark 0.9%
	29,000	Novozymes		4,041
		Industrial Enzymes
				4,041
		> Russia 0.9%
	107,000	Mail.ru - GDR (a)(b)		3,852
		Internet Social Networking & Games for Russian Speakers
				3,852
Europe: Total				197,544
Asia 32.1%
		> Japan 14.4%
	1,932,000	Kansai Paint		18,693
		Paint Producer in Japan, India, China & Southeast Asia
	4,450	Seven Bank		9,421
		ATM Processing Services
	8,550	Jupiter Telecommunications		8,993
		Largest Cable Service Provider in Japan
	189,300	Benesse		8,718
		Education Service Provider
	900	Orix JREIT		5,851
		Diversified REIT
	396,000	Gree		5,034
		Mobile Social Networking Game Developer/Platform
	241,000	Asahi Diamond Industrial		4,576
		Consumable Diamond Tools
	110,000	Ain Pharmaciez		3,868
		Dispensing Pharmacy/Drugstore Operator
				65,154
		> China 6.3%
	14,649,000	Jiangsu Expressway		16,811
		Chinese Toll Road Operator
	2,876,700	Zhaojin Mining Industry		11,769
		Gold Mining & Refining in China
				28,580

See accompanying notes to financial statements.

59

Columbia Acorn International Select

Statement of Investments, continued

Number of Shares			Value (000)
		> Singapore 5.9%
	10,800,000	Ascendas REIT	$	17,420
		Singapore Industrial Property Landlord
	3,750,000	Olam International		9,175
		Agriculture Supply Chain Manager
				26,595
		> South Korea 5.1%
	89,000	NHN (a)		17,760
		South Korea's Largest Online Search Engine
	151,000	Woongjin Coway		5,358
		South Korean Household Appliance Rental Service Provider
				23,118
		> Hong Kong 0.4%
	1,555,500	Mongolian Mining (a)		1,815
		Coking Coal Mining in Mongolia
				1,815
Asia: Total				145,262
Other Countries: 14.6%
		> Canada 5.4%
	287,000	Pan American Silver		11,827
		Silver Mining
	125,000	AG Growth		6,295
		Leading Manufacturer of Augers & Grain Handling Equipment
	210,400	CCL Industries		6,268
		Leading Global Label Manufacturer
				24,390
		> South Africa 3.5%
	271,000	Naspers		15,960
		Media in Africa, China, Russia & Other Emerging Markets
				15,960
		> Australia 3.1%
	961,000	UGL		14,183
		Engineering & Facilities Management
				14,183
		> United States 1.4%
	171,000	Atwood Oceanics (a)		6,390
		Offshore Drilling Contractor
				6,390
		> Israel 1.2%
	310,000	Israel Chemicals		5,316
		Producer of Potash, Phosphates, Bromine & Specialty Chemicals
				5,316
Other Countries: Total				66,239
Latin America 4.4%
		> Colombia 3.9%
	525,000	Pacific Rubiales Energy		17,820
		Oil Production & Exploration in Colombia
				17,820

Number of Shares or Principal Amount (000)			Value (000)
		> Argentina 0.5%
	1,000,000	Union Agriculture Group (a)(b)	$	2,200
		Farmland Operator in Uruguay
				2,200
Latin America: Total				20,020
Total Equities: 94.8% (Cost: $309,207)				429,065
Short-Term Obligations: 4.7%
		> Repurchase Agreement 4.2%
$	19,283	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by a U.S. Government Agency obligation maturing 4/28/14, market value $19,670 (repurchase proceeds $19,283)		19,283
				19,283
		> Commercial Paper 0.5%
	2,200	Toyota Motor Credit 0.20% due 1/21/11		2,200
				2,200
Total Short-Term Obligations 4.7% (Cost: $21,483)				21,483
Total Investments: 99.5% (Cost: $330,690)(c)(d)				450,548
Cash and Other Assets Less Liabilities: 0.5%				2,119
Total Net Assets: 100%			$	452,667

GDR = Global Depositary Receipts.

See accompanying notes to financial statements.

60

> Notes to Statement of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the market value of these securities amounted to $6,052, which represented 1.34% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Mail.ru - GDR	11/05/10-12/31/10		107,000	$	3,732	$	3,852
Union Agriculture Group	2/08/10		1,000,000		2,200		2,200
				$	5,932	$	6,052

(c)  At December 31, 2010, for federal income tax purposes, the cost of investments was $337,719 and net unrealized appreciation was $112,829, consisting of gross unrealized appreciation of $120,672 and gross unrealized depreciation of $7,843.

(d)  On December 31, 2010, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Euro	$	77,216		17.1
British Pound		72,488		16.0
Japanese Yen		65,154		14.4
U.S. Dollar		50,294		11.1
Hong Kong Dollar		30,395		6.7
Canadian Dollar		30,383		6.7
Singapore Dollar		26,595		5.9
South Korean Won		23,118		5.1
Other currencies less than 5% of total net assets		74,905		16.5
	$	450,548		99.5

The following table summarizes the inputs used, as December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Europe	$	8,394	$	189,150	$	-	$	197,544
Asia		-		145,262		-		145,262
Other Countries		30,780		35,459		-		66,239
Latin America		17,820		-		2,200		20,020
Total Equities		56,994		369,871		2,200		429,065
Total Short-Term Obligations		-		21,483		-		21,483
Total Investments	$	56,994	$	391,354	$	2,200	$	450,548

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sales price on the foreign exchange or market on which they trade. The Fund may use a systematic fair valuation model provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements.

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities acquired via private placement that are not yet trading are valued using a market approach for which management has determined that the original transaction price is the best representation of fair value. The original cost may be adjusted for the market movement in an index, ETF or similar security during the period it does not trade.

See accompanying notes to financial statements.

61

Columbia Acorn International Select

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

  The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)		Purchases		Sells		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Latin America
Argentina	$	-	$	-	$	-	$	2,200	$	-	$	-	$	-	$	2,200
	$	-	$	-	$	-	$	2,200	$	-	$	-	$	-	$	2,200

  The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  For more information on valuation inputs, and their aggregation into the levels used in the tables above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

62

Columbia Acorn International Select

Portfolio Diversification

At December 31, 2010, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value (000)		Percentage of Net Assets
> Industrial Goods & Services
Other Industrial Services	$	42,492		9.4
Industrial Materials & Specialty Chemicals		32,647		7.2
Machinery		31,420		6.9
Electrical Components		20,205		4.5
Outsourcing Services		18,525		4.1
Conglomerates		5,017		1.1
		150,306		33.2
> Information
Internet Related		37,572		8.3
Instrumentation		17,944		4.0
Financial Processors		9,205		2.0
CATV		8,993		2.0
Gaming Equipment & Services		5,034		1.1
Business Software		3,355		0.7
		82,103		18.1
> Energy & Minerals
Mining		40,486		9.0
Oil Services		20,807		4.6
Oil & Gas Producers		17,820		3.9
Agricultural Commodities		2,200		0.5
		81,313		18.0
> Other Industries
Real Estate		28,205		6.2
Transportation		16,811		3.7
Regulated Utilities		4,373		1.0
		49,389		10.9

	Value (000)		Percentage of Net Assets
> Consumer Goods & Services
Other Consumer Services	$	14,076		3.1
Food & Beverage		9,175		2.0
Nondurables		6,268		1.4
Retail		3,868		0.9
		33,387		7.4
> Finance
Banks		9,421		2.1
Brokerage & Money Management		6,193		1.3
Insurance		3,534		0.8
		19,148		4.2
> Health Care
Pharmaceuticals		9,016		2.0
Health Care Services		4,403		1.0
		13,419		3.0
Total Equities:		429,065		94.8
Short-Term Obligations:		21,483		4.7
Total Investments:		450,548		99.5
Cash and Other Assets Less Liabilities:		2,119		0.5
Net Assets:	$	452,667		100.0

See accompanying notes to financial statements.

63

Columbia Acorn Select

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Consumer Goods & Services
Career Education		1,600,000		1,900,000
Hertz		8,500,000		8,650,000
IFM Investments (Century 21 China RE) - ADR (China)		2,100,000		2,300,000
Energy & Minerals
Canadian Overseas Petroleum (United Kingdom)		0		7,200,000
Canadian Overseas Petroleum - Subscription Receipts (United Kingdom)		0		16,800,000
Canadian Overseas Petroleum - Warrants (United Kingdom)		0		3,600,000
Houston American Energy		1,050,000		1,184,800
Kirkland Lake Gold (Canada)		0		1,000,000
Petrodorado (Colombia)		3,005,500		11,256,000
Real Goods Solar		1,400,000		1,500,000
Union Agriculture Group (Argentina)		0		9,090,909
Information
Mail.ru - GDR (Russia)		0		507,563
Mettler Toledo		100,000		120,000
Navigant Consulting		1,451,900		2,300,000
VisionChina Media - ADR (China)		3,242,000		3,675,000
WNS - ADR (India)		4,147,878		4,200,000
Industrial Goods & Services
Ametek		1,100,000		1,860,000
Expeditors International of Washington		600,000		750,000
Neopost (France)		0		107,000
Pall		0		400,000
Finance
Discover Financial Services		4,850,000		5,150,000
Other Industries
Wisconsin Energy		200,000		250,000
Health Care
Akorn		0		977,671

	Number of Shares
	09/30/10		12/31/10
Sales
Consumer Goods & Services
Abercrombie & Fitch		1,650,000		1,600,000
Expedia		2,500,000		484,810
ITT Educational Services		1,050,000		1,000,000
lululemon athletica		394,917		350,000
Tractor Supply Company		120,000		0
Energy & Minerals
Pacific Rubiales Energy (Colombia)		5,250,000		4,600,000
Petroamerica (Colombia)		16,443,900		0
Tetra Technologies		3,700,000		0
Information
CardTronics		2,100,000		779,395
Sanmina-SCI		8,000,000		7,100,000
Industrial Goods & Services
Quanta Services		1,650,000		928,000
Finance
CNO Financial Group		13,500,000		12,500,000
Eaton Vance		450,260		0
Other Industries
American Commercial Lines		850,000		0

See accompanying notes to financial statements.

64

Columbia Acorn Select

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 95.1%
Consumer Goods & Services 26.0%
		>Retail 9.4%
	1,600,000	Abercrombie & Fitch	$	92,208
		Teen Apparel Retailer
	3,800,000	Safeway		85,462
		Supermarkets
	350,000	lululemon athletica (a)(b)		23,947
		Premium Active Apparel Retailer
	3,500,000	Wet Seal (a)		12,950
		Specialty Apparel Retailer
				214,567
		>Travel 6.0%
	8,650,000	Hertz (a)		125,338
		Largest U.S. Rental Car Operator
	484,810	Expedia		12,164
		Online Travel Services Company
				137,502
		>Educational Services 4.5%
	1,000,000	ITT Educational Services (a)		63,690
		Post-secondary Degree Services
	1,900,000	Career Education (a)		39,387
		Post-secondary Education
				103,077
		>Apparel 2.8%
	1,135,000	Coach		62,777
		Designer & Retailer of Branded Leather Accessories
				62,777
		>Casinos & Gaming 1.6%
	335,000,000	RexLot Holdings (China)		35,341
		Lottery Equipment Supplier in China
				35,341
		>Leisure Products 0.7%
	500,000	Thor Industries		16,980
		RV & Bus Manufacturer
				16,980
		>Other Consumer Services 0.5%
	2,300,000	IFM Investments (Century 21 China RE) - ADR (China) (a)(c)		11,500
		Provides Real Estate Services in China
				11,500
		>Food & Beverage 0.5%
	1,000,000	GLG Life Tech (Canada) (a)		10,740
		Produce an All-natural Sweetener Extracted from the Stevia Plant
				10,740
Consumer Goods & Services: Total				592,484
Energy & Minerals 20.3%
		>Oil & Gas Producers 14.9%
	4,600,000	Pacific Rubiales Energy (Colombia)		156,140
		Oil Production & Exploration in Colombia
	32,240,000	Canacol Energy (Columbia) (a)(c)		50,907
	4,000,000	Canacol Energy (Colombia) (a)(c)(d)		6,190
		Oil Producer in South America

Number of Shares			Value (000)
	35,950,000	ShaMaran Petroleum (Iraq) (a)(c)	$	49,172
		Oil Exploration in Kurdistan
	17,144,000	Petrodorado (Colombia) (a)(c)(d)		11,997
	11,256,000	Petrodorado (Columbia) (a)(c)		8,038
	17,144,000	Petrodorado - Warrants (Colombia) (a)(c)(d)		7,242
		Oil & Gas Exploration & Production in Colombia, Peru & Paraguay
	1,184,800	Houston American Energy (b)		21,433
		Oil & Gas Exploration & Production in Colombia
	16,800,000	Canadian Overseas Petroleum - Subscription Receipts (United Kingdom) (a)(d)		14,075
	7,200,000	Canadian Overseas Petroleum (United Kingdom) (a)(d)		5,180
	3,600,000	Canadian Overseas Petroleum - Warrants (United Kingdom) (a)(d)		851
		Oil & Gas Exploration & Production in the North Sea
	13,125,000	Petromanas (Canada) (a)(d)		5,110
	5,000,000	Petromanas (Canada) (a)		1,986
	6,562,500	Petromanas - Warrants (Canada) (a)(d)		776
		Exploring for Oil in Albania
				339,097
		>Alternative Energy 2.1%
	3,200,000	Canadian Solar (China) (a)(b)(c)		39,648
		Solar Cell & Module Manufacturer
	4,500,000	Synthesis Energy Systems (China) (a)(c)		5,265
		Owner/Operator of Gasification Plants
	1,500,000	Real Goods Solar (a)(c)		3,750
		Residential Solar Energy Installer
				48,663
		>Agricultural Commodities 1.9%
	38,000,000	Eacom Timber (Canada) (a)(c)(d)		24,345
		Canadian Lumber Producer
	9,090,909	Union Agriculture Group (Argentina) (a)(d)		20,000
		Farmland Operator in Uruguay
				44,345
		>Mining 0.7%
	1,000,000	Kirkland Lake Gold (Canada) (a)		16,062
		Gold Mining
				16,062
		>Oil Services 0.7%
	11,324,000	Tuscany International Drilling (Colombia) (a)(c)(d)		15,626
	1,900,000	Tuscany International Drilling - Warrants (Colombia) (a)(c)(d)		243
		South America-based Drilling Rig Contractor
				15,869
Energy & Minerals: Total				464,036

See accompanying notes to financial statements.

65

Columbia Acorn Select

Statement of Investments, continued

Number of Shares			Value (000)
Information 20.0%
		>Mobile Communications 6.9%
	1,550,000	Crown Castle International (a)	$	67,936
		Communications Towers
	900,000	American Tower (a)		46,476
		Communications Towers
	15,000,000	Globalstar (a)(b)(c)		21,750
		Satellite Mobile Voice & Data Carrier
	505,000	SBA Communications (a)		20,675
		Communications Towers
				156,837
		>Contract Manufacturing 3.6%
	7,100,000	Sanmina-SCI (a)(c)		81,508
		Electronic Manufacturing Services
				81,508
		>Computer Services 2.1%
	4,200,000	WNS - ADR (India) (a)(b)(c)		48,594
		Offshore BPO (Business Process Outsourcing) Services
				48,594
		>Business Software 1.8%
	7,000,000	Novell (a)		41,440
		Directory, Operating System & Identity Management Software
				41,440
		>Computer Hardware & Related Equipment 1.7%
	750,000	Amphenol		39,585
		Electronic Connectors
				39,585
		>Business Information & Marketing Services 0.9%
	2,300,000	Navigant Consulting (a)		21,160
		Financial Consulting Firm
				21,160
		>Internet Related 0.8%
	507,563	Mail.ru - GDR (Russia) (a)(d)		18,272
		Internet Social Networking & Games for Russian Speakers
				18,272
		>Instrumentation 0.8%
	120,000	Mettler Toledo (a)		18,145
		Laboratory Equipment
				18,145
		>Advertising 0.8%
	3,675,000	VisionChina Media - ADR (China) (a)(b)(c)		17,052
		Advertising on Digital Screens in China's Mass Transit System
				17,052
		>Financial Processors 0.6%
	779,395	CardTronics (a)		13,796
		Operates the World's Largest Network of ATMs
				13,796
Information: Total				456,389

Number of Shares			Value (000)
Industrial Goods & Services 12.8%
		>Machinery 4.5%
	1,860,000	Ametek	$	73,005
		Aerospace/Industrial Instruments
	400,000	Pall		19,832
		Filtration & Fluids Clarification
	107,000	Neopost (France)		9,323
		Postage Meter Machines
				102,160
		>Waste Management 2.4%
	1,500,000	Waste Management		55,305
		U.S. Garbage Collection & Disposal
				55,305
		>Industrial Materials & Specialty Chemicals 2.0%
	1,000,000	Nalco Holding Company		31,940
		Provider of Water Treatment & Process Chemicals & Services
	1,800,000	ChemSpec International - ADR (China)		13,464
		Specialty Chemicals with Focus on Fluorinated Chemical Manufacturing
				45,404
		>Other Industrial Services 1.8%
	750,000	Expeditors International of Washington		40,950
		International Freight Forwarder
				40,950
		>Industrial Distribution 1.3%
	220,000	WW Grainger		30,384
		Industrial Distribution
				30,384
		>Outsourcing Services 0.8%
	928,000	Quanta Services (a)		18,486
		Electrical & Telecom Construction Services
				18,486
Industrial Goods & Services: Total				292,689
Finance 11.2%
		>Credit Cards 4.2%
	5,150,000	Discover Financial Services		95,429
		Credit Card Company
				95,429
		>Insurance 3.7%
	12,500,000	CNO Financial Group (a)		84,750
		Life, Long-term Care & Medical Supplement Insurance
				84,750
		>Brokerage & Money Management 3.3%
	6,000,000	MF Global (a)		50,160
		Futures Broker
	1,100,000	SEI Investments		26,169
		Mutual Fund Administration & Investment Management
				76,329
Finance: Total				256,508

See accompanying notes to financial statements.

66

Number of Shares or Principal Amount (000)			Value (000)
Other Industries 4.0%
		>Transportation 2.3%
	1,300,000	JB Hunt Transport Services	$	53,053
		Truck & Intermodal Carrier
				53,053
		>Real Estate 1.0%
	1,200,000	BioMed Realty Trust		22,380
		Life Science-focused Office Buildings
				22,380
		>Regulated Utilities 0.7%
	250,000	Wisconsin Energy		14,715
		Wisconsin Utility
				14,715
Other Industries: Total				90,148
Health Care 0.8%
		>Biotechnology & Drug Delivery 0.5%
	1,500,000	NPS Pharmaceuticals (a)		11,851
		Orphan Drugs & Healthy Royalties
				11,851
		>Pharmaceuticals 0.3%
	977,671	Akorn (a)		5,934
		Develops, Manufactures & Sells Specialty Generic Drugs
				5,934
Health Care: Total				17,785
Total Equities: 95.1% (Cost: $1,522,342)				2,170,039
Securities Lending Collateral: 1.4%
	32,972,313	Dreyfus Government Cash Management Fund (e) (7 day yield of 0.01%)		32,972
Total Securities Lending Collateral: (Cost: $32,972)				32,972
Short-Term Obligations: 4.2%
		>Repurchase Agreement 3.3%
$	75,207	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by a U.S. Government Agency obligation maturiting 8/26/14, market value $76,713 (repurchase proceeds $75,208)		75,207
				75,207

Principal Amount (000)			Value (000)
		>Commercial Paper 0.9%
$	11,200	Toyota Motor Credit 0.20% due 1/21/11	$	11,199
	9,550	ConocoPhillips (f) 0.26% due 1/14/11		9,549
				20,748
Total Short-Term Obligations: (Amortized Cost: $95,955)				95,955
Total Investments: 100.7% (Cost: $1,651,269)(g)				2,298,966
Obligation to Return Collateral for Securities Loaned: (1.4)%				(32,972	)
Cash and Other Assets Less Liabilities: 0.7%				16,861
Total Net Assets: 100.0%			$	2,282,855

ADR = American Depositary Receipts

GDR = Global Depositary Receipts

See accompanying notes to financial statements.

67

Columbia Acorn Select

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  All or a portion of this security was on loan at December 31, 2010. The total market value of Fund securities on loan at December 31, 2010 was $31,854.

(c)  An affiliated person of the Fund may include any company in which the Fund owns five percent or more of its outstanding voting shares.

  Holdings and transactions in these affiliated companies during the year ended December 31, 2010, are as follows:

Affiliates	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
American Commercial Lines*		1,125,000		250,000		1,375,000		-	$	-	$	-
Canacol Energy		32,240,000		4,000,000		-		36,240,000		57,097		-
Canadian Solar		1,900,000		1,300,000		-		3,200,000		39,648		-
CardTronics*		2,620,000		-		1,840,605		779,395		13,796		-
China Mass Media - ADR*		1,662,685		-		1,662,685		-		-		-
CNO Financial Group*		13,500,000		-		1,000,000		12,500,000		84,750		-
Eacom Timber		-		38,000,000		-		38,000,000		24,345		-
Globalstar		13,400,800		1,599,200		-		15,000,000		21,750		-
IFM Investments (Century 21 China RE) - ADR		-		2,300,000		-		2,300,000		11,500		-
Petrodorado**		-		45,544,000		-		45,544,000		27,277		-
Real Goods Solar		1,400,000		100,000		-		1,500,000		3,750		-
Sanmina-SCI		8,200,000		-		1,100,000		7,100,000		81,508		-
ShaMaran Petroleum		31,000,000		4,950,000		-		35,950,000		49,172		-
SkillSoft - ADR*		9,000,000		-		9,000,000		-		-		-
Synthesis Energy Systems		2,200,000		2,300,000		-		4,500,000		5,265		-
Tetra Technologies*		5,000,000		-		5,000,000		-		-		-
Tuscany International Drilling**		-		13,224,000		-		13,224,000		15,869		-
VisionChina Media - ADR		4,250,000		1,425,959		2,000,959		3,675,000		17,052		-
WNS - ADR		3,913,900		286,100		-		4,200,000		48,594		-
Total of Affiliated Transactions		131,412,385		115,279,259		22,979,249		223,712,395	$	501,373	$	-

*  At December 31, 2010, the Fund owned less than five percent of the company's outstanding voting shares.

**  Includes the effects of a corporate action.

  The aggregate cost and value of these affiliated companies at December 31, 2010, were $395,668 and $402,826, respectively. Investments in affiliated companies represented 17.7% of the Fund's total net assets at December 31, 2010.

(d)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the value of these securities amounted to $129,907, which represented 5.69% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Eacom Timber	3/17/10		38,000,000	$	18,812	$	24,345
Union Agriculture Group	12/08/10		9,090,909		20,000		20,000
Mail.ru - GDR	11/05/10-12/31/10		507,563		18,629		18,272
Tuscany International Drilling	2/12/10-3/23/10		11,324,000		12,989		15,626
Canadian Overseas Petroleum - Subscription Receipts	11/24/10		16,800,000		8,234		14,075
Petrodorado	11/20/09		17,144,000		3,607		11,997
Petrodorado - Warrants	11/20/09		17,144,000		2,118		7,242
Canacol Energy	4/15/10		4,000,000		2,963		6,190
Canadian Overseas Petroleum	11/24/10		7,200,000		3,188		5,180
Petromanas	5/20/10		13,125,000		4,561		5,110
Canadian Overseas Petroleum - Warrants	11/24/10		3,600,000		341		851
Petromanas - Warrants	5/20/10		6,562,500		380		776
Tuscany International Drilling - Warrants	2/12/10		1,900,000		235		243
				$	96,057	$	129,907

(e)  Investment made with cash collateral received from securities lending activity.

(f)  Security exempt from registration under Section 4(2) of the Securities Act of 1933. This security may only be resold in exempt transactions to qualified buyers. Private resales of this security to qualified institutional buyers are also exempt from registration pursuant to Rule 144A under the Securities Act of 1933. At December 31, 2010, this security had an aggregate value of $9,549, which represented 0.4% of total net assets.

(g)  At December 31, 2010, for federal income tax purposes, the cost of investments was $1,700,305 and net unrealized appreciation was $598,661, consisting of gross unrealized appreciation of $790,213 and gross unrealized depreciation of $191,552.

See accompanying notes to financial statements.

68

> Notes to Statement of Investments (dollar values in thousands)

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Consumer Goods & Services	$	557,143	$	35,341	$	-	$	592,484
Energy & Minerals		352,401		91,635		20,000		464,036
Information		456,389		-		-		456,389
Industrial Goods & Services		283,366		9,323		-		292,689
Finance		256,508		-		-		256,508
Other Industries		90,148		-		-		90,148
Health Care		17,785		-		-		17,785
Total Equities		2,013,740		136,299		20,000		2,170,039
Total Securities Lending Collateral		32,972		-		-		32,972
Total Short-Term Obligations		-		95,955		-		95,955
Total Investments	$	2,046,712	$	232,254	$	20,000	$	2,298,966

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sales price on the foreign exchange or market on which they trade. The Fund may use a systematic fair valuation model provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements. Securities acquired via private placement that have a holding period or an extended settlement period are valued at a discount to the same shares that are trading freely on the m arket. These discounts are determined by the adviser's experience with similar securities or situations. Factors may include, but are not limited to, trade volume, shares outstanding and stock price. Warrants which do not trade are valued as a percentage of the actively trading common stocks using a model based on Black Scholes.

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities acquired via private placement that are not yet trading are valued using a market approach for which management has determined that the original transaction price is the best representation of fair value. The original cost may be adjusted for the market movement in an index, ETF or similar security during the period it does not trade.

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/ (Loss)			Change in Unrealized Appreciation (Depreciation)		Purchases		Sales			Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Equities
Consumer Goods & Services	$	181	$	(20,560	)	$	20,380	$	-	$	(1	)	$	-	$	-	$	-
Energy & Minerals		-		-			-		20,000		-			-		-		20,000
	$	181	$	(20,560	)	$	20,380	$	20,000	$	(1	)	$	-	$	-	$	20,000

  The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  The change in unrealized appreciation attributed to securities owned at December 31, 2010, which were valued using significant unobservable inputs (Level 3) amounted to $20,380. This amount is included in net change in unrealized appreciation (depreciation) on the Statements of Changes in Net Assets.

  For more information on valuation inputs, and their aggregation into the levels used in the tables above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

69

Columbia Thermostat Fund

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
		> Affiliated Stock Funds: 59.7%
	388	Columbia Acorn International, Class I	$	15,884
	1,204	Columbia Dividend Income Fund, Class I		15,741
	563	Columbia Marsico Growth Fund, Class I		11,638
	385	Columbia Acorn Fund, Class I		11,623
	547	Columbia Contrarian Core Fund, Class I		7,837
	272	Columbia Acorn Select, Class I		7,829
	650	Columbia Large Cap Enhanced Core Fund, Class I		7,816
Total Stock Funds (Cost: $59,637)				78,368
		> Affiliated Bond Funds: 39.7%
	2,874	Columbia Intermediate Bond Fund, Class I		26,035
	1,402	Columbia U.S. Treasury Index Fund, Class I		15,604
	1,334	Columbia Conservative High Yield Fund, Class Z		10,470
Total Bond Funds (Cost: $52,047)				52,109

Principal Amount (000)			Value (000)
Short-Term Obligation: 0.5%
		> Repurchase Agreement: 0.5%
$	705	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by a U.S. Government Agency obligation maturing 9/08/14, market value $722 (repurchase proceeds $705)	$	705
Total Short-Term Obligation (Cost: $705)				705
Total Investments: 99.9% (Cost: $112,389)(a)				131,182
Cash and Other Assets Less Liabilities: 0.1%				93
Total Net Assets: 100.0%			$	131,275

> Notes to Statement of Investments (dollar values in thousands)

(a)  At December 31, 2010, for federal income tax purposes, the cost of investments was $112,602 and net unrealized appreciation was $18,580, consisting of gross unrealized appreciation of $19,312 and gross unrealized depreciation of $732.

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Total Stock Funds	$	78,368	$	-	$	-	$	78,368
Total Bond Funds		52,109		-		-		52,109
Total Short-Term Obligation		-		705		-		705
Total Investments	$	130,477	$	705	$	-	$	131,182

  The Fund's assets assigned to the Level 2 category include certain short-term obligations generally valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

  For more information on valuation inputs, and their aggregation into the levels used in the table above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

70

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71

Columbia Acorn Family of Funds

Statements of Assets and Liabilities

December 31, 2010	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select			Columbia Acorn Select			Columbia Thermostat Fund
(in thousands)
Assets:
Unaffiliated investments, at cost	$	9,605,670		$	4,209,981		$	1,206,929		$	330,690		$	1,255,601		$	705
Affiliated investments, at cost (See Note 4)		2,324,758			97,243			4,479			—			395,668			111,684
Unaffiliated investments, at value (including securities on loan: Columbia Acorn Fund $363,573; Columbia Acorn International $51,194; Columbia Acorn USA $15,262; Columbia Acorn International Select $–; Columbia Acorn Select $31,854; Columbia Thermostat Fund $–)	$	15,053,040		$	5,997,341		$	1,722,280		$	450,548		$	1,896,140		$	705
Affiliated investments, at value (See Note 4)		3,446,513			114,116			3,294			—			402,826			130,477
Cash		1,627			5,195			14			687			509			—	*
Foreign currency (cost: Columbia Acorn Fund $28;		29			23,259			—			21			151			—
Columbia Acorn International $22,292; Columbia Acorn International Select $21; Columbia Acorn Select $151)
Net unrealized appreciation on forward foreign currency exchange contracts		—			11,287			—			—			—			—
Receivable for:
Investments sold		33,520			799			98			2,318			26,550			—
Fund shares sold		18,452			41,702			1,308			442			8,550			364
Dividends and interest		8,519			6,392			821			642			1,230			—	*
Securities lending income		372			142			16			14			34			—
Foreign tax reclaims		144			924			—			50			—			—
Expense reimbursement due from Adviser		—			—			—			—			—			12
Trustees' Deferred Compensation Investments		3,047			802			238			—			309			—
Other assets		216			71			20			6			29			1
Total Assets		18,565,479			6,202,030			1,728,089			454,728			2,336,328			131,559
Liabilities:
Collateral on securities loaned		375,541			53,018			15,768			—			32,972			—
Expense reimbursement due to Adviser		—			—			—			—	*		—			—
Payable for:
Investments purchased		34,913			9,387			5,534			816			6,574			—
Fund shares redeemed		37,678			6,943			6,224			637			11,071			121
Management fee		9,717			3,815			1,218			353			1,538			11
Administration fee		605			200			56			15			76			4
12b-1 Service & Distribution fees		1,641			270			82			27			246			46
Reports to shareholders		620			300			78			40			165			33
Deferred Trustees' fees		3,047			802			238			44			309			29
Transfer agent fees		2,501			608			292			42			369			20
Trustees' fees		—	*		—	*		1			—	*		—	*		—	*
Professional fee		136			67			30			24			34			13
Custody fees		285			1,020			14			58			108			—
Chief compliance officer expenses		47			16			4			1			6			—	*
Foreign capital gains tax		—			507			—			—			—			—
Other liabilities		36			14			4			4			5			7
Total Liabilities		466,767			76,967			29,543			2,061			53,473			284
Net Assets	$	18,098,712		$	6,125,063		$	1,698,546		$	452,667		$	2,282,855		$	131,275
Composition of Net Assets:
Paid in capital	$	11,409,140		$	4,691,850		$	1,213,358		$	370,640		$	1,772,391		$	141,101
Undistributed/(overdistributed) net investment income (Accumulated net investment loss)		(48,598	)		5,502			(238	)		(1,132	)		(17,217	)		1,479
Accumulated net realized gain/(loss)		169,015			(388,458	)		(28,740	)		(36,711	)		(120,017	)		(30,098	)
Net unrealized appreciation/(depreciation) on:
Investments		6,569,125			1,804,233			514,166			119,858			647,697			18,793
Foreign capital gains tax		—			(507	)		—			—			—			—
Foreign currency translations		30			12,443			—			12			1			—
Net Assets	$	18,098,712		$	6,125,063		$	1,698,546		$	452,667		$	2,282,855		$	131,275
Net asset value per share – Class A (a)	$	29.24		$	40.87		$	27.54		$	28.01		$	27.94		$	12.58
(Net assets/shares)		($3,639,788/124,485)			($810,603/19,836)			($214,097/7,775)			($71,668/2,559)			($555,263/19,872)			($44,527/3,541)
Maximum offering price per share – Class A (b)	$	31.02		$	43.36		$	29.22		$	29.72		$	29.64		$	13.35
(Net asset value per share/front- end sales charge)		($29.24/0.9425)			($40.87/0.9425)			($27.54/0.9425)			($28.01/0.9425)			($27.94/0.9425)			($12.58/0.9425)
Net asset value and offering price per share – Class B (a)	$	27.14		$	39.96		$	25.60		$	26.72		$	26.06		$	12.64
(Net assets/shares)		($287,650/10,599)			($29,368/735)			($9,222/360)			($3,030/113)			($72,203/2,771)			($28,752/2,274)
Net asset value and offering price per share – Class C (a)	$	26.85		$	39.79		$	25.39		$	26.58		$	25.83		$	12.62
(Net assets/shares)		($829,181/30,882)			($110,931/2,788)			($36,101/1,422)			($11,885/447)			($98,445/3,811)			($21,866/1,733)
Net asset value and offering price per share – Class I (c)	$	30.19		$	40.92		$	28.56		$	28.33		$	28.74	(e)
(Net assets/shares)		($11,627/385)			($66,581/1,627)			($28,993/1,015)			($3/0**)			($7,832/273)
Net asset value and offering price per share – Class Z (d)	$	30.19		$	40.92		$	28.56		$	28.33		$	28.73		$	12.44
(Net assets/shares)		($13,330,466/441,587)			($5,107,580/124,833)			($1,410,133/49,379)			($366,081/12,923)			($1,549,112/53,914)			($36,130/2,904)

(a)  Redemption price per share is equal to net asset value less any applicable contingent deferred sales charge and redemption fee.

(b)  On sales of $50,000 or more the offering price is reduced.

(c)  Shares commenced operations on September 27, 2010.

(d)  Redemption price per share is equal to net asset value less any applicable redemption fee.

(e)  Due to rounding of shares outstanding.

*  Rounds to less than $500.

**  Rounds to less than 500 shares.

See accompanying notes to financial statements.

72

Columbia Acorn Family of Funds

Statements of Operations
For the Year Ended December 31, 2010

(in thousands)	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select			Columbia Acorn Select			Columbia Thermostat Fund
Investment Income:
Dividend income	$	109,440		$	102,078		$	9,549		$	8,419		$	10,990		$	—
Dividend income from affiliates (See Note 4)		19,561			2,570			—			—			—			—
Dividends from affiliated investment company shares (See Note 4)		—			—			—			—			—			2,653
Interest income		762			277			10			33			161			1
Securitites lending income, net		3,053			1,005			149			49			169			—
		132,816			105,930			9,708			8,501			11,320			2,654
Foreign taxes withheld		(1,906	)		(8,508	)		(15	)		(606	)		(101	)		—
Total Investment Income		130,910			97,422			9,693			7,895			11,219			2,654
Expenses:
Management fee		99,409			37,945			12,548			3,892			16,589			125
Administration fee		6,176			1,979			580			165			813			50
12b-1 Service and Distribution fees:
Class A		7,754			1,613			476			159			1,297			107
Class B		2,783			241			98			24			574			223
Class C		7,388			924			323			110			920			206
Transfer agent fees:
Class A		3,089			1,119			192			113			583			68
Class B		818			91			36			12			195			63
Class C		950			167			41			26			144			36
Class Z		4,362			1,992			681			99			689			17
Custody fees		1,081			3,963			57			233			267			—
Trustees' fees		835			276			83			34			113			13
Reports to shareholders		2,117			1,153			315			198			506			112
Professional fees		502			217			80			50			97			26
Chief compliance officer expenses (See Note 4)		510			159			48			14			69			4
Other expenses		511			244			107			101			147			65
Total expenses		138,285			52,083			15,665			5,230			23,003			1,115
Less custody fees paid indirectly		(1	)		(1	)		—	*		—	*		(1	)		—
Less reimbursement of expenses by Investment Adviser		—			—			—			(2	)		—			(267	)
Net Expenses		138,284			52,082			15,665			5,228			23,002			848
Net Investment Income/(Loss)		(7,374	)		45,340			(5,972	)		2,667			(11,783	)		1,806
Net Realized and Unrealized Gain (Loss) on Portfolio Positions:
Net realized gain/(loss) on:
Unaffiliated investments		972,387			241,838			96,553			42,552			59,857			(2,634	)
Affiliated investments (See Note 4)		139,546			5,786			(1,208	)		—			(38,281	)		—
Foreign currency transactions and forward foreign currency   exchange contracts		(1,053	)		34,536			—			(25	)		(185	)		—
Distributions from affiliated investment company shares		—			—			—			—			—			658
Net realized gain/(loss)		1,110,880			282,160			95,345			42,527			21,391			(1,976	)
Net change in net unrealized appreciation/(depreciation) on:
Unaffiliated investments		1,864,477			741,944			224,623			38,172			283,122			—
Affiliated investments (See Note 4)		758,959			6,050			4,434			—			123,090			19,741
Foreign currency translations and forward foreign currency   exchange contracts		(106	)		9,798			—			21			1			—
Foreign capital gains tax		200			710			—			—			—			—
Net change in unrealized appreciation/ (depreciation)		2,623,530			758,502			229,057			38,193			406,213			19,741
Net realized and unrealized gain		3,734,410			1,040,662			324,402			80,720			427,604			17,765
Net Increase in Net Assets resulting from Operations	$	3,727,036		$	1,086,002		$	318,430		$	83,387		$	415,821		$	19,571

*  Rounds to less than $500.

See accompanying notes to financial statements.

73

Columbia Acorn Family of Funds

Statements of Changes in Net Assets

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2010			2009			2010			2009			2010			2009
Operations:
Net investment income/(loss)	$	(7,374	)	$	2,492		$	45,340		$	39,229		$	(5,972	)	$	(4,927	)
Net realized gain/(loss) on investments, foreign currency transactions, forward foreign currency exchange contracts and foreign capital gains tax		971,334			(227,359	)		276,374			(246,346	)		96,553			(20,041	)
Net realized gain/(loss) on affiliated investments and distributions from affiliated investment companies and affiliated investment company shares		139,546			(100,539	)		5,786			(3,829	)		(1,208	)		(110	)
Net change in net unrealized appreciation/(depreciation) on investments, foreign currency translations, forward foreign currency exchange contracts and foreign capital gains tax		1,864,571			3,343,490			752,452			1,558,895			224,623			437,114
Net change in net unrealized appreciation/(depreciation) on affiliated investment companies and affiliated investment company shares		758,959			1,143,521			6,050			49,345			4,434			1,994
Net Increase from Operations		3,727,036			4,161,605			1,086,002			1,397,294			318,430			414,030
Distributions to Shareholders From:
Net investment income – Class A		(2,387	)		—			(12,578	)		(6,102	)		—			—
Net realized gain – Class A		(100,919	)		—			—			—			—			—
Net investment income – Class B		—			—			(290	)		(290	)		—			—
Net realized gain – Class B		(9,116	)		—			—			—			—			—
Net investment income – Class C		—			—			(714	)		(348	)		—			—
Net realized gain – Class C		(25,102	)		—			—			—			—			—
Net investment income – Class I		—	*		—			(9	)		—			—			—
Net realized gain – Class I		—	*		—			—			—			—			—
Net investment income – Class Z		(18,634	)		(20,981	)		(109,328	)		(53,467	)		—			—
Net realized gain – Class Z		(361,156	)		—			—			—			—			—
Total Distributions to Shareholders		(517,314	)		(20,981	)		(122,919	)		(60,207	)		—			—
Share Transactions:
Subscriptions – Class A		843,928			639,685			317,458			181,444			55,029			54,531
Distributions reinvested – Class A		94,158			—			10,862			5,737			—			—
Redemptions – Class A		(866,166	)		(744,769	)		(221,501	)		(140,626	)		(59,786	)		(66,724	)
Net Increase/(Decrease) – Class A		71,920			(105,084	)		106,819			46,555			(4,757	)		(12,193	)
Subscriptions – Class B		989			100			35			14			2			5
Distributions reinvested – Class B		7,325			—			260			264			—			—
Redemptions – Class B		(312,686	)		(224,032	)		(15,278	)		(14,833	)		(13,951	)		(9,892	)
Net Decrease – Class B		(304,372	)		(223,932	)		(14,983	)		(14,555	)		(13,949	)		(9,887	)
Subscriptions – Class C		76,903			58,069			24,476			14,494			1,669			2,513
Distributions reinvested – Class C		19,273			—			590			265			—			—
Redemptions – Class C		(145,469	)		(151,419	)		(17,799	)		(18,021	)		(4,671	)		(5,210	)
Net Increase/(Decrease) – Class C		(49,293	)		(93,350	)		7,267			(3,262	)		(3,002	)		(2,697	)
Subscriptions – Class I (a)(b)		13,063			—			66,675			—			28,852			—
Distributions reinvested – Class I		—			—			9			—			—			—
Redemptions – Class I		(1,538	)		—			(2,003	)		—			(293	)		—
Net Increase – Class I		11,525			—			64,681			—			28,559			—
Subscriptions – Class Z		2,077,687			1,484,719			1,216,447			671,256			260,284			246,578
Distributions reinvested – Class Z		324,149			17,690			76,344			38,426			—			—
Redemptions – Class Z		(1,969,778	)		(1,364,770	)		(726,019	)		(486,805	)		(276,628	)		(190,623	)
Net Increase/(Decrease) – Class Z		432,058			137,639			566,772			222,877			(16,344	)		55,955
Net Increase/(Decrease) from Share Transactions		161,838			(284,727	)		730,556			251,615			(9,493	)		31,178
Redemption Fees		—			—			239			259			—			—
Increase from regulatory settlements (See Note 9)		1			40			447			1,210			—			5
Total Increase/(Decrease) in Net Assets		3,371,561			3,855,937			1,694,325			1,590,171			308,937			445,213
Net Assets:
Beginning of period		14,727,151			10,871,214			4,430,738			2,840,567			1,389,609			944,396
End of period	$	18,098,712		$	14,727,151		$	6,125,063		$	4,430,738		$	1,698,546		$	1,389,609
Undistributed/(Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(48,598	)	$	(20,794	)	$	5,502		$	39,113		$	(238	)	$	(275	)

(a)  Shares commenced operations on September 27, 2010.

(b)  Shares reflect activity for the period September 27, 2010 through December 31, 2010.

*  Rounds to less than $500.

See accompanying notes to financial statements.

74

	Columbia Acorn International Select						Columbia Acorn Select						Columbia Thermostat Fund
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2010			2009			2010			2009			2010			2009
Operations:
Net investment income/(loss)	$	2,667		$	2,398		$	(11,783	)	$	(10,372	)	$	1,806		$	1,281
Net realized gain/(loss) on investments, foreign currency transactions, forward foreign currency exchange contracts and foreign capital gains tax		42,527			(31,407	)		59,672			31,689			—			—
Net realized gain/(loss) on affiliated investments and distributions from affiliated investment companies and affiliated investment company shares		—			—			(38,281	)		(71,935	)		(1,976	)		(18,231	)
Net change in net unrealized appreciation/(depreciation) on investments, foreign currency translations, forward foreign currency exchange contracts and foreign capital gains tax		38,193			127,633			283,123			521,770			—			—
Net change in net unrealized appreciation/(depreciation) on affiliated investment companies and affiliated investment company shares		—			—			123,090			316,510			19,741			51,494
Net Increase from Operations		83,387			98,624			415,821			787,662			19,571			34,544
Distributions to Shareholders From:
Net investment income – Class A		(776	)		(456	)		—			—			(678	)		(7	)
Net realized gain – Class A		—			—			—			—			—			—
Net investment income – Class B		(25	)		—			—			—			(239	)		—
Net realized gain – Class B		—			—			—			—			—			—
Net investment income – Class C		(65	)		—			—			—			(124	)		—
Net realized gain – Class C		—			—			—			—			—			—
Net investment income – Class I		—			—			—			—			—			—
Net realized gain – Class I		—			—			—			—			—			—
Net investment income – Class Z		(5,241	)		(3,077	)		—			—			(625	)		(115	)
Net realized gain – Class Z		—			—			—			—			—			—
Total Distributions to Shareholders		(6,107	)		(3,533	)		—			—			(1,666	)		(122	)
Share Transactions:
Subscriptions – Class A		18,214			30,670			115,498			98,691			8,937			5,619
Distributions reinvested – Class A		675			439			—			—			609			6
Redemptions – Class A		(23,778	)		(28,558	)		(187,411	)		(190,444	)		(13,847	)		(14,381	)
Net Increase/(Decrease) – Class A		(4,889	)		2,551			(71,913	)		(91,753	)		(4,301	)		(8,756	)
Subscriptions – Class B		—	*		—			34			39			4			—
Distributions reinvested – Class B		22			—			—			—			218			—
Redemptions – Class B		(1,418	)		(1,493	)		(30,406	)		(23,638	)		(8,516	)		(12,541	)
Net Decrease – Class B		(1,396	)		(1,493	)		(30,372	)		(23,599	)		(8,294	)		(12,541	)
Subscriptions – Class C		1,883			1,872			6,743			6,147			3,195			1,960
Distributions reinvested – Class C		55			—			—			—			109			—
Redemptions – Class C		(3,121	)		(3,109	)		(19,302	)		(21,888	)		(5,530	)		(10,176	)
Net Increase/(Decrease) – Class C		(1,183	)		(1,237	)		(12,559	)		(15,741	)		(2,226	)		(8,216	)
Subscriptions – Class I (a)(b)		3			—			8,577			—			—			—
Distributions reinvested – Class I		—			—			—			—			—			—
Redemptions – Class I		—			—			(931	)		—			—			—
Net Increase – Class I		3			—			7,646			—			—			—
Subscriptions – Class Z		67,172			127,520			358,116			278,829			7,895			2,684
Distributions reinvested – Class Z		1,451			833			—			—			560			106
Redemptions – Class Z		(96,502	)		(59,794	)		(328,729	)		(310,353	)		(18,853	)		(6,183	)
Net Increase/(Decrease) – Class Z		(27,879	)		68,559			29,387			(31,524	)		(10,398	)		(3,393	)
Net Increase/(Decrease) from Share Transactions		(35,344	)		68,380			(77,811	)		(162,617	)		(25,219	)		(32,906	)
Redemption Fees		10			33			—			—			—			—
Increase from regulatory settlements (See Note 9)		46			265			—			—			—			—
Total Increase/(Decrease) in Net Assets		41,992			163,769			338,010			625,045			(7,314	)		1,516
Net Assets:
Beginning of period		410,675			246,906			1,944,845			1,319,800			138,589			137,073
End of period	$	452,667		$	410,675		$	2,282,855		$	1,944,845		$	131,275		$	138,589
Undistributed/(Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(1,132	)	$	1,978		$	(17,217	)	$	(8,359	)	$	1,479		$	1,247

See accompanying notes to financial statements.

75

Columbia Acorn Family of Funds

Statements of Changes in Net Assets, continued

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA
Changes in Shares of Beneficial Interest:	Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2010			2009			2010			2009			2010			2009
Subscriptions – Class A		32,735			33,142			8,744			6,366			2,334			3,208
Shares issued in reinvestment – Class A		3,306			—			325			208			—			—
Less shares redeemed – Class A		(34,053	)		(39,655	)		(6,188	)		(5,549	)		(2,521	)		(3,839	)
Net Increase/(Decrease) – Class A		1,988			(6,513	)		2,881			1,025			(187	)		(631	)
Subscriptions – Class B		38			5			1			—	*		—	*		—	*
Shares issued in reinvestment – Class B		276			—			9			10			—			—
Less shares redeemed – Class B		(13,126	)		(12,472	)		(444	)		(588	)		(636	)		(582	)
Net Decrease – Class B		(12,812	)		(12,467	)		(434	)		(578	)		(636	)		(582	)
Subscriptions – Class C		3,197			3,215			700			497			76			148
Shares issued in reinvestment – Class C		733			—			19			10			—			—
Less shares redeemed – Class C		(6,190	)		(8,764	)		(519	)		(740	)		(214	)		(327	)
Net Increase/(Decrease) – Class C		(2,260	)		(5,549	)		200			(233	)		(138	)		(179	)
Subscriptions – Class I (a)(b)		436			—			1,677			—			1,025			—
Shares issued in reinvestment – Class I		—			—			—	*		—			—			—
Less shares redeemed – Class I		(51	)		—			(50	)		—			(10	)		—
Net Increase – Class I		385			—			1,627			—			1,015			—
Subscriptions – Class Z		78,950			75,517			33,971			23,146			10,643			14,152
Shares issued in reinvestment – Class Z		11,048			750			2,239			1,391			—			—
Less shares redeemed – Class Z		(74,926	)		(70,272	)		(20,195	)		(18,261	)		(11,173	)		(10,509	)
Net Increase/(Decrease) – Class Z		15,072			5,995			16,015			6,276			(530	)		3,643
Net Increase/(Decrease) in Shares of Beneficial Interest		2,373			(18,534	)		20,289			6,490			(476	)		2,251

(a)  Shares commenced operations on September 27, 2010.

(b)  Shares reflect activity for the period September 27, 2010 through December 31, 2010.

*  Rounds to less than 500.

See accompanying notes to financial statements.

76

	Columbia Acorn International Select						Columbia Acorn Select						Columbia Thermostat Fund
Changes in Shares of Beneficial Interest:	Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2010			2009			2010			2009			2010			2009
Subscriptions – Class A		746			1,653			4,815			5,917			765			646
Shares issued in reinvestment – Class A		31			22			—			—			56			1
Less shares redeemed – Class A		(982	)		(1,497	)		(7,851	)		(11,758	)		(1,223	)		(1,674	)
Net Increase/(Decrease) – Class A		(205	)		178			(3,036	)		(5,841	)		(402	)		(1,027	)
Subscriptions – Class B		—	*		—			2			2			—	*		—
Shares issued in reinvestment – Class B		1			—			—			—			21			—
Less shares redeemed – Class B		(62	)		(85	)		(1,342	)		(1,512	)		(744	)		(1,410	)
Net Decrease – Class B		(61	)		(85	)		(1,340	)		(1,510	)		(723	)		(1,410	)
Subscriptions – Class C		83			103			299			371			275			212
Shares issued in reinvestment – Class C		2			—			—			—			10			—
Less shares redeemed – Class C		(138	)		(174	)		(870	)		(1,474	)		(485	)		(1,207	)
Net Increase/(Decrease) – Class C		(53	)		(71	)		(571	)		(1,103	)		(200	)		(995	)
Subscriptions – Class I (a)(b)		—	*		—			305			—			—			—
Shares issued in reinvestment – Class I		—			—			—			—			—			—
Less shares redeemed – Class I		—			—			(32	)		—			—			—
Net Increase – Class I		—	*		—			273			—			—			—
Subscriptions – Class Z		2,699			6,808			14,221			15,845			697			307
Shares issued in reinvestment – Class Z		66			42			—			—			51			12
Less shares redeemed – Class Z		(3,845	)		(3,083	)		(13,400	)		(18,178	)		(1,710	)		(727	)
Net Increase/(Decrease) – Class Z		(1,080	)		3,767			821			(2,333	)		(962	)		(408	)
Net Increase/(Decrease) in Shares of Beneficial Interest		(1,399	)		3,789			(3,853	)		(10,787	)		(2,287	)		(3,840	)

See accompanying notes to financial statements.

77

Columbia Acorn Family of Funds

Financial Highlights

Columbia Acorn Fund

Class Z Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	24.68		$	17.71		$	29.61		$	29.71		$	28.17
Income from Investment Operations
Net investment income (a)		0.02			0.04			0.06			0.15	(b)		0.13
Net realized and unrealized gain/(loss)		6.37			6.98			(11.29	)		2.17			3.92
Total from Investment Operations		6.39			7.02			(11.23	)		2.32			4.05
Less Distributions to Shareholders
From net investment income		(0.04	)		(0.05	)		(0.01	)		(0.12	)		(0.13	)
From net realized gains		(0.84	)		—			(0.66	)		(2.30	)		(2.38	)
Total Distributions to Shareholders		(0.88	)		(0.05	)		(0.67	)		(2.42	)		(2.51	)
Increase from regulatory settlements		0.00	(c)		0.00	(c)		—			—			—
Net Asset Value, End of Period	$	30.19		$	24.68		$	17.71		$	29.61		$	29.71
Total Return (d)		26.00	%		39.65	%		(38.55	)%		7.69	%(e)(f)		14.45	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		0.76	%		0.77	%		0.76	%		0.74	%		0.74	%
Net investment income (g)		0.09	%		0.18	%		0.26	%		0.46	%		0.45	%
Waiver/Reimbursement		—			—			—			0.00	%(h)		0.01	%
Portfolio turnover rate		28	%		27	%		21	%		20	%		22	%
Net assets at end of period (in millions)	$	13,330		$	10,527		$	7,446		$	13,038		$	12,128

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.03 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by less than 0.01% and less than $0.01, respectively.

(g)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(h)  Rounds to less than 0.01%.

Columbia Acorn International

Class Z Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	34.26		$	23.13		$	43.60		$	40.31		$	33.44
Income from Investment Operations
Net investment income (a)		0.35			0.34			0.60			0.43			0.35
Net realized and unrealized gain/(loss)		7.23			11.31			(20.26	)		6.56			10.94
Total from Investment Operations		7.58			11.65			(19.66	)		6.99			11.29
Less Distributions to Shareholders
From net investment income		(0.92	)		(0.53	)		(0.21	)		(0.34	)		(0.51	)
From net realized gains		—			—			(0.60	)		(3.36	)		(3.91	)
Total Distributions to Shareholders		(0.92	)		(0.53	)		(0.81	)		(3.70	)		(4.42	)
Redemption Fees
Redemption fees added to paid in capital (a)(b)		0.00			0.00			0.00			0.00			0.00
Increase from regulatory settlements		0.00	(b)		0.01			—			—			—
Net Asset Value, End of Period	$	40.92		$	34.26		$	23.13		$	43.60		$	40.31
Total Return (c)		22.70	%		50.97	%		(45.89	)%		17.28	%(d)		34.53	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		0.97	%		0.99	%		0.96	%		0.91	%		0.94	%
Net investment income (e)		0.99	%		1.23	%		1.72	%		0.96	%		0.92	%
Waiver/Reimbursement		—			—			—			0.00	%(f)		0.01	%
Portfolio turnover rate		25	%		31	%		38	%		28	%		31	%
Net assets at end of period (in millions)	$	5,108		$	3,728		$	2,372		$	4,918		$	3,836

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Rounds to less than $0.01 per share.

(c)  Total return at net asset value assuming all distributions reinvested.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Rounds to less than 0.01%.

See accompanying notes to financial statements.

78

Columbia Acorn USA

Class Z Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	23.19		$	16.39		$	27.97		$	28.66		$	27.03
Income from Investment Operations
Net investment loss (a)		(0.08	)		(0.07	)		(0.07	)		(0.01	)(b)		(0.02	)
Net realized and unrealized gain/(loss)		5.45			6.87			(10.55	)		1.03			2.26
Total from Investment Operations		5.37			6.80			(10.62	)		1.02			2.24
Less Distributions to Shareholders
From net realized gains		—			—			(0.96	)		(1.71	)		(0.61	)
Increase from regulatory settlements		—			0.00	(c)		—			—			—
Net Asset Value, End of Period	$	28.56		$	23.19		$	16.39		$	27.97		$	28.66
Total Return (d)		23.16	%		41.49	%		(39.22	)%		3.46	%(e)(f)		8.28	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.01	%		1.03	%		1.01	%		0.98	%		0.98	%
Net investment loss (g)		(0.34	)%		(0.36	)%		(0.32	)%		(0.03	)%		(0.07	)%
Waiver/Reimbursement		—			—			—			0.00	%(h)		0.01	%
Portfolio turnover rate		32	%		28	%		23	%		21	%		13	%
Net assets at end of period (in millions)	$	1,410		$	1,158		$	758		$	1,214		$	1,214

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.09 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by less than 0.01% and less than $0.01, respectively.

(g)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(h)  Rounds to less than 0.01%.

Columbia Acorn International Select

Class Z Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	23.64		$	18.19		$	32.02		$	27.97		$	20.57
Income from Investment Operations
Net investment income (a)		0.18			0.17			0.28			0.14	(b)		0.10
Net realized and unrealized gain/(loss)		4.89			5.50			(13.53	)		5.96			7.35
Total from Investment Operations		5.07			5.67			(13.25	)		6.10			7.45
Less Distributions to Shareholders
From net investment income		(0.38	)		(0.24	)		(0.04	)		(0.28	)		(0.05	)
From net realized gains		—			—			(0.54	)		(1.77	)		—
Total Distributions to Shareholders		(0.38	)		(0.24	)		(0.58	)		(2.05	)		(0.05	)
Redemption Fees
Redemption fees added to paid in capital (a)(c)		0.00			0.00			0.00			0.00			0.00
Increase from regulatory settlements		0.00	(c)		0.02			—			—			—
Net Asset Value, End of Period	$	28.33		$	23.64		$	18.19		$	32.02		$	27.97
Total Return (d)		21.89	%		31.52	%		(42.10	)%		21.86	%(e)		36.27	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		1.16	%		1.20	%		1.21	%		1.18	%		1.27	%
Net investment income (f)		0.75	%		0.84	%		1.09	%		0.44	%		0.44	%
Waiver/Reimbursement		—			—			—			0.00	%(g)		0.01	%
Portfolio turnover rate		42	%		56	%		68	%		57	%		47	%
Net assets at end of period (in millions)	$	366		$	331		$	186		$	204		$	129

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.07 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(g)  Rounds to less than 0.01%.

See accompanying notes to financial statements.

79

Columbia Acorn Family of Funds

Financial Highlights, continued

Columbia Acorn Select

Class Z Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	23.38		$	14.07		$	28.41		$	26.59		$	22.77
Income from Investment Operations
Net investment loss (a)		(0.10	)		(0.08	)		(0.12	)		(0.07	)		(0.06	)
Net realized and unrealized gain/(loss)		5.45			9.39			(13.53	)		2.53			4.51
Total from Investment Operations		5.35			9.31			(13.65	)		2.46			4.45
Less Distributions to Shareholders
From net investment income		—			—			—			—			(0.04	)
From net realized gains		—			—			(0.69	)		(0.64	)		(0.59	)
Total Distributions to Shareholders		—			—			(0.69	)		(0.64	)		(0.63	)
Net Asset Value, End of Period	$	28.73		$	23.38		$	14.07		$	28.41		$	26.59
Total Return (b)		22.88	%		66.17	%		(49.18	)%(c)		9.20	%(d)		19.68	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		0.97	%		0.99	%		0.95	%		0.91	%		0.96	%
Net investment loss (e)		(0.41	)%		(0.47	)%		(0.51	)%		(0.24	)%		(0.26	)%
Waiver/Reimbursement		—			—			—			0.00	%(f)		0.02	%
Portfolio turnover rate		28	%		19	%		28	%		14	%		21	%
Net assets at end of period (in millions)	$	1,549		$	1,241		$	780		$	1,571		$	909

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Total return at net asset value assuming all distributions reinvested.

(c)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by 0.101% and $0.01, respectively.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Rounds to less than 0.01%.

Columbia Thermostat Fund

Class Z Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	10.80		$	8.19		$	12.26		$	12.57		$	12.50
Income from Investment Operations
Net investment income (a)		0.21			0.13			0.24			0.52			0.49
Net realized and unrealized gain/(loss)		1.66			2.51			(3.96	)		0.53			0.84
Total from Investment Operations		1.87			2.64			(3.72	)		1.05			1.33
Less Distributions to Shareholders
From net investment income		(0.23	)		(0.03	)		(0.28	)		(0.57	)		(0.54	)
From net realized gains		—			—			(0.07	)		(0.79	)		(0.72	)
Total Distributions to Shareholders		(0.23	)		(0.03	)		(0.35	)		(1.36	)		(1.26	)
Net Asset Value, End of Period	$	12.44		$	10.80		$	8.19		$	12.26		$	12.57
Total Return (b)(c)		17.58	%		32.29	%		(30.53	)%		8.49	%		10.86	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (d)(e)		0.25	%		0.25	%		0.25	%		0.25	%		0.25	%
Net investment income (e)		1.87	%		1.48	%		2.23	%		4.05	%		3.84	%
Waiver/Reimbursement		0.12	%		0.14	%		0.08	%		0.15	%		0.13	%
Portfolio turnover rate		118	%		17	%		130	%		128	%		66	%
Net assets at end of period (in millions)	$	36		$	42		$	35		$	36		$	31

(a)  Per share data was calculated using the average shares outstanding during the period. Recognition of net investment income by the Fund is affected by the timing of the declaration of dividends by the underlying investment companies in which the Fund invests.

(b)  Total return at net asset value assuming all distributions reinvested.

(c)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(d)  Does not include expenses of the investment companies in which the Fund invests.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

See accompanying notes to financial statements.

80

Columbia Acorn Family of Funds

Notes to Financial Statements

1.  Nature of Operations

Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select and Columbia Thermostat Fund (the Funds) are each a series of Columbia Acorn Trust (the Trust), an open-end management investment company organized as a Massachusetts business trust. The investment objective of each Fund is to seek long-term capital appreciation.

Columbia Thermostat Fund pursues its investment objective by investing in shares of other mutual funds. As a "fund of funds" under normal circumstances, the Fund allocates at least 95% of its net assets among a selected group of stock and bond mutual funds (portfolio funds) according to the current level of the Standard & Poor's (S&P) 500 Index in relation to predetermined ranges set by Columbia Wanger Asset Management, LLC (the Adviser). The Fund may invest up to 5% of its net assets plus any cash received that day in cash, repurchase agreements, high quality short-term paper and government securities.

Each Fund may issue an unlimited number of shares. Each Fund currently has five classes of shares—Class A, Class B, Class C, Class I and Class Z—except Columbia Thermostat Fund, which does not have Class I shares. Effective February 29, 2008, the Funds no longer offer Class B shares (other than through dividend reinvestment).

Class A shares are sold with a front-end sales charge. Class A shares bought without an initial sales charge in accounts aggregating $1 million up to $50 million at the time of purchase are subject to a 1.00% contingent deferred sales charge (CDSC) if the shares are redeemed within 12 months of the date of purchase.

Class B shares are subject to a CDSC if redeemed within six years of purchase. Class B shares will convert to Class A shares automatically eight years after purchase.

Class C shares are offered at net asset value but are subject to a CDSC on redemptions made within one year after purchase.

Class I shares are offered continuously at net asset value. There are certain restrictions on the purchase of Class I shares.

Class Z shares are offered at net asset value. There are certain restrictions on who may purchase Class Z shares. Generally, Class Z shares of a Fund may be exchanged for shares of another fund distributed by Columbia Management Distributors, Inc. at no additional charge.

The financial highlights for the Fund's Class A, Class B, Class C and Class I shares are presented in a separate annual report.

Differences in class expenses may result in payment of different dividend distributions for each class. All of the Funds' share classes have equal rights with respect to voting, subject to Fund or class specific matters.

2.  Significant Accounting Policies

The preparation of financial statements in accordance with accounting principles generally accepted in the United States of America (GAAP) requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.

>Security valuation

Securities of the Funds are valued at market value or, if a market quotation for a security is not readily available or is deemed not to be reliable because of events or circumstances that have occurred between the market quotation and the time as of which the security is to be valued, the security is valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. With respect to Columbia Thermostat Fund, investments in portfolio funds are valued at their net asset values as reported by the portfolio funds. A security traded on a securities exchange or in an over-the-counter market in which transaction prices are reported is valued at the last sales price at the time of valuation. A security traded principally on NASDAQ is valued at the NASDAQ official closing price. Mutual Funds and Exchange Traded Funds are valued at their closing net asset value as reported to NASDAQ. A security for which there is no reported sale on the valuation date is valued at the latest bid quotation. Short-term investments maturing in 60 days or less are valued at amortized cost, which approximates market value. A security for which a market quotation is not readily available and any other assets are valued at their fair value determined in good faith under consistently applied procedures established by the Board of Trustees. The Funds have retained an independent statistical fair value pricing service that employs a systematic methodology to assist in the fair valuation process for securities principally traded in a foreign market in order to adjust for possible changes in value that may occur between the close of the foreign exchange and the time as of which the securities are to be valued. If a security is valued at fair value, that value may be different from the last quoted market price for the security.

81

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

Various inputs are used in determining the value of each Fund's investments. These inputs are summarized in the three broad levels listed below:

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

• Level 3 – significant unobservable inputs (including management's own assumptions in determining the value of investments)

The inputs or methodologies used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Examples of the types of securities in which the Funds would typically invest and how they are classified within this hierarchy are as follows. Typical Level 1 securities include exchange traded domestic equities, mutual funds whose NAVs are published each day and exchange traded foreign equities that are not statistically fair valued. Typical Level 2 securities include exchange traded foreign equities that are statistically fair valued, forward foreign currency exchange contracts and short-term investments valued at amortized cost. Additionally, securities fair valued by the Fund's Valuation Committee that rely on significant observable inputs are also included in Level 2. Typical Level 3 securities include any security fair valued by the Funds' Valuation Committee that relies on significant unobservable inputs.

>Repurchase agreements

Each Fund may engage in repurchase agreement transactions. Each Fund, through its custodian, receives delivery of underlying securities collateralizing repurchase agreements. The counterparty is required to maintain collateral that is at all times at least equal to the repurchase price including interest. In the event of default or bankruptcy by the counterparty to the agreement, realization and/or retention of the collateral may be subject to legal proceedings.

>Foreign currency translations

Values of investments denominated in foreign currencies are converted into U.S. dollars using the New York spot market rate of exchange at the time of valuation. Purchases and sales of investments and dividend and interest income are translated into U.S. dollars using the spot market rate of exchange prevailing on the respective dates of such transactions. The gain or loss resulting from changes in foreign exchange rates is included with net realized and unrealized gain or loss from investments, as appropriate.

>Forward foreign currency exchange contracts

Columbia Acorn International may enter into forward foreign currency exchange contracts in order to seek to minimize the risk from adverse changes in the relationship between the U.S. dollar and foreign currencies. A forward foreign currency exchange contract is a commitment to purchase or sell a foreign currency at a future date at a negotiated forward rate. Forward foreign currency exchange contracts are valued at the interpolated forward exchange rate of the underlying currencies and any market gain or loss, arising from the difference between the original value and the current value of such contract, is included as a component of unrealized gain/(loss) on the Statements of Operations. Open forward foreign currency exchange contracts, if any, are disclosed in the Notes to the Statement of Investments. As forward foreign currency exchange contracts are closed the resulting gain or loss, arising from the difference between the original val ue of the contract and the closing value of such contract, is included as a component of realized gain/(loss) on the Statements of Operations.

A forward foreign currency exchange contract would limit the risk of loss due to a decline in the value of a particular currency; however, it also would limit any potential gain that might result should the value of the currency increase instead of decrease. These contracts may involve market risk in excess of the unrealized gain or loss reflected on the Statements of Assets and Liabilities. In addition, a Fund could be exposed to counterparty risks if counterparties to the contracts are unable to meet the terms of their contracts. The counterparty risk exposure is, therefore, closely monitored and contracts are only executed with high credit quality financial institutions.

A Fund may use forward foreign currency exchange contracts to buy or sell a foreign currency when the Adviser believes it has exposure to a foreign currency which may suffer or enjoy a movement against another foreign currency to which the Fund has exposure. A Fund will not attempt to hedge all of its foreign portfolio positions.

For additional information on derivative instruments, please see Note 5.

>Securities lending

Each Fund, except Columbia Thermostat Fund, may lend securities up to one-third of the value of its total assets to certain approved brokers, dealers and other financial institutions to earn additional income. In lending its securities, the Fund

82

retains the benefits of owning the securities, including receipt of dividends or interest generated by the security. Each Fund also receives a fee for the loan. Each Fund has the ability to recall the loans at any time and could do so in order to vote proxies or to sell the loaned securities. Each loan is collateralized by cash that exceeds the value of the securities on loan. The market value of the loaned securities is determined daily at the close of business of each Fund and any additional required collateral is delivered to each Fund on the next business day. Each Fund has elected to invest the cash collateral in the Dreyfus Government Cash Management Fund, and the income earned is paid to each Fund, net of any fees remitted to Goldman Sachs Agency Lending as the lending agent and net of any borrower rebates. The Adviser does not retain any fees earned by the lending program. Generally, in the event of borrower default, a Fund has the right to use the collateral to offset any losses incurred. In the event a Fund is delayed or prevented from exercising its right to dispose of the collateral, there may be a potential loss to a Fund. Some of these losses may be indemnified by the lending agent. Each Fund bears the risk of loss with respect to the investment of collateral.

The net lending income earned in 2010 by each Fund is included in the Statements of Operations.

>Security transactions and investment income

Security transactions, investment income and shareholder fund transactions are accounted for on the trade date (date the order to buy or sell is executed) and dividend income and realized gain distributions from other funds are recorded on the ex-dividend date, except that certain dividends from foreign securities are recorded as soon as the information is available to the Funds. Interest income is recorded on the accrual basis and includes amortization of discounts on debt obligations when required for federal income tax purposes. Realized gains and losses from security transactions are recorded on an identified cost basis.

Awards, if any, from class action litigation related to securities owned may be recorded as a reduction of cost of those securities. If the applicable securities are no longer owned, the proceeds are recorded as realized gains.

The Funds estimate the tax character of distributions from real estate investment trusts (REITs). Distributions received in excess of income are recorded as a reduction of the cost of the related investments. If the applicable securities are no longer owned, any distributions received in excess of income are recorded as realized gains.

>Restricted securities

Restricted securities are securities that may only be resold upon registration under federal securities laws or in transactions exempt from registration. In some cases, the issuer of restricted securities has agreed to register such securities for resale at the issuer's expense either upon demand by the Funds or in connection with another registered offering of the securities. Many restricted securities may be resold in the secondary market in transactions exempt from registration. Such restricted securities may be determined to be liquid under criteria established by the Board of Trustees.

>Fund share valuation

Fund shares are sold and redeemed on a daily basis at net asset value, subject to any applicable sales charge. Net asset value per share is determined daily as of the close of trading on the New York Stock Exchange (NYSE) on each day the NYSE is open for trading. Generally, income, expenses and realized and unrealized gain/(losses) of a Fund are allocated to each class proportionately on a daily basis for purposes of determining the net asset value of each class. The Rule 12b-1 service and distribution fees and transfer agency fees are charged to each specific class as expenses are incurred. Redemption fees are accounted for as an addition to paid in capital for purposes of determining the net asset value of each class.

>Custody fees/credits

Custody fees are reduced based on each Fund's cash balances maintained with the custodian. The amount is disclosed as a reduction of total expenses on the Statements of Operations.

>Federal income taxes

It is each Fund's policy to comply with the provisions of the Internal Revenue Code available to regulated investment companies and, in the manner provided therein, distribute substantially all their taxable income, as well as any net realized gain on sales of investments and foreign currency transactions reportable for federal income tax purposes. Columbia Thermostat Fund distributes all of its taxable income, as well as any net realized gain on sales of portfolio fund shares and any distributions of net realized gains received by the Fund from its portfolio funds, reportable for federal income tax purposes. Accordingly, the Funds paid no federal income taxes and no federal income tax provision was required.

>Foreign capital gains taxes

Realized gains in certain countries may be subject to foreign taxes at the fund level, at rates ranging from approximately 10% to 15%. The Funds accrue for such foreign taxes on net realized and unrealized gains at the appropriate rate for each jurisdiction.

83

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

>Distributions to Shareholders

Distributions to shareholders are recorded on the ex-dividend date.

>Indemnification

In the normal course of business, the Trust on behalf of the Funds enters into contracts that contain a variety of representations and warranties and that provide general indemnities. A Fund's maximum exposure under these arrangements is unknown, as this would involve future claims against the Fund. Also, under the Trust's organizational documents, the trustees and officers of the Trust are indemnified against certain liabilities that may arise out of their duties to the Trust. However, based on experience, the Funds expect the risk of loss due to these warranties and indemnities to be remote.

3.  Federal Tax Information

The timing and character of income and capital gain distributions are determined in accordance with income tax regulations, which may differ from GAAP. Reclassifications are made to the Funds' capital accounts for permanent tax differences to reflect income and gains available for distribution (or available capital loss carryforwards) under income tax regulations.

For the year ended December 31, 2010, permanent book and tax basis differences resulting primarily from differing treatments for net operating losses, foreign currency transactions, passive foreign investment company (PFIC) adjustments, short-term capital gain distributions from investments in mutual funds and proceeds from litigation settlements were identified and reclassified among the components of each Fund's net assets as follows:

	Undistributed/ (Overdistributed) or (Accumulated) Net Investment Income (Loss)		Accumulated Net Realized Gain/(Loss)			Paid-in Capital
(in thousands)
Columbia Acorn Fund	$	590	$	(589	)	$	(1	)
Columbia Acorn International		43,968		(42,361	)		(1,607	)
Columbia Acorn USA		6,009		—			(6,009	)
Columbia Acorn International Select		330		(284	)		(46	)
Columbia Acorn Select		2,926		(2,926	)		—
Columbia Thermostat Fund		92		(92	)		—

Net investment income/(loss) and net realized gains/(losses), as disclosed on the Statements of Operations, and net assets were not affected by these reclassifications.

The tax character of distributions paid during the years ended December 31, 2010 and December 31, 2009 was as follows:

	December 31, 2010				December 31, 2009
	Ordinary Income*		Long-Term Capital Gains		Ordinary Income*		Long-Term Capital Gains
(in thousands)
Columbia Acorn Fund	$	21,020	$	496,293	$	20,981	$	—
Columbia Acorn International		122,919		—		60,207		—
Columbia Acorn USA		—		—		—		—
Columbia Acorn International Select		6,107		—		3,533		—
Columbia Acorn Select		—		—		—		—
Columbia Thermostat Fund		1,666		—		122		—

*For tax purposes short-term capital gain distributions, if any, are considered ordinary income distributions.

As of December 31, 2010, the components of distributable earnings on a tax basis were as follows:

	Undistributed Ordinary Income		Undistributed Long-Term Capital Gains		Net Unrealized Appreciation*
(in thousands)
Columbia Acorn Fund	$	38,838	$	183,753	$	6,469,997
Columbia Acorn International		156,914		—		1,662,843
Columbia Acorn USA		—		—		513,833
Columbia Acorn International Select		5,840		—		112,829
Columbia Acorn Select		31,148		—		598,661
Columbia Thermostat Fund		1,509		—		18,580

* The differences between book-basis and tax-basis net unrealized appreciation/(depreciation) are primarily due to deferral of losses from wash sales and PFIC adjustments.

The following capital loss carryforwards, determined as of December 31, 2010, may be available to reduce taxable income arising from future net realized gains on investments, if any, to the extent permitted by the Internal Revenue Code:

	Year of Expiration
	2011- 2015		2016		2017		2018		Total
(in thousands)
Columbia Acorn International	$	—	$	—	$	386,385	$	—	$	386,385
Columbia Acorn USA		—		—		28,408		—		28,408
Columbia Acorn International Select		—		—		36,610		—		36,610
Columbia Acorn Select		—		3,592		115,445		—		119,037
Columbia Thermostat Fund		—		5,193		21,738		2,954		29,885

Capital loss carryforwards that were utilized for the Funds during the year ended December 31, 2010 were as follows:

(in thousands)
Columbia Acorn Fund	$	409,911
Columbia Acorn International		238,546
Columbia Acorn USA		85,334
Columbia Acorn International Select		40,289
Columbia Acorn Select		8,679

84

Management is required to determine whether a tax position of the Funds is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any related appeals or litigation processes, based on the technical merits of the position. The tax benefit to be recognized by the Funds is measured as the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. Management is not aware of any tax positions for which it is reasonably possible that the total amounts of unrecognized tax benefits will significantly change in the next twelve months. However, management's conclusions may be subject to review and adjustment at a later date based on factors including, but not limited to, new tax laws, regulations, and administrative interpretations (including relevant court decisions). The Funds' federal tax returns for the prior three fiscal years remain s ubject to examination by the Internal Revenue Service.

4.  Transactions with Affiliates

CWAM is a wholly owned subsidiary of Columbia Management, which in turn is an indirect, wholly owned subsidiary of Ameriprise Financial, Inc. (Ameriprise Financial). CWAM furnishes continuing investment supervision to the Funds and is responsible for the overall management of the Funds' business affairs.

After the close of business on April 30, 2010, (the Closing), Ameriprise Financial acquired a portion of the asset management business of Columbia Management Group, LLC (the Transaction), including 100% of CWAM. On May 27, 2010, the shareholders of the Funds approved a new investment advisory agreement with CWAM to provide advisory services to the Funds. There were no changes to the Funds' advisory fee rate under the new agreement.

CWAM received a monthly advisory fee based on each Fund's average daily net assets at the following annual rates:

Columbia Acorn Fund

Average Daily Net Assets	Annual Fee Rate
Up to $700 million		0.74	%
$700 million to $2 billion		0.69	%
$2 billion to $6 billion		0.64	%
$6 billion and over		0.63	%

Columbia Acorn International

Average Daily Net Assets	Annual Fee Rate
Up to $100 million		1.19	%
$100 million to $500 million		0.94	%
$500 million and over		0.74	%

Columbia Acorn USA

Average Daily Net Assets	Annual Fee Rate
Up to $200 million		0.94	%
$200 million to $500 million		0.89	%
$500 million to $2 billion		0.84	%
$2 billion to $3 billion		0.80	%
$3 billion and over		0.70	%

Columbia Acorn International Select

Average Daily Net Assets		Annual Fee Rate
	Up to $500 million		0.94	%
	$500 million and over		0.90	%

Columbia Acorn Select

Average Daily Net Assets	Annual Fee Rate
Up to $700 million		0.85	%
$700 million to $2 billion		0.80	%
$2 billion to $3 billion		0.75	%
$3 billion and over		0.70	%

Columbia Thermostat Fund

	Annual Fee Rate
All Average Daily Net Assets		0.10	%

For the year ended December 31, 2010, the Funds' effective investment advisory fee rates were as follows:

Columbia Acorn Fund	0.64	%
Columbia Acorn International	0.77	%
Columbia Acorn USA	0.86	%
Columbia Acorn International Select	0.94	%
Columbia Acorn Select	0.82	%
Columbia Thermostat Fund	0.10	%

>Expense Limit

CWAM has voluntarily agreed to reimburse the ordinary operating expenses (exclusive of brokerage commissions, interest, taxes and extraordinary expenses, but inclusive of custodial charges relating to overdrafts, if any) after giving effect to any balance credits from the Funds' custodian, exceeding annually the average daily net assets of the Funds as follows:

Fund	Class Z
Columbia Acorn International Select		1.45	%
Columbia Acorn Select		1.35	%

This arrangement may be modified or terminated by either the Funds or CWAM on 30 days notice.

CWAM has contractually agreed to waive fees and/or reimburse expenses of Columbia Thermostat Fund so that the ordinary operating expenses (exclusive of distribution and service fees, interest and fees on borrowings, and expenses

85

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

associated with the Fund's investment in other investment companies, but including custodian charges relating to overdrafts, if any), after giving effect to any balance credits from the Fund's custodian, will not exceed 0.25% annually of the Fund's average daily net assets through April 30, 2011. There is no guarantee that this arrangement will continue thereafter.

Expenses reimbursed by CWAM to Columbia Acorn International Select and Columbia Thermostat Fund for the year ended December 31, 2010, were $1,817 and $266,413, respectively.

CWAM provides administrative services and receives an administration fee from the Funds at the following annual rates:

Columbia Acorn Trust

Aggregate Average Daily Net Assets of the Trust:	Annual Fee Rate
Up to $8 billion		0.050	%
$8 billion to $16 billion		0.040	%
$16 billion to $35 billion		0.030	%
$35 billion to $45 billion		0.025	%
$45 billion and over		0.015	%

For the year ended December 31, 2010, each Fund's effective administration fee rate was 0.04% of average daily net assets. Prior to the Closing, CWAM had delegated to Columbia Management Advisors, LLC (CMA) an indirect, wholly owned subsidiary of Bank of America Corporation (BOA), responsibility to provide certain sub-administrative services to the Funds. Following the Closing, Columbia Management succeeded CMA as sub-administrator and continued providing certain sub-administrative services to the Funds.

Prior to the Closing, Columbia Management Distributors, Inc., an indirect subsidiary of BOA, served as the Funds' distributor and principal underwriter. In connection with the Closing, Columbia Management Investment Distributors, Inc., (formerly, Riversource Fund Distributors, Inc.) (CMID) a wholly owned subsidiary of Ameriprise Financial, became the distributor of the Funds. There were no changes to the underwriting discount structure of the Funds or the service or distribution fee rates paid by the Funds as a result of the Closing.

Each Fund has adopted a Rule 12b-1 (distribution and service) plan which requires it to pay CMID a monthly service fee equal to 0.25% annually of the average daily net assets attributable to Class A, Class B and Class C shares and a monthly distribution fee equal to 0.50% and 0.75%, annually, of the average daily net assets attributable to Class B and Class C shares, respectively. CMID receives no compensation with respect to Class Z shares.

Prior to the Closing, Columbia Management Services, Inc., an indirect, wholly owned subsidiary of BOA, provided shareholder services to the Funds and contracted with Boston Financial Data Services (BFDS) to serve as sub-transfer agent. Following the Closing, Columbia Management Investment Services Corp. (CMIS), (formerly, Riversource Service Corporation), a wholly owned subsidiary of Ameriprise Financial, became the transfer agent of the Funds. The transfer agent fee rates paid by the Funds did not change as a result of the change in transfer agent. For its services, each Fund pays CMIS a monthly fee at the annual rate of $17.00 per open account. CMIS also receives reimbursement for certain out-of-pocket expenses. The arrangement with BFDS has been continued by CMIS.

Class I shares do not pay transfer agent fees.

Certain officers and trustees of the Trust are also officers of CWAM. The Trust makes no direct payments to its officers and trustees who are affiliated with CWAM.

The Board of Trustees appointed a Chief Compliance Officer of the Trust in accordance with federal securities regulations. The Funds, along with other affiliated funds, pay their pro-rata share of the expenses associated with the Office of the Chief Compliance Officer. Those expenses are disclosed separately as "Chief compliance officer expenses" in the Statements of Operations.

The Trust offers a deferred compensation plan for its independent trustees. Under that plan, a trustee may elect to defer all or a portion of his or her compensation. Amounts deferred are retained by the Trust and may represent an unfunded obligation of the Trust. The value of amounts deferred is determined by reference to the change in value of Class Z shares of one or more series of the Trust or a money market fund specified by the trustee. Benefits under the deferred compensation plan are payable when the trustee ceases to be a member of the Board of Trustees.

An affiliated person of a Fund may include any company in which a Fund owns five percent or more of its outstanding voting shares. On December 31, 2010, Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA and Columbia Acorn Select each held five percent or more of the outstanding voting securities of one or more companies. Details of investments in those affiliated companies are presented on pages 33, 34, 45, 56 and 67, respectively.

During the year ended December 31, 2010, the Funds engaged in purchase and sale transactions with funds that have a common investment adviser (or affiliated investment advisers), common directors/trustees, and/or common officers.

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Those transactions complied with Rule 17a-7 under the Investment Company Act of 1940 and were as follows:

	Purchases		Sales
(in thousands)
Columbia Acorn Fund	$	12,585	$	683
Columbia Acorn International		7,383		1,715
Columbia Acorn USA		704		1,016
Columbia Acorn International Select		334		381
Columbia Acorn Select		1,350		12,647

5.  Objectives and Strategies for Investing in Derivative Instruments

Columbia Acorn International uses derivative instruments including forward foreign currency exchange contracts in order to meet its investment objectives. The Fund employs strategies in differing combinations to permit it to increase, decrease or change the level of exposure to market risk factors. The achievement of any strategy involving derivatives depends on analysis of various risk factors, and if the strategies for the use of derivatives do not work as intended, the Fund may not achieve its investment objectives.

In pursuit of its investment objectives, the Fund is exposed to the following market risks:

Foreign Exchange Rate Risk: Foreign exchange rate risk relates to the change in the U.S. dollar value of a security held that is denominated in a foreign currency. The U.S. dollar value of a foreign-currency-denominated security will decrease as the dollar appreciates against the currency, while the U.S. dollar value will increase as the dollar depreciates against the currency.

The following note provides more detailed information about the derivative type held by the Columbia Acorn International:

Forward Foreign Currency Exchange Contracts

• The Fund entered into forward foreign currency exchange contracts to shift its investment exposure from one currency to another.

• The Fund used forward foreign currency exchange contracts to shift its U.S. dollar exposure in order to achieve a representative weighted mix of major currencies relative to its benchmark and/or to recover an underweight country exposure in its portfolio relative to its benchmark.

Forward foreign currency exchange contracts are agreements to exchange one currency for another at a future date at a specified price. These contracts are used to seek to minimize the exposure to foreign exchange rate fluctuations during the period between the trade and settlement dates of the contract. The Fund may utilize forward foreign currency exchange contracts in connection with the settlement of purchases and sales of securities. The Fund may also enter into these contracts to seek to reduce the exposure to adverse price movements in certain other foreign-currency-denominated assets. Contracts to buy are used to acquire exposure to foreign currencies, while contracts to sell are used to reduce the exposure to foreign exchange rate fluctuations. Forward foreign currency exchange contracts are valued daily at the current exchange rate of the underlying currency, resulting in unrealized gains (losses) which become realized at the time the forward foreign currency exchange contracts are closed or mature. Realized and unrealized gains (losses) arising from such transactions are included in net realized and unrealized gains (losses) on foreign currency transactions. The use of forward foreign currency exchange contracts does not eliminate fluctuations in the prices of the Fund's portfolio securities. While the maximum potential loss from such contracts is the aggregate face value in U.S. dollars at the time the contract was opened, exposure is typically limited to the change in value of the contract (in U.S. dollars) over the period it remains open. The Fund could also be exposed to risk that counterparties of the contracts may be unable to fulfill the terms of the contracts.

During the year ended December 31, 2010, Columbia Acorn International entered into 146 forward foreign currency exchange contracts.

The following table is a summary of the value of Columbia Acorn International's derivative instruments as of December 31, 2010.

  Fair Value of Derivative Instruments

	Asset
	Statement of Assets and Liabilities	Fair Value
(in thousands)
	Unrealized appreciation on forward foreign currency exchange contracts	$	11,287

The effect of derivative instruments on Columbia Acorn International's Statement of Operations for the year ended December 31, 2010 was as follows:

Amount of Realized Gain or (Loss) and Change in Unrealized Appreciation or (Depreciation)
On Derivatives Recognized in Income

	Risk Exposure	Realized Gain/(Loss)		Change in Unrealized Appreciation/ (Depreciation)
(in thousands)
Forward foreign currency exchange contracts	Foreign Exchange Rate Risk	$	34,627	$	8,803

6.  Borrowing Arrangements

The Trust participates in a $150 million credit facility, along with another Trust managed by CWAM, which was entered into

87

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

to facilitate portfolio liquidity. Under the facility, interest is charged to each participating fund based on its borrowings at a rate per annum equal to the higher of Federal Funds Rate or Overnight LIBOR plus 1.25%. In addition, a commitment fee of 0.15% per annum of the unutilized line of credit was accrued and apportioned among the participating funds based on their relative net assets. The commitment fee is included in "Other expenses" in the Statements of Operations. No amounts were borrowed by any Fund under this facility for the year ended December 31, 2010. The Trust enters into this line of credit for one year durations. The Trust has secured the line of credit for the entire year of 2011.

7.  Investment Transactions

The aggregate cost of purchases and proceeds from sales, other than short-term obligations, for the year ended December 31, 2010, were:

Columbia Acorn Fund

(in thousands)
Investment securities
Purchases	$	4,129,651
Proceeds from sales		4,459,270

Columbia Acorn International

(in thousands)
Investment securities
Purchases	$	1,668,861
Proceeds from sales		1,164,147

Columbia Acorn USA

(in thousands)
Investment securities
Purchases	$	454,468
Proceeds from sales		469,161

Columbia Acorn International Select

(in thousands)
Investment securities
Purchases	$	163,811
Proceeds from sales		204,032

Columbia Acorn Select

(in thousands)
Investment securities
Purchases	$	580,228
Proceeds from sales		529,594

Columbia Thermostat Fund

(in thousands)
Investment securities
Purchases	$	146,478
Proceeds from sales		174,366

8.  Redemption Fees

For the year ended December 31, 2010, the redemption fees imposed by Columbia Acorn International and Columbia Acorn International Select amounted to $239,708 and $10,223, respectively, and are accounted for as additions to paid in capital. Effective September 1, 2010, Columbia Acorn International and Columbia Acorn International Select ceased to impose redemption fees.

9.  Regulatory Settlements with Third Parties

During the year ended December 31, 2010, Columbia Acorn International and Columbia Acorn International Select received payments totaling $446,565 and $46,265, respectively, representing distributions from a fair fund established in connection with a regulatory settlement between the Securities and Exchange Commission and a third party broker dealer relating to alleged market timing and late trading in mutual funds, including the Funds. The payments have been included in "Increase from regulatory settlements" in the Statements of Changes in Net Assets.

10.  Information Regarding Pending and Settled Legal Proceedings

In June 2004, an action captioned John E. Gallus et al. v. American Express Financial Corp. and American Express Financial Advisors Inc. was filed in the United States District Court for the District of Arizona. The plaintiffs allege that they are investors in several American Express Company (now known as legacy RiverSource) mutual funds and they purport to bring the action derivatively on behalf of those funds under the Investment Company Act of 1940. The plaintiffs allege that fees allegedly paid to the defendants by the funds for investment advisory and administrative services are excessive. The plaintiffs seek remedies including restitution and rescission of investment advisory and distribution agreements. The plaintiffs voluntarily agreed to transfer this case to the United States District Court for the Distri ct of Minnesota (the District Court). In response to defendants' motion to dismiss the complaint, the District Court dismissed one of plaintiffs' four claims and granted plaintiffs limited discovery. Defendants moved for summary judgment in April 2007. Summary judgment was granted in the defendants' favor on July 9, 2007. The plaintiffs filed a notice of appeal with the Eighth Circuit Court of Appeals (the Eighth Circuit) on August 8, 2007. On April 8, 2009, the Eighth Circuit reversed summary judgment and remanded to the District Court for further proceedings. On August 6, 2009, defendants filed a writ of certiorari with the U.S. Supreme Court (the Supreme Court), asking the Supreme Court to stay the District Court proceedings

88

while the Supreme Court considers and rules in a case captioned Jones v. Harris Associates, which involves issues of law similar to those presented in the Gallus case. On March 30, 2010, the Supreme Court issued its ruling in Jones v. Harris Associates, and on April 5, 2010, the Supreme Court vacated the Eighth Circuit's decision in the Gallus case and remanded the case to the Eighth Circuit for further consideration in light of the Supreme Court's decision in Jones v. Harris Associates. On June 4, 2010, the Eighth Circuit remanded the Gallus case to the District Cou rt for further consideration in light of the Supreme Court's decision in Jones v. Harris Associates. On December 9, 2010, the District Court reinstated its July 9, 2007 summary judgment order in favor of the defendants. On January 10, 2011, plaintiffs filed a notice of appeal with the Eighth Circuit.

In December 2005, without admitting or denying the allegations, American Express Financial Corporation (AEFC, which is now known as Ameriprise Financial, Inc. (Ameriprise Financial)), entered into settlement agreements with the Securities and Exchange Commission (SEC) and Minnesota Department of Commerce (MDOC) related to market timing activities. As a result, AEFC was censured and ordered to cease and desist from committing or causing any violations of certain provisions of the Investment Advisers Act of 1940, the Investment Company Act of 1940, and various Minnesota laws. AEFC agreed to pay disgorgement of $10 million and civil money penalties of $7 million. AEFC also agreed to retain an independent distribution consultant to assist in developing a plan for distribution of all disgorgement and civil penalties ordered by the SEC in accordance with various undertakings detailed at http://www.sec.gov/litigation/admin/ia-2451.pdf. Ameriprise Financial and its affiliates have cooperated with the SEC and the MDOC in these legal proceedings, and have made regular reports to the RiverSource, Seligman and Threadneedle funds' Boards of Directors/Trustees.

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Funds are not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Funds or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Funds. Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.s ec.gov.

There can be no assurance that these matters, or the adverse publicity associated with them, will not result in increased fund redemptions, reduced sale of fund shares or other adverse consequences to the Funds. Further, although we believe proceedings are not likely to have a material adverse effect on the Funds or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Funds, these proceedings are subject to uncertainties and, as such, we are unable to estimate the possible loss or range of loss that may result. An adverse outcome in one or more of these proceedings could result in adverse judgments, settlements, fines, penalties or other relief that could have a material adverse effect on the consolidated financial condition or results of operations of Ameriprise Financial.

**********

CWAM and the Trustees of the Trust (collectively, the Columbia defendants) were named as defendants in class and derivative complaints that were consolidated in a Multi-District Action (the MDL Action) in the federal district court of Maryland. These lawsuits contend that defendants permitted certain investors to market time their trades in certain Columbia Acorn Funds. The MDL Action is ongoing. However, all claims against the Trust and the Independent Trustees of the Trust have been dismissed.

Columbia Acorn Trust and CWAM are also defendants in a state court class action lawsuit that alleges, in summary, that the Trust and CWAM exposed shareholders of Columbia Acorn International to trading by market timers by allegedly: (a) failing to properly evaluate daily whether a significant event affecting the value of the Fund's securities had occurred after foreign markets had closed but before the calculation of the Fund's net asset value (NAV); (b) failing to implement the Fund's portfolio valuation and share pricing policies and procedures; and (c) failing to know and implement applicable rules and regulations concerning the calculation of NAV (the Fair Valuation Lawsuit). The United States Court of Appeals for the Seventh Circuit ruled that the plaintiffs' state law claims were preempted under federal law, resulting in the dismissal of plaintiffs' complaint. Plaintiffs appealed the Seventh Circuit's ruling to the United States Supre me Court. The Supreme Court reversed the Seventh Circuit's ruling on jurisdictional grounds and the case was remanded to the state court.

89

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

On March 21, 2005, a class action complaint was filed against the Trust and CWAM seeking to rescind the contingent deferred sales charge (CDSC) assessed upon redemption of Class B shares of the Columbia Acorn Funds (the CDSC Lawsuit). In addition to the rescission of sales charges, plaintiffs seek recovery of actual damages, attorneys' fees and costs. The case was transferred to the MDL Action in the federal district court of Maryland.

On September 14, 2007, the plaintiffs and the Columbia defendants named in the MDL Action, including the Columbia family of funds, entered into a stipulation of settlement with respect to all Columbia-related claims in the MDL Action described above, including the CDSC and Fair Valuation Lawsuits.

On April 23, 2010, the parties to the MDL Action filed a motion seeking: (a) preliminary approval of the MDL settlements; (b) the conditional certification of the plaintiff class for purposes of settlement; (c) approval of the form and manner of giving notice to the plaintiff class of the proposed settlements; and, (d) approval of the proposed schedule for various deadlines in connection with the final settlement hearing. The motion was presented to and approved by the court on May 7, 2010.

On October 21, 2010, the court held a final hearing regarding the MDL settlements and on October 25, 2010 issued a final judgment and related orders that: (a) approved the settlements as fair, reasonable and adequate, and in the best interests of members of both the plaintiff class and current shareholders of the Columbia funds, including the Columbia Acorn Funds; (b) dismissed with prejudice all complaints against the Columbia defendants; and (c) approved a plan of distribution for the amounts due to the plaintiff class as established in the settlements. The orders of settlement do not create any liability for the Columbia Acorn Funds.

CWAM believes that the lawsuits described in the four preceding paragraphs are not likely to materially affect its ability to provide investment management services to the Funds.

90

Report of Independent Registered Public Accounting Firm

To the Board of Trustees and Shareholders of
Columbia Acorn Trust:

In our opinion, the accompanying statement of assets and liabilities, including the statement of investments, and the related statements of operations and of changes in net assets and the financial highlights present fairly, in all material respects, the financial position of Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select and Columbia Thermostat Fund (each a series of the Columbia Acorn Trust, hereinafter referred to as the "Funds") at December 31, 2010, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended and the financial highlights for each of the five years in the period then ended, in conformity with accounting principles generally accepted in the United States of America. These financial statements and financial highlights (hereafter referred to as "financial statements") are the responsibility of the Funds' management; our responsibility is to express an opinion on these financial statements based on our audits. We conducted our audits of these financial statements in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits, which included confirmation of securities at December 31, 2010 by correspondence with the custodian, brokers and transfer agent, provide a reasonable basis for our opinion.

PricewaterhouseCoopers LLP
Chicago, Illinois
February 16, 2011

91

Columbia Acorn Family of Funds

Federal Income Tax Information (in thousands) (Unaudited) — Class A, B, C, I and Z shares

Columbia Acorn Fund

The Fund hereby designates as a capital gain dividend with respect to the fiscal year ended December 31, 2010 $714,049, or, if subsequently determined to be different, the net capital gain of such year.

100.00% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2010 qualified for the corporate dividends received deduction.

For non-corporate shareholders 100.00%, or the maximum amount allowable under the Jobs and Growth Tax Relief Reconciliation Act of 2003, of ordinary income distributed by the Fund for the fiscal year ended December 31, 2010 may represent qualified dividend income.

Columbia Acorn International

Foreign taxes paid during the fiscal years ended December 31, 2010 and 2009 of $7,871 and $1,789 respectively are being passed through to shareholders. These represent $0.05 and $0.01 per share, respectively. Eligible shareholders may claim these amounts as a foreign tax credit.

Gross income derived from sources within foreign countries was $104,523 ($0.70 per share) for the fiscal year ended December 31, 2010.

For non-corporate shareholders, 100.00% or the maximum amount allowable under the Jobs and Growth Tax Relief Reconciliation Act of 2003, of the ordinary income distributed by the Fund for the fiscal year ended December 31, 2010 may represent qualified dividend income.

Columbia Acorn International Select

Foreign taxes paid during the fiscal year ended December 31, 2010, of $516 are being passed through to shareholders. This represents $0.03 per share. Eligible shareholders may claim this amount as a foreign tax credit.

Gross income derived from sources within foreign countries was $8,297 ($0.52 per share) for the fiscal year ended December 31, 2010.

For non-corporate shareholders, 100.00% or the maximum amount allowable under the Jobs and Growth Tax Relief Reconciliation Act of 2003, of the ordinary income distributed by the Fund for the fiscal year ended December 31, 2010 may represent qualified dividend income.

Columbia Thermostat Fund

For non-corporate shareholders, 100.00% or the maximum amount allowable under the Jobs and Growth Tax Relief Reconciliation Act of 2003, of the ordinary income distributed by the Fund for the fiscal year ended December 31, 2010 may represent qualified dividend income.

100.00% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2010 qualified for the corporate dividends received deduction.

92

Board of Trustees and Management of
Columbia Acorn Funds

Each trustee may serve a term of unlimited duration. The Trust's By-laws generally require that a trustee retire at the end of the calendar year in which the trustee attains the age of 75 years. The trustees appoint their own successors, provided that at least two-thirds of the trustees, after such appointment, have been elected by shareholders. Shareholders may remove a trustee, with or without cause, upon the vote of two-thirds of the Trust's outstanding shares at any meeting called for that purpose. A trustee may be removed, with or without cause, upon the vote of a majority of the trustees. The names of the trustees and officers of the Trust, the date each was first elected or appointed to office, their principal business occupations during at least the last five years, number of portfolios in the fund complex they oversee, and other directorships they hold, are shown below. Each trustee serves in such capacity for each of the six serie s of Columbia Acorn Trust and for each of the four series of Wanger Advisors Trust.

The address for the trustees and officers of the Trust is Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. The Funds' Statement of Additional Information includes additional information about the Funds' trustees and officers. You may obtain a free copy of the Statement of Additional Information by writing or calling toll-free:

Columbia Wanger Asset Management, LLC
Shareholder Services Group
227 W. Monroe, Suite 3000
Chicago IL 60606
1-800-922-6769

Name, Position(s) with Columbia Acorn Trust and Age at December 31, 2010	Year First Elected or Appointed to Office*		Principal Occupation(s) during Past Five Years	Number of Portfolios in Fund Complex Overseen by Trustee/Officer		Other Directorships in addition to Columbia Acorn Trust
Trustees who are not interested persons of Columbia Acorn Trust:
Laura M. Born, 45, Trustee		2007	Adjunct Assistant Professor of Finance, University of Chicago Booth School of Business; formerly, Managing Director – Investment Banking, JP Morgan Chase & Co. (broker/dealer) 2002-2007; prior thereto, associated with JP Morgan as an investment professional since 1991.		10	Wanger Advisors Trust
Michelle L. Collins, 50, Trustee		2008	President, Cambium LLC (financial advisory firm) since 2007; Advisory Board Member, Svoboda Capital Partners LLC (private equity firm) since 2007; Managing Director Svoboda Capital Partners LLC, 1998-2006.		10	Wanger Advisors Trust; Bucyrus International, Inc. (mining equipment manufacturer); Molex, Inc. (electronics components manufacturer); CDW Corporation (electronics components manufacturer) (until October 2007).
Maureen M. Culhane, 62, Trustee		2007	Retired. Formerly, Vice President, Goldman Sachs Asset Management, L.P. (investment adviser), 2005-2007, and Vice President (Consultant) – Strategic Relationship Management, Goldman Sachs & Co., 1999-2005.		10	Wanger Advisors Trust
Margaret M. Eisen, 57, Trustee		2002	Chief Investment Officer, EAM International LLC (corporate finance and asset management) since 2003; Managing Director, CFA Institute, 2005-2008.		10	Wanger Advisors Trust; Antigenics, Inc. (biotechnology and pharmaceuticals) (until June 2009).
John C. Heaton, 51, Trustee		2010	Joseph L. Gidwitz Professor of Finance, University of Chicago Booth School of Business; financial consultant.		10	Wanger Advisors Trust
Steven N. Kaplan, 51, Trustee and Vice Chairman of the Board		1999	Neubauer Family Professor of Entrepreneurship and Finance, University of Chicago Booth School of Business.		10	Wanger Advisors Trust; Accretive Health, Inc. (healthcare management services provider); Morningstar, Inc. (provider of independent investment research).
David C. Kleinman, 75, Trustee(1)		1972	Adjunct Professor of Strategic Management, University of Chicago Booth School of Business; business consultant.		10	Wanger Advisors Trust; Sonic Foundry, Inc. (rich media systems and software).
Allan B. Muchin, 74, Trustee		1998	Chairman Emeritus, Katten Muchin Rosenman LLP (law firm).		10	Wanger Advisors Trust
David B. Small, 54, Trustee		2010	Managing Director, Chairman of Investment Committee, Grosvenor Capital Management, L.P. (investment adviser).		10	Wanger Advisors Trust

93

Name, Position(s) with Columbia Acorn Trust and Age at December 31, 2010	Year First Elected or Appointed to Office*		Principal Occupation(s) during Past Five Years	Number of Portfolios in Fund Complex Overseen by Trustee/Officer		Other Directorships in addition to Columbia Acorn Trust
Trustees who are not interested persons of Columbia Acorn Trust: (continued)
James A. Star, 49, Trustee and Chairman of the Board		2006	President, Longview Asset Management LLC (investment adviser) since 2003; associated with Longview or its predecessors and affiliates since 1994.		10	Wanger Advisors Trust
Trustees who are interested persons of Columbia Acorn Trust:
Charles P. McQuaid, 57, Trustee and President(2)		1992	President and Chief Investment Officer, CWAM or its predecessors, since October 2003; associated with CWAM or its predecessors as an investment professional since 1978.		10	Wanger Advisors Trust
David J. Rudis, 57, Trustee(3)		2010	National Checking and Debit Executive, and Illinois President, Bank of America, 2007 to 2009; President, Consumer Banking Group, LaSalle National Bank, 2004 to 2007.		10	Wanger Advisors Trust
Trustee Emeritus
Ralph Wanger, 76, Trustee Emeritus(4)		1970	Founder, CWAM. Formerly, President, Chief Investment Officer and portfolio manager, CWAM or its predecessors, July 1992 – September 2003; Director, Wanger Investment Company PLC; Consultant, CWAM or its predecessors, September 2003 – September 2005.		10	Wanger Advisors Trust
Officers of Columbia Acorn Trust:
Ben Andrews, 44, Vice President		2004	Portfolio manager and analyst, CWAM or its predecessors, since 1998; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2004.		10	None
Michael G. Clarke, 41, Assistant Treasurer		2004	Vice President, Columbia Management Investment Advisers, LLC since May 2010; Managing Director of Fund Administration, Columbia Management Advisors, LLC, from September 2004 to April 2010; senior officer of Columbia Family of Funds and affiliated funds since 2002.		10	None
Joseph F. DiMaria, 43, Assistant Treasurer		2010	Vice President, Mutual Fund Administration, Columbia Management Investment Advisers, LLC, since May 2010; Director of Fund Administration, Columbia Management Advisors, LLC from January 2006 to April 2010; Head of Tax/Compliance and Assistant Treasurer, Columbia Management Advisors, LLC, from November 2004 to December 2005.		10	None
P. Zachary Egan, 42, Vice President		2003	Director of International Research, CWAM or its predecessors, since December 2004; Vice President, Columbia Acorn Trust since 2003 and Wanger Advisors Trust since 2007; portfolio manager and analyst, CWAM or its predecessors, since 1999.		10	None
John Kunka, 40, Assistant Treasurer		2006	Director of Accounting and Operations, CWAM or its predecessors, since May 2006; Manager of Mutual Fund Operations, Calamos Advisors, Inc. (investment advisor), September 2005 – May 2006; prior thereto, Manager of Mutual Fund Administration, Van Kampen Investments.		10	None
Joseph C. LaPalm, 41, Vice President		2006	Chief Compliance Officer, CWAM since 2005; prior thereto, compliance officer, William Blair & Company (investment firm).		10	None

94

Name, Position(s) with Columbia Acorn Trust and Age at December 31, 2010	Year First Elected or Appointed to Office*		Principal Occupation(s) during Past Five Years	Number of Portfolios in Fund Complex Overseen by Trustee/Officer		Other Directorships in addition to Columbia Acorn Trust
Officers of Columbia Acorn Trust: (continued)
Bruce H. Lauer, 53, Vice President, Secretary and Treasurer		1995	Chief Operating Officer, CWAM or its predecessors, since April 2000; Vice President, Secretary and Treasurer, Columbia Acorn Trust and Wanger Advisors Trust, since 1995; Director, Wanger Investment Company PLC; formerly, Director, Banc of America Capital Management (Ireland) Ltd.; and formerly, Director, Bank of America Global Liquidity Funds, PLC.		10	None
Louis J. Mendes III, 46, Vice President		2003	Portfolio manager and analyst, CWAM or its predecessors, since 2001; Vice President, Columbia Acorn Trust since 2003 and Wanger Advisors Trust since 2005.		10	None
Robert A. Mohn, 49, Vice President		1997	Director of Domestic Research, CWAM or its predecessors, since March 2004; Vice President, Columbia Acorn Trust and Wanger Advisors Trust, since 1997; portfolio manager and analyst, CWAM or its predecessors, since August 1992.		10	None
Christopher J. Olson, 46, Vice President		2001	Portfolio manager and analyst, CWAM or its predecessors, since January 2001; Vice President, Columbia Acorn Trust and Wanger Advisors Trust, since 2001.		10	None
Scott R. Plummer, 51 Assistant Secretary		2010	Chief Legal Officer and Assistant Secretary, Columbia Management Investment Advisers, LLC (or its predecessor) since June 2005; Vice President and Lead Chief Counsel – Asset Management, Ameriprise Financial since May 2010 (previously Vice President and Chief Counsel – Asset Management, from 2005 to April 2010, and Vice President – Asset Management Compliance from 2004 to 2005); Vice President, Chief Counsel and Assistant Secretary, Columbia Management Investment Distributors, Inc. (or its predecessor) since 2008; Vice President, General Counsel and Secretary, Ameriprise Certificate Company since 2005; Chief Counsel, RiverSource Distributors, Inc. from 2006 to 2010; Vice President, General Counsel and Secretary, RiverSource Funds, since December 2006; Senior Vice President, Secretary and Chief Legal Officer, Columbia Family of Funds since May 2010.		10	None
Christopher O. Petersen, 41 Assistant Secretary		2010	Vice President and Chief Counsel, Ameriprise Financial since January 2010 (formerly Vice President and Group Counsel or Counsel from April 2004 to January 2010); Assistant Secretary of RiverSource Funds since January 2007.		10	None
Robert P. Scales, 58, Chief Compliance Officer, Chief Legal Officer, Senior Vice President and General Counsel		2004	Chief Compliance Officer, Chief Legal Officer, Senior Vice President and General Counsel, Columbia Acorn Trust and Wanger Advisors Trust, since 2004.		10	None
Linda Roth-Wiszowaty, 41, Assistant Secretary		2006	Business support analyst, CWAM, since April 2007; prior thereto executive administrator, CWAM or its predecessors, and executive assistant to the Chief Operating Officer of CWAM or its predecessors.		10	None

*  Dates prior to April 1992 correspond to the date of first election or appointment as a trustee or officers of The Acorn Fund, Inc., the predecessor trust to Columbia Acorn Trust.

(1)  Mr. Kleinman retired at the end of calendar year 2010.

(2)  Mr. McQuaid is an "interested person" of Columbia Acorn Trust and of CWAM, as defined in the Investment Company Act of 1940 because he is an officer of the Trust and of CWAM.

(3)  Mr. Rudis commenced service as a Trustee on January 1, 2011. Mr. Rudis is an "interested person" of Columbia Acorn Trust, as defined in the New York Attorney General's Assurance of Discontinuance ("Order") entered into in February 2005 by Columbia Management Advisors, LLC (an indirect subsidiary of Bank of America Corporate ("BOA")) and Columbia Management Distributors, Inc. (an indirect subsidiary of BOA), because of his former employment as a BOA executive.

(4)  As permitted under the Columbia Acorn Trust's By-Laws, Mr. Wanger serves as a non-voting Trustee Emeritus of the Trust.

95

Columbia Acorn Family of Funds

Fourth Quarter Class Z Share Information (Unaudited)

Minimum Initial Investment in		Minimum Subsequent
all Funds	$0 to $2,000,	Investment in all Funds	$100
	available only to
	certain eligible	Exchange Fee	None
	investors

Columbia Acorn Fund		ACRNX
	Management Fee		0.64	%
	12b-1 Fee		None
	Other Expenses		0.12	%
	Net Expense Ratio		0.76	%
Columbia Acorn International		ACINX
	Management Fee		0.77	%
	12b-1 Fee		None
	Other Expenses		0.20	%
	Net Expense Ratio		0.97	%
Columbia Acorn USA		AUSAX
	Management Fee		0.86	%
	12b-1 Fee		None
	Other Expenses		0.15	%
	Net Expense Ratio		1.01	%
Columbia Acorn International Select		ACFFX
	Management Fee		0.94	%
	12b-1 Fee		None
	Other Expenses		0.22	%
	Net Expense Ratio		1.16	%
Columbia Acorn Select		ACTWX
	Management Fee		0.82	%
	12b-1 Fee		None
	Other Expenses		0.15	%
	Net Expense Ratio		0.97	%
Columbia Thermostat Fund		COTZX
	Management Fee		0.10	%
	12b-1 Fee		None
	Other Expenses		0.15	%*
	Net Expense Ratio		0.25	%*

    Fees and expenses are for the year ended December 31, 2010. Some share classes of Columbia Acorn Select and Columbia Acorn International Select include the effect of the contractual undertaking by Columbia Wanger Asset Management, LLC (CWAM) to waive fees and/or reimburse the Funds for any ordinary operating expenses (exclusive of brokerage commissions, interest, taxes and extraordinary expenses, but inclusive of custodian charges relating to overdrafts, if any), after giving effect to any balance credits from the Funds' custodian, in excess of the annual rate of the Funds as follows:

Fund	Class Z
Columbia Acorn International Select		1.45	%
Columbia Acorn Select		1.35	%

    These arrangements may be modified or terminated by either the Funds or CWAM upon 30 days notice. Columbia Thermostat Fund's fees and expenses include the effect of CWAM's contractual undertaking to waive fees and/or reimburse the Fund for any ordinary operating expenses (exclusive of distribution and service fees, interest and fees on borrowings and expenses associated with the Fund's investments in other investment companies, but including custodian charges relating to overdrafts, if any), after giving effect to any balance credits from the Fund's custodian, in excess of the annual rate of 0.25% of the average daily net assets. Columbia Thermostat Fund's waiver/reimbursement arrangement is contractual through April 30, 2011. There is no guarantee that this arrangement will continue thereafter.

  *  Does not include estimated fees and expenses of 0.79% incurred by the Fund from the underlying portfolio funds in which it invests.

96

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97

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98

Columbia Acorn Family of Funds

Investment Adviser

Columbia Wanger Asset Management, LLC
227 West Monroe Street, Suite 3000
Chicago, Illinois 60606

1-800-922-6769

Distributor*

Columbia Management Investment Distributors, Inc.
One Financial Center
Boston, Massachusetts 02111-2621

Transfer Agent, Dividend Disbursing Agent*

Columbia Management Investment Services Corp.
P. O. Box 8081
Boston, Massachusetts 02266-8081

1-800-345-6611

Legal Counsel to the Funds

Perkins Coie LLP
Washington, DC

Legal Counsel to the Independent Trustees

Drinker Biddle & Reath LLP
Philadelphia, Pennsylvania

Independent Registered Public Accounting Firm

PricewaterhouseCoopers LLP
Chicago, Illinois

*As of May 1, 2010

This report, including the schedules of investments, is submitted for the general information of the shareholders of Columbia Acorn Trust.

A description of the policies and procedures that the Funds use to determine how to vote proxies and a copy of the Funds' voting record are available (i) without charge, upon request, by calling 800-922-6769 and (ii) on the Securities and Exchange Commission's website at www.sec.gov. Information regarding how the Funds voted proxies relating to portfolio securities during the 12-month period ended June 30, is available from the SEC's website. Information regarding how the Funds voted proxies relating to portfolio securities is also available at http://institutional.columbiamanagement.com.

The Funds file a complete schedule of portfolio holdings with the SEC for the first and third quarters of each fiscal year on Form N-Q. The Funds' Form N-Q is available on the SEC's website at www.sec.gov and may be reviewed and copied at the SEC's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330.

Investors should consider the investment objectives, risks, charges and expenses of a mutual fund carefully before investing. For a free prospectus, which contains this and other important information about the funds, visit www.columbiamanagement.com. Read the prospectus carefully before investing.

Columbia Acorn Funds are distributed by Columbia Management Investment Distributors, Inc., member FINRA and managed by Columbia Wanger Asset Management, LLC.

Find out what's new – visit our web site at:

www.columbiamanagement.com

Our e-mail address is:

ServiceInquiries@ColumbiaManagement.com

Shareholders should not include personal information such as account numbers, Social Security numbers or taxpayer identification numbers in e-mail. We are unable to accept account transactions sent via e-mail.

PRESORTED

FIRST-CLASS MAIL

U.S. POSTAGE PAID

HOLLISTON, MA

PERMIT NO. 20

Columbia Management^®

Columbia Acorn Family of Funds
Class Z Shares

Annual Report, December 31, 2010

For More Information

You'll find more information about the Columbia Acorn Family of Funds in the documents described below. Contact Columbia Funds as follows to obtain these documents free of charge:

By Mail:  Columbia Funds
c/o Columbia Management Investment Services Corp.
P.O. Box 8081 Boston, MA 02266-8081

By Telephone: 800.345.6611

Online: www.columbiamanagement.com

Shareholder Communications with the Board

The Funds' Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Prospectuses and the Statement of Additional Information (SAI)

The prospectuses and the SAI provide more detailed information about the Funds and their policies. The SAI is legally part of each prospectus (it's incorporated by reference). A copy of each has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Funds (including their prospectuses, the SAI and shareholder reports) at the SEC's Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC's website at http://www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov. You can also obtain copies of this information by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-0102.

The investment company registration number of Columbia Acorn Trust, of which each of these Funds is a series, is 811-01829.

© 2011 Columbia Management Investment Advisers, LLC. All rights reserved.

One Financial Center, Boston, MA 02111-2621

800.345.6611 www.columbiamanagement.com

C-1561 A (2/11) 112994

Columbia Management^®

Columbia Acorn Family of Funds
Class Z Shares

Annual Report, December 31, 2010

For More Information

You'll find more information about the Columbia Acorn Family of Funds in the documents described below. Contact Columbia Funds as follows to obtain these documents free of charge:

By Mail:  Columbia Funds
c/o Columbia Management Investment Services Corp.
P.O. Box 8081 Boston, MA 02266-8081

By Telephone: 800.345.6611

Online: www.columbiamanagement.com

Shareholder Communications with the Board

The Funds' Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Prospectuses and the Statement of Additional Information (SAI)

The prospectuses and the SAI provide more detailed information about the Funds and their policies. The SAI is legally part of each prospectus (it's incorporated by reference). A copy of each has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Funds (including their prospectuses, the SAI and shareholder reports) at the SEC's Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC's website at http://www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov. You can also obtain copies of this information by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-0102.

The investment company registration number of Columbia Acorn Trust, of which each of these Funds is a series, is 811-01829.

© 2011 Columbia Management Investment Advisers, LLC. All rights reserved.

One Financial Center, Boston, MA 02111-2621

800.345.6611 www.columbiamanagement.com

C-1561 A (2/11) 112994

Columbia Management^®

Columbia Acorn Family of Funds
Class Z Shares

Annual Report, December 31, 2010

For More Information

You'll find more information about the Columbia Acorn Family of Funds in the documents described below. Contact Columbia Funds as follows to obtain these documents free of charge:

By Mail:  Columbia Funds
c/o Columbia Management Investment Services Corp.
P.O. Box 8081 Boston, MA 02266-8081

By Telephone: 800.345.6611

Online: www.columbiamanagement.com

Shareholder Communications with the Board

The Funds' Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Prospectuses and the Statement of Additional Information (SAI)

The prospectuses and the SAI provide more detailed information about the Funds and their policies. The SAI is legally part of each prospectus (it's incorporated by reference). A copy of each has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Funds (including their prospectuses, the SAI and shareholder reports) at the SEC's Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC's website at http://www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov. You can also obtain copies of this information by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-0102.

The investment company registration number of Columbia Acorn Trust, of which each of these Funds is a series, is 811-01829.

C-1561 A (2/11) 112994

Q4 2010

Columbia Acorn Family of Funds

Class A, B, C and I Shares

Managed by Columbia Wanger Asset Management, LLC

Annual Report

December 31, 2010

n  Columbia^SM
Acorn® Fund

n  Columbia^SM
Acorn International®

n  Columbia^SM
Acorn USA®

n  Columbia^SM
Acorn International Select^SM

n  Columbia^SM
Acorn Select^SM

n  Columbia^SM
Thermostat Fund^SM

Not FDIC insured • No bank guarantee • May lose value

The views expressed in the "Squirrel Chatter II" and "In a Nutshell" commentaries reflect the current views of the respective authors. These views are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult to predict so actual outcomes and results may differ significantly from the views expressed. These views are subject to change at any time based upon economic, market or other conditions and the respective authors disclaim any responsibility to update such views. These views may not be relied upon as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied upon as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific company's securities should not be construed as a recommendation or investment advice and there can be no assurance that as of the date of publica tion of this report, the securities mentioned in each Fund's portfolio are still held or that the securities sold have not been repurchased.

Letter to Shareholders from the
Columbia Acorn Board of Trustees

40 Years of Vision, Stability and Growth

Fellow Shareholders:

This has been an eventful year for the Columbia Acorn Funds. Early in the year, the Board negotiated new management and administrative agreements with the Funds' adviser, Columbia Wanger Asset Management ("CWAM"), following its acquisition by Ameriprise Financial, Inc. These new agreements were crafted with the objective of preserving CWAM's autonomy and culture and ensuring that the terms of these agreements were in Fund shareholders' best interests. Finally, I am especially pleased to report that the CWAM investment team remains in place following the ownership transition. Together with Ameriprise's expressed commitment to support and maintain the unique culture of CWAM and the Acorn Funds, your trustees are optimistic that the necessary foundation has been laid to perpetuate a vibrant and successful investment organization.

Last year's letter spoke of change and continuity in the governance of your Funds. That process has continued with the retirement of two long-serving trustees, David Kleinman and Jack Wing, and the selection of three new trustees, David Small, John Heaton and David Rudis. Mr. Small is a senior partner at Grosvenor Capital Management, a successful manager of investment partnerships. Mr. Rudis was formerly the president of LaSalle Bank, a major Chicago bank until its sale a few years ago, and Mr. Heaton is a distinguished professor of finance at the University of Chicago. Our new trustees collectively bring extensive business, investment and financial expertise to the job of overseeing your Funds, and we are glad to have them on board. At the same time, we will miss David and Jack, each of whom served shareholders faithfully and well for many years.

The markets continued to recover in 2010, and all the Funds delivered strong absolute returns during the year. While these results are important, your trustees—each a shareholder—focus especially on long-term performance. To this end, we salute present and past members of the investment team at CWAM for the remarkable record that they have created for the Acorn Fund. Since the Fund's inception 40 years ago, the original Class Z shares have enjoyed average annual total returns in excess of the S&P 500, as have the Fund's other classes of shares, which were instituted in 2000. As a result of this performance, the Acorn Fund was ranked the number one U.S.-based mutual fund over its lifetime, ahead of 149 other U.S.-based funds in existence during the period.* This is an extraordinary legacy, which your trustees will work to see perpetuated.

Thank you for your confidence in the Acorn Funds, and best wishes for the new year.

James A. Star
Independent Chairman of the Board of Trustees
Columbia Acorn Trust

*  According to Morningstar, Columbia Acorn Fund Class Z ranked #1 of 149 U.S.-based mutual funds in existence since June 10, 1970. These rankings are based on returns for Z Class shares for the period June 10, 1970, the inception date of the Fund, to December 31, 2010. Please refer to Page 3 for complete performance data.

	From Inception to 12/31/10		10 years		5 years		1 year
Acorn Fund compound return		15.01%		9.40%		5.91%		26.00%
Morningstar ranking		1 of 149		10 of 167		24 of 169		14 of 169

Source: ©2011 Morningstar, Inc. All rights reserved. Morningstar rankings are based on annualized total returns and do not reflect sales charges. Criteria: Open-ended mutual funds; inception date on or before Columbia Acorn Fund; oldest share class only; USD-based currency.

Columbia Acorn Family of Funds

Table of Contents

NAVs and Estimated Year-End Distributions	1
Share Class Performance	2
Fund Performance vs. Benchmarks	3
Descriptions of Indexes	4
Squirrel Chatter II: The Keys to Prosperity	5
Understanding Your Expenses	8
Columbia Acorn Fund
In a Nutshell	10
At a Glance	11
Major Portfolio Changes	22
Statement of Investments	25
Columbia Acorn International
In a Nutshell	12
At a Glance	13
Major Portfolio Changes	39
Statement of Investments	41
Portfolio Diversification	50
Columbia Acorn USA
In a Nutshell	14
At a Glance	15
Major Portfolio Changes	51
Statement of Investments	52

Columbia Acorn International Select
In a Nutshell	16
At a Glance	17
Major Portfolio Changes	60
Statement of Investments	61
Portfolio Diversification	65
Columbia Acorn Select
In a Nutshell	18
At a Glance	19
Major Portfolio Changes	66
Statement of Investments	67
Columbia Thermostat Fund
In a Nutshell	20
At a Glance	21
Statement of Investments	72
Columbia Acorn Family of Funds
Statements of Assets and Liabilities	74
Statements of Operations	75
Statements of Changes in Net Assets	76
Financial Highlights	80
Notes to Financial Statements	92
Report of Independent Registered Public Accounting Firm	102
Federal Income Tax Information	103
Board of Trustees and Management of Columbia Acorn Funds	104
Columbia Acorn Family of Funds Information	107

Columbia Acorn Family of Funds

Net Asset Value Per Share as of 12/31/10

	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn International Select		Columbia Acorn Select		Columbia Thermostat Fund
Class A	$	29.24	$	40.87	$	27.54	$	28.01	$	27.94	$	12.58
Class B	$	27.14	$	39.96	$	25.60	$	26.72	$	26.06	$	12.64
Class C	$	26.85	$	39.79	$	25.39	$	26.58	$	25.83	$	12.62
Class I	$	30.19	$	40.92	$	28.56	$	28.33	$	28.74		NA

2010 Year-End Distributions

The following table details the year-end distributions for the Columbia Acorn Funds. Except for Columbia Thermostat Fund, the record date was December 14, 2010, the ex-dividend date was December 15, 2010, and the payable date was December 16, 2010. For Columbia Thermostat Fund, the record date was December 21, 2010, the ex-dividend date was December 22, 2010, and the payable date was December 23, 2010.

	Short-term Capital Gains		Long-term Capital Gains		Ordinary Income		Reinvestment Price
Columbia Acorn Fund Class A		None	$	0.8374		None	$	28.62
Columbia Acorn Fund Class B		None	$	0.8374		None	$	26.57
Columbia Acorn Fund Class C		None	$	0.8374		None	$	26.29
Columbia Acorn Fund Class I		None	$	0.8374	$	0.0243	$	29.54
Columbia Acorn International Class A		None		None	$	0.1999	$	39.75
Columbia Acorn International Class B and C		None		None		None		NA
Columbia Acorn International Class I		None		None	$	0.3418	$	39.79
Columbia Acorn USA Class A, B, C and I		None		None		None		NA
Columbia Acorn International Select Class A, B, C and I		None		None		None		NA
Columbia Acorn Select Class A, B, C and I		None		None		None		NA
Columbia Thermostat Fund Class A		None		None	$	0.0394	$	12.52
Columbia Thermostat Fund Class B and C		None		None		None		NA

1

Columbia Acorn Family of Funds

Share Class Performance Average Annual Total Returns through 12/31/10

	Class A						Class B*						Class C						Class I†
	Without Sales Charge			With Sales Charge			Without Sales Charge			With Sales Charge			Without Sales Charge			With Sales Charge			Without Sales Charge
Columbia Acorn Fund (10/16/00)
3 months**		14.48	%		7.89	%		14.36	%		9.36	%		14.25	%		13.25	%		14.57	%
1 year		25.61	%		18.39	%		24.81	%		19.81	%		24.63	%		23.63	%		NA
3 years		2.34	%		0.34	%		1.69	%		0.73	%		1.52	%		1.52	%		NA
5 years		5.61	%		4.36	%		4.96	%		4.62	%		4.78	%		4.78	%		NA
10 years		8.98	%		8.34	%		8.28	%		8.28	%		8.17	%		8.17	%		NA
Life of fund		9.54	%		8.91	%		8.84	%		8.84	%		8.74	%		8.74	%		15.94	%**
Columbia Acorn International (10/16/00)
3 months**		8.46	%		2.23	%		8.32	%		3.32	%		8.27	%		7.27	%		8.61	%
1 year		22.23	%		15.21	%		21.49	%		16.49	%		21.34	%		20.34	%		NA
3 years		-0.30	%		-2.24	%		-0.93	%		-1.90	%		-1.07	%		-1.07	%		NA
5 years		9.22	%		7.94	%		8.54	%		8.25	%		8.38	%		8.38	%		NA
10 years		8.88	%		8.24	%		8.17	%		8.17	%		8.09	%		8.09	%		NA
Life of fund		8.16	%		7.53	%		7.46	%		7.46	%		7.37	%		7.37	%		9.50	%**
Columbia Acorn USA (10/16/00)
3 months**		16.35	%		9.66	%		16.21	%		11.21	%		16.10	%		15.10	%		16.43	%
1 year		22.78	%		15.72	%		21.96	%		16.96	%		21.83	%		20.83	%		NA
3 years		1.64	%		-0.34	%		0.98	%		0.00	%		0.84	%		0.84	%		NA
5 years		3.18	%		1.97	%		2.52	%		2.16	%		2.38	%		2.38	%		NA
10 years		8.33	%		7.69	%		7.62	%		7.62	%		7.54	%		7.54	%		NA
Life of fund		8.92	%		8.30	%		8.22	%		8.22	%		8.14	%		8.14	%		17.82	%**
Columbia Acorn International Select (10/16/00)
3 months**		7.94	%		1.73	%		7.79	%		2.79	%		7.74	%		6.74	%		8.09	%
1 year		21.41	%		14.43	%		20.63	%		15.63	%		20.45	%		19.45	%		NA
3 years		-2.82	%		-4.72	%		-3.44	%		-4.39	%		-3.59	%		-3.59	%		NA
5 years		8.68	%		7.40	%		7.96	%		7.67	%		7.81	%		7.81	%		NA
10 years		6.28	%		5.66	%		5.57	%		5.57	%		5.49	%		5.49	%		NA
Life of fund		5.81	%		5.20	%		5.11	%		5.11	%		5.03	%		5.03	%		8.50	%**
Columbia Acorn Select (10/16/00)
3 months**		13.95	%		7.40	%		13.80	%		8.80	%		13.74	%		12.74	%		14.05	%
1 year		22.49	%		15.45	%		21.72	%		16.72	%		21.55	%		20.55	%		NA
3 years		0.94	%		-1.03	%		0.28	%		-0.70	%		0.13	%		0.13	%		NA
5 years		5.98	%		4.73	%		5.28	%		4.96	%		5.12	%		5.12	%		NA
10 years		8.44	%		7.80	%		7.71	%		7.71	%		7.62	%		7.62	%		NA
Life of fund		8.90	%		8.27	%		8.18	%		8.18	%		8.09	%		8.09	%		16.17	%**
Columbia Thermostat Fund (3/3/03)††
3 months**		7.40	%		1.23	%		7.21	%		2.21	%		7.13	%		6.13	%		—
1 year		17.28	%		10.54	%		16.64	%		11.64	%		16.43	%		15.43	%		—
3 years		2.38	%		0.38	%		1.83	%		0.85	%		1.61	%		1.61	%		—
5 years		5.12	%		3.88	%		4.56	%		4.23	%		4.33	%		4.33	%		—
Life of fund		7.87	%		7.06	%		7.26	%		7.26	%		7.07	%		7.07	%		—

*The Funds no longer accept investments from new or existing shareholders in Class B shares.

**Not annualized.

†Class I shares commenced operations on September 27, 2010. This share class is offered at net asset value without sales charge and is available only to qualifying institutional investors.

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end updates.

Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower.

The "with sales charge" returns include the maximum initial sales charge of 5.75% for Class A shares, the applicable contingent deferred sales charge (CDSC) for Class B shares (5%, 4%, 3%, 3%, 2%, 1% and 0% for the first through seventh years after purchase, respectively), and the maximum CDSC of 1.00% of Class C shares during the first year after purchase.

††A "fund of funds" bears its allocable share of the costs and expenses of the underlying funds in which it invests. Such funds are thus subject to two levels of fees and potentially higher expense ratios than would be associated with an investment in a fund that invests and trades directly in financial instruments under the direction of a single manager.

All results shown assume reinvestment of distributions and do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption of fund shares.

2

Columbia Acorn Family of Funds

Fund Performance vs. Benchmarks Average Annual Total Returns through 12/31/10

Class A Shares, without sales charge	4th quarter*			1 year			3 years			5 years			10 years			Life of Fund
Columbia Acorn Fund (LACAX) (10/16/00)		14.48	%		25.61	%		2.34	%		5.61	%		8.98	%		9.54	%
Russell 2500 Index		14.86	%		26.71	%		2.48	%		4.86	%		6.98	%		7.17	%
S&P 500 Index**		10.76	%		15.06	%		-2.86	%		2.29	%		1.41	%		1.01	%
Lipper Small-Cap Core Funds Index		15.40	%		25.71	%		2.88	%		4.76	%		6.96	%		7.03	%
Lipper Mid-Cap Growth Funds Index		13.93	%		25.66	%		0.11	%		6.22	%		2.59	%		1.03	%
Columbia Acorn International (LAIAX) (10/16/00)		8.46	%		22.23	%		-0.30	%		9.22	%		8.88	%		8.16	%
S&P Global Ex-U.S. Between $500M and $5B Index		10.58	%		24.36	%		0.28	%		8.19	%		11.75	%		11.38	%
S&P Global Ex-U.S. SmallCap Index		10.65	%		22.96	%		-1.11	%		7.29	%		10.69	%		10.37	%
MSCI EAFE Index		6.61	%		7.75	%		-7.02	%		2.46	%		3.50	%		3.55	%
Lipper International Small/Mid Growth Funds Index		11.64	%		23.77	%		-1.96	%		6.34	%		7.63	%		6.68	%
Columbia Acorn USA (LAUAX) (10/16/00)		16.35	%		22.78	%		1.64	%		3.18	%		8.33	%		8.92	%
Russell 2000 Index		16.25	%		26.85	%		2.22	%		4.47	%		6.33	%		6.30	%
Russell 2500 Index		14.86	%		26.71	%		2.48	%		4.86	%		6.98	%		7.17	%
S&P 500 Index**		10.76	%		15.06	%		-2.86	%		2.29	%		1.41	%		1.01	%
Lipper Small-Cap Growth Funds Index		15.57	%		26.08	%		-0.04	%		3.92	%		2.58	%		1.70	%
Columbia Acorn Int'l Select (LAFAX) (10/16/00)		7.94	%		21.41	%		-2.82	%		8.68	%		6.28	%		5.81	%
S&P Developed Ex-U.S. Between $2B and $10B Index		9.75	%		20.16	%		-3.22	%		4.95	%		8.22	%		8.39	%
MSCI EAFE Index		6.61	%		7.75	%		-7.02	%		2.46	%		3.50	%		3.55	%
Lipper International Small/Mid Growth Funds Index		11.64	%		23.77	%		-1.96	%		6.34	%		7.63	%		6.68	%
Columbia Acorn Select (LTFAX) (10/16/00)		13.95	%		22.49	%		0.94	%		5.98	%		8.44	%		8.90	%
S&P MidCap 400 Index		13.50	%		26.64	%		3.52	%		5.74	%		7.16	%		7.35	%
S&P 500 Index**		10.76	%		15.06	%		-2.86	%		2.29	%		1.41	%		1.01	%
Lipper Mid-Cap Growth Funds Index		13.93	%		25.66	%		0.11	%		6.22	%		2.59	%		1.03	%
Columbia Thermostat Fund (CTFAX) (3/3/03)†		7.40	%		17.28	%		2.38	%		5.12	%		—			7.87	%
S&P 500 Index		10.76	%		15.06	%		-2.86	%		2.29	%		—			7.38	%
Barclays Capital U.S. Aggregate Bond Index		-1.30	%		6.54	%		5.90	%		5.80	%		—			4.89	%
Lipper Flexible Portfolio Funds Index		7.29	%		12.91	%		0.68	%		4.75	%		—			8.22	%
50/50 Blended Benchmark††		4.65	%		11.29	%		2.04	%		4.44	%		—			6.45	%

*Not annualized.

**The comparison to the S&P 500 Index is presented to show performance against a widely recognized market index over the life of the Fund.

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end updates.

Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers or expense reimbursement arrangements, performance results would have been lower.

†A "fund of funds" bears its allocable share of the costs and expenses of the underlying funds in which it invests. Such funds are thus subject to two levels of fees and potentially higher expense ratios than would be associated with an investment in a fund that invests and trades directly in financial instruments under the direction of a single manager.

††The 50/50 Blended Benchmark is a custom supplemental benchmark established by the adviser.

All results shown assume reinvestment of distributions and do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption of fund shares.

Unlike mutual funds, indexes are not actively managed and do not incur fees or expenses. It is not possible to invest directly in an index. For index definitions, see Page 4.

3

Columbia Acorn Family of Funds

Descriptions of Indexes Included in this Report

•50/50 Blended Benchmark, established by the Fund's adviser, is an equally weighted custom composite of Columbia Thermostat Fund's primary equity and primary debt benchmarks, the S&P 500 Index and the Barclays Capital U.S. Aggregate Bond Index, respectively. The percentage of the Fund's assets allocated to underlying stock and bond portfolio funds will vary, and accordingly the composition of the Fund's portfolio will not always reflect the composition of the 50/50 Blended Benchmark.

•Barclays Capital U.S. Aggregate Bond Index is a market value-weighted index that tracks the daily price, coupon, pay-downs and total return performance of fixed-rate, publicly placed, dollar-denominated and non-convertible investment grade debt issues with at least $250 million par amount outstanding and with at least one year to final maturity.

•Lipper Indexes include the largest funds tracked by Lipper, Inc. in the named category. Lipper Small-Cap Core Funds Index, 30 largest small-cap core funds; Lipper Mid-Cap Growth Funds Index, 30 largest mid-cap growth funds, including Columbia Acorn Fund and Columbia Acorn Select; Lipper International Small/Mid Growth Funds Index, 10 largest non-U.S. small/mid growth funds, including Columbia Acorn International; Lipper Small-Cap Growth Funds Index, 30 largest small-cap growth funds, including Columbia Acorn USA; Lipper International Funds Index, 30 largest non-U.S. funds, excluding non-U.S. small-cap funds; Lipper Flexible Portfolio Funds Index, an equal-weighted index of the 30 largest mutual funds within the Flexible Portfolio fund classification, as defined by Lipper.

•Morgan Stanley Capital International Europe, Australasia, Far East (MSCI EAFE) Index is a capitalization-weighted index that tracks the total return of common stocks in 22 developed-market countries within Europe, Australasia and the Far East. The returns of the MSCI EAFE Index are presented net of taxes.

•Russell 2000 Index measures the performance of the 2,000 smallest companies in the Russell 3000 Index, which represents approximately 8% of the total market capitalization of the Russell 3000 Index.

•Russell 2500 Index measures the performance of the 2,500 smallest companies in the Russell 3000 Index, which represents approximately 17% of the total market capitalization of the Russell 3000 Index.

•Standard & Poor's (S&P) 500 Index tracks the performance of 500 widely held, large-capitalization U.S. stocks.

•Standard & Poor's (S&P) MidCap 400 Index is a market value-weighted index that tracks the performance of 400 mid-cap U.S. companies.

•S&P Developed Ex-U.S. Between $2B and $10B Index is a subset of the broad market selected by the index sponsor representing the mid-cap developed market, excluding the United States.

•S&P Global Ex-U.S. SmallCap Index consists of the bottom 20% of institutionally investable capital of developed and emerging countries, outside the United States. The performance of the S&P Global Ex-U.S. SmallCap Index is provided to show how Columbia Acorn International's performance compares to foreign market performance with a similar geographic distribution and wider market cap range than the Fund's primary benchmark.

•S&P Global Ex-U.S. Between $500M and $5B Index is a subset of the broad market selected by the index sponsor representing the mid- and small-cap developed and emerging markets, excluding the United States.

Unlike mutual funds, indexes are not managed and do not incur fees or expenses. It is not possible to invest directly in an index.

4

Squirrel Chatter II: The Keys to Prosperity

In 1651, Thomas Hobbes described human life as "poor, nasty, brutish and short." Today, 360 years later, humanity has achieved record levels of prosperity, safety and longevity. The United Nations estimates that poverty was reduced more in the last 50 years than the previous 500.¹ In the developing world, life expectancy rose from 44 years to 64 years from 1950 to 1999, while in the developed world, life expectancy rose from 66 years to 78 years.²

Hobbes's perspective was accurate for his time. There was very little growth in worldwide per capita GDP until about 1820; income in Europe had dropped for centuries following the decline and collapse of the Roman Empire.³ England and much of Europe were caught in a Malthusian trap, with population gyrating up and down largely due to plagues, famines and wars. But sometime around 1820, economic growth accelerated, and per capita GDP growth has averaged over 2% yearly since then, compounding into excellent gains in living standards.⁴ Why?

Four Conditions for Growth

William Bernstein's The Birth of Plenty, How Prosperity in the Modern World was Created is a fascinating history of worldwide economic circumstances. He discusses reasons for the successes and failures of many empires and countries. Bernstein believes that four institutional conditions are necessary for sustained growth: property rights and civil liberties, scientific rationalism, efficient capital markets, and fast and cheap transportation and communications. He notes that these four factors existed temporarily in sixteenth century Holland, then firmly in the English speaking countries, and in the last 50 years, increasingly over much of the world.⁵

Physical and intellectual property rights plus civil liberties create incentives and intellectual freedom to work hard, innovate and create wealth. In empires, totalitarian states and feudalistic societies, incentives to produce beyond immediate needs are nil, because governments or lords tend to impose confiscatory taxes and arbitrarily seize property. Bernstein believes that Rome fell, in part, due to excessive taxation on farmers. He also thinks that an independent judiciary is necessary to enforce property rights and civil liberties.

Scientific rationalism is needed for technological progress and innovation. Throughout history, various regimes run by church and state ossified due to the rejection of scientific observations in favor of dogma or preconceived beliefs. During medieval times, for example, astronomers who concluded the earth revolved around the sun were tortured. Bernstein cites the trial of Galileo as a turning point toward scientific rationalism. Early inventors then tended to be tinkerers rather than scientists, but science became increasingly important. For example, by the nineteenth century the steel industry had initiated the use of modern science laboratories staffed by full-time researchers.⁶

Efficient capital markets enable entrepreneurs and enterprises to raise capital at reasonable costs. I remember Jesse Jackson citing a lack of capital as a cause for inner city poverty: "Capitalism without capital is just plain ism."⁷ Bernstein notes that entrepreneurs once had huge downside risk from failures, namely debtors prisons in recent centuries and enslavement by creditors in ancient times. The creation of limited liability corporations during the nineteenth century in Britain and the United States was a breakthrough in reducing downside risks for capitalists.

Fast and cheap transportation and communication are also needed for prosperity. Bernstein explains that before railroads and the telegraph, transportation and communication were horribly expensive and slow. Rarely could bulk goods be transported over land more than 20 miles a day, and theft was rampant. Local crop failures often caused starvation. Mass markets did not exist. The reach of rail and telegraph grew incredibly rapidly during their first decades, spurring economic growth.

Bernstein provides plenty of case studies of regimes and countries that stagnated or failed due to the lack of one or more conditions, ranging from ancient societies and Japan under the samurai to Communist countries of the twentieth century. He states, "Institutions, not the bounty of nature or freedom from imperialist domination, separate the winners from the losers in the global economy."⁸

5

Trade Drives Prosperity

Matt Ridley's The Rational Optimist, How Prosperity Evolves adds substantial perspective to Bernstein's work and provides comforting thoughts about the future. Though Ridley does not mention Bernstein by name, it is clear that he agrees with Bernstein's basic contentions. Ridley sees property rights as the primary key to prosperity. He quotes a study by MIT economist Daron Acemoglu, which compared measures of property rights to economic growth across countries and determined that three-quarters of the variation of economic growth is explained by property rights.⁹ Ridley adds, "In a sample of 127 countries, the sixty-three with higher economic freedom had more than four times the income per capita and twice the growth rate of the countries that did not."¹⁰

Ridley's emphasis is on trade, which he believes allows increasing specialization, expertise, productivity and innovation. Humans seem to be hard-wired for trade. Archaeological evidence indicates that some 100,000 years ago humans began to barter.¹¹ People traded things and also absorbed ideas. Human intelligence became collective and cumulative. Ridley states that, more recently, the history of the modern world is a history of ideas meeting, mixing, mating and mutating.¹² Innovation results from an exchange of ideas. I think of the iPhone. Steve Jobs utilizes technologies and resources developed over centuries and components originated in many countries to make an incredibly inno vative and useful device.

Ridley notes that societies that halted trade regressed. After ocean levels rose 10,000 years ago and cut off Tasmania from Australia, people there gradually lost the ability to fish and make tools out of bones. European mariners discovered Tasmanians wearing nothing but wallaby pelts and seal-fat grease.¹³ As another example of a closed-off society, Ridley writes, "China went from a state of economic and technological exuberance in around AD 1000 to one of dense population, agrarian backwardness and desperate poverty in 1950;" per capita income there was about flat in those 950 years.¹⁴

Ridley takes a libertarian view, highly skeptical of government. He states, "...governments generally tend to be good things at first and bad things the longer they last. First they improve society's ability to flourish by providing central services and removing impediments to trade and specialization... But...governments gradually employ more and more ambitious elites who... give themselves more and more rules to enforce, until they kill the goose that lays the golden eggs. ... Because it is a monopoly, government brings inefficiency and stagnation to most things it runs..."¹⁵

Ridley asserts that African governments have largely caused economic problems in Africa. He writes that famines in Darfur and Zimbabwe were the result of government policies. Setting up a company in Tanzania takes 379 days and $5,500, a huge sum there. Botswana has done substantially better, growing per capita GDP nearly 8% annually since its independence in 1966. That growth exceeded China's, and is largely due to secure property rights, Ridley says. Ridley is optimistic for much of Africa, however. Cell phones are spreading rapidly, providing both communication and micro-finance (two of Bernstein's conditions for prosperity). Ridley cites wonderful examples of products and labor reaching optimal markets and payments being made over cell phones.¹⁶

Ridley has comforting thoughts about the future, debunking naysayers. He notes that (oddly enough) over time humans have temporarily exhausted or driven to extinction renewable resources like forests and certain animal species, while non-renewable resources have lasted much longer than many expected. In 1865, an economist said Britain's coal was running out, and as early as 1914 the U.S. Bureau of Mines wrote that American oil reserves would last 10 years.¹⁷

Ridley believes supplies of oil, coal and gas "will last decades, perhaps centuries, and people will find alternatives long before they run out."¹⁸ He states that prices of conventional fuels need to rise and prices of alternatives need to fall, and both will occur as conventional supplies run down and efficiencies of alternatives rise. Ridley notes that wind, solar and biomass alternatives envelop enormous quantities of land. He denounces organic farming, noting that if farm yields fell back to 1961 levels, 82% of the land area of the earth would be needed for farming, up from 38%. "The Dark Ages were a massive experiment in back-to-the-land hippy lifestyle (without the trust fund)," he says.¹⁹

6

Ridley largely dismisses climate change fears. The scenario that calls for significant climate change by the year 2100 is a scenario of dramatic economic growth. He believes the world, and especially developing countries, will be much, much richer and better able to adapt to and mitigate climate change. In the meantime, carbon intensity²⁰ of the worldwide economy is rapidly dropping, as wood, dung and coal become relatively less important and natural gas and nuclear power gain share, in an environment of substantially more efficient lighting, heating, transportation and manufacturing.

While some of Ridley's arguments seem a bit over the top, I think they generally appear coherent and largely believable. As to the climate change issue, I advocate taking reasonable steps to mitigate global warming. Most of my family's road miles are in a hybrid vehicle and both my home and Columbia Wanger Asset Management have adopted compact florescent lighting. Several years ago we calculated that replacing over 100 incandescent bulbs at the office saved enough electricity to power three average-sized homes.

I agree that prosperity is driven by the factors named by Bernstein and Ridley and, though there are imbalances in world economics, I think things will be okay. The Great Recession has ended, growth has resumed and the keys to prosperity remain in place. Many parts of the developing world are booming and we have invested accordingly. About 22% of Columbia Acorn International is invested in the developing world and many Fund investments in non-emerging market companies have some business tied to developing markets. Other Columbia Acorn Funds also own some stocks that benefit directly or indirectly from developing markets.

Charles P. McQuaid

President and Chief Investment Officer
Columbia Wanger Asset Management, LLC

The information and data provided in this analysis are derived from sources that we deem to be reliable and accurate. These views are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult to predict so actual outcomes and results may differ significantly from the views expressed. The views/opinions expressed in Squirrel Chatter II are those of the author and not of the Columbia Acorn Trust Board, are subject to change at any time based upon economic, market or other conditions, may differ from views expressed by other Columbia Management associates and the respective parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund.

The information included on Pages 5, 6 and 7 of this report is unaudited.

¹  Ridley, Matt, The Rational Optimist, How Prosperity Evolves, (New York, New York, HarperCollins 2010), p. 15.

²  Bernstein, William J., The Birth of Plenty, How the Prosperity of the Modern World was Created, (New York, New York, McGraw-Hill 2004), p. 10.

³  Ibid, p. 3.

⁴  Ibid, p. 12, 23.

⁵  Ibid, p. 15-17.

⁶  Ibid, p. 123.

⁷  Rev. Jesse Jackson quoted in an article that appeared in Ebony magazine, August 1967, titled "Apostles of Economics," p. 84.

⁸  Bernstein, William J., op. cit, p. 293.

⁹  Ridley, Matt, op. cit, p. 321.

¹⁰  Ibid, p. 117.

¹¹  Ibid, p. 350.

¹²  Ibid, p. 272.

¹³  Ibid, p. 78.

¹⁴  Ibid, p. 180.

¹⁵  Ibid, p. 182.

¹⁶  Ibid, p. 320-326.

¹⁷  Ibid, p. 237.

¹⁸  Ibid, p. 238.

¹⁹  Ibid, p. 144, 175.

²⁰  Carbon intensity is defined as the amount of CO_² produced divided by worldwide GDP.

7

Understanding Your Expenses

As a Fund shareholder, you incur two types of costs. There are transaction costs, which generally include sales charges on purchases and may include redemption or exchange fees. There are also ongoing costs, which generally include investment advisory fees, distribution and service (Rule 12b-1) fees and other Fund expenses. The following information is intended to help you understand your ongoing costs of investing in the Columbia Acorn Funds and to compare these costs with the ongoing costs of investing in other mutual funds.

Analyzing Your Fund's Expenses

To illustrate these ongoing costs, we have provided examples and calculated the expenses paid by investors in the Class A, B and C shares of the Columbia Acorn Funds for the last six months. The information in the following table is based on an initial investment of $1,000, which is invested at the beginning of the reporting period and held for the entire period. Expense information is calculated two ways and each method provides you with different results. The amount listed in the "Actual" column is calculated using each Fund's actual operating expenses and total return for the period. The amount listed in the "Hypothetical" column assumes that the return each year is 5% before expenses and then applies each Fund's actual expense ratio for the period to the hypothetical return. You should not use the hypothetical account values and expenses to estimate either your actual account balance at the end of the period or the expenses you paid du ring the reporting period. See "Compare With Other Funds" for details on using the hypothetical data.

July 1, 2010 - December 31, 2010

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during the period ($)				Fund's annualized expense ratio (%)*
	Actual		Hypothetical		Actual		Hypothetical		Actual		Hypothetical		Actual
Columbia Acorn Fund
Class A		1,000.00		1,000.00		1,298.90		1,019.71		6.32		5.55		1.09
Class B		1,000.00		1,000.00		1,295.50		1,017.09		9.32		8.19		1.61
Class C		1,000.00		1,000.00		1,294.00		1,015.93		10.64		9.35		1.84
Class I**		1,000.00		1,000.00		1,159.40		1,021.63		2.00		3.62		0.71
Columbia Acorn International
Class A		1,000.00		1,000.00		1,281.20		1,018.15		8.05		7.12		1.40
Class B		1,000.00		1,000.00		1,277.90		1,015.58		10.97		9.70		1.91
Class C		1,000.00		1,000.00		1,276.50		1,014.52		12.16		10.76		2.12
Class I**		1,000.00		1,000.00		1,095.00		1,020.47		2.56		4.79		0.94
Columbia Acorn USA
Class A		1,000.00		1,000.00		1,311.40		1,018.55		7.69		6.72		1.32
Class B		1,000.00		1,000.00		1,308.10		1,015.78		10.88		9.50		1.87
Class C		1,000.00		1,000.00		1,306.10		1,014.72		12.09		10.56		2.08
Class I**		1,000.00		1,000.00		1,178.20		1,020.47		2.66		4.79		0.94
Columbia Acorn International Select
Class A		1,000.00		1,000.00		1,263.40		1,017.09		9.19		8.19		1.61
Class B		1,000.00		1,000.00		1,258.60		1,014.12		12.52		11.17		2.20
Class C		1,000.00		1,000.00		1,258.50		1,013.21		13.55		12.08		2.38
Class I**		1,000.00		1,000.00		1,085.00		1,019.46		3.09		5.80		1.14

8

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during the period ($)				Fund's annualized expense ratio (%)*
	Actual		Hypothetical		Actual		Hypothetical		Actual		Hypothetical		Actual
Columbia Acorn Select
Class A		1,000.00		1,000.00		1,288.20		1,018.65		7.50		6.61		1.30
Class B		1,000.00		1,000.00		1,284.40		1,015.63		10.94		9.65		1.90
Class C		1,000.00		1,000.00		1,283.20		1,014.77		11.91		10.51		2.07
Class I**		1,000.00		1,000.00		1,161.70		1,020.62		2.56		4.63		0.91
Columbia Thermostat Fund***
Class A		1,000.00		1,000.00		1,197.30		1,022.68		2.77		2.55		0.50
Class B		1,000.00		1,000.00		1,192.50		1,020.16		5.53		5.09		1.00
Class C		1,000.00		1,000.00		1,191.70		1,018.90		6.91		6.36		1.25

It is important to note that the expense amounts shown in the table are meant to highlight only ongoing costs of investing in the Funds and do not reflect any transaction costs, such as sales charges, redemption or exchange fees. Therefore, the hypothetical examples provided may not help you determine the relative total costs of owning different funds. If these transaction costs were included, your costs would have been higher.

*Expenses paid during the period are equal to each Fund's annualized expense ratio, multiplied by the average account value over the period and then multiplied by the number of days in the Fund's most recent fiscal half-year and divided by 365.

**Class I shares were initially offered by the Funds on September 27, 2010.

***Columbia Thermostat Fund's expenses do not include fees and expenses incurred by the Fund from the underlying portfolio funds in which it invests. Had the investment adviser and/or any of its affiliates not waived fees or reimbursed a portion of expenses, account value at the end of the period would have been reduced.

Compare With Other Funds

Since all mutual funds are required to include the same hypothetical calculations about expenses in shareholder reports, you can use this information to compare the ongoing cost of investing in the Funds with other funds. To do so, compare the 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of other funds. As you compare hypothetical examples of other funds, it is important to note that hypothetical examples are meant to highlight the continuing costs of investing in a fund and do not reflect any transaction costs, such as sales charges or redemption or exchange fees.

Estimating Your Actual Expenses

To estimate the expenses that you actually paid over the period, first you will need your account balance at the end of the period:

•  For shareholders who receive their account statements from Columbia Management Investment Services Corp., your account balance is available online at columbiafunds.com or by calling Shareholder Services at (800) 922-6769.

•  For shareholders who receive their account statements from their brokerage firm, contact your brokerage firm to obtain your account balance.

1.  Divide your ending account balance by $1,000. For example, if an account balance was $8,600 at the end of the period, the result would be 8.6.

2.  In the section of the table titled "Expenses paid during the period," locate the amount for your Fund. You will find this number is in the column labeled "Actual." Multiply this number by the result from step 1. Your answer is an estimate of the expenses you paid on your account during the period.

9

Columbia Acorn Fund

In a Nutshell

Charles P. McQuaid	Robert A. Mohn
Lead Portfolio Manager	Co-Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

lululemon athletica	1.5	%
FMC Technologies	1.5	%
Ametek	1.5	%
Donaldson	1.4	%
Fugro	1.2	%
Pacific Rubiales Energy	0.9	%
Abercrombie & Fitch	0.9	%
Coach	0.6	%
Silver Wheaton	0.5	%
Southwestern Energy	0.4	%
Talbots	0.2	%

Columbia Acorn Fund rose 25.61% (Class A shares, without sales charge) in 2010, building on its 39.26% gain achieved in 2009. We are happy to say that at year end 2010, the Fund, adjusted for distributions, was within 0.9% of its all-time high, which was achieved in October 2007, prior to the Great Recession. As shown on Page 3, Columbia Acorn Fund's gains for 2010 were a bit below its primary benchmark, the Russell 2500 Index, in line with peer funds as represented by Lipper, and well above the large-cap S&P 500 Index. During the fourth quarter of 2010, the Fund rose 14.48%, approximately matching its benchmark and again beating the S&P 500.

Active apparel company lululemon athletica was up 125% during the year and 53% in the quarter and was the Fund's top dollar winner in both periods. Handbag designer and retailer Coach also did well, rising 53% for the year and 29% for the quarter. Both companies had excellent product offerings and fine earnings growth.

Other retail stocks held in the Fund had mixed results. Teen apparel retailer Abercrombie & Fitch jumped 68% in the year and 47% in the quarter, as it became more price-competitive and gained market share. Women's specialty apparel retailer Charming Shoppes and branded multi-channel retailer J Crew Group had disappointing results for the year, sinking 45% and 30% respectively, while Talbots, a women's retailer, was the biggest dollar loser in the quarter, dropping 35%. We sold the Fund's positions in Charming Shoppes and J Crew. We weighted consumer stocks correctly, as lululemon's dollar gains were five-times that of the largest consumer stock loser in the Fund and Abercrombie & Fitch's gains were more than twice that of the biggest loser.

Industrial stocks provided fine upside. Aerospace and industrial instrument maker Ametek measured a 55% gain during the year and 23% in the quarter, ranking in the Fund's top five dollar contributors for both periods. Filter maker Donaldson rose 39% in the year and 24% in the quarter. Both companies reported excellent earnings gains. Industrial stocks made up 18.5% of the Fund at year end.

Oil production and service stocks did very well. Oil and gas wellhead manufacturer FMC Technologies was the Fund's second largest dollar winner during the year, rising 54%, and Colombian oil producer Pacific Rubiales Energy nailed third place, gaining 130%. During the quarter, these stocks were up 30% and 21%, respectively. Holland-based sub-sea oilfield services provider Fugro jumped 48% in the year and 25% in the quarter. Natural gas related stocks, in contrast, fizzled. Oil and gas producer Southwestern Energy was off 22% during the year and was the Fund's largest dollar loser, surrendering less than one-third of FMC's gains. Believing that oil prices are likely to stay high relative to natural gas prices, we shifted some investments accordingly.

The portion of Columbia Acorn Fund's portfolio invested in foreign stocks was up 41.24% in the year and accounted for 12.6% of Fund assets at year end.* In addition to the strong international energy names mentioned above, Canada's Silver Wheaton, a company that invests in mines in exchange for favorable purchases of silver by-product, glistened with a 160% gain in the year and a 46% gain in the quarter.

Small- and mid-cap stocks outperformed larger caps in both 2009 and 2010 and are currently valued somewhat higher than large caps. Takeovers of small- and mid-cap companies are accelerating, and we believe that large companies and private capital groups have buying power and increasing confidence in the economy. Columbia Acorn Fund had 13 stocks subject to new or increased takeover offers during the year, mostly in the fourth quarter. Small- and mid-cap earnings growth was greater than large-cap earnings growth in 2010. We believe that, should takeovers and faster earnings growth continue, small- and mid-cap stocks could continue to outperform large caps.

*These returns are not comparable to mutual fund returns, as they are gross of fees and other expenses and do not portray the cash effects incurred by actual mutual funds. Columbia Acorn Fund's foreign stockholdings were not purchased as a balanced, stand-alone portfolio.

Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies. International investing involves special risks, including foreign taxation, currency risks, risks associated with possible differences in financial standards and other risks associated with future political and economic developments.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

10

Columbia Acorn Fund

At a Glance (Class A Shares - LACAX)

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

through December 31, 2010

Inception 10/16/00		1 year			5 years			10 years
Returns before taxes	NAV POP		25.61 18.39	%		5.61 4.36	%		8.98 8.34	%
Returns after taxes on distributions	NAV POP		25.06 17.87			4.95 3.71			8.44 7.80
Returns after taxes on distributions and sale of fund shares	NAV POP		17.35 12.62			4.78 3.70			7.89 7.30
Russell 2500 Index (pretax)*			26.71			4.86			6.98

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Public offering price (POP) returns include the maximum sales charge of 5.75% for Class A shares. Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC).

Columbia Acorn Fund Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn Fund Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	Crown Castle International Communications Towers	1.5	%
2.	lululemon athletica Premium Active Apparel Retailer	1.5	%
3.	FMC Technologies Oil & Gas Wellhead Manufacturer	1.5	%
4.	Ametek Aerospace/Industrial Instruments	1.5	%
5.	Donaldson Industrial Air Filtration	1.4	%
6.	Mettler Toledo Laboratory Equipment	1.3	%
7.	Informatica Enterprise Data Integration Software	1.3	%
8.	Fugro (Netherlands) Sub-sea Oilfield Services	1.2	%
9.	Amphenol Electronic Connectors	1.1	%
10.	Expeditors International of Washington International Freight Forwarder	1.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn Fund (Class A)

October 16, 2000 through December 31, 2010

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes a 5.75% maximum initial sales charge. The Russell 2500 Index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder may pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $18.1 billion

11

Columbia Acorn International

In a Nutshell

P. Zachary Egan	Louis J. Mendes III
Co-Portfolio Manager	Co-Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund's Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

Zhaojin Mining Industry	1.1	%
Mr. Price	0.8	%
Shandong Weigao	0.6	%
Shriram Transport Finance	0.5	%
Intralot	0.4	%
CIR	0.3	%

Columbia Acorn International finished the year up 22.23% (Class A shares, without sales charge), underperforming the 24.36% return of the S&P Global Ex-U.S. Between $500M and $5B Index, the Fund's primary benchmark. The Fund's 2010 fourth quarter return was 8.46%, versus a benchmark return of 10.58%. Smaller international stocks continued to outperform their larger-cap counterparts for the second consecutive year, and for four out of the last five years. The large-cap MSCI EAFE Index returned 7.75% in the year.

Emerging market demand continues to explain much of the ongoing rebound from 2008 in corporate earnings and stock returns around the world. While the U.S. grapples with rising budget deficits and Europeans ponder the possibility of default among one or more euro zone members, formerly troubled economies such as Thailand and Brazil now enjoy strong economic growth and corporate earnings and comparatively good public balance sheets. Indeed, as reported in the Financial Times, the World Bank calculates that domestic demand in developing economies contributed fully 46% of global growth in 2010.*

We believe this represents a significant opportunity for investors, although a highly differentiated one, as valuation and other intervening variables often stand between GDP growth and stock returns. While China, for example, continued to post high growth in 2010, its stock market (as measured by the Hang Seng China Enterprises Index) rose less than 2%. Emerging market stocks represented, in the course of the year, almost one quarter of Columbia Acorn International's assets. However, emerging market demand for goods and services provided by companies domiciled elsewhere remains a core component of the Fund's strategy, so implicit emerging market exposure is higher. With these companies we seek to access growth at either a more reasonable price or with less risk.

Unsurprisingly, emerging market stocks were among the largest contributors to positive returns in 2010. South African apparel, household and sporting goods retailer Mr. Price rose over 100% as improved merchandising and working capital levels bolstered the company's already strong fundamentals. Zhaojin Mining Industry, a Chinese gold miner, posted a similar return on the back of rising gold prices, value-accretive acquisitions, exploration on current properties, and rising production. Also in China, Shandong Weigao, a manufacturer of vertically integrated hospital consumables, rose over 70% on strong demand for medical consumables and improving results from its joint venture with Medtronic. In India, Shriram Transport Finance also increased over 70% on high growth and low defaults in its core used truck finance business.

Disappointments in 2010 included Greek lottery company Intralot, which declined nearly 40% on adverse tax developments in Bulgaria and Greece and start-up costs in the United States and Italy. A weak currency in Bulgaria further impacted earnings. Japanese retailer Point fell 30% on weak same-store sales and heavy upfront investments. We no longer hold this name in the Fund. Italian holding company CIR fell 29% as gas prices squeezed its electricity generation business.

It is notable that the U.S. dollar has fallen over 30% versus the yen, 28% versus the Swiss franc, and over 55% versus gold over the last five years. As managers, we take an agnostic view on currency, notwithstanding volatile movements and long-term uncertainties about the creditworthiness of certain countries. Instead, we consider carefully how currency movements might impact competitiveness and profitability within individual companies. And we seek to hedge out some of the risk relative to our benchmark caused by overweighting or underweighting countries or regions. Particularly in the present context of "quantitative easing" (printing money) and competitive devaluation, however, we take comfort as managers and investors in the Fund, knowing that equities confer claims on real businesses. Among the attractions of an internationally diversified equity portfolio is the possibility it offers of retaining purchasing power through economic cyc les and bouts of monetary experimentation. We believe it may prove to be an important component of a capital preservation strategy.

*Beattie, Alan, "World Bank backs efforts to counter rapid inflows, "Financial Times, January 13, 2011, p. 4.

International investing involves special risks, including foreign taxation, currency risks, risks associated with possible differences in financial standards and other risks associated with future political and economic developments. Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies. Investing in emerging markets may involve greater risks than investing in more developed countries. In addition, concentration of investments in a single region may result in greater volatility.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

12

Columbia Acorn International

At a Glance (Class A Shares - LAIAX)

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

through December 31, 2010

Inception 10/16/00		1 year			5 years			10 years
Returns before taxes	NAV POP		22.23 15.21	%		9.22 7.94	%		8.88 8.24	%
Returns after taxes on distributions	NAV POP		22.05 15.03			8.55 7.27			8.45 7.81
Returns after taxes on distributions and sale of fund shares	NAV POP		15.00 10.40			8.00 6.86			7.87 7.28
S&P Global Ex-US Between $500M and $5B Index (pretax)*			24.36			8.19			11.75

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Public offering price (POP) returns include the maximum sales charge of 5.75% for Class A shares. Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC).

Columbia Acorn International Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn International Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	Naspers (South Africa) Media in Africa, China, Russia & Other Emerging Markets	1.6	%
2.	Hexagon (Sweden) Measurement Equipment & Software	1.5	%
3.	Olam International (Singapore) Agriculture Supply Chain Manager	1.4	%
4.	Localiza Rent A Car (Brazil) Car Rental	1.2	%
5.	Kansai Paint (Japan) Paint Producer in Japan, India, China & Southeast Asia	1.2	%
6.	Imtech (Netherlands) Electromechanical & Information & Communications Technologies Installation & Maintenance	1.2	%
7.	Zhaojin Mining Industry (China) Gold Mining & Refining in China	1.1	%
8.	Fugro (Netherlands) Sub-sea Oilfield Services	1.0	%
9.	NHN (South Korea) South Korea's Largest Online Search Engine	1.0	%
10.	Advance Residence Investment (Japan) Residential REIT	1.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn International (Class A)

October 16, 2000 through December 31, 2010

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes a 5.75% maximum initial sales charge. The S&P Global Ex-U.S. Between $500M and $5B Index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder may pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $6.1 billion

13

Columbia Acorn USA

In a Nutshell

Robert A. Mohn

Co-Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

FMC Technologies	2.6	%
Informatica	2.6	%
Ametek	2.2	%
Nordson	2.0	%
tw telecom	1.6	%
lululemon athletica	1.6	%
Atmel	1.4	%
Abercrombie & Fitch	1.4	%
Finisar	1.3	%
ITT Educational Services	0.6	%
Global Payments	0.5	%
Monolithic Power Systems	0.3	%
Talbots	0.2	%
Equinix	0.2	%

*The Lehman Brothers bankruptcy was announced on Monday, September 15, 2008. On Friday, September 12, 2008, Columbia Acorn USA's net asset value (NAV) was $23.45 (Class A shares). On December 31, 2010, the Fund's NAV was $27.54. In 2008, the Fund's peak NAV was $27.44. As of December 31, 2010, the Fund was just 3.24% below its dividend-adjusted, all-time high, which it reached on June 4, 2007.

Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

Columbia Acorn USA ended the fourth quarter of 2010 up 16.35% (Class A shares, without sales charge), which compares to a 16.25% gain for its primary benchmark, the Russell 2000 Index. Small-cap stocks were very strong in 2010. For the annual period, the Fund was up 22.78% while its benchmark gained 26.85%. The Fund's relative annual return was hurt by poor performance of some of the Fund's positions in women's apparel stocks and small-cap semiconductor names, as well as the Fund's overweight position in the lagging telecom sector.

Several stocks in the retail, technology and industrial sectors were among the Fund's winners for the quarter and the year. lululemon athletica, a retailer of premium activewear, enjoyed blistering sales growth of 56% over the prior year, driving the Fund's investment up 53% in the fourth quarter and more than 125% for the year. Teen apparel retailer Abercrombie & Fitch grew same-store sales by 15% in December, outpacing competitors, most of whom posted negative year-over-year sales for this important retail month. The stock was up 47% in the fourth quarter and had an annual gain of 70% in the Fund.

Technology winners included Atmel, a leader in touchscreen microcontrollers, radio frequency and memory semiconductors. Its business has benefited from surging sales of smart phones and tablet computers. Atmel gained 55% in the fourth quarter and was up 130% for the Fund during the year. Finisar provides optical sub-systems and components for communications networks. The Fund's investment rose 67% in the quarter and 169% for the year as the company benefited from a surge in demand for data transmission and storage. Informatica, a data integration software provider that helps companies manage their disparate data streams, has also enjoyed strong revenue growth and Fund gains in the stock were 15% in the quarter and 70% for the year.

Two niche industrial companies rounded out the list of top contributors. Ametek, a manufacturer of aerospace and industrial instruments, gained 23% in the fourth quarter and was up 55% for the Fund during the year. Nordson, a maker of dispensing systems for adhesives and coatings, was up 25% in the quarter and 52% for the year in Columbia Acorn USA. Both companies have benefited from strong revenue growth and productivity improvements through wise expense control.

Outside these winning sectors, FMC Technologies, the largest position in the Fund at the end of 2010, was the top contributor to performance in the fourth quarter and ranked second for the year. Order flow at this oil and gas wellhead manufacturer climbed dramatically, nearly reaching pre-recession peaks. The stock was up 30% for the quarter and 54% for the year.

Laggards for the quarter included fiber optic telephone and data services provider tw telecom. Its stock fell 8% on underwhelming sales growth. Women's specialty retailer Talbots fell 35% in the quarter on declining sales. Equinix, a provider of offsite data centers for larger companies, suffered from price cutting in its sector and difficulties in integrating a recent acquisition. The stock fell 21% in the fourth quarter.

For the annual period, ITT Educational Services, a provider of post-secondary degree education, suffered as new regulatory requirements dogged the for-profit education sector, leading to declines in new enrollment. The stock was down 33% in the Fund for the year. Credit card processor Global Payments fell 14% during the annual period as a pricing war in its Canadian credit and debit processing business drove down margins. Monolithic Power Systems, a manufacturer of high performance analog and mixed-signal integrated circuits, fell 31% for the year due to pricing pressure and management's reduction of company profit margin targets.

Here are some fun facts for long-term stock investors: at the end of 2010, the S&P 500 large-cap index was higher than it was that fateful day before Lehman Brothers went bankrupt in September 2008, and so was Acorn USA; the Russell 2000 small-cap index was trading higher than at any point during the entire year of 2008, and so was Acorn USA; and the S&P 400 mid-cap index ended 2010 a mere 2% below its all-time high! Acorn USA was 3% below its all-time high.* A stock market Rip Van Winkle waking up from his stress-free, two-year nap would find the market just as he left it. Turns out, buy and HOLD actually works quite well.

14

Columbia Acorn USA

At a Glance (Class A Shares - LAUAX)

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

through December 31, 2010

Inception 10/16/00		1 year			5 years			10 years
Returns before taxes	NAV POP		22.78 15.72	%		3.18 1.97	%		8.33 7.69	%
Returns after taxes on distributions	NAV POP		22.78 15.72			2.82 1.61			8.03 7.39
Returns after taxes on distributions and sale of fund shares	NAV POP		14.81 10.22			2.71 1.66			7.36 6.78
Russell 2000 Index (pretax)*			26.85			4.47			6.33

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Public offering price (POP) returns include the maximum sales charge of 5.75% for Class A shares. Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC).

Columbia Acorn USA Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn USA Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	FMC Technologies Oil & Gas Wellhead Manufacturer	2.6	%
2.	Informatica Enterprise Data Integration Software	2.6	%
3.	Ametek Aerospace/Industrial Instruments	2.2	%
4.	Nordson Dispensing Systems for Adhesives & Coatings	2.0	%
5.	Micros Systems Information Systems for Hotels, Restaurants & Retailers	1.8	%
6.	Atwood Oceanics Offshore Drilling Contractor	1.7	%
7.	tw telecom Fiber Optic Telephone/Data Services	1.6	%
8.	Mettler Toledo Laboratory Equipment	1.6	%
9.	lululemon athletica Premium Active Apparel Retailer	1.6	%
10.	Gaylord Entertainment Convention Hotels	1.6	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn USA (Class A)

October 16, 2000 through December 31, 2010

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes a 5.75% maximum initial sales charge. The Russell 2000 Index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder may pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $1.7 billion

15

Columbia Acorn International Select

In a Nutshell

Christopher J. Olson

Lead Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund's Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

Serco	4.1	%
Hexagon	4.0	%
Pacific Rubiales Energy	3.9	%
Naspers	3.5	%
Fugro	3.2	%
Pan American Silver	2.6	%
Zhaojin Mining Industry	2.6	%
United Drug	2.0	%
Cobham	1.6	%
Micro Focus	0.7	%

Columbia Acorn International Select ended the fourth quarter of 2010 up 7.94% (Class A shares, without sales charge), underperforming its primary benchmark, the S&P Developed Ex-U.S. Between $2B and $10B Index, which gained 9.75%. For the annual period, the Fund's 21.41% return topped the benchmark's 20.16% gain in what turned out to be a very strong year for the global equity markets.

Top contributors to Fund performance in the quarter and year included two names in the energy sector. Pacific Rubiales Energy, a Colombian oil exploration and development company, benefited from new oilfield discoveries. The stock was up 20% for the fourth quarter and 129% for the year in the Fund. In the Netherlands, sub-sea oilfield services provider Fugro had a 25% gain in the fourth quarter and ended the year up 48% as customers confirmed their commitment to deep water drilling and higher oil prices led to a recovery in oil industry exploration spending.

Two mining companies were among the top contributors. China's Zhaojin Mining Industry had another strong quarter, gaining 34% and ending the year up 113%. The company continued to benefit from strong production and exploration profiles and rising gold prices. In Canada, Pan American Silver, a silver miner, was up 36% for the quarter and 55% for the year. Silver prices rose 83% over the year and the company continued to move forward on two large exploration projects.

The Fund's investment in Swedish measurement equipment manufacturer Hexagon gained 15% in the quarter and ended the year up 70%. The company has been enjoying strong sales growth both in Europe and emerging markets. Naspers, a media company with assets in South Africa, China and other emerging markets, was up 20% for the quarter and 48% for the year. Results in the company's underlying businesses remained strong, driven by increasing levels of Internet usage throughout its emerging market Internet holdings.

Underperformers in the quarter included UK facilities management company Serco, down 11% on concerns the government austerity program in the United Kingdom would reduce its sales growth. Irish pharmaceutical wholesaler United Drug was off 15% in the quarter on Irish budgetary concerns and worries over the impact cuts could have on the domestic economy. Cobham, a UK manufacturer of aerospace components, was down 10% in the quarter and also ranked among the worst performers for the year, with an annual decline of 17%, as the uncertainty regarding U.S. and UK defense budget cuts delayed sales. Other laggards for the year included MegaStudy, a South Korean provider of online education services that fell 33% after the government moved to subsidize its publicly run competitors. We sold the Fund's position in MegaStudy in the second quarter of 2010. Micro Focus, a UK legacy software provider, had an annual loss of 26% on news of the departure of t he company's CFO and a revenue growth downgrade.

International investing involves special risks, including foreign taxation, currency risks, risks associated with possible differences in financial standards and other risks associated with future political and economic developments. Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies. Investing in emerging markets may involve greater risks than investing in more developed countries.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

16

Columbia Acorn International Select

At a Glance (Class A Shares - LAFAX)

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

through December 31, 2010

Inception 10/16/00		1 year			5 years			10 years
Returns before taxes	NAV POP		21.41 14.43	%		8.68 7.40	%		6.28 5.66	%
Returns after taxes on distributions	NAV POP		21.29 14.31			8.42 7.14			6.16 5.53
Returns after taxes on distributions and sale of fund shares	NAV POP		14.26 9.71			7.59 6.46			5.57 5.01
S&P Developed Ex-US Between $2B and $10B Index (pretax)*			20.16			4.95			8.22

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Public offering price (POP) returns include the maximum sales charge of 5.75% for Class A shares. Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC).

Columbia Acorn International Select Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn International Select Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	Kansai Paint (Japan) Paint Producer in Japan, India, China & Southeast Asia	4.1	%
2.	Serco (United Kingdom) Facilities Management	4.1	%
3.	Hexagon (Sweden) Measurement Equipment & Software	4.0	%
4.	Pacific Rubiales Energy (Colombia) Oil Production & Exploration in Colombia	3.9	%
5.	NHN (South Korea) South Korea's Largest Online Search Engine	3.9	%
6.	Ascendas REIT (Singapore) Singapore Industrial Property Landlord	3.8	%
7.	Jiangsu Expressway (China) Chinese Toll Road Operator	3.7	%
8.	Naspers (South Africa) Media in Africa, China, Russia & Other Emerging Markets	3.5	%
9.	Fugro (Netherlands) Sub-sea Oilfield Services	3.2	%
10.	UGL (Australia) Engineering & Facilities Management	3.1	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn International Select (Class A)

October 16, 2000 through December 31, 2010

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes a 5.75% maximum initial sales charge. The S&P Developed Ex-U.S. Between $2B and $10B Index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder may pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $452.7 million

17

Columbia Acorn Select

In a Nutshell

Ben Andrews

Lead Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

Fund's Positions
in Mentioned Holdings

As a percentage of net assets,
as of 12/31/10

Pacific Rubiales Energy	6.8	%
ITT Educational Services	2.8	%
Canacol Energy	2.5	%
ShaMaran Petroleum	2.2	%
Canadian Solar	1.7	%
Career Education	1.7	%
Union Agriculture Group	0.9	%
Kirkland Lake Gold	0.7	%

Columbia Acorn Select gained 13.95% (Class A shares, without sales charge) in the fourth quarter of 2010. This exceeded the 13.50% rise in the Fund's primary benchmark, the S&P MidCap 400 Index. For the year, the Fund was up 22.49%, underperforming the 26.64% gain of its benchmark, as we were not able to completely offset the relative lag from earlier in the year. The Fund handily beat the large-cap S&P 500 Index's 10.76% fourth quarter gain and its 15.06% return for the full year.

Our investments in the oil industry helped the portfolio greatly, not so much because the price of oil went up 15% a barrel in 2010, but because the oil companies we owned were successful at finding oil, which was our thesis for making the investments. Over the past three years, we've focused on Colombia and the area known as Kurdistan in northern Iraq. Fund investments in Colombia have been a multi-year success for the portfolio, with Pacific Rubiales Energy, an oil exploration and development company, and Canacol Energy, an oil production company, together adding 8.80% to performance in 2010. The improved security provided by government forces has allowed small petroleum companies in Colombia to look more broadly for oil for the first time in more than 20 years. The fall of Saddam Hussein in Iraq allowed the Kurds to open up their semi-autonomous region within Iraq to outside investment. ShaMaran Petroleum, a company that cobbled together several exploration blocks in Kurdistan, found oil this year and its stock added 1.90% to our portfolio for the year.

On the downside, Fund investments in for-profit, post-secondary education companies ITT Educational Services and Career Education hurt returns. We've been investors in for-profit education stocks for a long time. We are believers in this industry as its student placement rates, and the career earnings of its graduates, have always been consistent and strong. We believe that many of these schools will continue to provide the same benefits for their students and make a solid profit, even if proposed "gainful employment standards" are implemented by the U.S. Department of Education. We did decrease the Fund's exposure to this sector upon realizing the negative impact that this proposed legislation could have. We intend to watch the for-profit education industry to see whether solid student and earnings growth return under the new standards and to evaluate the Fund's investments in the industry.

Canadian Solar, a solar cell and module manufacturer based in China, cost the portfolio 2.02% for the year. Solar panel pricing has been erratic as the industry is often in over supply or under supply due to its reliance on government subsidies. We invested in one of the low-cost producers of solar panels, believing that the industry is close to standing on its own two feet without big subsidies, which should fuel growth. While Canadian Solar is becoming one of the main players in the solar industry, the sector needs to improve for its stock to benefit.

During the fourth quarter of 2010, we sold out of seven companies and purchased eight new names. We made our first investments in the precious metals and farmland industries. We purchased Kirkland Lake Gold, a Canadian gold mining company that is expanding existing operations to increase production, and Union Agriculture Group, a farmland operator in Uruguay.

I'm relieved that the expiring income tax cuts were extended for another two years and I believe that the 2% cut in payroll taxes is another positive. My hope is that consumers continue to repair their balance sheets and the government starts to cut spending! Overall, I'm optimistic as a slow economic recovery is evident, but stock market valuations are not cheap, so caution is in order.

Risks include stock market fluctuations due to economic and business developments. The Fund also has potentially greater price volatility due to the Fund's concentration in a limited number of stocks of mid-size companies. The Fund is a non-diversified fund and may, therefore, have a greater risk of loss from a few issuers than a similar fund that invests more broadly. The Fund may not operate as a non-diversified fund at all times. International investments involve greater potential risks, including less regulation, currency fluctuations, economic instability and political developments.

Portfolio holdings are subject to change periodically and may not be representative of current holdings.

18

Columbia Acorn Select

At a Glance (Class A Shares - LTFAX)

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

through December 31, 2010

Inception 10/16/00		1 year			5 years			10 years
Returns before taxes	NAV POP		22.49 15.45	%		5.98 4.73	%		8.44 7.80	%
Returns after taxes on distributions	NAV POP		22.49 15.45			5.75 4.50			8.23 7.59
Returns after taxes on distributions and sale of fund shares	NAV POP		14.62 10.04			5.15 4.06			7.46 6.87
S&P MidCap 400 Index (pretax)*			26.64			5.74			7.16

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Public offering price (POP) returns include the maximum sales charge of 5.75% for Class A shares. Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC).

Columbia Acorn Select Portfolio Diversification

as a percentage of net assets, as of 12/31/10

Columbia Acorn Select Top 10 Holdings

as a percentage of net assets, as of 12/31/10

1.	Pacific Rubiales Energy (Colombia) Oil Production & Exploration in Colombia	6.8	%
2.	Hertz Largest U.S. Rental Car Operator	5.5	%
3.	Discover Financial Services Credit Card Company	4.2	%
4.	Abercrombie & Fitch Teen Apparel Retailer	4.0	%
5.	Safeway Supermarkets	3.7	%
6.	CNO Financial Group Life, Long-term Care & Medical Supplement Insurance	3.7	%
7.	Sanmina-SCI Electronic Manufacturing Services	3.6	%
8.	Ametek Aerospace/Industrial Instruments	3.2	%
9.	Crown Castle International Communications Towers	3.0	%
10.	ITT Educational Services Post-secondary Degree Services	2.8	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

The Growth of a $10,000 Investment in Columbia Acorn Select (Class A)

October 16, 2000 through December 31, 2010

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes a 5.75% maximum initial sales charge. The S&P MidCap 400 Index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. Although the index is provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder may pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $2.3 billion

19

Columbia Thermostat Fund

In a Nutshell

Charles P. McQuaid

Lead Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end performance updates.

A "fund of fund" bears its allocable share of the costs and expenses of the underlying funds in which it invests. Such funds are thus subject to two levels of fees and potentially higher expense ratios than would be associated with a fund that invests and trades directly in financial instruments under the direction of a single manager.

Columbia Thermostat Fund gained 7.40% (Class A shares, without sales charge) in the fourth quarter of 2010, compared to a 10.76% gain of its primary equity benchmark, the S&P 500 Index, and a 1.30% drop of the Fund's primary debt benchmark, the Barclays Capital U.S. Aggregate Bond Index. For the annual period, the Fund's 17.28% gain beat a 15.06% return for the large-cap S&P 500 and the 6.54% gain of the Barclays index.

Selling stock funds on the strength of the equity markets, we made three reallocations during the fourth quarter into bond funds. At the end of the period, the Fund had a 60% exposure to its underlying stock funds and 40% exposure to its underlying bond funds.

The Fund's equity positions had returns ranging from 14.57% (Columbia Acorn Fund) to 8.39% (Columbia Dividend Income Fund) in the quarter. Similarly, for the annual period, Columbia Acorn Fund's 26.00% gain was at the top while Columbia Dividend Income Fund's 13.02% was the lowest.

On the bond side, Columbia Conservative High Yield Fund posted the only gain among the underlying bond funds for the fourth quarter, up 2.14%. For the annual period, the weighted average income return was 8.28%, less than half that of the equity portion, which had a 19.18% weighted average annual gain.

Given its structure and investment objective, one would expect Columbia Thermostat Fund's returns to fall between its debt and equity benchmarks. That was not the case in 2010 as Fund performance topped both benchmarks. We attribute this to good selection of underlying funds and to the stock market trading in a range that was optimal for the Fund's rebalancing points during much of the year. As you may recall, we added to the Fund's international equity exposure earlier this year while reducing large-cap domestic equity weights. Our domestic mid-cap and international emphasis boosted the Fund's performance.

Results of the Funds Owned in Columbia Thermostat Fund as of December 31, 2010

Stock Funds	Weightings			4th
Fund	in category			quarter			1 year
Columbia Acorn International		20	%		8.57	%		22.70	%
Columbia Dividend Income Fund		20	%		8.39	%		13.02	%
Columbia Acorn Fund		15	%		14.57	%		26.00	%
Columbia Marsico Growth Fund		15	%		13.93	%		19.74	%
Columbia Acorn Select		10	%		14.05	%		22.88	%
Columbia Contrarian Core Fund		10	%		13.56	%		16.21	%
Columbia Large Cap Enhanced Core Fund		10	%		9.89	%		13.32	%
Weighted Average Equity Return		100	%		11.42	%		19.18	%
Bond Funds	Weightings			4th
Fund	in category			quarter			1 year
Columbia Intermediate Bond Fund		50	%		-0.57	%		7.91	%
Columbia U.S. Treasury Index Fund		30	%		-2.56	%		5.67	%
Columbia Conservative High Yield Fund		20	%		2.14	%		13.00	%
Weighted Average Income Return/Loss		100	%		-0.61	%		8.28	%

Columbia Thermostat Fund
Rebalancing in the Fourth Quarter

October 6, 2010	70% stocks, 30% bonds
November 5, 2010	65% stocks, 35% bonds
December 22, 2010	60% stocks, 40% bonds

The value of an investment in the Fund is based primarily on the performance of the underlying portfolio funds and the allocation of the Fund's assets among them. An investment in the underlying portfolio funds may present certain risks, including stock market fluctuations that occur in response to economic and business developments; and a greater degree of social, political and economic volatility associated with international investing. Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies. Value stocks may also be subject to specific business risks that have caused the stocks to be out of favor. Lower-rated and medium quality debt securities are more speculative and incur more risk. International investing involves special risks, including foreign taxation, currency risks, risks associated with possible differences in fin ancial standards and other risks associated with future political and economic developments. Changes in interest rates and changes in the financial strength of issuers of lower-rated bonds may also affect underlying fund performance. The Fund is also subject to the risk that the investment adviser's decisions regarding asset classes and underlying portfolio funds will not anticipate market trends successfully, resulting in a failure to preserve capital or lower total return. In addition, the Fund may buy and sell shares of the portfolio funds frequently. This may result in higher transaction costs and additional tax liability. This is not an offer of the shares of any other mutual fund mentioned herein.

20

Columbia Thermostat Fund

At a Glance (Class A Shares - CTFAX)

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results would have been lower. Please visit columbiamanagement.com for daily and most recent month-end updates.

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

through December 31, 2010

Inception 3/3/03		1 year			5 years			Life of fund
Returns before taxes	NAV POP		17.28 10.54	%		5.12 3.88	%		7.87 7.06	%
Returns after taxes on distributions	NAV POP		17.00 10.27			3.90 2.68			6.64 5.84
Returns after taxes on distributions and sale of fund shares	NAV POP		11.53 7.13			3.85 2.79			6.31 5.58
S&P 500 Index (pretax)*			15.06			2.29			7.38
Barclays Capital U.S. Aggregate Bond Index (pretax)*			6.54			5.80			4.89
Lipper Flexible Portfolio Funds Index (pretax)			12.91			4.75			8.22

All results shown assume reinvestment of distributions.

*The Fund's primary stock and bond benchmarks, respectively.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

Public offering price (POP) returns include the maximum sales charge of 5.75% for Class A shares. Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC).

Columbia Thermostat Fund Asset Allocation

as a percentage of net assets, as of 12/31/10

Columbia Thermostat Fund Portfolio Weightings

as a percentage of assets in each investment category, as of 12/31/10

Stock Mutual Funds

Columbia Acorn International, Class I	20	%
Columbia Dividend Income Fund, Class I	20	%
Columbia Acorn Fund, Class I	15	%
Columbia Marsico Growth Fund, Class I	15	%
Columbia Acorn Select, Class I	10	%
Columbia Contrarian Core Fund, Class I	10	%
Columbia Large Cap Enhanced Core Fund, Class I	10	%

Bond Mutual Funds

Columbia Intermediate Bond Fund, Class I	50	%
Columbia U.S. Treasury Index Fund, Class I	30	%
Columbia Conservative High Yield Fund, Class Z	20	%

The Growth of a $10,000 Investment in Columbia Thermostat Fund (Class A)

March 3, 2003 through December 31, 2010

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes a 5.75% maximum initial sales charge. The indexes are unmanaged and returns for both the indexes and the Fund include reinvested dividends and capital gains. Although the indexes are provided for use in assessing the Fund's performance, the Fund's holdings may differ significantly from those in the index. It is not possible to invest directly in an index. The graph does not reflect taxes that a shareholder may pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund: $131.3 million

21

Columbia Acorn Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Information
AboveNet		1,100,000		1,200,000
Applied Micro Circuits		0		1,650,000
Ariba		0		500,000
Concur Technologies		1,035,000		1,480,000
IMAX (Canada)		0		800,000
Infinera		800,000		1,925,000
IPG Photonics		2,600,000		2,710,000
Ixia		681,003		1,470,000
Mail.ru - GDR (Russia)		0		464,305
Microsemi		2,085,000		2,345,000
Netgear		1,100,000		1,200,000
Plexus		1,677,807		1,790,000
Polycom		1,745,000		1,955,000
SPS Commerce		0		856,429
Trimble Navigation		1,545,000		1,935,000
Verisk Analytics		0		450,000
WMS Industries		790,000		1,050,000
Industrial Goods & Services
Albany International		1,000,000		1,100,000
Arcadis (Netherlands)		261,990		626,524
FMC Corp.		0		300,000
GrafTech International		1,980,000		2,340,000
Marel (Iceland)		0		10,000,000
Neopost (France)		205,000		280,000
Oshkosh		2,608,607		3,650,000
St. Joe		0		500,000
Ushio (Japan)		1,000,000		1,134,100
Consumer Goods & Services
Bravo Brio Restaurant Group		0		367,900
Career Education		2,600,000		2,800,000
Cheesecake Factory		330,000		450,000
Crocs		800,000		1,400,000
Deckers Outdoor		0		1,120,000
Diamond Foods		810,000		1,300,000
DSW		403,700		525,000
Guess?		0		1,550,000
Hanesbrands		250,000		700,000
Lance		0		240,000
Lifetime Fitness		1,960,000		2,190,000
Localiza Rent A Car (Brazil)		1,100,000		2,000,000
Melco Crown Entertainment - ADR (Hong Kong)		0		3,000,000
Phillips-Van Heusen		500,000		1,055,000
Shutterfly		1,531,492		1,700,000
Steven Madden		0		400,000
Tesla Motors		294,000		400,000
The Fresh Market		0		66,000
Warnaco Group		612,972		2,190,000

	Number of Shares
	09/30/10		12/31/10
Energy & Minerals
Alange Energy (Colombia)		12,100,000		17,100,000
Augusta Resource		0		800,000
Canadian Overseas Petroleum (United Kingdom)		0		2,520,000
Canadian Overseas Petroleum - Subscription Receipts (United Kingdom)		0		5,880,000
Duluth Metals (Canada)		2,800,000		3,154,000
Mongolian Mining (Hong Kong)		0		5,215,500
Oil States International		0		200,000
Petroamerica (Colombia)		13,000,000		30,275,000
STR Holdings		400,000		500,000
Swift Energy		0		275,000
Union Agriculture Group (Argentina)		0		6,818,182
Finance
Alliance Data Systems		0		140,000
Associated Banc-Corp		5,063,800		5,413,800
Brown & Brown		0		900,000
First Busey		1,614,507		3,299,507
Hanover Insurance Group		1,230,000		1,320,000
Tower Group		900,000		1,225,000
TriCo Bancshares		1,136,175		1,350,000
Whitney Holding		2,200,000		4,000,000
Health Care
Akorn		759,718		2,659,068
Alimera Sciences		0		361,450
Allos Therapeutics		5,981,889		7,035,000
BioMarin Pharmaceutical		3,205,000		3,920,421
Chelsea Therapeutics		2,649,300		3,449,900
Community Health Systems		0		1,300,000
Health Management Associates		0		2,650,000
Idenix Pharmaceuticals		2,800,000		3,340,255
InterMune		0		1,088,500
Isis Pharmaceuticals		2,350,000		4,500,000
Micromet		3,500,000		5,500,000
Nabi Biopharmaceuticals		0		1,383,454
Neogen		0		77,602
Onyx Pharmaceuticals		900,000		1,200,000
Pacific Biosciences of California		0		932,768
Patterson Companies		0		1,100,000
Seattle Genetics		4,114,900		4,180,918
Sirona Dental Systems		1,500,000		1,800,000
United Therapeutics		860,000		1,110,000
Other Industries
Associated Estates Realty		1,500,000		2,200,000
Dupont Fabros Technology		1,300,000		1,935,579

See accompanying notes to financial statements.

22

	Number of Shares
	09/30/10		12/31/10
Purchases (continued)
Other Industries—continued
Federal Realty Investment Trust		480,000		641,165
Mapletree Logistics Trust (Singapore)		40,000,000		43,201,999
Post Properties		0		367,240
Rush Enterprises, Class A		2,500,000		2,800,000
Rush Enterprises, Class B		500,000		550,000

	Number of Shares
	09/30/10		12/31/10
Sales
Information
Actuate		3,700,000		1,500,000
Akamai		440,000		0
Avid Technology		700,000		0
Cogent Communications		3,400,000		2,800,000
CommScope		1,045,000		0
Finisar		1,875,000		1,725,000
Hong Kong Exchanges and Clearing (Hong Kong)		1,790,000		750,000
iGate		5,000,000		2,913,065
Mediacom Communications		3,000,000		0
Singapore Exchange (Singapore)		8,000,000		5,000,000
SRA International		1,780,893		1,655,000
Industrial Goods & Services
Mine Safety Appliances		1,687,699		1,525,000
Republic Services		1,500,000		1,000,000
Ritchie Brothers Auctioneers		687,500		0
Serco (United Kingdom)		2,900,000		2,559,000
Watsco		250,000		100,000
Consumer Goods & Services
Charming Shoppes		5,717,981		0
Chico's FAS		4,762,000		2,562,000
Coldwater Creek		4,773,374		1,384,597
Dress Barn		1,175,000		0
Expedia		4,500,000		3,900,000
Express		1,345,000		0
Flowers Foods		819,000		0
G-III Apparel Group		260,260		0
J Crew Group		1,784,000		0
Jones Apparel Group		2,025,000		0
lululemon athletica		4,135,000		4,035,000
P.F. Chang's China Bistro		370,000		300,000
Penn National Gaming		1,750,000		1,590,000
Pier 1 Imports		5,700,000		5,600,000
Pinnacle Entertainment		4,050,000		3,400,000
Princeton Review		2,970,000		2,000,000
Rue21		517,696		0
Smart Balance		2,000,000		0
Talbots		4,900,000		4,150,000
True Religion Apparel		2,397,000		2,047,000
Urban Outfitters		2,009,700		1,180,000
Vail Resorts		1,450,000		1,250,000
Wet Seal		4,815,600		0
Energy & Minerals
Core Laboratories (Netherlands)		696,000		641,000
Horizon North Logistics (Canada)		2,953,900		2,890,900
Oceaneering International		275,000		0

See accompanying notes to financial statements.

23

Columbia Acorn Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited), continued

	Number of Shares
	09/30/10		12/31/10
Sales (continued)
Energy & Minerals—continued
Silver Wheaton (Canada)		2,450,000		2,250,000
Southwestern Energy		2,160,000		1,800,000
Finance
Aspen Insurance		1,000,000		390,919
Assurant		700,000		121,342
Delphi Financial Group		1,450,000		1,000,000
H&E Equipment Services		3,033,300		3,000,000
Housing Development Finance (India)		1,625,000		1,300,000
Markel		100,000		0
Health Care
Acorda Therapeutics		1,550,000		900,000
Alexion Pharmaceuticals		2,800,000		2,100,000
Amylin Pharmaceuticals		1,550,000		0
Cepheid		3,350,000		2,415,000
Human Genome Sciences		1,100,000		0
ICU Medical		850,000		42,278
Illumina		1,100,000		506,000
Nanosphere		1,500,000		1,480,056
Nektar Therapeutics		3,300,000		2,700,000
Owens & Minor		600,000		200,000
PSS World Medical		3,300,000		0
QIAGEN (Netherlands)		1,435,000		0
Vermillion		694,849		0
Other Industries
American Commercial Lines		602,000		0
JB Hunt Transport Services		1,980,000		1,850,000
Macerich		752,161		530,000
Terna (Italy)		5,833,000		3,333,000

See accompanying notes to financial statements.

24

Columbia Acorn Fund

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 97.2%
Information 26.9%
		> Business Software 6.2%
	5,200,000	Informatica (a)(b)	$	228,956
		Enterprise Data Integration Software
	2,700,000	Micros Systems (a)		118,422
		Information Systems for Hotels, Restaurants & Retailers
	2,100,000	ANSYS (a)		109,347
		Simulation Software for Engineers & Designers
	1,480,000	Concur Technologies (a)		76,856
		Web Enabled Cost & Expense Management Software
	1,100,000	Quality Systems (c)		76,802
		IT Systems for Medical Groups & Ambulatory Care Centers
	12,500,000	Novell (a)		74,000
		Directory, Operating System & Identity Management Software
	2,250,000	Blackbaud (b)		58,275
		Software & Services for Non-profits
	9,000,000	Art Technology Group (a)(b)		53,820
		Software & Tools to Optimize Websites for E-Commerce
	1,800,000	NetSuite (a)		45,000
		End to End IT Systems Solutions Delivered Over the Web
	2,025,000	Kenexa (a)(b)		44,125
		Recruiting & Workforce Management Solutions
	1,400,000	Constant Contact (a)(c)		43,386
		E-mail & Other Marketing Campaign Management Systems Delivered Over the Web
	2,000,000	Tyler Technologies (a)(b)		41,520
		Financial, Tax, Court & Document Management Systems for Local Governments
	850,000	Red Hat (a)		38,803
		Maintenance & Support for Open Source & Middleware
	700,000	Blackboard (a)(c)		28,910
		Education Software
	920,000	Jack Henry & Associates		26,818
		Systems Financial Institutions
	345,000	Advent Software (a)(c)		19,982
		Asset Management & Trading Systems
	856,429	SPS Commerce (a)(b)		13,532
		Supply Chain Management Software Delivered via the Web
	500,000	Ariba (a)		11,745
		Cost Management Software
	1,500,000	Actuate (a)		8,550
		Information Delivery Software & Solutions
	1,000,000	InContact (a)		3,300
		Call Center Systems Delivered via the Web & Telecommunications Services
				1,122,149

Number of Shares			Value (000)
		> Instrumentation 3.3%
	1,600,000	Mettler Toledo (a)	$	241,936
		Laboratory Equipment
	5,915,000	Hexagon (Sweden) (c)		126,861
		Measurement Equipment & Software
	2,710,000	IPG Photonics (a)(b)		85,690
		Fiber Lasers
	1,935,000	Trimble Navigation (a)		77,265
		GPS-based Instruments
	300,000	Dionex (a)		35,403
		Ion & Liquid Chromatography
	600,000	FLIR Systems (a)		17,850
		Infrared Cameras
	400,000	Hamamatsu Photonics (Japan)		14,612
		Optical Sensors for Medical & Industrial Applications
				599,617
		> Computer Hardware & Related Equipment 2.9%
	3,750,000	Amphenol		197,925
		Electronic Connectors
	2,225,000	II-VI (a)(b)		103,151
		Laser Optics & Specialty Materials
	1,140,000	Dolby Laboratories (a)		76,038
		Audio Technology for Consumer Electronics
	1,605,000	Zebra Technologies (a)		60,974
		Bar Code Printers
	1,200,000	Netgear (a)		40,416
		Networking Products for Small Business & Home
	800,000	Nice Systems - ADR (Israel) (a)		27,920
		Audio & Video Recording Solutions
	605,000	Stratasys (a)(c)		19,747
		Rapid Prototyping Systems
				526,171
		> Mobile Communications 2.3%
	6,300,000	Crown Castle International (a)		276,129
		Communications Towers
	3,150,000	SBA Communications (a)		128,961
		Communications Towers
	1,000,000	MetroPCS Communications (a)		12,630
		Discount Cellular Telephone Services
	1,500,000	Globalstar (a)(c)		2,175
		Satellite Mobile Voice & Data Carrier
				419,895
		> Telecommunications Equipment 1.9%
	1,045,000	F5 Networks (a)		136,017
		Internet Traffic Management Equipment
	1,955,000	Polycom (a)		76,206
		Video Conferencing Equipment
	1,725,000	Finisar (a)		51,215
		Optical Sub-systems & Components
	1,260,000	Blue Coat Systems (a)		37,636
		WAN Acceleration & Network Security
	1,470,000	Ixia (a)		24,667
		Telecom Network Test Equipment
	1,925,000	Infinera (a)		19,885
		Optical Networking Equipment
				345,626

See accompanying notes to financial statements.

25

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Semiconductors & Related Equipment 1.9%
	7,470,000	Atmel (a)	$	92,030
		Microcontrollers, Radio Frequency & Memory Semiconductors
	2,345,000	Microsemi (a)		53,701
		Analog/Mixed-signal Semiconductors
	3,440,000	ON Semiconductor (a)		33,987
		Mixed-signal & Power Management Semiconductors
	4,500,000	Entegris (a)		33,615
		Semiconductor Materials Management Products
	1,035,000	Supertex (a)(b)		25,026
		Analog/Mixed-signal Semiconductors
	500,000	Littelfuse		23,530
		Little Fuses
	1,900,000	IXYS (a)(b)		22,078
		Power Semiconductors
	1,765,000	Pericom Semiconductor (a)(b)		19,380
		Interface Integrated Circuits (ICs) & Frequency Control Products
	1,650,000	Applied Micro Circuits (a)		17,622
		Communications Semiconductors
	800,000	Monolithic Power Systems (a)		13,216
		High Performance Analog & Mixed-signal Integrated Circuits (ICs)
				334,185
		> Telephone and Data Services 1.8%
	9,500,000	tw telecom (a)(b)		161,975
		Fiber Optic Telephone/Data Services
	1,200,000	AboveNet		70,152
		Metropolitan Fiber Communications Services
	2,800,000	Cogent Communications (a)(b)		39,592
		Internet Data Pipelines
	9,600,000	PAETEC Holding (a)(b)		35,904
		Telephone/Data Services for Business
	2,000,000	General Communications (a)		25,320
		Commercial Communications & Consumer CATV, Web & Phone in Alaska
				332,943
		> Gaming Equipment & Services 1.1%
	3,725,000	Bally Technologies (a)(b)		157,158
		Slot Machines & Software
	1,050,000	WMS Industries (a)		47,502
		Slot Machine Provider
				204,660
		> Computer Services 1.1%
	2,913,065	iGate (b)		57,416
		IT & BPO (Business Process Outsourcing) Services
	1,655,000	SRA International (a)		33,845
		Government IT Services
	2,000,000	Virtusa (a)(b)		32,720
		Offshore IT Outsourcing
	1,560,000	Acxiom (a)		26,754
		Database Marketing Services
	1,045,000	ExlService Holdings (a)		22,447
		BPO (Business Process Outsourcing)

Number of Shares			Value (000)
	4,500,000	Hackett Group (a)(b)	$	15,795
		IT Integration & Best Practice Research
	1,000,000	WNS - ADR (India) (a)		11,570
		Offshore BPO (Business Process Outsourcing) Services
				200,547
		> CATV 1.0%
	3,000,000	Discovery Communications, Series C (a)		110,070
		Cable TV Programming
	1,250,000	Liberty Global, Series A (a)(c)		44,225
		Cable TV Franchises Outside the USA
	17,770	Jupiter Telecommunications (Japan)		18,691
		Largest Cable Service Provider in Japan
				172,986
		> Financial Processors 0.9%
	2,429,000	Global Payments		112,244
		Credit Card Processor
	5,000,000	Singapore Exchange (Singapore)		32,805
		Singapore Equity & Derivatives Market Operator
	750,000	Hong Kong Exchanges and Clearing (Hong Kong)		17,011
		Hong Kong Equity & Derivatives Market Operator
				162,060
		> Internet Related 0.6%
	188,000	NHN (South Korea) (a)		37,514
		South Korea's Largest Online Search Engine
	435,000	Equinix (a)		35,348
		Network Neutral Data Centers
	464,305	Mail.ru - GDR (Russia) (a)(d)		16,715
		Internet Social Networking & Games for Russian Speakers
	1,000,000	Terremark Worldwide (a)		12,950
		Data Center Colocation & IT Managed Services Provider
	1,000,000	TheStreet.com		2,670
		Financial Information Websites
				105,197
		> Electronics Distribution 0.6%
	3,125,000	Avnet (a)		103,219
		Electronic Components Distribution
				103,219
		> Contract Manufacturing 0.5%
	1,790,000	Plexus (a)		55,383
		Electronic Manufacturing Services
	2,800,000	Sanmina-SCI (a)		32,144
		Electronic Manufacturing Services
				87,527
		> Business Information & Marketing Services 0.4%
	900,000	FTI Consulting (a)		33,552
		Financial Consulting Firm
	3,100,000	Navigant Consulting (a)(b)		28,520
		Financial Consulting Firm
	450,000	Verisk Analytics (a)		15,336
		Risk & Decision Analytics
				77,408

See accompanying notes to financial statements.

26

Number of Shares			Value (000)
		> Entertainment Programming 0.1%
	800,000	IMAX (Canada) (a)	$	22,440
		IMAX Movies, Theatre Equipment & Theatre Joint Ventures
				22,440
		> Consumer Software 0.1%
	3,567,000	THQ (a)(b)		21,616
		Entertainment Software
				21,616
		> Radio 0.1%
	1,541,000	Salem Communications (b)		4,885
		Radio Stations for Religious Programming
	164,991	Saga Communications (a)		4,343
		Radio Stations in Small & Mid-sized Cities
	2,400,000	Spanish Broadcasting System (a)(b)		1,699
		Spanish Language Radio Stations
				10,927
		> TV Broadcasting 0.1%
	2,500,000	Entravision Communications (a)		6,425
		Spanish Language TV & Radio Stations
	1,750,000	Gray Television (a)		3,272
		Mid-market Affiliated TV Stations
				9,697
		> Advertising —%
	1,500,000	VisionChina Media - ADR (China) (a)(c)		6,960
		Advertising on Digital Screens in China's Mass Transit System
				6,960
Information: Total				4,865,830
Industrial Goods & Services 18.5%
		> Machinery 9.6%
	6,750,000	Ametek		264,937
		Aerospace/Industrial Instruments
	4,200,000	Donaldson (b)		244,776
		Industrial Air Filtration
	1,500,000	Nordson		137,820
		Dispensing Systems for Adhesives & Coatings
	3,650,000	Oshkosh (a)		128,626
		Specialty Truck Manufacturer
	3,100,000	Pentair		113,181
		Pumps & Water Treatment
	2,565,000	Clarcor (b)		110,013
		Mobile & Industrial Filters
	2,375,000	Kennametal		93,718
		Consumable Cutting Tools
	1,800,000	Pall		89,244
		Filtration & Fluids Clarification
	2,200,000	ESCO Technologies (b)		83,248
		Automatic Electric Meter Readers
	1,820,000	MOOG (a)		72,436
		Motion Control Products for Aerospace, Defense & Industrial Markets
	1,150,000	WABCO Holdings (a)		70,070
		Truck & Bus Component Supplier

Number of Shares			Value (000)
	1,700,000	HEICO	$	63,444
		FAA Approved Aircraft Replacement Parts
	1,300,000	Kaydon		52,936
		Specialized Friction & Motion Control Products
	805,000	Toro		49,620
		Turf Maintenance Equipment
	1,525,000	Mine Safety Appliances		47,473
		Safety Equipment
	600,000	Wabtec		31,734
		Freight & Transit Component Supplier
	1,600,000	Generac (a)		25,872
		Stand-by Power Generators
	280,000	Neopost (France)		24,395
		Postage Meter Machines
	3,500,000	Jain Irrigation Systems (India)		16,484
		Agricultural Micro-irrigation Systems & Food Processing
	10,000,000	Marel (Iceland) (a)		8,713
		Largest Manufacturer of Poultry & Fish Processing Equipment
	1,250,000	Spartan Motors		7,613
		Specialty Truck & Chassis Manufacturer
				1,736,353
		> Industrial Materials & Specialty Chemicals 2.7%
	1,750,000	Sociedad Quimica y Minera de Chile - ADR (Chile)		102,235
		Producer of Specialty Fertilizers, Lithium & Iodine
	1,530,000	Albemarle		85,343
		Refinery Catalysts & Other Specialty Chemicals
	1,800,000	Nalco Holding Company		57,492
		Provider of Water Treatment & Process Chemicals & Services
	340,000	Novozymes (Denmark)		47,377
		Industrial Enzymes
	753,000	Mersen (France)		34,514
		Advanced Industrial Materials
	1,260,000	Drew Industries (b)		28,627
		RV & Manufactured Home Components
	1,100,000	Albany International		26,059
		Paper Machine Clothing & Advanced Textiles
	300,000	FMC Corp.		23,967
		Niche Specialty Chemicals
	350,000	Greif		21,665
		Industrial Packaging
	2,200,000	Kansai Paint (Japan)		21,286
		Paint Producer in Japan, India, China & Southeast Asia
	9,000	Sika (Switzerland)		19,752
		Chemicals for Construction & Industrial Applications
	400,000	Silgan Holdings		14,324
		Metal & Plastic Packaging
				482,641

See accompanying notes to financial statements.

27

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Other Industrial Services 2.1%
	3,200,000	Expeditors International of Washington	$	174,720
		International Freight Forwarder
	1,850,000	Imtech (Netherlands)		70,184
		Electromechanical & Information & Communications Technologies Installation & Maintenance
	1,300,000	Forward Air		36,894
		Freight Transportation Between Airports
	1,600,000	Mobile Mini (a)		31,504
		Portable Storage Units Leasing
	1,000,000	UTI Worldwide		21,200
		Freight Forwarding & Logistics
	1,050,000	TrueBlue (a)		18,890
		Temporary Manual Labor
	626,524	Arcadis (Netherlands)		14,580
		Engineering Consultants
	900,000	American Reprographics (a)		6,831
		Document Management & Logistics
				374,803
		> Industrial Distribution 1.0%
	900,000	WW Grainger		124,299
		Industrial Distribution
	2,600,000	Interline Brands (a)(b)		59,202
		Industrial Distribution
	100,000	Watsco		6,308
		HVAC Distribution
				189,809
		> Electrical Components 0.8%
	1,440,000	Acuity Brands		83,045
		Commercial Lighting Fixtures
	1,134,100	Ushio (Japan)		21,604
		Industrial Light Sources
	600,000	Ibiden (Japan)		18,907
		Electronic Parts & Ceramics
	351,000	Saft (France)		12,922
		Niche Battery Manufacturer
				136,478
		> Construction 0.6%
	66,000	NVR (a)		45,607
		D.C. Homebuilder
	1,800,000	Mills Estruturas e Serviços de Engenharia (Brazil)		22,337
		Civil Engineering & Construction
	700,000	Simpson Manufacturing		21,637
		Wall Joint Maker
	700,000	Lumber Liquidators (a)(c)		17,437
		Hardwood Flooring Retailer
	500,000	St. Joe (a)(c)		10,925
		Florida Panhandle Landowner
				117,943
		> Outsourcing Services 0.6%
	1,950,000	Quanta Services (a)		38,844
		Electrical & Telecom Construction Services
	1,210,000	Administaff		35,453
		Professional Employer Organization
	2,559,000	Serco (United Kingdom)		22,163
		Facilities Management

Number of Shares			Value (000)
	600,000	GP Strategies (a)	$	6,144
		Training Programs
				102,604
		> Waste Management 0.5%
	1,672,500	Waste Connections		46,044
		Solid Waste Management
	1,000,000	Republic Services		29,860
		Solid Waste Management
	280,000	Clean Harbors (a)		23,542
		Hazardous Waste Services & Disposal
				99,446
		> Conglomerates 0.3%
	2,225,287	Aalberts Industries (Netherlands)		46,909
		Flow Control & Heat Treatment
				46,909
		> Steel 0.3%
	2,340,000	GrafTech International (a)		46,426
		Industrial Graphite Materials Producer
				46,426
		> Water —%
	1,750,000	Mueller Water Products		7,298
		Fire Hydrants, Valves & Ductile Iron Pipes
				7,298
Industrial Goods & Services: Total				3,340,710
Consumer Goods & Services 16.8%
		> Retail 4.2%
	4,035,000	lululemon athletica (a)(b)(c)		276,075
		Premium Active Apparel Retailer
	2,835,000	Abercrombie & Fitch		163,381
		Teen Apparel Retailer
	1,700,000	Shutterfly (a)(b)		59,551
		Internet Photo-centric Retailer
	5,600,000	Pier 1 Imports (a)		58,800
		Home Furnishing Retailer
	5,225,000	Saks (a)(c)		55,907
		Luxury Department Store Retailer
	1,180,000	Urban Outfitters (a)		42,256
		Apparel & Home Specialty Retailer
	4,150,000	Talbots (a)(b)		35,358
		Women's Specialty Retailer
	2,562,000	Chico's FAS		30,821
		Women's Specialty Retailer
	525,000	DSW (a)		20,527
		Branded Footwear Retailer
	1,371,366	Gaiam (b)		10,560
		Healthy Living Catalogs & E-Commerce
	1,384,597	Coldwater Creek (a)		4,389
		Women's Apparel Retailer
	66,000	The Fresh Market (a)		2,719
		Specialty Food Retailer
				760,344
		> Apparel 3.2%
	2,190,000	Warnaco Group (a)		120,603
		Global Branded Apparel Manufacturer

See accompanying notes to financial statements.

28

Number of Shares			Value (000)
		> Apparel—continued
	2,100,000	Coach	$	116,151
		Designer & Retailer of Branded Leather Accessories
	1,120,000	Deckers Outdoor (a)		89,309
		Fashion Footwear Wholesaler
	1,550,000	Guess?		73,346
		Branded Apparel, Accessories & Licensor
	1,055,000	Phillips-Van Heusen		66,476
		Apparel Wholesaler & Retailer
	2,047,000	True Religion Apparel (a)(b)		45,566
		Premium Denim
	1,400,000	Crocs (a)		23,968
		Branded Footwear Wholesaler & Retailer
	700,000	Hanesbrands (a)		17,780
		Apparel Wholesaler
	400,000	Steven Madden (a)		16,688
		Wholesaler/Retailer of Fashion Footwear
				569,887
		> Travel 2.7%
	3,850,000	Gaylord Entertainment (a)(b)		138,369
		Convention Hotels
	3,900,000	Expedia		97,851
		Online Travel Services Company
	4,600,000	Avis Budget Group (a)		71,576
		Second Largest Car Rental Company
	1,250,000	Vail Resorts (a)		65,050
		Ski Resort Operator & Developer
	3,000,000	Hertz (a)		43,470
		Largest U.S. Rental Car Operator
	970,000	Choice Hotels		37,122
		Franchisor of Budget Hotel Brands
	2,000,000	Localiza Rent A Car (Brazil)		32,417
		Car Rental
				485,855
		> Food & Beverage 1.6%
	2,200,000	Hansen Natural (a)		115,016
		Alternative Beverages
	37,000,000	Olam International (Singapore)		90,529
		Agriculture Supply Chain Manager
	1,300,000	Diamond Foods (b)(c)		69,134
		Culinary Ingredients & Snack Foods
	1,200,000	GLG Life Tech (Canada) (a)		12,888
		Produce an All-natural Sweetener Extracted from the Stevia Plant
	240,000	Lance		5,625
		Snack Foods
	22,800	Sodastream (a)		720
		Home Beverage Carbonation System
				293,912
		> Educational Services 1.0%
	1,080,000	ITT Educational Services (a)(c)		68,785
		Post-secondary Degree Services
	2,800,000	Career Education (a)		58,044
		Post-secondary Education
	1,700,000	Universal Technical Institute (b)		37,434
		Vocational Training

Number of Shares			Value (000)
	200,000	New Oriental Education & Technology - ADR (China) (a)	$	21,046
		China's Largest Private Education Service Provider
	2,000,000	Princeton Review (a)		2,360
		College Preparation Courses
	2,000,000	Voyager Learning, Contingent Value Rights (a)(d)		262
		Education Services for the K-12 Market
				187,931
		> Furniture & Textiles 0.8%
	2,800,000	Herman Miller		70,840
		Office Furniture
	4,000,000	Knoll (b)		66,920
		Office Furniture
	1,000,000	Interface		15,650
		Modular & Broadloom Carpet
				153,410
		> Other Consumer Services 0.7%
	2,190,000	Lifetime Fitness (a)(b)		89,768
		Sport & Fitness Club Operator
	14,000,000	Lifestyle International (Hong Kong)		34,402
		Mid- to High-end Department Store Operator in Hong Kong & China
	1,325,000	IFM Investments (Century 21 China RE) - ADR (China) (a)		6,625
		Provides Real Estate Services in China
				130,795
		> Casinos & Gaming 0.7%
	1,590,000	Penn National Gaming (a)		55,888
		Regional Casino Operator
	3,400,000	Pinnacle Entertainment (a)(b)		47,668
		Regional Casino Operator
	3,000,000	Melco Crown Entertainment - ADR (Hong Kong) (a)(c)		19,080
		Macau Casino Operator
				122,636
		> Nondurables 0.5%
	1,600,000	Helen of Troy (a)(b)		47,584
		Hair Dryers & Curling Irons
	550,000	Energizer Holdings (a)		40,095
		Household & Personal Care Products
				87,679
		> Other Durable Goods 0.4%
	1,720,000	Jarden		53,097
		Branded Household Products
	400,000	Tesla Motors (a)(c)		10,652
		Design, Manufacture & Sell High Performance Electric Vehicles
	180,000	Cavco Industries (a)		8,404
		Manufactured Homes
				72,153
		> Restaurants 0.4%
	2,000,000	AFC Enterprises (a)(b)		27,800
		Popeye's Restaurants
	300,000	P.F. Chang's China Bistro (c)		14,538
		Mandarin Style Restaurants

See accompanying notes to financial statements.

29

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Restaurants—continued
	450,000	Cheesecake Factory (a)	$	13,797
		Casual Dining Restaurants
	367,900	Bravo Brio Restaurant Group (a)		7,053
		Upscale Casual Italian Restaurants
				63,188
		> Consumer Goods Distribution 0.3%
	2,100,000	Pool		47,334
		Distributor of Swimming Pool Supplies & Equipment
				47,334
		> Leisure Products 0.2%
	1,190,000	Thor Industries		40,412
		RV & Bus Manufacturer
				40,412
		> Other Entertainment 0.1%
	370,000	CTS Eventim (Germany)		22,848
		Event Ticket Sales
				22,848
Consumer Goods & Services: Total				3,038,384
Energy & Minerals 10.8%
		> Oil Services 4.2%
	3,100,000	FMC Technologies (a)		275,621
		Oil & Gas Wellhead Manufacturer
	2,570,626	Fugro (Netherlands)		211,260
		Sub-sea Oilfield Services
	3,200,000	Atwood Oceanics (a)		119,584
		Offshore Drilling Contractor
	1,670,000	ShawCor (Canada)		55,611
		Oil & Gas Pipeline Products
	1,750,000	Tesco (a)		27,790
		Developing New Well Drilling Technologies
	375,000	Bristow (a)		17,756
		Largest Provider of Helicopter Services to Offshore Oil & Gas Producers
	10,719,200	Tuscany International Drilling (Colombia) (a)(b)(d)		14,791
	2,600,000	Tuscany International Drilling - Warrants (Colombia) (a)(b)(d)		333
		South America-based Drilling Rig Contractor
	200,000	Oil States International (a)		12,818
		Diversified North American Oil Service Provider
	375,000	Gulfmark Offshore (a)		11,400
		Operator of Offshore Supply Vessels
	500,000	Black Diamond Group (Canada)		10,817
		Provides Accommodations/Equipment for Oil Sands Exploitation
	2,890,900	Horizon North Logistics (Canada) (a)		8,635
		Provides Diversified Oil Service Offering in Northern Canada
				766,416
		> Oil & Gas Producers 4.2%
	4,910,550	Pacific Rubiales Energy (Colombia)		166,681
		Oil Production & Exploration in Colombia
	1,800,000	Southwestern Energy (a)		67,374
		Oil & Gas Producer

Number of Shares			Value (000)
	2,700,000	Denbury Resources (a)	$	51,543
		Oil Producer Using Co2 Injection
	2,400,000	Tullow Oil (United Kingdom)		47,185
		Oil & Gas Producer
	910,000	Ultra Petroleum (a)		43,471
		Oil & Gas Producer
	715,000	SM Energy		42,135
		Oil & Gas Producer
	695,000	Range Resources		31,261
		Oil & Gas Producer
	650,000	Baytex (Canada)		30,470
		Oil & Gas Producer in Canada
	22,000,000	ShaMaran Petroleum (Iraq) (a)		30,091
		Oil Exploration in Kurdistan
	779,000	Rosetta Resources (a)		29,322
		Oil & Gas Producer Exploring in South Texas & Montana
	24,000,000	Petrodorado (Colombia) (a)(b)(d)		16,795
	24,000,000	Petrodorado - Warrants (Colombia) (a)(b)(d)		10,138
		Oil & Gas Exploration & Production in Colombia, Peru & Paraguay
	850,000	Northern Oil & Gas (a)		23,128
		Small E&P Company in North Dakota Bakken
	1,200,000	Houston American Energy (c)		21,708
		Oil & Gas Exploration & Production in Colombia
	583,000	Carrizo Oil & Gas (a)		20,108
		Oil & Gas Producer
	30,275,000	Petroamerica (Colombia) (a)(b)		18,574
		Oil Exploration & Production in Colombia
	37,500,000	Petromanas (Canada) (a)(b)(d)		14,599
	18,750,000	Petromanas - Warrants (Canada) (a)(b)(d)		2,218
		Exploring for Oil in Albania
	1,400,000	Gran Tierra Energy (Colombia) (a)		11,391
		Oil Exploration & Production in Colombia, Peru & Argentina
	275,000	Swift Energy (a)		10,766
		Oil & Gas Exploration & Production Co.
	6,300,000	Canacol Energy (Colombia) (a)(d)		9,749
		Oil Producer in South America
	250,000	Cabot Oil & Gas		9,462
		Large Natural Gas Producer in Appalachia & Gulf Coast
	17,100,000	Alange Energy (Colombia) (a)(c)		9,287
		Oil & Gas Exploration/Production in Colombia
	8,000,000	Petrolifera Petroleum (Colombia) (a)(b)(d)		4,889
	5,950,000	Petrolifera Petroleum (Colombia) (a)(b)		3,710
		Oil & Gas Exploration & Production in South America
	1,198,100	Pan Orient (Canada) (a)		8,013
		Growth Oriented & Return Focused Asian Explorer
	5,880,000	Canadian Overseas Petroleum - Subscription Receipts (United Kingdom) (a)(d)		4,926
	2,520,000	Canadian Overseas Petroleum (United Kingdom) (a)(d)		1,813
	1,260,000	Canadian Overseas Petroleum - Warrants (United Kingdom) (a)(d)		298
		Oil & Gas Exploration & Production in the North Sea

See accompanying notes to financial statements.

30

Number of Shares			Value (000)
		> Oil & Gas Producers—continued
	228,200	Oasis Petroleum (a)	$	6,189
		Oil Producer in North Dakota
	750,000	Vaalco Energy (a)		5,370
		Oil & Gas Producer
				752,664
		> Mining 1.9%
	2,250,000	Silver Wheaton (Canada) (a)		87,840
		Silver Mining Royalty Company
	641,000	Core Laboratories (Netherlands) (c)		57,081
		Oil & Gas Reservoir Consulting
	880,000	Pan American Silver (Canada)		36,265
		Silver Mining
	7,500,000	Zhaojin Mining Industry (China)		30,684
		Gold Mining & Refining in China
	10,000,000	Orko Silver (Canada) (a)(b)		28,160
		Silver Exploration & Development
	1,000,000	Ivanhoe Mines (Canada) (a)		23,132
	1,000,000	Ivanhoe Mines - Rights (Canada) (a)		1,348
		Copper Mine Project in Mongolia
	3,250,000	Northam Platinum (South Africa)		22,349
		Platinum Mining in South Africa
	400,000	Royal Gold		21,852
		Precious Metals Mining Royalty Company
	2,400,000	Alexco Resource (a)		19,656
		Mining, Exploration & Environmental Services
	3,154,000	Duluth Metals (Canada) (a)		9,199
		Copper & Nickel Miner
	5,215,500	Mongolian Mining (Hong Kong) (a)		6,086
		Coking Coal Mining in Mongolia
	236,400	Tahoe Resources (Canada) (a)(d)		3,425
		Silver Project in Guatemala
	800,000	Augusta Resource (a)(c)		3,048
		U.S. Copper/Molybdenum Mine
				350,125
		> Alternative Energy 0.2%
	3,000,000	GT Solar International (a)(c)		27,360
		Largest Manufacturer of Furnaces & Reactors to Produce & Cast Polysilicon
	500,000	STR Holdings (a)(c)		10,000
		Makes Encapsulant for Solar Power Modules/Provides Quality Assurance
	1,800,000	Synthesis Energy Systems (China) (a)		2,106
		Owner/Operator of Gasification Plants
				39,466
		> Oil Refining, Marketing & Distribution 0.2%
	600,000	Vopak (Netherlands)		28,343
		World's Largest Operator of Petroleum & Chemical Storage Terminals
				28,343
		> Agricultural Commodities 0.1%
	6,818,182	Union Agriculture Group (Argentina) (a)(d)		15,000
		Farmland Operator in Uruguay
				15,000
Energy & Minerals: Total				1,952,014

Number of Shares			Value (000)
Finance 10.0%
		> Banks 4.1%
	2,800,000	BOK Financial	$	149,520
		Tulsa-based Southwest Bank
	6,004,115	Valley National Bancorp		85,859
		New Jersey/New York Bank
	5,413,800	Associated Banc-Corp		82,019
		Midwest Bank
	1,260,000	SVB Financial Group (a)		66,843
		Bank to Venture Capitalists
	1,045,000	City National		64,121
		Bank & Asset Manager
	4,150,000	TCF Financial		61,461
		Great Lakes Bank
	4,000,000	Whitney Holding		56,600
		Gulf Coast Bank
	2,860,000	MB Financial (b)		49,535
		Chicago Bank
	3,640,000	CVB Financial (c)		31,559
		Inland Empire Business Bank
	1,350,000	TriCo Bancshares (b)		21,803
		California Central Valley Bank
	1,121,188	Sandy Spring Bancorp		20,663
		Baltimore/D.C. Bank
	772,632	Hudson Valley		19,130
		Metro New York City Bank
	3,299,507	First Busey		15,508
		Illinois Bank
	2,640,000	Wilmington Trust		11,458
		Delaware Trust Bank
	706,559	Eagle Bancorp (a)		10,196
		Metro D.C. Bank
	246,505	Pacific Continental		2,480
		Pacific Northwest Bank
	583,872	Green Bankshares (a)(c)		1,868
		Tennessee Bank
				750,623
		> Insurance 2.3%
	2,820,000	Leucadia National		82,288
		Insurance Holding Company
	9,400,000	CNO Financial Group (a)		63,732
		Life, Long-term Care & Medical Supplement Insurance
	1,320,000	Hanover Insurance Group		61,670
		Personal & Commercial Lines Insurance
	1,200,000	HCC Insurance Holdings		34,728
		Specialty Insurance
	1,225,000	Tower Group		31,336
		Commercial & Personal Lines Insurance
	1,000,000	Delphi Financial Group		28,840
		Workers Compensation & Group Employee Benefit Products & Services
	832,000	Willis Group (Ireland)		28,812
		Insurance Broker
	1,420,000	Selective Insurance Group		25,773
		Commercial & Personal Lines Insurance
	1,600,000	Symetra Financial		21,920
		Life Insurance

See accompanying notes to financial statements.

31

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Insurance—continued
	900,000	Brown & Brown	$	21,546
		Insurance Broker
	390,919	Aspen Insurance		11,188
		Commercial Lines Insurance/Reinsurance
	121,342	Assurant		4,674
		Specialty Insurance
				416,507
		> Finance Companies 1.8%
	1,505,202	World Acceptance (a)(b)		79,475
		Personal Loans
	2,350,000	McGrath Rentcorp (b)		61,617
		Temporary Space & IT Rentals
	1,480,000	GATX		52,214
		Rail Car Lessor
	2,532,500	Aaron Rents		51,638
		Rent to Own
	3,000,000	H&E Equipment Services (a)(b)		34,710
		Heavy Equipment Leasing
	1,650,000	CAI International (a)(b)		32,340
		International Container Leasing
	1,091,000	Marlin Business Services (a)(b)		13,801
		Small Equipment Leasing
	78,500	Textainer Group Holdings		2,237
		Top International Container Leasor
				328,032
		> Brokerage & Money Management 1.5%
	6,198,000	SEI Investments		147,450
		Mutual Fund Administration & Investment Management
	3,391,000	Eaton Vance		102,510
		Specialty Mutual Funds
	700,000	Investment Technology Group (a)		11,459
		Electronic Trading
	452,146	Kaiser Federal Financial Group		5,236
		Los Angeles Savings & Loan
				266,655
		> Savings & Loans 0.2%
	1,300,000	Housing Development Finance (India)		21,135
		Indian Mortgage Lender
	1,024,069	ViewPoint Financial		11,971
		Texas Thrift
	1,010,000	Provident New York Bancorp		10,595
		New York State Thrift
	65,991	Berkshire Hills Bancorp		1,458
		Northeast Thrift
				45,159
		> Credit Cards 0.1%
	140,000	Alliance Data Systems (a)		9,944
		Diversified Credit Card Provider
				9,944
Finance: Total				1,816,920
Health Care 9.1%
		> Biotechnology & Drug Delivery 3.4%
	3,920,421	BioMarin Pharmaceutical (a)		105,577
		Biotech Focused on Orphan Diseases

Number of Shares			Value (000)
	1,110,000	United Therapeutics (a)	$	70,174
		Biotech Focused on Rare Diseases
	4,180,918	Seattle Genetics (a)		62,505
		Antibody-based Therapies for Cancer
	4,500,000	Isis Pharmaceuticals (a)		45,540
		Biotech Pioneer in Anti-sense Drugs
	5,500,000	Micromet (a)(b)		44,660
		Next-generation Antibody Technology
	1,200,000	Onyx Pharmaceuticals (a)		44,244
		Commercial-stage Biotech Focused on Cancer
	1,088,500	InterMune (a)		39,621
		Drugs for Pulmonary Fibrosis & Hepatitis C
	2,700,000	Nektar Therapeutics (a)		34,695
		Drug Delivery Technologies
	7,035,000	Allos Therapeutics (a)(b)		32,431
		Cancer Drug Development
	3,449,900	Chelsea Therapeutics (a)(b)		25,874
		Biotech Focused on Rare Diseases
	1,200,000	Auxilium Pharmaceuticals (a)(c)		25,320
		Biotech Focused on Niche Disease Areas
	3,200,000	NPS Pharmaceuticals (a)		25,280
		Orphan Drugs & Healthy Royalties
	900,000	Acorda Therapeutics (a)		24,534
		Biopharma Company Focused on Nervous Disorder Drugs
	3,340,255	Idenix Pharmaceuticals (a)		16,835
		Developer of Drugs for Infectious Diseases
	3,500,000	Array Biopharma (a)(b)		10,465
		Drugs for Cancer & Inflammatory Diseases
	1,383,454	Nabi Biopharmaceuticals (a)		8,010
		Biotech Focused on Vaccines
	1,450,000	Anthera Pharmaceuticals (a)		7,076
		Biotech Focused on Cardiovascular, Cancer & Immunology
	359,944	MicroDose Technologies (a)(d)		94
		Drug Inhaler Development
	94,715	Locus Pharmaceuticals (a)(d)		9
		High Throughput Rational Drug Design
				622,944
		> Medical Equipment & Devices 3.4%
	2,100,000	Alexion Pharmaceuticals (a)		169,155
		Biotech Focused on Orphan Diseases
	1,000,000	Edwards Lifesciences (a)		80,840
		Heart Valves
	1,800,000	Sirona Dental Systems (a)		75,204
		Manufacturer of Dental Equipment
	1,065,000	Haemonetics (a)		67,287
		Blood & Plasma Collection Equipment
	3,150,000	American Medical Systems (a)		59,409
		Medical Devices to Treat Urological Conditions
	750,000	Gen-Probe (a)		43,762
		Molecular In-vitro Diagnostics
	500,000	Idexx Laboratories (a)(c)		34,610
		Diagnostic Equipment & Services for Veterinarians
	1,150,000	Orthofix International (a)(b)		33,350
		Bone Fixation & Stimulation Devices
	506,000	Illumina (a)		32,050
		Leading Tools & Service Provider for Genetic Analysis

See accompanying notes to financial statements.

32

Number of Shares			Value (000)
		> Medical Equipment & Devices—continued
	932,768	Pacific Biosciences of California (a)(c)	$	14,840
		Genome Sequencing
	1,480,056	Nanosphere (a)(b)		6,453
		Molecular Diagnostics Company with Best of Breed Platform
				616,960
		> Health Care Services 1.4%
	1,250,000	Mednax (a)		84,112
		Physician Management for Pediatric & Anesthesia Practices
	1,300,000	Community Health Systems (a)		48,581
		Non-urban Hospitals
	4,250,000	eResearch Technology (a)(b)		31,238
		Clinical Research Services
	400,000	HMS Holdings (a)		25,908
		Cost Containment Services
	2,650,000	Health Management Associates (a)		25,281
		Non-urban Hospitals
	500,000	AthenaHealth (a)(c)		20,490
		Revenue Cycle Management for Physician Offices
	700,000	Allscripts Healthcare Solutions (a)		13,489
		IT for Physician Offices & Hospitals
				249,099
		> Medical Supplies 0.8%
	2,415,000	Cepheid (a)		54,941
		Molecular Diagnostics
	650,000	Henry Schein (a)		39,904
		Largest Distributor of Healthcare Products
	1,100,000	Patterson Companies		33,693
		Dental, Veterinarian & Medical Distributor
	200,000	Owens & Minor		5,886
		Distribution of Medical Supplies
	77,602	Neogen (a)		3,184
		Food & Animal Safety Products
	42,278	ICU Medical (a)		1,543
		Intravenous Therapy Products
				139,151
		> Pharmaceuticals 0.1%
	2,659,068	Akorn (a)		16,141
		Develops, Manufactures & Sells Specialty Generic Drugs
	2,272,582	United Drug (Ireland)		6,377
		Irish Pharmaceutical Wholesaler & Outsourcer
	361,450	Alimera Sciences (a)(c)		3,752
		Ophthalmogy-focused Pharmaceutical Company
				26,270
Health Care: Total				1,654,424
Other Industries 5.1%
		> Real Estate 3.0%
	4,000,000	BioMed Realty Trust		74,600
		Life Science-focused Office Buildings
	641,165	Federal Realty Investment Trust		49,966
		Shopping Centers
	1,935,579	Dupont Fabros Technology (c)		41,170
		Technology-focused Office Buildings

Number of Shares			Value (000)
	1,120,000	Kilroy Realty	$	40,846
		Southern California Office & Industrial Properties
	720,000	Digital Realty Trust (c)		37,109
		Technology-focused Office Buildings
	2,200,000	Associated Estates Realty (b)		33,638
		Multi-family Properties
	43,201,999	Mapletree Logistics Trust (Singapore)		32,485
		Asian Logistics Landlord
	1,850,000	Extra Space Storage		32,190
		Self Storage Facilities
	900,000	Corporate Office Properties		31,455
		Office Buildings
	530,000	Macerich		25,106
		Regional Shopping Malls
	15,000,000	Ascendas REIT (Singapore)		24,194
		Singapore Industrial Property Landlord
	3,000,000	Education Realty Trust (b)		23,310
		Student Housing
	700,000	Washington REIT		21,693
		Washington D.C. Diversified Properties
	3,750,000	DCT Industrial Trust		19,912
		Industrial Properties
	2,800	Orix JREIT (Japan)		18,204
		Diversified REIT
	3,050,000	Kite Realty Group		16,501
		Community Shopping Centers
	367,240	Post Properties		13,331
		Multi-family Properties
	37,407	Security Capital European Realty (Luxembourg) (a)(d)(e)		—
		Self Storage Properties
				535,710
		> Transportation 1.2%
	1,850,000	JB Hunt Transport Services		75,498
		Truck & Intermodal Carrier
	2,800,000	Rush Enterprises, Class A (a)(b)		57,232
	550,000	Rush Enterprises, Class B (a)(b)		9,889
		Truck Sales & Services
	2,730,000	Heartland Express		43,735
		Regional Trucker
	1,110,000	World Fuel Services		40,138
		Global Fuel Broker
				226,492
		> Regulated Utilities 0.9%
	2,000,000	Northeast Utilities		63,760
		Regulated Electric Utility
	900,000	Wisconsin Energy		52,974
		Wisconsin Utility
	500,000	ALLETE		18,630
		Regulated Electric Utility in Minnesota
	333,000	Red Eléctrica de España (Spain)		15,657
		Spanish Power Transmission
	3,333,000	Terna (Italy)		14,079
		Italian Power Transmission
				165,100
Other Industries: Total				927,302
Total Equities: 97.2% (Cost: $11,026,459)				17,595,584

See accompanying notes to financial statements.

33

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares or Principal Amount (000)			Value (000)
Securities Lending Collateral – 2.1%
	375,541,061	Dreyfus Government Cash Management Fund (f) (7 day yield of 0.01%)	$	375,541
Total Securities Lending Collateral: (Cost: $375,541)				375,541
Short-Term Obligations: 2.9%
		>Repurchase Agreement 2.5%
$	453,434	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by U.S. Government Agency obligations with various maturities to 9/08/14, market value $462,507 (repurchase proceeds $453,440)		453,434
				453,434
		>Commercial Paper 0.4%
	50,000	Toyota Motor Credit 0.20% Due 1/21/11		49,995
	25,000	ConocoPhillips (g) 0.25% Due 1/07/11		24,999
				74,994
Total Short-Term Obligations: (Amortized Cost: $528,428)				528,428
Total Investments: 102.2% (Cost: $11,930,428)(h)(i)				18,499,553
Obligation to Return Collateral for Securities Loaned: (2.1)%				(375,541	)
Cash and Other Assets Less Liabilities: (0.1)%				(25,300	)
Total Net Assets: 100.0%			$	18,098,712

ADR = American Depositary Receipts

GDR = Global Depository Receipts

See accompanying notes to financial statements.

34

> Notes to Statement of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  An affiliated person of the Fund may include any company in which the Fund owns five percent or more of its outstanding voting shares. Holdings and transactions in these affiliated companies during the year ended December 31, 2010, are as follows:

Affiliates	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
Abercrombie & Fitch*		4,500,000		-		1,665,000		2,835,000	$	163,381	$	2,031
Actuate*		3,700,000		-		2,200,000		1,500,000		8,550		-
Administaff*		1,428,224		-		218,224		1,210,000		35,453		629
AFC Enterprises		2,000,000		-		-		2,000,000		27,800		-
Allos Therapeutics		2,800,000		4,235,000		-		7,035,000		32,431		-
AMAG Pharmaceuticals*		600,000		650,000		1,250,000		-		-		-
AmeriCredit*		7,235,000		250,000		7,485,000		-		-		-
AnnTaylor Stores*		3,500,000		-		3,500,000		-		-		-
Anthera Pharmaceuticals*		-		1,450,000		-		1,450,000		7,076		-
Array Biopharma		-		3,500,000		-		3,500,000		10,465		-
Art Technology Group		2,594,654		6,405,346		-		9,000,000		53,820		-
Associated Estates Realty		-		2,200,000		-		2,200,000		33,638		255
Bally Technologies		4,025,000		-		300,000		3,725,000		157,158		-
Blackbaud		1,800,000		450,000		-		2,250,000		58,275		990
CAI International		1,650,000		-		-		1,650,000		32,340		-
Cepheid*		2,500,000		1,065,000		1,150,000		2,415,000		54,941		-
Charming Shoppes*		7,500,000		2,300,000		9,800,000		-		-		-
Chattem*		1,010,000		-		1,010,000		-		-		-
Chelsea Therapeutics		-		3,449,900		-		3,449,900		25,874		-
Clarcor		2,627,500		-		62,500		2,565,000		110,013		1,020
Cogent Communications		4,200,000		-		1,400,000		2,800,000		39,592		-
Coldwater Creek*		-		4,950,442		3,565,845		1,384,597		4,389		-
Diamond Foods		550,475		749,525		-		1,300,000		69,134		143
Donaldson		4,200,000		-		-		4,200,000		244,776		2,079
Drew Industries		1,600,000		-		340,000		1,260,000		28,627		1,890
Education Realty Trust		-		3,000,000		-		3,000,000		23,310		370
eResearch Technology		4,250,000		-		-		4,250,000		31,238		-
ESCO Technologies		2,200,000		-		-		2,200,000		83,248		528
Gaiam		1,371,366		-		-		1,371,366		10,560		411
Gaylord Entertainment		3,700,000		1,189,500		1,039,500		3,850,000		138,369		-
H&E Equipment Services		3,300,000		-		300,000		3,000,000		34,710		-
Hackett Group		4,500,000		-		-		4,500,000		15,795		-
HEICO**		1,225,000		475,000		-		1,700,000		63,444		165
Helen of Troy		1,700,000		-		100,000		1,600,000		47,584		-
Herman Miller*		2,800,000		-		-		2,800,000		70,840		246
ICU Medical*		850,000		200,000		1,007,722		42,278		1,543		-
iGate		5,000,000		-		2,086,935		2,913,065		57,416		1,075
II-VI		2,400,000		-		175,000		2,225,000		103,151		-
Informatica		7,000,000		-		1,800,000		5,200,000		228,956		-
Interline Brands		2,600,000		-		-		2,600,000		59,202		-
IPG Photonics		2,750,000		435,000		475,000		2,710,000		85,690		-
IXYS		1,900,000		-		-		1,900,000		22,078		-
Kenexa		2,425,000		-		400,000		2,025,000		44,125		-
Knoll		4,000,000		-		-		4,000,000		66,920		480
Lifetime Fitness		2,150,000		230,000		190,000		2,190,000		89,768		-
lululemon athletica		4,200,000		485,000		650,000		4,035,000		276,075		-
Marlin Business Services		1,091,000		-		-		1,091,000		13,801		-
MB Financial		2,305,600		554,400		-		2,860,000		49,535		107
McGrath Rentcorp		2,350,000		-		-		2,350,000		61,617		2,103
Mediacom Communications*		4,000,000		-		4,000,000		-		-		-
Micromet		1,400,000		4,100,000		-		5,500,000		44,660		-
Mine Safety Appliances*		1,975,000		-		450,000		1,525,000		47,473		1,705
Nanosphere		1,232,900		267,100		19,944		1,480,056		6,453		-
Navigant Consulting		2,500,000		600,000		-		3,100,000		28,520		-
NPS Pharmaceuticals*		2,700,000		500,000		-		3,200,000		25,280		-
Orko Silver		10,000,000		-		-		10,000,000		28,160		-
Orthofix International		1,000,000		150,000		-		1,150,000		33,350		-
PAETEC Holding		9,600,000		-		-		9,600,000		35,904		-

See accompanying notes to financial statements.

35

Columbia Acorn Fund

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

Affiliates	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
Pericom Semiconductor		1,765,000		-		-		1,765,000	$	19,380	$	-
Petroamerica		-		30,275,000		-		30,275,000		18,574		-
Petrodorado***		48,000,000		-		-		48,000,000		26,933		-
Petrolifera Petroleum		264,000		13,686,000		-		13,950,000		8,599		-
Petromanas***		-		56,250,000		-		56,250,000		16,817		-
Pinnacle Entertainment		4,050,000		-		650,000		3,400,000		47,668		-
Princeton Review*		3,000,000		-		1,000,000		2,000,000		2,360		-
PSS World Medical*		2,750,000		550,000		3,300,000		-		-		-
Rush Enterprises		3,000,000		350,000		-		3,350,000		67,121		-
Salem Communications		1,541,000		-		-		1,541,000		4,885		308
Shutterfly		-		1,700,000		-		1,700,000		59,551		-
SkillSoft - ADR*		9,500,000		-		9,500,000		-		-		-
Spanish Broadcasting System		2,400,000		-		-		2,400,000		1,699		-
SPS Commerce		-		856,429		-		856,429		13,532		-
Supertex		1,035,000		-		-		1,035,000		25,026		-
Switch & Data Facilities*		2,500,000		-		2,500,000		-		-		-
Talbots		4,250,000		650,000		750,000		4,150,000		35,358		-
THQ		3,200,000		600,000		233,000		3,567,000		21,616		-
TriCo Bancshares		1,200,000		250,000		100,000		1,350,000		21,803		476
True Religion Apparel		1,500,000		975,000		428,000		2,047,000		45,566		-
Tuscany International Drilling***		-		28,048,000		14,728,800		13,319,200		15,124		-
tw telecom		9,500,000		-		-		9,500,000		161,975		-
Tyler Technologies		1,134,260		1,315,740		450,000		2,000,000		41,520		-
Universal Technical Institute		1,750,301		-		50,301		1,700,000		37,434		2,550
Vail Resorts*		1,950,000		-		700,000		1,250,000		65,050		-
Vermillion*		-		694,849		694,849		-		-		-
Virtusa		1,800,000		200,000		-		2,000,000		32,720		-
World Acceptance		1,545,000		-		39,798		1,505,202		79,475		-
Xenoport*		-		2,100,000		2,100,000		-		-		-
Total of Affiliated Transactions		268,131,280		182,342,231		131,865,418		366,608,093	$	3,996,294	$	19,561

*  At December 31, 2010, the Fund owned less than five percent of the company's outstanding voting shares.

**  Includes the effects of a 2:1 stock split.

***  Includes the effects of a corporate action.

  The aggregate cost and value of these affiliated companies at December 31, 2010, were $2,324,758 and $3,446,513, respectively. Investments in affiliated companies represented 19.0% of the Fund's total net assets at December 31, 2010.

(c)  All or a portion of this security was on loan at December 31, 2010. The total market value of Fund securities on loan at December 31, 2010 was $363,573.

(d)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the market value of these securities amounted to $116,054, which represented 0.64% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Petrodorado	11/20/09		24,000,000	$	5,049	$	16,795
Mail.ru - GDR	11/5/10-12/31/10		464,305		16,518		16,715
Union Agriculture Group	12/08/10		6,818,182		15,000		15,000
Tuscany International Drilling	2/12/10-3/23/10		10,719,200		12,997		14,791
Petromanas	5/20/10		37,500,000		13,032		14,599
Petrodorado - Warrants	11/20/09		24,000,000		2,965		10,138
Canacol Energy	4/15/10		6,300,000		4,667		9,749
Canadian Overseas Petroleum - Subscription Receipts	11/24/10		5,880,000		2,882		4,926
Petrolifera Petroleum	4/06/10		8,000,000		6,768		4,889
Tahoe Resources	5/28/10		236,400		1,350		3,425
Petromanas - Warrants	5/20/10		18,750,000		1,086		2,218
Canadian Overseas Petroleum	11/24/10		2,520,000		1,116		1,813
Tuscany International Drilling - Warrants	2/12/10		2,600,000		322		333
Canadian Overseas Petroleum - Warrants	11/24/10		1,260,000		119		298
Voyager Learning, Contingent Value Rights	12/24/09		2,000,000		-		262

See accompanying notes to financial statements.

36

> Notes to Statement of Investments (dollar values in thousands)

Security	Acquisition Dates	Shares		Cost		Value
MicroDose Technologies	11/24/00		359,944	$	2,005	$	94
Locus Pharmaceuticals	9/05/01-2/08/07		94,715		7,780		9
Security Capital European Realty	8/20/98-7/20/99		37,407		205		-
				$	93,861	$	116,054

(e)  Security has no value.

(f)  Investment made with cash collateral received from securities lending activity.

(g)  Security exempt from registration under Section 4(2) of the Securities Act of 1933. This security may only be resold in exempt transactions to qualified buyers. Private resales of this security to qualified institutional buyers are also exempt from registration pursuant to Rule 144A under the Securities Act of 1933. At December 31, 2010, this security had an aggregate value of $24,999, which represented 0.1% of total net assets.

(h)  At December 31, 2010, for federal income tax purposes, the cost of investments was $12,029,556 and net unrealized appreciation was $6,469,997, consisting of gross unrealized appreciation of $7,237,867 and gross unrealized depreciation of $767,870.

(i)  On December 31, 2010, the market value of foreign securities represented 12.61% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percentage of Net Assets
Netherlands	$	428,357		2.37
Canada		355,060		1.96
Colombia		266,338		1.47
Singapore		180,013		1.00
Sweden		126,861		0.70
Japan		113,304		0.63
Chile		102,235		0.57
Hong Kong		76,579		0.42
United Kingdom		76,385		0.42
France		71,831		0.40
China		67,421		0.37
Brazil		54,754		0.30
India		49,189		0.27
Denmark		47,377		0.26
	Value		Percentage of Net Assets
South Korea	$	37,514		0.21
Ireland		35,189		0.19
Iraq		30,091		0.17
Israel		27,920		0.15
Germany		22,848		0.13
South Africa		22,349		0.12
Switzerland		19,752		0.11
Russia		16,715		0.09
Spain		15,657		0.09
Argentina		15,000		0.08
Italy		14,079		0.08
Iceland		8,713		0.05
Luxembourg		-		-
Total Foreign Portfolio	$	2,281,531		12.61

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Information	$	4,618,335	$	247,495	$	-	$	4,865,830
Industrial Goods & Services		2,938,582		402,128		-		3,340,710
Consumer Goods & Services		2,857,927		180,195		262		3,038,384
Energy & Minerals		1,507,133		429,881		15,000		1,952,014
Finance		1,795,785		21,135		-		1,816,920
Health Care		1,647,944		6,377		103		1,654,424
Other Industries		822,683		104,619		-		927,302
Total Equities		16,188,389		1,391,830		15,365		17,595,584
Total Securities Lending Collateral		375,541		-		-		375,541
Total Short-Term Obligations		-		528,428		-		528,428
Total Investments	$	16,563,930	$	1,920,258	$	15,365	$	18,499,553

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sales price on the foreign exchange or market on which they trade. The Fund may use a systematic fair valuation model provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements. Securities acquired via private placement that have a holding period or an extended settlement period are valued at a discount to the same shares that are trading freely on the m arket. These discounts are determined by the adviser's experience with similar securities or situations. Factors may include, but are not limited to, trade volume, shares outstanding and stock price. Warrants which do not trade are valued as a percentage of the actively trading common stock using a model based on Black Scholes.

See accompanying notes to financial statements.

37

Columbia Acorn Fund

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities acquired via private placement that are not yet trading are valued using a market approach for which management has determined that the original transaction price is the best representation of fair value. The original cost may be adjusted for the market movement in an index, ETF or similar security during the period it does not trade. Securities for which no market exists are valued based upon a market approach using some unobservable inputs which may include, but are not limited to, projected earnings, available cash, line of business, multiples, and consideration of th e prioritization of the equity in a company's capital structure.

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

  The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Equities
Consumer Goods & Services	$	336	$	-	$	(74	)	$	-	$	-	$	-	$	-	$	262
Energy & Minerals		-		-		-			15,000		-		-		-		15,000
Health Care		176		-		(73	)		-		-		-		-		103
	$	512	$	-	$	(147	)	$	15,000	$	-	$	-	$	-	$	15,365

  The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  The change in unrealized depreciation attributed to securities owned at December 31, 2010, which were valued using significant unobservable inputs (Level 3) amounted to $147. This amount is included in net change in unrealized appreciation on the Statement of Changes in Net Assets.

  For more information on valuation inputs, and their aggregation into the levels used in the table above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

38

Columbia Acorn International

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Asia
> Japan
Asahi Diamond Industrial		511,700		1,000,000
Daiseki		787,200		1,181,200
Kansai Paint		7,140,000		7,556,000
Nippon Sheet Glass		1,860,000		7,174,000
Pigeon		397,500		439,800
Ushio		950,000		1,041,800
> China
51job - ADR		0		247,000
China Communication Services		30,000,000		45,000,000
China Xiniya Fashion - ADR		0		1,766,700
Noah Holdings - ADR		0		223,100
Zhaojin Mining Industry		13,930,000		16,138,000
> Singapore
Goodpack		9,540,600		11,000,000
> India
Infrastructure Development Finance		3,785,000		4,730,000
Jain Irrigation Systems		1,280,000		6,400,000
Manappuram General Finance		0		3,115,000
REI Agro		23,000,000		30,575,000
S. Kumars Nationwide		7,702,000		9,600,000
> Hong Kong
L'Occitane International		8,336,150		10,500,000
Melco Crown Entertainment - ADR		5,000,000		7,000,000
Mongolian Mining		0		23,335,500
Sa Sa International		0		23,470,900
> South Korea
NHN		280,000		304,000
Woongjin Coway		909,000		1,157,000
> Thailand
Home Product Center		0		31,101,200
Europe
> United Kingdom
Archipelago Resources		20,823,776		24,346,593
Chemring		890,000		964,000
FlyBe		0		1,731,900
JLT Group		0		1,426,274
Petropavlovsk		1,768,000		1,976,000
SKIL Ports & Logistics		0		1,650,000
Sterling Resources		0		1,549,500
Sterling Resources		0		1,050,500
Workspace Group		54,275,000		60,304,000
> Netherlands
Aalberts Industries		1,968,060		2,258,060

	Number of Shares
	09/30/10		12/31/10
Arcadis		1,120,284		1,164,669
USG People		916,600		1,264,600
> France
Gemalto		383,000		460,000
Neopost		470,000		590,000
Norbert Dentressangle		201,101		213,724
Toreador Resources		0		372,000
> Germany
Rheinmetall		0		365,000
> Sweden
Orc Software		0		708,342
> Italy
Tod's		340,000		452,200
> Portugal
Banco Comercial Português		16,574,000		21,618,000
> Iceland
Marel		34,999,999		35,369,999
> Russia
Mail.ru		0		833,742
Other Countries
> Canada
DeeThree Exploration		0		1,042,877
Ivanhoe Mines		0		744,000
Ivanhoe Mines - Rights		0		850,000
> United States
BioMarin Pharmaceutical		725,000		1,010,534
Onex Capital		0		187,600
> South Africa
Northam Platinum		4,541,900		5,780,900
> Senegal
Sonatel		33,000		43,000
> Egypt
Paints & Chemical Industries (Pachin)		96,872		220,342
Latin America
> Brazil
MRV Engenharia		3,000,000		3,300,000
Suzano		5,375,000		5,937,000
> Mexico
Grupo Aeroportuario del Sureste - ADR		533,400		550,000
> Argentia
Madalena Ventures		0		5,400,000
Union Agriculture Group		0		6,818,182

See accompanying notes to financial statements.

39

Columbia Acorn International

Major Portfolio Changes in the Fourth Quarter (Unaudited), continued

	Number of Shares
	09/30/10		12/31/10
Sales
Asia
> Japan
Point		406,030		0
Zenrin		294,100		0
> China
Shandong Weigao		13,626,200		12,277,200
> Singapore
CDL Hospitality Trust		24,136,100		23,000,000
Olam International		37,000,000		35,000,000
Singapore Exchange		5,000,000		4,000,000
> India
Educomp Solutions		1,148,000		0
Shriram Transport Finance		2,700,000		1,835,000
> Hong Kong
Hong Kong Exchanges and Clearing		1,900,000		750,000
> South Korea
MegaStudy		172,000		121,132
Mirae Asset Securities		376,000		0
Taewoong		179,000		64,008
> Taiwan
Everlight Electronics		14,000,000		7,206,000
Yuanta Financial Holdings		27,000,000		0
Europe
> United Kingdom
Micro Focus		4,025,000		2,195,200
N Brown Group		2,266,644		0
> Netherlands
QIAGEN		650,000		0
> Germany
Tognum		390,355		0
Wincor Nixdorf		145,321		0
> Italy
Terna		7,674,000		4,111,000
> Ireland
Paddy Power		575,000		431,000
Other Countries
> Canada
Horizon North Logistics		2,262,100		2,214,100
> United States
Alexion Pharmaceuticals		625,000		411,000
Hewlett Packard Co.		26,300,000		0
Oceaneering International		192,000		0
Ritchie Brothers Auctioneers		679,000		0

	Number of Shares
	09/30/10		12/31/10
> Australia
Billabong International		2,200,000		0
Hastie Group		11,236,457		6,152,918
Latin America
> Brazil
Localiza Rent A Car		4,900,000		4,600,000
> Mexico
Urbi Desarrollos Urbanos		6,837,700		0

See accompanying notes to financial statements.

40

Columbia Acorn International

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 93.7%
Asia 37.8%
		>Japan 16.4%
	7,556,000	Kansai Paint	$	73,107
		Paint Producer in Japan, India, China & Southeast Asia
	27,000	Advance Residence Investment (a)		60,432
		Residential REIT
	21,000	Seven Bank		44,459
		ATM Processing Services
	6,400	Orix JREIT		41,608
		Diversified REIT
	1,846,000	Aeon Delight		36,341
		Facility Maintenance & Management
	20,900	Wacom		33,205
		Computer Graphic Illustration Devices
	8,071	Start Today		32,246
		Online Japanese Apparel Retailer
	274,000	Nakanishi		29,012
		Dental Tools & Machinery
	3,283,000	Kamigumi		27,557
		Port Cargo Handling & Logistics
	3,400	Fukuoka		26,632
		Diversified REIT in Fukuoka
	710,000	Hamamatsu Photonics		25,937
		Optical Sensors for Medical & Industrial Applications
	5,100	Osaka Securities Exchange		25,714
		Osaka Securities Exchange
	789,000	Tsumura		25,539
		Traditional Chinese/Japanese Herbal Rx Drugs (Kampo)
	24,022	Jupiter Telecommunications		25,267
		Largest Cable Service Provider in Japan
	707,000	Ain Pharmaciez		24,862
		Dispensing Pharmacy/Drugstore Operator
	1,343,000	Hoshizaki Electric		24,858
		Commercial Kitchen Equipment
	868,000	Kintetsu World Express		24,814
		Airfreight Logistics
	1,181,200	Daiseki (b)		24,634
		Waste Disposal & Recycling
	1,905,500	Asics		24,479
		Footwear & Apparel
	906,000	Aeon Mall		24,310
		Suburban Shopping Mall Developer, Owner & Operator
	800,000	Olympus		24,191
		Medical Equipment (Endoscopes) & Cameras
	977,000	Glory		24,047
		Currency Handling Systems & Related Equipment
	711,000	Ibiden		22,405
		Electronic Parts & Ceramics
	509,000	Makita		20,810
		Power Tools
	972,500	Torishima Pump Manufacturing		20,511
		Industrial Pump for Power Generation & Water Supply Systems

Number of Shares			Value (000)
	1,595,000	Gree	$	20,277
		Mobile Social Networking Game Developer/ Platform
	1,041,800	Ushio		19,845
		Industrial Light Sources
	942,000	Tamron		19,606
		Camera Lens Maker
	7,174,000	Nippon Sheet Glass		19,346
		Sheet Glass for Building & Automotive Use
	1,000,000	Asahi Diamond Industrial		18,989
		Consumable Diamond Tools
	408,700	Benesse		18,821
		Education Service Provider
	675,780	Icom		18,514
		Two Way Radio Communication Equipment
	1,501,000	Rohto Pharmaceutical		17,539
		Health & Beauty Products
	2,870	Kakaku.com		17,067
		Online Price Comparison Services for Consumers
	1,750,000	Suruga Bank		16,286
		Regional Bank
	587,800	Miura		15,686
		Industrial Boiler Manufacturer
	1,000,000	Japan Airport Terminal		15,424
		Airport Terminal Operator at Haneda
	439,800	Pigeon		14,950
		Baby Care Products
	1,986	Mori Hills		7,680
		Tokyo Centric Diversified REIT
				1,007,007
		>China 6.4%
	16,138,000	Zhaojin Mining Industry		66,024
		Gold Mining & Refining in China
	36,700,000	Jiangsu Expressway		42,117
		Chinese Toll Road Operator
	12,199,600	China Yurun Food		40,337
		Meat Processor in China
	12,277,200	Shandong Weigao		34,749
		Vertically Integrated Hospital Consumable Manufacturing
	33,160,400	China Green		32,423
		Chinese Fruit & Vegetable Grower & Processor
	1,110,000	Mindray - ADR (b)		29,304
		Medical Device Manufacturer
	278,315	New Oriental Education & Technology - ADR (a)		29,287
		China's Largest Private Education Service Provider
	45,000,000	China Communication Services		26,805
		China's Telecom Infrastructure Service Provider
	240,000,000	RexLot Holdings		25,319
		Lottery Equipment Supplier in China
	29,425,300	Wasion Group		19,458
		Electronic Power Meter Total Solution Provider
	1,766,700	China Xiniya Fashion - ADR (a)(b)		16,183
		Men's Apparel Provider in China

See accompanying notes to financial statements.

41

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		>China—continued
	18,910,000	Sino Ocean Land	$	12,383
		Property Developer in China
	247,000	51job - ADR (a)		12,165
		Integrated Human Resources Service Provider
	223,100	Noah Holdings - ADR (a)(b)		4,361
		Wealth Management Product Distributor in China
	83,200	XueDa Education Group - ADR (a)		938
		Chinese Tutoring
	15,300,000	Fu Ji Food & Catering Services (a)(c)		79
		Food Catering Service Provider in China
				391,932
		>Singapore 4.6%
	35,000,000	Olam International		85,635
		Agriculture Supply Chain Manager
	66,000,000	Mapletree Logistics Trust		49,628
		Asian Logistics Landlord
	23,000,000	CDL Hospitality Trust		37,278
		Hotel Owner/Operator
	20,000,000	Ascendas REIT		32,259
		Singapore Industrial Property Landlord
	37,010,000	Mapletree Industrial Trust (a)		31,434
		Singapore Industrial REIT
	4,000,000	Singapore Exchange		26,244
		Singapore Equity & Derivatives Market Operator
	11,000,000	Goodpack		17,571
		International Bulk Container Leasing
				280,049
		>India 3.5%
	565,000	Asian Paints		36,454
		India's Largest Paint Company
	1,835,000	Shriram Transport Finance		32,215
		Truck Financing in India
	6,400,000	Jain Irrigation Systems		30,143
		Agricultural Micro-irrigation Systems & Food Processing
	4,730,000	Infrastructure Development Finance		19,363
		Infrastructure Finance in India
	30,575,000	REI Agro		18,633
		Basmati Rice Processing
	9,600,000	S. Kumars Nationwide (a)		18,582
		Textiles, Clothing & Retail
	1,100,000	Housing Development Finance		17,883
		Indian Mortgage Lender
	4,800,000	Mundra Port & Special Economic Zone		15,431
		Indian West Coast Shipping Port
	2,125,000	Patel Engineering		14,494
		Civil Engineering & Construction
	3,115,000	Manappuram General Finance		10,380
		Short-term Lending Collateralized by Household Gold
				213,578
		>Hong Kong 3.1%
	22,154,200	Lifestyle International		54,439
		Mid- to High-end Department Store Operator in Hong Kong & China

Number of Shares			Value (000)
	7,000,000	Melco Crown Entertainment - ADR (a)(b)	$	44,520
		Macau Casino Operator
	10,500,000	L'Occitane International (a)		29,044
		Skin Care & Cosmetics Producer
	23,335,500	Mongolian Mining (a)		27,230
		Coking Coal Mining in Mongolia
	750,000	Hong Kong Exchanges and Clearing		17,011
		Hong Kong Equity & Derivatives Market Operator
	23,470,900	Sa Sa International		14,615
		Chinese Discount Cosmetics Retailer
				186,859
		>South Korea 2.0%
	304,000	NHN (a)		60,662
		South Korea's Largest Online Search Engine
	1,157,000	Woongjin Coway		41,054
		South Korean Household Appliance Rental Service Provider
	121,132	MegaStudy (a)		18,805
		Online Education Service Provider
	64,008	Taewoong (a)		2,648
		Niche Custom Forging
				123,169
		>Taiwan 1.7%
	7,200,000	Simplo Technology		52,352
		World's Largest Notebook Battery Pack Supplier
	1,599,620	Formosa International Hotels		28,310
		Hotel, Food & Beverage Operation & Hospitality Management Services
	7,206,000	Everlight Electronics		20,859
		LED Packager
				101,521
		>Thailand 0.1%
	31,101,200	Home Product Center		9,079
		DIY Home Improvement Retailer
				9,079
Asia: Total				2,313,194
Europe 35.5%
		>United Kingdom 6.8%
	6,700,000	Serco		58,027
		Facilities Management
	2,000,000	Intertek Group		55,348
		Testing, Inspection & Certification Services
	964,000	Chemring		43,646
		Defense Manufacturer of Countermeasures & Energetics
	1,976,000	Petropavlovsk		35,244
		Gold & Iron Ore Mining in Russia
	8,873,000	Cobham		28,152
		Aerospace Components
	24,346,593	Archipelago Resources (a)		23,155
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
	60,304,000	Workspace Group (d)		22,095
		United Kingdom Real Estate

See accompanying notes to financial statements.

42

Number of Shares			Value (000)
		>United Kingdom—continued
	682,000	Rotork	$	19,437
		Valve Actuators for Oil & Water Pipelines
	4,600,000	RPS Group		16,524
		Environmental Consulting & Planning
	3,262,210	Abcam		16,276
		Online Sales of Antibodies
	1,426,274	JLT Group		13,987
		International Business Insurance Broker
	690,000	Tullow Oil		13,566
		Oil & Gas Producer
	2,195,200	Micro Focus		13,303
		United Kingdom Legacy Software Provider
	1,250,000	Smith & Nephew		13,184
		Medical Equipment & Supplies
	304,000	Premier Oil (a)		9,242
		Oil & Gas Producer in Europe, Pakistan & Asia
	3,500,000	PureCircle (a)(b)		9,031
		Natural Sweeteners
	1,731,900	FlyBe (a)		8,573
		Largest European Regional Airline
	1,650,000	SKIL Ports & Logistics (a)		6,316
		Indian Container Port Project
	1,549,500	Sterling Resources (a)		5,377
	1,050,500	Sterling Resources (a)(e)		3,572
		Oil & Gas Exploration - Europe
				414,055
		>Netherlands 6.5%
	1,922,517	Imtech		72,936
		Electromechanical & Information & Communications Technologies Installation & Maintenance
	763,202	Fugro		62,722
		Sub-sea Oilfield Services
	1,040,200	Vopak		49,137
		World's Largest Operator of Petroleum & Chemical Storage Terminals
	1,476,800	Unit 4 Agresso (d)		47,807
		Business Software Development
	2,258,060	Aalberts Industries		47,600
		Flow Control & Heat Treatment
	1,240,557	Koninklijke TenCate		46,417
		Advanced Textiles & Industrial Fabrics
	1,164,669	Arcadis		27,104
		Engineering Consultants
	1,264,600	USG People (a)		25,686
		Temporary Staffing Services
	206,000	Core Laboratories		18,344
		Oil & Gas Reservoir Consulting
				397,753
		>France 4.7%
	590,000	Neopost		51,405
		Postage Meter Machines
	599,200	Eurofins Scientific		43,158
		Food, Pharmaceuticals & Materials Screening & Testing
	900,000	Saft		33,134
		Niche Battery Manufacturer

Number of Shares			Value (000)
	274,100	Rubis (b)	$	31,921
		Tank Storage & Liquefied Petroleum Gas Distribution
	322,200	Pierre & Vacances		25,997
		Vacation Apartment Lets
	539,000	Mersen		24,705
		Advanced Industrial Materials
	669,000	Teleperformance		22,573
		Call Center Operator
	460,000	Gemalto		19,575
		Smart Card Products & Solutions
	213,724	Norbert Dentressangle		18,935
		Leading European Logistics & Transport Group
	1,671,100	Hi-Media (a)(b)		7,816
		Online Advertiser in Europe
	372,000	Toreador Resources (a)(b)		5,774
		Drilling for Oil in France's Paris Basin
				284,993
		>Germany 3.5%
	305,000	Vossloh		38,949
		Rail Infrastructure & Diesel Locomotives
	610,000	CTS Eventim		37,668
		Event Ticket Sales
	365,000	Rheinmetall		29,355
		Defense & Automotive
	2,120,000	Wirecard (b)		29,041
		Online Payment Processing & Risk Management
	1,250,000	Rhoen-Klinikum		27,517
		Health Care Services
	110,000	Rational		24,282
		Commercial Ovens
	515,000	Elringklinger		18,226
		Automobile Components
	312,500	Deutsche Beteiligungs		8,769
		Private Equity Investment Management
				213,807
		>Switzerland 3.1%
	325,000	Kuehne & Nagel		45,152
		Freight Forwarding/Logistics
	185,000	Geberit		42,778
		Plumbing Supplies
	185,000	Partners Group		35,110
		Private Markets Asset Management
	15,500	Sika		34,017
		Chemicals for Construction & Industrial Applications
	720,000	Bank Sarasin & Cie		32,809
		Private Banking
				189,866
		>Sweden 2.5%
	4,382,000	Hexagon		93,982
		Measurement Equipment & Software
	3,887,000	Sweco		33,663
		Engineering Consultants
	1,078,000	East Capital Explorer (a)		13,587
		Sweden-based Russia/Central Eastern Europe Investment Fund

See accompanying notes to financial statements.

43

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		>Sweden—continued
	708,342	Orc Software (b)	$	13,457
		Software for Securities Trading, Analysis & Risk Management
				154,689
		>Italy 2.2%
	452,200	Tod's		44,693
		Leather Shoes & Bags
	2,083,000	Ansaldo STS		29,826
		Railway Systems Integrator
	4,311,600	Credito Emiliano		26,677
		Italian Regional Bank
	9,796,000	CIR (a)		17,998
		Italian Holding Company
	4,111,000	Terna		17,365
		Italian Power Transmission
				136,559
		>Ireland 1.1%
	12,110,000	United Drug (d)		33,983
		Irish Pharmaceutical Wholesaler & Outsourcer
	431,000	Paddy Power		17,682
		Irish Betting Services
	297,000	Aryzta (a)		13,887
		Baked Goods
				65,552
		>Finland 0.9%
	967,777	Stockmann (b)		36,603
		Department Store & Fashion Retailer in Scandinavia & Russia
	1,756,000	Poyry		21,468
		Engineering Consultants
				58,071
		>Denmark 0.9%
	306,000	Novozymes		42,639
		Industrial Enzymes
	74,296	SimCorp		11,920
		Software for Investment Managers
				54,559
		>Portugal 0.7%
	7,235,000	Redes Energéticas Nacionais		24,944
		Portuguese Power Transmission & Gas Transportation
	21,618,000	Banco Comercial Português		16,813
		Largest Portuguese Banking Franchise
				41,757
		>Iceland 0.5%
	35,369,999	Marel (a)		30,817
		Largest Manufacturer of Poultry & Fish Processing Equipment
				30,817
		>Russia 0.5%
	833,742	Mail.ru - GDR (a)(e)		30,015
		Internet Social Networking & Games for Russian Speakers
				30,015

Number of Shares			Value (000)
		>Czech Republic 0.5%
	121,268	Komercni Banka	$	28,697
		Leading Czech Republic Universal Bank
				28,697
		>Spain 0.4%
	579,000	Red Eléctrica de España		27,223
		Spanish Power Transmission
				27,223
		>Greece 0.3%
	6,475,300	Intralot		21,546
		Lottery & Gaming Systems & Services
				21,546
		>Poland 0.3%
	893,900	Central European Distribution (a)		20,470
		Largest Spirits Company in Central & Eastern Europe
				20,470
		>Norway 0.1%
	340,964	Atea		3,431
		Leading Nordic IT Hardware/Software Re-seller & Installation Company
				3,431
Europe: Total				2,173,860
Other Countries 14.5%
		>Canada 4.8%
	1,710,000	ShawCor		56,943
		Oil & Gas Pipeline Products
	850,000	Ivanhoe Mines (a)		19,662
	744,000	Ivanhoe Mines (a)(b)(f)		17,052
	850,000	Ivanhoe Mines - Rights (a)		1,146
	744,000	Ivanhoe Mines - Rights (a)(f)		1,042
		Copper Mine Project in Mongolia
	1,301,612	CCL Industries		38,775
		Leading Global Label Manufacturer
	735,000	Baytex		34,455
		Oil & Gas Producer in Canada
	540,000	AG Growth		27,193
		Leading Manufacturer of Augers & Grain Handling Equipment
	1,355,000	Guyana Goldfields (a)(e)		14,509
		Gold Mining Projects in Guyana
	753,000	Eldorado Gold		14,010
		Gold Miner in Turkey, Greece, China & Brazil
	872,700	Tahoe Resources (a)(e)		12,644
		Silver Project in Guatemala
	530,000	Black Diamond Group		11,466
		Provides Accommodations/Equipment for Oil Sands Exploitation
	1,350,000	DeeThree Exploration (a)(d)(e)		5,721
	1,042,877	DeeThree Exploration (a)(d)		4,510
		Canadian Oil & Gas Producer
	1,480,610	Pan Orient (a)		9,902
		Growth Oriented & Return Focused Asian Explorer
	12,500,000	Eacom Timber (a)(e)		8,008
		Canadian Lumber Producer

See accompanying notes to financial statements.

44

Number of Shares			Value (000)
		>Canada—continued
	2,214,100	Horizon North Logistics (a)	$	6,614
		Provides Diversified Oil Service Offering in Northern Canada
	12,500,000	Petromanas (a)(e)		4,866
	6,250,000	Petromanas - Warrants (a)(e)		739
		Exploring for Oil in Albania
	3,730,000	Bowood Energy (a)(e)		2,206
		Small E&P Targeting Alberta Bakken
	49,900	WestFire Energy (a)		346
		Oil Producer in Alberta & Saskatchewan
				291,809
		>United States 3.6%
	1,340,000	Atwood Oceanics (a)		50,076
		Offshore Drilling Contractor
	918,000	World Fuel Services		33,195
		Global Fuel Broker
	411,000	Alexion Pharmaceuticals (a)		33,106
		Biotech Focused on Orphan Diseases
	329,000	FMC Technologies (a)		29,251
		Oil & Gas Wellhead Manufacturer
	1,010,534	BioMarin Pharmaceutical (a)		27,214
		Biotech Focused on Orphan Diseases
	391,000	Bristow (a)		18,514
		Largest Provider of Helicopter Services to Offshore Oil & Gas Producers
	568,000	Textainer Group Holdings		16,182
		Top International Container Leasor
	187,600	Onex Capital		5,704
		Private Equity Firm
	324,000	Tesco (a)		5,145
		Developing New Well Drilling Technologies
	15,600	Sodastream (a)		492
		Home Beverage Carbonation System
				218,879
		>South Africa 3.0%
	1,644,000	Naspers		96,818
		Media in Africa, China, Russia & Other Emerging Markets
	4,600,000	Mr. Price		46,437
		South African Retailer of Apparel, Household & Sporting Goods
	5,780,900	Northam Platinum		39,753
		Platinum Mining in South Africa
				183,008
		>Australia 1.8%
	2,482,000	UGL		36,632
		Engineering & Facilities Management
	7,189,283	SAI Global		35,883
		Publishing, Certification & Compliance Services
	319,000	Cochlear		26,236
		Cochlear Implants
	6,152,918	Hastie Group		6,010
		Mechanical, Electrical & Hydraulic (MEH) Engineering
	731,000	Seek		4,957
		Online Job Listing & Education
				109,718

Number of Shares			Value (000)
		>Israel 0.8%
	2,890,000	Israel Chemicals	$	49,562
		Producer of Potash, Phosphates, Bromine & Specialty Chemicals
				49,562
		>Kazakhstan 0.3%
	1,770,000	Halyk Savings Bank of Kazakhstan - GDR (a)		17,789
		Largest Retail Bank & Insurer in Kazakhstan
				17,789
		>Senegal 0.2%
	43,000	Sonatel		13,490
		Leading Telecoms Operator in Western Africa
				13,490
		>Egypt —%
	220,342	Paints & Chemical Industries (Pachin)		2,050
		Paints & Inks in Egypt
				2,050
Other Countries: Total				886,305
Latin America 5.9%
		>Brazil 4.3%
	4,600,000	Localiza Rent A Car		74,558
		Car Rental
	5,937,000	Suzano		52,859
		Brazilian Pulp & Paper Producer
	1,300,000	Natura		37,358
		Direct Retailer of Cosmetics
	3,000,000	Mills Estruturas e Serviços de Engenharia		37,228
		Civil Engineering & Construction
	3,300,000	MRV Engenharia		31,046
		Brazilian Low-income Property Developer
	5,000,000	PDG Realty		30,614
		Brazilian Low-income Property Developer
				263,663
		>Chile 0.8%
	862,000	Sociedad Quimica y Minera de Chile - ADR		50,358
		Producer of Specialty Fertilizers, Lithium & Iodine
				50,358
		>Mexico 0.5%
	550,000	Grupo Aeroportuario del Sureste - ADR		31,048
		Mexican Airport Operator
				31,048
		>Argentina 0.3%
	6,818,182	Union Agriculture Group (a)(e)		15,000
		Farmland Operator in Uruguay
	5,400,000	Madalena Ventures (a)(e)		4,364
		Oil & Gas Exploration in Argentina
				19,364
Latin America: Total				364,433
Total Equities: 93.7% (Cost: $3,933,559)				5,737,792

See accompanying notes to financial statements.

45

Columbia Acorn International

Statement of Investments, continued

Number of Shares or Principal Amount (000)			Value (000)
Securities Lending Collateral: 0.9%
	53,018,320	Dreyfus Government Cash Management Fund (g) (7 day yield of 0.01%)	$	53,018
Total Securities Lending Collateral: (Cost: $53,018)				53,018
Short-Term Obligations: 5.2%
		>Repurchase Agreement 4.4%
$	270,852	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by U.S. Government Agency obligations with various maturities to 4/28/14, market value $276,271 (repurchase proceeds $270,856)		270,852
				270,852
		>Commercial Paper 0.8%
	29,300	Toyota Motor Credit 0.20% due 1/21/11		29,297
	20,500	ConocoPhillips (h) 0.24% due 1/18/11		20,498
				49,795
Total Short-Term Obligations: (Amortized Cost: $320,647)				320,647
Total Investments: 99.8% (Cost: $4,307,224)(i)(j)				6,111,457
Obligation to Return Collateral for Securities Loaned: (0.9)%				(53,018	)
Cash and Other Assets Less Liabilities: 1.1%				66,624
Total Net Assets: 100.0%			$	6,125,063

ADR = American Depositary Receipts

GDR = Global Depositary Receipts

See accompanying notes to financial statements.

46

> Notes to Statements of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  All or a portion of this security was on loan at December 31, 2010. The total market value of Fund securities on loan at December 31, 2010 was $51,194.

(c)  Illiquid security.

(d)  An affiliated person of the Fund may include any company in which the Fund owns five percent or more of its outstanding voting shares.

  Holdings and transactions in these affiliated companies during the year ended December 31, 2010, are as follows:

Affiliates	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
DeeThree Exploration		-		2,392,877		-		2,392,877	$	10,231	$	-
Koninklijke TenCate*		1,372,989		40,382		172,814		1,240,557		46,417		1,119
Nippon Residential Investment*		12,500		-		12,500		-		-		1,155
Unit 4 Aggresso		1,385,000		91,800		-		1,476,800		47,807		296
United Drug		8,100,000		4,010,000		-		12,110,000		33,983		-
Workspace Group		-		60,304,000		-		60,304,000		22,095		-
Total of Affiliated Transactions		10,870,489		66,839,059		185,314		77,524,234	$	160,533	$	2,570

*  At December 31, 2010, the Fund owned less than five percent of the company's outstanding voting shares.

  The aggregate cost and value of these affiliated companies at December 31, 2010, was $97,243 and $114,116, respectively. Investments in affiliated companies represented 1.9% of total net assets at December 31, 2010.

(e)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the market value of these securities amounted to $101,644, which represented 1.66% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Mail.ru - GDR	11/05/10-12/31/10		833,742	$	28,667	$	30,015
Union Agriculture Group	12/08/10		6,818,182		15,000		15,000
Guyana Goldfields	1/19/10		1,355,000		9,134		14,509
Tahoe Resources	5/28/10		872,700		4,984		12,644
Eacom Timber	3/17/10		12,500,000		6,188		8,008
DeeThree Exploration	9/07/10		1,350,000		3,525		5,721
Petromanas	5/20/10		12,500,000		4,344		4,866
Madalena Ventures	10/21/10		5,400,000		3,422		4,364
Sterling Resources	12/02/10		1,050,500		3,135		3,572
Bowood Energy	9/17/10		3,730,000		907		2,206
Petromanas - Warrants	5/20/10		6,250,000		362		739
				$	79,668	$	101,644

(f)  Security is traded on a U.S. exchange.

(g)  Investment made with cash collateral received from securities lending activity.

(h)  Security exempt from registration under Section 4(2) of the Securities Act of 1933. This security may only be resold in exempt transactions to qualified buyers. Private resales of this security to qualified institutional buyers are also exempt from registration pursuant to Rule 144A under the Securities Act of 1933. At December 31, 2010, this security had an aggregate value of $20,498, which represented 0.3% of total net assets.

(i)  At December 31, 2010, for federal income tax purposes, the cost of investments was $4,448,614 and net unrealized apppreciation was $1,662,843, consisting of gross unrealized appreciation of $1,863,992 and gross unrealized depreciation of $201,149.

(j)  On December 31, 2010, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Euro	$	1,223,144		20.0
Japanese Yen		1,007,007		16.6
U.S. Dollar		930,489		15.2
Hong Kong Dollar		442,033		7.2
British Pound		405,106		6.6
Other currencies less than 5% of total net assets		2,103,678		34.2
	$	6,111,457		99.8

See accompanying notes to financial statements.

47

Columbia Acorn International

Statement of Investments, continued

> Notes to Statements of Investments (dollar values in thousands)

  At December 31, 2010, the Fund had entered into the following forward foreign currency exchange contracts:

Forward Foreign Currency Exchange Contracts to Buy	Forward Foreign Currency Exchange Contracts to Sell	Principal Amount in Foreign Currency		Principal Amount in U.S. Dollar		Settlement Date	Unrealized Appreciation
AUD	USD		27,790	$	27,300	1/14/11	$	1,092
AUD	USD		9,746		9,700	1/14/11		257
AUD	USD		27,911		27,300	2/15/11		1,103
AUD	USD		9,785		9,700	2/15/11		257
AUD	USD		37,457		37,000	3/15/11		981
CAD	USD		28,726		28,500	1/14/11		385
CAD	USD		7,555		7,500	1/14/11		96
CAD	USD		28,839		28,500	2/15/11		480
CAD	USD		7,560		7,500	2/15/11		97
CAD	USD		36,310		36,000	3/15/11		462
USD	EUR		49,199		69,100	1/14/11		3,356
USD	EUR		15,632		20,900	1/14/11		11
USD	EUR		50,409		69,100	2/15/11		1,746
USD	EUR		15,634		20,900	2/15/11		10
USD	EUR		67,339		90,000	3/15/11		37
JPY	USD		1,082,620		13,300	1/14/11		36
JPY	USD		308,887		3,700	1/14/11		105
JPY	USD		1,094,723		13,300	2/15/11		189
JPY	USD		308,780		3,700	2/15/11		105
JPY	USD		1,418,327		17,000	3/15/11		482
				$	540,000		$	11,287

The counterparty for all forward foreign currency exchange contracts is State Street Bank and Trust Company.

AUD = Australian Dollar

CAD = Canadian Dollar

EUR = Euro

JPY = Japanese Yen

USD = United States Dollar

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Asia	$	136,758	$	2,176,357	$	79	$	2,313,194
Europe		79,980		2,093,880		-		2,173,860
Other Countries		461,995		424,310		-		886,305
Latin America		81,406		268,027		15,000		364,433
Total Equities		760,139		4,962,574		15,079		5,737,792
Total Securities Lending Collateral		53,018		-		-		53,018
Total Short-Term Obligations		-		320,647		-		320,647
Total Investments	$	813,157	$	5,283,221	$	15,079	$	6,111,457
Unrealized Appreciation on Forward Foreign Currency Exchange Contracts		-		11,287		-		11,287
Total	$	813,157	$	5,294,508	$	15,079	$	6,122,744

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sales price on the foreign exchange or market on which they trade. The Fund may use a systematic fair valuation model provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements. Forward foreign currency exchange contracts are valued at the prevailing forward exchange rate of the underlying currencies. Securities acquired via private placement that have a holding period or an extended settlement period are valued at a discount to the same shares that are trading freely on the market. These discounts are determined by the adviser's experience with similar securities or situations. Factors may include, but are not limited to, trade volume, shares outstanding and stock price.

See accompanying notes to financial statements.

48

> Notes to Statements of Investments (dollar values in thousands)

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities for which no market exists are valued based upon a market approach using some unobservable inputs which may include, but are not limited to, projected earnings, available cash, line of business, multiples, and consideration of the prioritization of the equity in a company's capital structure. Securities acquired via private placement that are not yet trading are valued using a market approach for which management has determined that the original transaction price is the best representation of fair value. The original cost may be adjusted for the market movement in an ind ex, ETF or similar security during the period it does not trade.

  The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Equities
Asia	$	158	$	-	$	(79	)	$	-	$	-	$	-	$	-	$	79
Latin America		-		-		-			15,000		-		-		-		15,000
	$	158	$	-	$	(79	)	$	15,000	$	-	$	-	$	-	$	15,079

  The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  The change in unrealized depreciation attributed to securities owned at December 31, 2010, which were valued using significant unobservable inputs (Level 3) amounted to $79. This amount is included in net change in unrealized appreciation (depreciation) on the Statements of Changes in Net Assets.

  The following table shows transfers between Level 1 and Level 2 of the fair value hierarchy.

Transfers In				Transfers Out
Level 1		Level 2		Level 1		Level 2
$	152,770	$	-	$	-	$	152,770

  Financial assets were transferred from Level 2 to Level 1 as they resumed trading during the period.

  For more information on valuation inputs, and their aggregation into the levels used in the tables above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

49

Columbia Acorn International

Portfolio Diversification

At December 31, 2010, the Fund's portfolio investments as a percent of net assets were diversified as follows:

	Value (000)		Percentage of Net Assets
> Industrial Goods & Services
Other Industrial Services	$	514,717		8.4
Machinery		398,588		6.5
Industrial Materials & Specialty Chemicals		396,880		6.5
Electrical Components		147,183		2.4
Construction		94,501		1.5
Outsourcing Services		83,714		1.4
Conglomerates		65,598		1.1
Industrial Distribution		17,571		0.3
		1,718,752		28.1
> Consumer Goods & Services
Food & Beverage		220,988		3.6
Nondurables		182,357		2.9
Retail		151,549		2.5
Travel		109,128		1.8
Casinos & Gaming		109,066		1.8
Other Consumer Services		107,658		1.8
Apparel		95,846		1.6
Educational Services		67,851		1.1
Other Entertainment		65,977		1.1
Consumer Electronics		19,606		0.3
		1,130,026		18.5
> Energy & Minerals
Mining		289,815		4.7
Oil Services		240,730		3.9
Oil & Gas Producers		104,641		1.7
Oil Refining, Marketing & Distribution		81,059		1.4
Agricultural Commodities		75,867		1.2
		792,112		12.9
> Information
Internet Related		209,518		3.4
Instrumentation		119,919		2.0
Computer Hardware & Related Equipment		105,132		1.7
Business Software		73,030		1.2
Financial Processors		72,296		1.2
Telephone and Data Services		36,063		0.6
Telecommunications Equipment		26,805		0.5
CATV		25,267		0.4
Semiconductors & Related Equipment		20,859		0.3
Gaming Equipment & Services		20,277		0.3
Mobile Communications		18,514		0.3
Computer Services		16,888		0.3
Business Information & Marketing Services		16,524		0.3
Advertising		7,816		0.1
		768,908		12.6

	Value (000)			Percentage of Net Assets
> Other Industries
Real Estate	$	383,090			6.2
Regulated Utilities		69,532			1.1
Transportation		168,276			2.8
		620,898			10.1
> Finance
Banks		170,084			2.8
Finance Companies		94,556			1.5
Brokerage & Money Management		90,275			1.5
Savings & Loans		17,883			0.3
Insurance		13,987			0.2
		386,785			6.3
> Health Care
Medical Equipment & Devices		189,782			3.1
Pharmaceuticals		59,522			1.0
Health Care Services		27,517			0.4
Biotechnology & Drug Delivery		27,214			0.4
Medical Supplies		16,276			0.3
		320,311			5.2
Total Equities:		5,737,792			93.7
Securities Lending Collateral:		53,018			0.9
Short-Term Obligations:		320,647			5.2
Total Investments:		6,111,457			99.8
Obligation to Return Collateral for Securities Loaned:		(53,018	)		(0.9	)
Cash and Other Assets Less Liabilities:		66,624			1.1
Net Assets:	$	6,125,063			100.0

See accompanying notes to financial statements.

50

Columbia Acorn USA

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Information
Applied Micro Circuits		0		448,000
Ariba		0		278,000
Concur Technologies		142,000		171,000
ExlService Holdings		310,000		372,800
Finisar		526,000		732,000
Infinera		114,000		402,000
Ixia		199,200		234,000
SPS Commerce		0		322,000
WMS Industries		73,000		150,000
Consumer Goods & Services
Avis Budget Group		717,950		1,175,950
Deckers Outdoor		0		40,000
Diamond Foods		162,000		197,000
Pier 1 Imports		540,000		805,000
Shutterfly		145,600		254,000
Warnaco Group		60,000		192,000
Industrial Goods & Services
Forward Air		66,350		109,000
HEICO		217,732		308,732
St. Joe		0		284,000
Finance
Associated Banc-Corp		453,400		692,400
First Busey		678,200		1,478,200
Textainer Group Holdings		0		165,000
Tower Group		120,000		222,000
Energy & Minerals
Houston American Energy		0		260,438
Swift Energy		0		84,000
Health Care
Akorn		137,682		481,782
BioMarin Pharmaceutical		266,000		344,394
Chelsea Therapeutics		460,728		600,000
Health Management Associates		0		653,900
Idenix Pharmaceuticals		450,000		530,282
InterMune		0		92,400
Isis Pharmaceuticals		437,000		626,000
Micromet		540,000		810,000
Nabi Biopharmaceuticals		0		191,040
Onyx Pharmaceuticals		117,000		190,000
Pacific Biosciences of California		0		95,200
Sirona Dental Systems		80,000		184,000
United Therapeutics		100,000		137,000
Other Industries
Associated Estates Realty		186,000		405,000
Rush Enterprises, Class A		180,000		210,091

	Number of Shares
	09/30/10		12/31/10
Sales
Information
Actuate		230,000		0
Art Technology Group		959,000		0
Avid Technology		100,000		0
Crown Castle International		383,000		250,000
Entegris		750,000		675,000
Equinix	��	79,188		44,000
Consumer Goods & Services
Charming Shoppes		670,861		0
Coldwater Creek		455,956		145,376
Dress Barn		90,000		0
J Crew Group		241,000		0
Jones Apparel Group		281,000		0
Finance
Delphi Financial Group		110,000		0
Green Bankshares		264,703		247,500
H&E Equipment Services		542,600		201,000
Health Care
Acorda Therapeutics		196,000		122,900
Amylin Pharmaceuticals		145,000		0
Human Genome Sciences		59,000		0
Nektar Therapeutics		431,000		363,000
Orthofix International		165,000		0
PSS World Medical		467,300		0
Other Industries
Macerich		212,619		98,619
SL Green Realty		359,000		0

See accompanying notes to financial statements.

51

Columbia Acorn USA

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 99.6%
Information 33.5%
		> Business Software 8.7%
	985,000	Informatica (a)	$	43,370
		Enterprise Data Integration Software
	698,000	Micros Systems (a)		30,614
		Information Systems for Hotels, Restaurants & Retailers
	375,000	ANSYS (a)		19,526
		Simulation Software for Engineers & Designers
	370,000	Blackbaud		9,583
		Software & Services for Non-profits
	171,000	Concur Technologies (a)		8,880
		Web Enabled Cost & Expense Management Software
	278,000	Ariba (a)		6,530
		Cost Management Software
	110,000	Advent Software (a)		6,371
		Asset Management & Trading Systems
	135,000	Blackboard (a)(b)		5,575
		Education Software
	322,000	SPS Commerce (a)		5,088
		Supply Chain Management Software Delivered via the Web
	157,000	Jack Henry & Associates		4,577
		Systems Financial Institutions
	132,000	Constant Contact (a)		4,091
		E-mail & Other Marketing Campaign Management Systems Delivered Over the Web
	52,000	Quality Systems		3,631
		IT Systems for Medical Groups & Ambulatory Care Centers
				147,836
		> Semiconductors & Related Equipment 4.7%
	1,958,000	Atmel (a)		24,123
		Microcontrollers, Radio Frequency & Memory Semiconductors
	760,000	Microsemi (a)		17,404
		Analog/Mixed-signal Semiconductors
	1,061,750	ON Semiconductor (a)		10,490
		Mixed-signal & Power Management Semiconductors
	287,000	Supertex (a)		6,940
		Analog/Mixed-signal Semiconductors
	346,000	Monolithic Power Systems (a)		5,716
		High Performance Analog & Mixed-signal Integrated Circuits (ICs)
	675,000	Entegris (a)		5,042
		Semiconductor Materials Management Products
	448,000	Applied Micro Circuits (a)		4,785
		Communications Semiconductors
	430,000	Pericom Semiconductor (a)		4,721
		Interface Integrated Circuits (ICs) & Frequency Control Products
				79,221
		> Computer Hardware & Related Equipment 4.1%
	549,000	II-VI (a)		25,452
		Laser Optics & Specialty Materials

Number of Shares			Value (000)
	285,600	Amphenol	$	15,074
		Electronic Connectors
	324,000	Zebra Technologies (a)		12,309
		Bar Code Printers
	280,000	Nice Systems - ADR (Israel) (a)		9,772
		Audio & Video Recording Solutions
	196,000	Netgear (a)		6,601
		Networking Products for Small Business & Home
				69,208
		> Instrumentation 3.3%
	180,000	Mettler Toledo (a)		27,218
		Laboratory Equipment
	575,000	IPG Photonics (a)		18,181
		Fiber Lasers
	168,000	Trimble Navigation (a)		6,708
		GPS-based Instruments
	130,000	FLIR Systems (a)		3,868
		Infrared Cameras
				55,975
		> Telecommunications Equipment 3.0%
	732,000	Finisar (a)		21,733
		Optical Sub-systems & Components
	386,000	Polycom (a)		15,046
		Video Conferencing Equipment
	197,000	Blue Coat Systems (a)		5,884
		WAN Acceleration & Network Security
	402,000	Infinera (a)		4,153
		Optical Networking Equipment
	234,000	Ixia (a)		3,927
		Telecom Network Test Equipment
				50,743
		> Telephone and Data Services 2.7%
	1,617,000	tw telecom (a)		27,570
		Fiber Optic Telephone/Data Services
	177,000	AboveNet		10,347
		Metropolitan Fiber Communications Services
	2,030,000	PAETEC Holding (a)		7,592
		Telephone/Data Services for Business
				45,509
		> Mobile Communications 2.1%
	595,000	SBA Communications (a)		24,359
		Communications Towers
	250,000	Crown Castle International (a)		10,957
		Communications Towers
	88,000	Globalstar (a)		128
		Satellite Mobile Voice & Data Carrier
				35,444
		> Gaming Equipment & Services 1.8%
	570,000	Bally Technologies (a)		24,048
		Slot Machines & Software
	150,000	WMS Industries (a)		6,786
		Slot Machine Provider
				30,834
		> Computer Services 1.6%
	372,800	ExlService Holdings (a)		8,008
		BPO (Business Process Outsourcing)

See accompanying notes to financial statements.

52

Number of Shares			Value (000)
		> Computer Services—continued
	261,000	SRA International (a)	$	5,338
		Government IT Services
	235,000	iGate		4,632
		IT & BPO (Business Process Outsourcing) Services
	1,005,500	Hackett Group (a)		3,529
		IT Integration & Best Practice Research
	710,000	RCM Technologies (a)(c)		3,294
		Technology & Engineering Services
	172,000	Acxiom (a)		2,950
		Database Marketing Services
				27,751
		> Financial Processors 0.5%
	188,000	Global Payments		8,687
		Credit Card Processor
				8,687
		> Contract Manufacturing 0.5%
	261,000	Plexus (a)		8,075
		Electronic Manufacturing Services
				8,075
		> Internet Related 0.3%
	44,000	Equinix (a)		3,575
		Network Neutral Data Centers
	343,000	TheStreet.com		916
		Financial Information Websites
				4,491
		> Radio 0.1%
	511,100	Salem Communications		1,620
		Radio Stations for Religious Programming
	705,500	Spanish Broadcasting System (a)		499
		Spanish Language Radio Stations
	18,750	Saga Communications (a)		494
		Radio Stations in Small & Mid-sized Cities
				2,613
		> TV Broadcasting 0.1%
	975,000	Entravision Communications (a)		2,506
		Spanish Language TV & Radio Stations
				2,506
Information: Total				568,893
Consumer Goods & Services 17.5%
		> Retail 5.9%
	390,000	lululemon athletica (a)(b)		26,684
		Premium Active Apparel Retailer
	401,000	Abercrombie & Fitch		23,110
		Teen Apparel Retailer
	875,000	Saks (a)		9,362
		Luxury Department Store Retailer
	254,000	Shutterfly (a)		8,898
		Internet Photo-centric Retailer
	805,000	Pier 1 Imports (a)		8,452
		Home Furnishing Retailer
	614,000	Chico's FAS		7,386
		Women's Specialty Retailer

Number of Shares			Value (000)
	205,000	Urban Outfitters (a)	$	7,341
		Apparel & Home Specialty Retailer
	480,000	Talbots (a)		4,090
		Women's Specialty Retailer
	620,000	Wet Seal (a)		2,294
		Specialty Apparel Retailer
	104,508	Express		1,965
		Dual Gender Fashion Retailer
	145,376	Coldwater Creek (a)		461
		Women's Apparel Retailer
	9,000	The Fresh Market (a)		371
		Specialty Food Retailer
				100,414
		> Travel 3.8%
	739,700	Gaylord Entertainment (a)		26,585
		Convention Hotels
	1,175,950	Avis Budget Group (a)		18,298
		Second Largest Car Rental Company
	750,000	Hertz (a)		10,867
		Largest U.S. Rental Car Operator
	150,000	Vail Resorts (a)		7,806
		Ski Resort Operator & Developer
				63,556
		> Furniture & Textiles 1.9%
	980,000	Knoll		16,395
		Office Furniture
	540,000	Interface		8,451
		Modular & Broadloom Carpet
	260,000	Herman Miller		6,578
		Office Furniture
				31,424
		> Casinos & Gaming 1.2%
	372,000	Penn National Gaming (a)		13,076
		Regional Casino Operator
	455,000	Pinnacle Entertainment (a)		6,379
		Regional Casino Operator
				19,455
		> Apparel 1.1%
	192,000	Warnaco Group (a)		10,573
		Global Branded Apparel Manufacturer
	241,530	True Religion Apparel (a)		5,377
		Premium Denim
	40,000	Deckers Outdoor (a)		3,190
		Fashion Footwear Wholesaler
				19,140
		> Educational Services 0.8%
	153,700	ITT Educational Services (a)		9,789
		Post-secondary Degree Services
	165,000	Universal Technical Institute		3,633
		Vocational Training
				13,422
		> Other Durable Goods 0.7%
	161,000	Cavco Industries (a)		7,517
		Manufactured Homes
	140,000	Jarden		4,322
		Branded Household Products
				11,839

See accompanying notes to financial statements.

53

Columbia Acorn USA

Statement of Investments, continued

Number of Shares			Value (000)
		> Consumer Goods Distribution 0.6%
	472,000	Pool	$	10,639
		Distributor of Swimming Pool Supplies & Equipment
				10,639
		> Other Consumer Services 0.6%
	259,000	Lifetime Fitness (a)		10,616
		Sport & Fitness Club Operator
				10,616
		> Food & Beverage 0.6%
	197,000	Diamond Foods		10,476
		Culinary Ingredients & Snack Foods
				10,476
		> Leisure Products 0.3%
	162,000	Thor Industries		5,502
		RV & Bus Manufacturer
				5,502
		> Restaurants —%
	26,600	Bravo Brio Restaurant Group (a)		510
		Upscale Casual Italian Restaurants
				510
Consumer Goods & Services: Total				296,993
Industrial Goods & Services 15.2%
		> Machinery 10.9%
	941,250	Ametek		36,944
		Aerospace/Industrial Instruments
	373,600	Nordson		34,326
		Dispensing Systems for Adhesives & Coatings
	445,000	Donaldson		25,935
		Industrial Air Filtration
	587,000	ESCO Technologies		22,212
		Automatic Electric Meter Readers
	585,000	Pentair		21,358
		Pumps & Water Treatment
	308,732	HEICO		11,522
		FAA Approved Aircraft Replacement Parts
	195,000	MOOG (a)		7,761
		Motion Control Products for Aerospace, Defense & Industrial Markets
	177,000	Kennametal		6,985
		Consumable Cutting Tools
	111,000	WABCO Holdings (a)		6,763
		Truck & Bus Component Supplier
	162,000	Oshkosh (a)		5,709
		Specialty Truck Manufacturer
	71,800	Toro		4,426
		Turf Maintenance Equipment
	50,000	Kaydon		2,036
		Specialized Friction & Motion Control Products
				185,977
		> Electrical Components 1.0%
	280,000	Acuity Brands		16,148
		Commercial Lighting Fixtures
				16,148

Number of Shares			Value (000)
		> Industrial Materials & Specialty Chemicals 0.8%
	326,000	Drew Industries	$	7,407
		RV & Manufactured Home Components
	135,000	Albany International		3,198
		Paper Machine Clothing & Advanced Textiles
	54,000	Albemarle		3,012
		Refinery Catalysts & Other Specialty Chemicals
				13,617
		> Other Industrial Services 0.6%
	265,000	TrueBlue (a)		4,767
		Temporary Manual Labor
	109,000	Forward Air		3,093
		Freight Transportation Between Airports
	396,000	American Reprographics (a)		3,006
		Document Management & Logistics
				10,866
		> Steel 0.6%
	486,000	GrafTech International (a)		9,642
		Industrial Graphite Materials Producer
				9,642
		> Industrial Distribution 0.5%
	350,000	Interline Brands (a)		7,970
		Industrial Distribution
				7,970
		> Construction 0.4%
	284,000	St. Joe (a)(b)		6,205
		Florida Panhandle Landowner
				6,205
		> Waste Management 0.3%
	195,000	Waste Connections		5,368
		Solid Waste Management
				5,368
		> Water 0.1%
	550,000	Mueller Water Products		2,294
		Fire Hydrants, Valves & Ductile Iron Pipes
				2,294
Industrial Goods & Services: Total				258,087
Finance 11.0%
		> Banks 5.6%
	981,941	Valley National Bancorp		14,042
		New Jersey/New York Bank
	692,400	Associated Banc-Corp		10,490
		Midwest Bank
	659,800	TCF Financial		9,772
		Great Lakes Bank
	431,597	Lakeland Financial		9,262
		Indiana Bank
	532,000	MB Financial		9,214
		Chicago Bank
	170,000	SVB Financial Group (a)		9,018
		Bank to Venture Capitalists
	571,000	Whitney Holding		8,080
		Gulf Coast Bank

See accompanying notes to financial statements.

54

Number of Shares			Value (000)
		> Banks—continued
	1,478,200	First Busey	$	6,948
		Illinois Bank
	527,700	Pacific Continental		5,309
		Pacific Northwest Bank
	269,600	Eagle Bancorp (a)		3,890
		Metro D.C. Bank
	178,826	Sandy Spring Bancorp		3,296
		Baltimore/D.C. Bank
	210,000	CVB Financial (b)		1,821
		Inland Empire Business Bank
	90,000	TriCo Bancshares		1,453
		California Central Valley Bank
	851,247	Guaranty Bancorp (a)		1,200
		Colorado Bank
	245,000	Wilmington Trust		1,063
		Delaware Trust Bank
	247,500	Green Bankshares (a)(b)		792
		Tennessee Bank
				95,650
		> Finance Companies 3.3%
	345,000	World Acceptance (a)		18,216
		Personal Loans
	335,418	McGrath Rentcorp		8,795
		Temporary Space & IT Rentals
	240,000	GATX		8,467
		Rail Car Lessor
	412,500	Aaron Rents		8,411
		Rent to Own
	165,000	Textainer Group Holdings		4,701
		Top International Container Leasor
	230,000	CAI International (a)		4,508
		International Container Leasing
	201,000	H&E Equipment Services (a)		2,325
		Heavy Equipment Leasing
	99,200	Marlin Business Services (a)		1,255
		Small Equipment Leasing
				56,678
		> Brokerage & Money Management 1.0%
	209,500	Eaton Vance		6,333
		Specialty Mutual Funds
	675,000	MF Global (a)		5,643
		Futures Broker
	140,000	Investment Technology Group (a)		2,292
		Electronic Trading
	173,073	Kaiser Federal Financial Group		2,004
		Los Angeles Savings & Loan
				16,272
		> Savings & Loans 0.8%
	756,000	ViewPoint Financial		8,838
		Texas Thrift
	215,000	Berkshire Hills Bancorp		4,751
		Northeast Thrift
				13,589

Number of Shares			Value (000)
		> Insurance 0.3%
	222,000	Tower Group	$	5,679
		Commercial & Personal Lines Insurance
				5,679
Finance: Total				187,868
Energy & Minerals 8.5%
		> Oil Services 4.8%
	500,000	FMC Technologies (a)		44,455
		Oil & Gas Wellhead Manufacturer
	755,000	Atwood Oceanics (a)		28,215
		Offshore Drilling Contractor
	95,000	Bristow (a)		4,498
		Largest Provider of Helicopter Services to Offshore Oil & Gas Producers
	104,000	Exterran Holdings (a)		2,491
		Natural Gas Compressor Rental & Fabrication
	106,000	Tesco (a)		1,683
		Developing New Well Drilling Technologies
				81,342
		> Oil & Gas Producers 2.9%
	1,135,000	Quicksilver Resources (a)		16,730
		Natural Gas & Coal Steam Gas Producer
	133,000	SM Energy		7,838
		Oil & Gas Producer
	230,000	Northern Oil & Gas (a)		6,258
		Small E&P Company in North Dakota Bakken
	162,000	Carrizo Oil & Gas (a)		5,587
		Oil & Gas Producer
	129,000	Rosetta Resources (a)		4,856
		Oil & Gas Producer Exploring in South Texas & Montana
	260,438	Houston American Energy (b)		4,711
		Oil & Gas Exploration & Production in Colombia
	84,000	Swift Energy (a)		3,289
		Oil & Gas Exploration & Production Co.
	22,800	Oasis Petroleum (a)		618
		Oil Producer in North Dakota
				49,887
		> Mining 0.8%
	100,000	Core Laboratories (Netherlands)		8,905
		Oil & Gas Reservoir Consulting
	393,000	Alexco Resource (a)		3,218
		Mining, Exploration & Environmental Services
	180,000	Augusta Resource (a)		686
		U.S. Copper/Molybdenum Mine
				12,809
Energy & Minerals: Total				144,038
Health Care 8.1%
		> Biotechnology & Drug Delivery 4.8%
	344,394	BioMarin Pharmaceutical (a)		9,275
		Biotech Focused on Orphan Diseases
	137,000	United Therapeutics (a)		8,661
		Biotech Focused on Rare Diseases
	491,882	Seattle Genetics (a)		7,354
		Antibody-based Therapies for Cancer

See accompanying notes to financial statements.

55

Columbia Acorn USA

Statement of Investments, continued

Number of Shares			Value (000)
		> Biotechnology & Drug Delivery—continued
	190,000	Onyx Pharmaceuticals (a)	$	7,005
		Commercial-stage Biotech Focused on Cancer
	810,000	Micromet (a)		6,577
		Next-generation Antibody Technology
	626,000	Isis Pharmaceuticals (a)		6,335
		Biotech Pioneer in Anti-sense Drugs
	1,055,000	Allos Therapeutics (a)		4,864
		Cancer Drug Development
	600,000	NPS Pharmaceuticals (a)		4,740
		Orphan Drugs & Healthy Royalties
	363,000	Nektar Therapeutics (a)		4,665
		Drug Delivery Technologies
	600,000	Chelsea Therapeutics (a)		4,500
		Biotech Focused on Rare Diseases
	205,000	Auxilium Pharmaceuticals (a)(b)		4,325
		Biotech Focused on Niche Disease Areas
	92,400	InterMune (a)		3,363
		Drugs for Pulmonary Fibrosis & Hepatitis C
	122,900	Acorda Therapeutics (a)		3,350
		Biopharma Company Focused on Nervous Disorder Drugs
	530,282	Idenix Pharmaceuticals (a)		2,673
		Developer of Drugs for Infectious Diseases
	450,000	Array Biopharma (a)		1,345
		Drugs for Cancer & Inflammatory Diseases
	191,040	Nabi Biopharmaceuticals (a)		1,106
		Biotech Focused on Vaccines
	220,000	Anthera Pharmaceuticals (a)		1,074
		Biotech Focused on Cardiovascular, Cancer & Immunology
	18,181	Metabolex, Series A-1 (a)(d)		18
		Diabetes Drug Development
	738,060	Medicure - Warrants (a)(d)		2
		Cardiovascular Biotech Company
	37,500	Locus Pharmaceuticals, Series A-1, Pfd. (a)(d)		1
	19,329	Locus Pharmaceuticals, Series B-1, Pfd. (a)(d)		1
		High Throughput Rational Drug Design
	100,000	IsoRay - Warrants (a)(d)		1
		Radiology Cancer Company
				81,235
		> Medical Equipment & Devices 2.1%
	185,000	Alexion Pharmaceuticals (a)		14,902
		Biotech Focused on Orphan Diseases
	184,000	Sirona Dental Systems (a)		7,687
		Manufacturer of Dental Equipment
	76,000	Gen-Probe (a)		4,435
		Molecular In-vitro Diagnostics
	53,000	Idexx Laboratories (a)		3,669
		Diagnostic Equipment & Services for Veterinarians
	25,000	Illumina (a)		1,583
		Leading Tools & Service Provider for Genetic Analysis
	95,200	Pacific Biosciences of California (a)		1,515
		Genome Sequencing

Number of Shares			Value (000)
	72,000	American Medical Systems (a)	$	1,358
		Medical Devices to Treat Urological Conditions
	246,834	Nanosphere (a)		1,076
		Molecular Diagnostics Company with Best of Breed Platform
				36,225
		> Health Care Services 0.6%
	653,900	Health Management Associates (a)		6,238
		Non-urban Hospitals
	45,000	Mednax (a)		3,028
		Physician Management for Pediatric & Anesthesia Practices
				9,266
		> Medical Supplies 0.4%
	295,600	Cepheid (a)		6,725
		Molecular Diagnostics
	11,800	Neogen (a)		484
		Food & Animal Safety Products
				7,209
		> Pharmaceuticals 0.2%
	481,782	Akorn (a)		2,924
		Develops, Manufactures & Sells Specialty Generic Drugs
	54,800	Alimera Sciences (a)		569
		Ophthalmogy-focused Pharmaceutical Company
				3,493
Health Care: Total				137,428
Other Industries 5.8%
		> Real Estate 4.8%
	995,200	BioMed Realty Trust		18,560
		Life Science-focused Office Buildings
	915,000	Extra Space Storage		15,921
		Self Storage Facilities
	246,000	Corporate Office Properties		8,598
		Office Buildings
	1,450,000	Kite Realty Group		7,845
		Community Shopping Centers
	177,000	Kilroy Realty		6,455
		Southern California Office & Industrial Properties
	405,000	Associated Estates Realty		6,192
		Multi-family Properties
	1,058,000	DCT Industrial Trust		5,618
		Industrial Properties
	98,619	Macerich		4,672
		Regional Shopping Malls
	191,000	Dupont Fabros Technology		4,063
		Technology-focused Office Buildings
	400,000	Education Realty Trust		3,108
		Student Housing
				81,032
		> Transportation 1.0%
	210,091	Rush Enterprises, Class A (a)		4,294
	115,000	Rush Enterprises, Class B (a)		2,068
		Truck Sales & Services

See accompanying notes to financial statements.

56

Number of Shares or Principal Amount (000)			Value (000)
		> Transportation—continued
	156,000	World Fuel Services	$	5,641
		Global Fuel Broker
	310,000	Heartland Express		4,966
		Regional Trucker
				16,969
Other Industries: Total				98,001
Total Equities: 99.6% (Cost: $1,177,142)				1,691,308
Securities Lending Collateral: 0.9%
	15,767,797	Dreyfus Government Cash Management Fund (e) (7 day yield of 0.01%)		15,768
Total Securities Lending Collateral: (Cost: $15,768)				15,768
Short-Term Obligation: 1.1%
		> Repurchase Agreement: 1.1%
$	18,498	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by a U.S. Government Agency obligation maturing 4/28/14, market value $18,869 (repurchase proceeds $18,498)		18,498
Total Short Term Obligation: (Cost: $18,498)				18,498
Total Investments: 101.6% (Cost: $1,211,408)(f)				1,725,574
Obligation to Return Collateral for Securities Loaned: (0.9)%				(15,768	)
Cash and Other Assets Less Liabilities: (0.7)%				(11,260	)
Total Net Assets: 100.0%			$	1,698,546

ADR = American Depositary Receipts.

See accompanying notes to financial statements.

57

Columbia Acorn USA

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  All or a portion of this security was on loan at December 31, 2010. The total market value of Fund securities on loan at December 31, 2010 was $15,262.

(c)  An affiliated person of the Fund may include any company in which the Fund owns five percent or more of its outstanding voting shares.

  Holdings and transactions in these affiliated companies during the year ended December 31, 2010, are as follows:

Affiliate	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
Cavco Industries*		327,900		-		166,900		161,000	$	7,517	$	-
RCM Technologies		786,000		-		76,000		710,000		3,294		-
Total of Affiliated Transactions		1,113,900		-		242,900		871,000	$	10,811	$	-

*   At December 31, 2010, the Fund owned less than five percent of the company's outstanding voting shares.

  The aggregate cost and value of this affiliated company at December 31, 2010, were $4,479 and $3,294, respectively. Investments in the affiliated company represented 0.2% of total net assets at December 31, 2010.

(d)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the market value of these securities amounted to $23, which represented less than 0.01% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Metabolex, Series A-1	2/11/00		18,181	$	2,000	$	18
Medicure - Warrants	12/22/06		738,060		-		2
IsoRay - Warrants	3/21/07		100,000		-		1
Locus Pharmaceuticals, Series A-1 Pfd.	9/05/01		37,500		1,500		1
Locus Pharmaceuticals, Series B-1 Pfd.	2/08/07		19,329		56		1
				$	3,556	$	23

(e)  Investment made with cash collateral received from securities lending activity.

(f)  At December 31, 2010, for federal income tax purposes, the cost of investments was $1,211,741 and net unrealized appreciation was $513,833, consisting of gross unrealized appreciation of $618,098 and gross unrealized depreciation of $104,265.

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Information	$	568,893	$	-	$	-	$	568,893
Consumer Goods & Services		296,993		-		-		296,993
Industrial Goods & Services		258,087		-		-		258,087
Finance		187,868		-		-		187,868
Energy & Minerals		144,038		-		-		144,038
Health Care		137,405		3		20		137,428
Other Industries		98,001		-		-		98,001
Total Equities		1,691,285		3		20		1,691,308
Total Securities Lending Collateral		15,768		-		-		15,768
Total Short-Term Obligation		-		18,498		-		18,498
Total Investments	$	1,707,053	$	18,501	$	20	$	1,725,574

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Warrants which do not trade are valued as a percentage of the actively trading common stock using a model based on Black Scholes.

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

See accompanying notes to financial statements.

58

> Notes to Statement of Investments (dollar values in thousands)

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities for which no market exists are valued based upon a market approach using some unobservable inputs which may include, but are not limited to, projected earnings, available cash, line of business, multiples, and consideration of the prioritization of the equity in a company's capital structure.

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

  The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sells		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Equities
Health Care	$	25	$	-	$	(5	)	$	-	$	-	$	-	$	-	$	20
	$	25	$	-	$	(5	)	$	-	$	-	$	-	$	-	$	20

  The information in the above reconciliation represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  The change in unrealized depreciation attributed to securities owned at December 31, 2010, which were valued using significant unobservable inputs (Level 3) amounted to $5. This amount is included in net change in unrealized appreciation on the Statement of Changes in Net Assets.

  For more information on valuation inputs, and their aggregation into the levels used in the tables above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

59

Columbia Acorn International Select

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Europe
> United Kingdom
Archipelago Resources		0		422,600
Chemring		207,000		286,000
JLT Group		0		360,308
> Netherlands
Aalberts Industries		0		238,000
AkzoNobel		0		74,000
> Germany
Rheinmetall		0		67,000
> France
Neopost		101,355		126,000
> Ireland
United Drug		2,860,000		3,213,000
> Iceland
Marel		0		4,800,000
> Russia
Mail.ru - GDR		0		107,000
Asia
> Japan
Asahi Diamond Industrial		140,100		241,000
Gree		265,000		396,000
Kansai Paint		1,879,000		1,932,000
> Hong Kong
Mongolian Mining		0		1,555,500
Latin America
> Argentina
Union Agriculture Group		0		1,000,000

	Number of Shares
	09/30/10		12/31/10
Sales
Europe
> United Kingdom
Cobham		3,145,000		2,287,000
Intertek Group		530,000		412,000
Micro Focus		1,280,000		553,600
Serco		2,300,000		2,139,000
> Netherlands
Core Laboratories		82,000		51,000
> Spain
Red Eléctrica de España		127,000		93,000
Asia
> Japan
Ain Pharmaciez		164,000		110,000
Kamigumi		242,400		0
Rohto Pharmaceutical		343,300		0
> China
Jiangsu Expressway		17,450,000		14,649,000
Zhaojin Mining Industry		5,515,200		2,876,700
> Singapore
Olam International		4,100,000		3,750,000
Other Countries
> Canada
Eldorado Gold		243,250		0
Pan American Silver		548,000		287,000
> South Africa
Naspers		287,000		271,000
Latin America
> Columbia
Pacific Rubiales Energy		615,000		525,000

See accompanying notes to financial statements.

60

Columbia Acorn International Select

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 94.8%
Europe 43.7%
		> United Kingdom 16.0%
	2,139,000	Serco	$	18,525
		Facilities Management
	286,000	Chemring		12,949
		Defense Manufacturer of Countermeasures & Energetics
	412,000	Intertek Group		11,402
		Testing, Inspection & Certification Services
	568,000	Petropavlovsk		10,131
		Gold & Iron Ore Mining in Russia
	2,287,000	Cobham		7,256
		Aerospace Components
	13,467,511	Workspace Group		4,934
		United Kingdom Real Estate
	360,308	JLT Group		3,534
		International Business Insurance Broker
	553,600	Micro Focus		3,355
		United Kingdom Legacy Software Provider
	422,600	Archipelago Resources (a)		402
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
				72,488
		> Netherlands 8.5%
	175,427	Fugro		14,417
		Sub-sea Oilfield Services
	258,904	Imtech		9,822
		Electromechanical & Information & Communications Technologies Installation & Maintenance
	238,000	Aalberts Industries		5,017
		Flow Control & Heat Treatment
	74,000	AkzoNobel		4,597
		Largest Global Supplier of Protective Paints & Coatings
	51,000	Core Laboratories		4,542
		Oil & Gas Reservoir Consulting
				38,395
		> Germany 4.2%
	672,000	Wirecard		9,205
		Online Payment Processing & Risk Management
	67,000	Rheinmetall		5,389
		Defense & Automotive
	200,000	Rhoen-Klinikum		4,403
		Health Care Services
				18,997
		> Sweden 4.0%
	836,666	Hexagon		17,944
		Measurement Equipment & Software
				17,944
		> Switzerland 2.9%
	51,000	Kuehne & Nagel		7,085
		Freight Forwarding/Logistics
	135,900	Bank Sarasin & Cie		6,193
		Private Banking
				13,278

Number of Shares			Value (000)
		> France 2.4%
	126,000	Neopost	$	10,978
		Postage Meter Machines
				10,978
		> Ireland 2.0%
	3,213,000	United Drug		9,016
		Irish Pharmaceutical Wholesaler & Outsourcer
				9,016
		> Spain 1.0%
	93,000	Red Eléctrica de España		4,373
		Spanish Power Transmission
				4,373
		> Iceland 0.9%
	4,800,000	Marel (a)		4,182
		Largest Manufacturer of Poultry & Fish Processing Equipment
				4,182
		> Denmark 0.9%
	29,000	Novozymes		4,041
		Industrial Enzymes
				4,041
		> Russia 0.9%
	107,000	Mail.ru - GDR (a)(b)		3,852
		Internet Social Networking & Games for Russian Speakers
				3,852
Europe: Total				197,544
Asia 32.1%
		> Japan 14.4%
	1,932,000	Kansai Paint		18,693
		Paint Producer in Japan, India, China & Southeast Asia
	4,450	Seven Bank		9,421
		ATM Processing Services
	8,550	Jupiter Telecommunications		8,993
		Largest Cable Service Provider in Japan
	189,300	Benesse		8,718
		Education Service Provider
	900	Orix JREIT		5,851
		Diversified REIT
	396,000	Gree		5,034
		Mobile Social Networking Game Developer/Platform
	241,000	Asahi Diamond Industrial		4,576
		Consumable Diamond Tools
	110,000	Ain Pharmaciez		3,868
		Dispensing Pharmacy/Drugstore Operator
				65,154
		> China 6.3%
	14,649,000	Jiangsu Expressway		16,811
		Chinese Toll Road Operator
	2,876,700	Zhaojin Mining Industry		11,769
		Gold Mining & Refining in China
				28,580

See accompanying notes to financial statements.

61

Columbia Acorn International Select

Statement of Investments, continued

Number of Shares			Value (000)
		> Singapore 5.9%
	10,800,000	Ascendas REIT	$	17,420
		Singapore Industrial Property Landlord
	3,750,000	Olam International		9,175
		Agriculture Supply Chain Manager
				26,595
		> South Korea 5.1%
	89,000	NHN (a)		17,760
		South Korea's Largest Online Search Engine
	151,000	Woongjin Coway		5,358
		South Korean Household Appliance Rental Service Provider
				23,118
		> Hong Kong 0.4%
	1,555,500	Mongolian Mining (a)		1,815
		Coking Coal Mining in Mongolia
				1,815
Asia: Total				145,262
Other Countries: 14.6%
		> Canada 5.4%
	287,000	Pan American Silver		11,827
		Silver Mining
	125,000	AG Growth		6,295
		Leading Manufacturer of Augers & Grain Handling Equipment
	210,400	CCL Industries		6,268
		Leading Global Label Manufacturer
				24,390
		> South Africa 3.5%
	271,000	Naspers		15,960
		Media in Africa, China, Russia & Other Emerging Markets
				15,960
		> Australia 3.1%
	961,000	UGL		14,183
		Engineering & Facilities Management
				14,183
		> United States 1.4%
	171,000	Atwood Oceanics (a)		6,390
		Offshore Drilling Contractor
				6,390
		> Israel 1.2%
	310,000	Israel Chemicals		5,316
		Producer of Potash, Phosphates, Bromine & Specialty Chemicals
				5,316
Other Countries: Total				66,239
Latin America 4.4%
		> Colombia 3.9%
	525,000	Pacific Rubiales Energy		17,820
		Oil Production & Exploration in Colombia
				17,820

Number of Shares or Principal Amount (000)			Value (000)
		> Argentina 0.5%
	1,000,000	Union Agriculture Group (a)(b)	$	2,200
		Farmland Operator in Uruguay
				2,200
Latin America: Total				20,020
Total Equities: 94.8% (Cost: $309,207)				429,065
Short-Term Obligations: 4.7%
		> Repurchase Agreement 4.2%
$	19,283	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by a U.S. Government Agency obligation maturing 4/28/14, market value $19,670 (repurchase proceeds $19,283)		19,283
				19,283
		> Commercial Paper 0.5%
	2,200	Toyota Motor Credit 0.20% due 1/21/11		2,200
				2,200
Total Short-Term Obligations 4.7% (Cost: $21,483)				21,483
Total Investments: 99.5% (Cost: $330,690)(c)(d)				450,548
Cash and Other Assets Less Liabilities: 0.5%				2,119
Total Net Assets: 100%			$	452,667

GDR = Global Depositary Receipts.

See accompanying notes to financial statements.

62

> Notes to Statement of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the market value of these securities amounted to $6,052, which represented 1.34% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Mail.ru - GDR	11/05/10-12/31/10		107,000	$	3,732	$	3,852
Union Agriculture Group	2/08/10		1,000,000		2,200		2,200
				$	5,932	$	6,052

(c)  At December 31, 2010, for federal income tax purposes, the cost of investments was $337,719 and net unrealized appreciation was $112,829, consisting of gross unrealized appreciation of $120,672 and gross unrealized depreciation of $7,843.

(d)  On December 31, 2010, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Euro	$	77,216		17.1
British Pound		72,488		16.0
Japanese Yen		65,154		14.4
U.S. Dollar		50,294		11.1
Hong Kong Dollar		30,395		6.7
Canadian Dollar		30,383		6.7
Singapore Dollar		26,595		5.9
South Korean Won		23,118		5.1
Other currencies less than 5% of total net assets		74,905		16.5
	$	450,548		99.5

The following table summarizes the inputs used, as December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Europe	$	8,394	$	189,150	$	-	$	197,544
Asia		-		145,262		-		145,262
Other Countries		30,780		35,459		-		66,239
Latin America		17,820		-		2,200		20,020
Total Equities		56,994		369,871		2,200		429,065
Total Short-Term Obligations		-		21,483		-		21,483
Total Investments	$	56,994	$	391,354	$	2,200	$	450,548

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sales price on the foreign exchange or market on which they trade. The Fund may use a systematic fair valuation model provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements.

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities acquired via private placement that are not yet trading are valued using a market approach for which management has determined that the original transaction price is the best representation of fair value. The original cost may be adjusted for the market movement in an index, ETF or similar security during the period it does not trade.

See accompanying notes to financial statements.

63

Columbia Acorn International Select

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

  The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)		Purchases		Sells		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Latin America
Argentina	$	-	$	-	$	-	$	2,200	$	-	$	-	$	-	$	2,200
	$	-	$	-	$	-	$	2,200	$	-	$	-	$	-	$	2,200

  The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  For more information on valuation inputs, and their aggregation into the levels used in the tables above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

64

Columbia Acorn International Select

Portfolio Diversification

At December 31, 2010, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value (000)		Percentage of Net Assets
> Industrial Goods & Services
Other Industrial Services	$	42,492		9.4
Industrial Materials & Specialty Chemicals		32,647		7.2
Machinery		31,420		6.9
Electrical Components		20,205		4.5
Outsourcing Services		18,525		4.1
Conglomerates		5,017		1.1
		150,306		33.2
> Information
Internet Related		37,572		8.3
Instrumentation		17,944		4.0
Financial Processors		9,205		2.0
CATV		8,993		2.0
Gaming Equipment & Services		5,034		1.1
Business Software		3,355		0.7
		82,103		18.1
> Energy & Minerals
Mining		40,486		9.0
Oil Services		20,807		4.6
Oil & Gas Producers		17,820		3.9
Agricultural Commodities		2,200		0.5
		81,313		18.0
> Other Industries
Real Estate		28,205		6.2
Transportation		16,811		3.7
Regulated Utilities		4,373		1.0
		49,389		10.9

	Value (000)		Percentage of Net Assets
> Consumer Goods & Services
Other Consumer Services	$	14,076		3.1
Food & Beverage		9,175		2.0
Nondurables		6,268		1.4
Retail		3,868		0.9
		33,387		7.4
> Finance
Banks		9,421		2.1
Brokerage & Money Management		6,193		1.3
Insurance		3,534		0.8
		19,148		4.2
> Health Care
Pharmaceuticals		9,016		2.0
Health Care Services		4,403		1.0
		13,419		3.0
Total Equities:		429,065		94.8
Short-Term Obligations:		21,483		4.7
Total Investments:		450,548		99.5
Cash and Other Assets Less Liabilities:		2,119		0.5
Net Assets:	$	452,667		100.0

See accompanying notes to financial statements.

65

Columbia Acorn Select

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/10		12/31/10
Purchases
Consumer Goods & Services
Career Education		1,600,000		1,900,000
Hertz		8,500,000		8,650,000
IFM Investments (Century 21 China RE) - ADR (China)		2,100,000		2,300,000
Energy & Minerals
Canadian Overseas Petroleum (United Kingdom)		0		7,200,000
Canadian Overseas Petroleum - Subscription Receipts (United Kingdom)		0		16,800,000
Canadian Overseas Petroleum - Warrants (United Kingdom)		0		3,600,000
Houston American Energy		1,050,000		1,184,800
Kirkland Lake Gold (Canada)		0		1,000,000
Petrodorado (Colombia)		3,005,500		11,256,000
Real Goods Solar		1,400,000		1,500,000
Union Agriculture Group (Argentina)		0		9,090,909
Information
Mail.ru - GDR (Russia)		0		507,563
Mettler Toledo		100,000		120,000
Navigant Consulting		1,451,900		2,300,000
VisionChina Media - ADR (China)		3,242,000		3,675,000
WNS - ADR (India)		4,147,878		4,200,000
Industrial Goods & Services
Ametek		1,100,000		1,860,000
Expeditors International of Washington		600,000		750,000
Neopost (France)		0		107,000
Pall		0		400,000
Finance
Discover Financial Services		4,850,000		5,150,000
Other Industries
Wisconsin Energy		200,000		250,000
Health Care
Akorn		0		977,671

	Number of Shares
	09/30/10		12/31/10
Sales
Consumer Goods & Services
Abercrombie & Fitch		1,650,000		1,600,000
Expedia		2,500,000		484,810
ITT Educational Services		1,050,000		1,000,000
lululemon athletica		394,917		350,000
Tractor Supply Company		120,000		0
Energy & Minerals
Pacific Rubiales Energy (Colombia)		5,250,000		4,600,000
Petroamerica (Colombia)		16,443,900		0
Tetra Technologies		3,700,000		0
Information
CardTronics		2,100,000		779,395
Sanmina-SCI		8,000,000		7,100,000
Industrial Goods & Services
Quanta Services		1,650,000		928,000
Finance
CNO Financial Group		13,500,000		12,500,000
Eaton Vance		450,260		0
Other Industries
American Commercial Lines		850,000		0

See accompanying notes to financial statements.

66

Columbia Acorn Select

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
			Equities: 95.1%
Consumer Goods & Services 26.0%
		>Retail 9.4%
	1,600,000	Abercrombie & Fitch	$	92,208
		Teen Apparel Retailer
	3,800,000	Safeway		85,462
		Supermarkets
	350,000	lululemon athletica (a)(b)		23,947
		Premium Active Apparel Retailer
	3,500,000	Wet Seal (a)		12,950
		Specialty Apparel Retailer
				214,567
		>Travel 6.0%
	8,650,000	Hertz (a)		125,338
		Largest U.S. Rental Car Operator
	484,810	Expedia		12,164
		Online Travel Services Company
				137,502
		>Educational Services 4.5%
	1,000,000	ITT Educational Services (a)		63,690
		Post-secondary Degree Services
	1,900,000	Career Education (a)		39,387
		Post-secondary Education
				103,077
		>Apparel 2.8%
	1,135,000	Coach		62,777
		Designer & Retailer of Branded Leather Accessories
				62,777
		>Casinos & Gaming 1.6%
	335,000,000	RexLot Holdings (China)		35,341
		Lottery Equipment Supplier in China
				35,341
		>Leisure Products 0.7%
	500,000	Thor Industries		16,980
		RV & Bus Manufacturer
				16,980
		>Other Consumer Services 0.5%
	2,300,000	IFM Investments (Century 21 China RE) - ADR (China) (a)(c)		11,500
		Provides Real Estate Services in China
				11,500
		>Food & Beverage 0.5%
	1,000,000	GLG Life Tech (Canada) (a)		10,740
		Produce an All-natural Sweetener Extracted from the Stevia Plant
				10,740
Consumer Goods & Services: Total				592,484
Energy & Minerals 20.3%
		>Oil & Gas Producers 14.9%
	4,600,000	Pacific Rubiales Energy (Colombia)		156,140
		Oil Production & Exploration in Colombia
	32,240,000	Canacol Energy (Columbia) (a)(c)		50,907
	4,000,000	Canacol Energy (Colombia) (a)(c)(d)		6,190
		Oil Producer in South America

Number of Shares			Value (000)
	35,950,000	ShaMaran Petroleum (Iraq) (a)(c)	$	49,172
		Oil Exploration in Kurdistan
	17,144,000	Petrodorado (Colombia) (a)(c)(d)		11,997
	11,256,000	Petrodorado (Columbia) (a)(c)		8,038
	17,144,000	Petrodorado - Warrants (Colombia) (a)(c)(d)		7,242
		Oil & Gas Exploration & Production in Colombia, Peru & Paraguay
	1,184,800	Houston American Energy (b)		21,433
		Oil & Gas Exploration & Production in Colombia
	16,800,000	Canadian Overseas Petroleum - Subscription Receipts (United Kingdom) (a)(d)		14,075
	7,200,000	Canadian Overseas Petroleum (United Kingdom) (a)(d)		5,180
	3,600,000	Canadian Overseas Petroleum - Warrants (United Kingdom) (a)(d)		851
		Oil & Gas Exploration & Production in the North Sea
	13,125,000	Petromanas (Canada) (a)(d)		5,110
	5,000,000	Petromanas (Canada) (a)		1,986
	6,562,500	Petromanas - Warrants (Canada) (a)(d)		776
		Exploring for Oil in Albania
				339,097
		>Alternative Energy 2.1%
	3,200,000	Canadian Solar (China) (a)(b)(c)		39,648
		Solar Cell & Module Manufacturer
	4,500,000	Synthesis Energy Systems (China) (a)(c)		5,265
		Owner/Operator of Gasification Plants
	1,500,000	Real Goods Solar (a)(c)		3,750
		Residential Solar Energy Installer
				48,663
		>Agricultural Commodities 1.9%
	38,000,000	Eacom Timber (Canada) (a)(c)(d)		24,345
		Canadian Lumber Producer
	9,090,909	Union Agriculture Group (Argentina) (a)(d)		20,000
		Farmland Operator in Uruguay
				44,345
		>Mining 0.7%
	1,000,000	Kirkland Lake Gold (Canada) (a)		16,062
		Gold Mining
				16,062
		>Oil Services 0.7%
	11,324,000	Tuscany International Drilling (Colombia) (a)(c)(d)		15,626
	1,900,000	Tuscany International Drilling - Warrants (Colombia) (a)(c)(d)		243
		South America-based Drilling Rig Contractor
				15,869
Energy & Minerals: Total				464,036

See accompanying notes to financial statements.

67

Columbia Acorn Select

Statement of Investments, continued

Number of Shares			Value (000)
Information 20.0%
		>Mobile Communications 6.9%
	1,550,000	Crown Castle International (a)	$	67,936
		Communications Towers
	900,000	American Tower (a)		46,476
		Communications Towers
	15,000,000	Globalstar (a)(b)(c)		21,750
		Satellite Mobile Voice & Data Carrier
	505,000	SBA Communications (a)		20,675
		Communications Towers
				156,837
		>Contract Manufacturing 3.6%
	7,100,000	Sanmina-SCI (a)(c)		81,508
		Electronic Manufacturing Services
				81,508
		>Computer Services 2.1%
	4,200,000	WNS - ADR (India) (a)(b)(c)		48,594
		Offshore BPO (Business Process Outsourcing) Services
				48,594
		>Business Software 1.8%
	7,000,000	Novell (a)		41,440
		Directory, Operating System & Identity Management Software
				41,440
		>Computer Hardware & Related Equipment 1.7%
	750,000	Amphenol		39,585
		Electronic Connectors
				39,585
		>Business Information & Marketing Services 0.9%
	2,300,000	Navigant Consulting (a)		21,160
		Financial Consulting Firm
				21,160
		>Internet Related 0.8%
	507,563	Mail.ru - GDR (Russia) (a)(d)		18,272
		Internet Social Networking & Games for Russian Speakers
				18,272
		>Instrumentation 0.8%
	120,000	Mettler Toledo (a)		18,145
		Laboratory Equipment
				18,145
		>Advertising 0.8%
	3,675,000	VisionChina Media - ADR (China) (a)(b)(c)		17,052
		Advertising on Digital Screens in China's Mass Transit System
				17,052
		>Financial Processors 0.6%
	779,395	CardTronics (a)		13,796
		Operates the World's Largest Network of ATMs
				13,796
Information: Total				456,389

Number of Shares			Value (000)
Industrial Goods & Services 12.8%
		>Machinery 4.5%
	1,860,000	Ametek	$	73,005
		Aerospace/Industrial Instruments
	400,000	Pall		19,832
		Filtration & Fluids Clarification
	107,000	Neopost (France)		9,323
		Postage Meter Machines
				102,160
		>Waste Management 2.4%
	1,500,000	Waste Management		55,305
		U.S. Garbage Collection & Disposal
				55,305
		>Industrial Materials & Specialty Chemicals 2.0%
	1,000,000	Nalco Holding Company		31,940
		Provider of Water Treatment & Process Chemicals & Services
	1,800,000	ChemSpec International - ADR (China)		13,464
		Specialty Chemicals with Focus on Fluorinated Chemical Manufacturing
				45,404
		>Other Industrial Services 1.8%
	750,000	Expeditors International of Washington		40,950
		International Freight Forwarder
				40,950
		>Industrial Distribution 1.3%
	220,000	WW Grainger		30,384
		Industrial Distribution
				30,384
		>Outsourcing Services 0.8%
	928,000	Quanta Services (a)		18,486
		Electrical & Telecom Construction Services
				18,486
Industrial Goods & Services: Total				292,689
Finance 11.2%
		>Credit Cards 4.2%
	5,150,000	Discover Financial Services		95,429
		Credit Card Company
				95,429
		>Insurance 3.7%
	12,500,000	CNO Financial Group (a)		84,750
		Life, Long-term Care & Medical Supplement Insurance
				84,750
		>Brokerage & Money Management 3.3%
	6,000,000	MF Global (a)		50,160
		Futures Broker
	1,100,000	SEI Investments		26,169
		Mutual Fund Administration & Investment Management
				76,329
Finance: Total				256,508

See accompanying notes to financial statements.

68

Number of Shares or Principal Amount (000)			Value (000)
Other Industries 4.0%
		>Transportation 2.3%
	1,300,000	JB Hunt Transport Services	$	53,053
		Truck & Intermodal Carrier
				53,053
		>Real Estate 1.0%
	1,200,000	BioMed Realty Trust		22,380
		Life Science-focused Office Buildings
				22,380
		>Regulated Utilities 0.7%
	250,000	Wisconsin Energy		14,715
		Wisconsin Utility
				14,715
Other Industries: Total				90,148
Health Care 0.8%
		>Biotechnology & Drug Delivery 0.5%
	1,500,000	NPS Pharmaceuticals (a)		11,851
		Orphan Drugs & Healthy Royalties
				11,851
		>Pharmaceuticals 0.3%
	977,671	Akorn (a)		5,934
		Develops, Manufactures & Sells Specialty Generic Drugs
				5,934
Health Care: Total				17,785
Total Equities: 95.1% (Cost: $1,522,342)				2,170,039
Securities Lending Collateral: 1.4%
	32,972,313	Dreyfus Government Cash Management Fund (e) (7 day yield of 0.01%)		32,972
Total Securities Lending Collateral: (Cost: $32,972)				32,972
Short-Term Obligations: 4.2%
		>Repurchase Agreement 3.3%
$	75,207	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by a U.S. Government Agency obligation maturiting 8/26/14, market value $76,713 (repurchase proceeds $75,208)		75,207
				75,207

Principal Amount (000)			Value (000)
		>Commercial Paper 0.9%
$	11,200	Toyota Motor Credit 0.20% due 1/21/11	$	11,199
	9,550	ConocoPhillips (f) 0.26% due 1/14/11		9,549
				20,748
Total Short-Term Obligations: (Amortized Cost: $95,955)				95,955
Total Investments: 100.7% (Cost: $1,651,269)(g)				2,298,966
Obligation to Return Collateral for Securities Loaned: (1.4)%				(32,972	)
Cash and Other Assets Less Liabilities: 0.7%				16,861
Total Net Assets: 100.0%			$	2,282,855

ADR = American Depositary Receipts

GDR = Global Depositary Receipts

See accompanying notes to financial statements.

69

Columbia Acorn Select

Statement of Investments, continued

> Notes to Statement of Investments (dollar values in thousands)

(a)  Non-income producing security.

(b)  All or a portion of this security was on loan at December 31, 2010. The total market value of Fund securities on loan at December 31, 2010 was $31,854.

(c)  An affiliated person of the Fund may include any company in which the Fund owns five percent or more of its outstanding voting shares.

  Holdings and transactions in these affiliated companies during the year ended December 31, 2010, are as follows:

Affiliates	Balance of Shares Held 12/31/09		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/10		Value		Dividend
American Commercial Lines*		1,125,000		250,000		1,375,000		-	$	-	$	-
Canacol Energy		32,240,000		4,000,000		-		36,240,000		57,097		-
Canadian Solar		1,900,000		1,300,000		-		3,200,000		39,648		-
CardTronics*		2,620,000		-		1,840,605		779,395		13,796		-
China Mass Media - ADR*		1,662,685		-		1,662,685		-		-		-
CNO Financial Group*		13,500,000		-		1,000,000		12,500,000		84,750		-
Eacom Timber		-		38,000,000		-		38,000,000		24,345		-
Globalstar		13,400,800		1,599,200		-		15,000,000		21,750		-
IFM Investments (Century 21 China RE) - ADR		-		2,300,000		-		2,300,000		11,500		-
Petrodorado**		-		45,544,000		-		45,544,000		27,277		-
Real Goods Solar		1,400,000		100,000		-		1,500,000		3,750		-
Sanmina-SCI		8,200,000		-		1,100,000		7,100,000		81,508		-
ShaMaran Petroleum		31,000,000		4,950,000		-		35,950,000		49,172		-
SkillSoft - ADR*		9,000,000		-		9,000,000		-		-		-
Synthesis Energy Systems		2,200,000		2,300,000		-		4,500,000		5,265		-
Tetra Technologies*		5,000,000		-		5,000,000		-		-		-
Tuscany International Drilling**		-		13,224,000		-		13,224,000		15,869		-
VisionChina Media - ADR		4,250,000		1,425,959		2,000,959		3,675,000		17,052		-
WNS - ADR		3,913,900		286,100		-		4,200,000		48,594		-
Total of Affiliated Transactions		131,412,385		115,279,259		22,979,249		223,712,395	$	501,373	$	-

*  At December 31, 2010, the Fund owned less than five percent of the company's outstanding voting shares.

**  Includes the effects of a corporate action.

  The aggregate cost and value of these affiliated companies at December 31, 2010, were $395,668 and $402,826, respectively. Investments in affiliated companies represented 17.7% of the Fund's total net assets at December 31, 2010.

(d)  Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2010, the value of these securities amounted to $129,907, which represented 5.69% of total net assets.

  Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Eacom Timber	3/17/10		38,000,000	$	18,812	$	24,345
Union Agriculture Group	12/08/10		9,090,909		20,000		20,000
Mail.ru - GDR	11/05/10-12/31/10		507,563		18,629		18,272
Tuscany International Drilling	2/12/10-3/23/10		11,324,000		12,989		15,626
Canadian Overseas Petroleum - Subscription Receipts	11/24/10		16,800,000		8,234		14,075
Petrodorado	11/20/09		17,144,000		3,607		11,997
Petrodorado - Warrants	11/20/09		17,144,000		2,118		7,242
Canacol Energy	4/15/10		4,000,000		2,963		6,190
Canadian Overseas Petroleum	11/24/10		7,200,000		3,188		5,180
Petromanas	5/20/10		13,125,000		4,561		5,110
Canadian Overseas Petroleum - Warrants	11/24/10		3,600,000		341		851
Petromanas - Warrants	5/20/10		6,562,500		380		776
Tuscany International Drilling - Warrants	2/12/10		1,900,000		235		243
				$	96,057	$	129,907

(e)  Investment made with cash collateral received from securities lending activity.

(f)  Security exempt from registration under Section 4(2) of the Securities Act of 1933. This security may only be resold in exempt transactions to qualified buyers. Private resales of this security to qualified institutional buyers are also exempt from registration pursuant to Rule 144A under the Securities Act of 1933. At December 31, 2010, this security had an aggregate value of $9,549, which represented 0.4% of total net assets.

(g)  At December 31, 2010, for federal income tax purposes, the cost of investments was $1,700,305 and net unrealized appreciation was $598,661, consisting of gross unrealized appreciation of $790,213 and gross unrealized depreciation of $191,552.

See accompanying notes to financial statements.

70

> Notes to Statement of Investments (dollar values in thousands)

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Consumer Goods & Services	$	557,143	$	35,341	$	-	$	592,484
Energy & Minerals		352,401		91,635		20,000		464,036
Information		456,389		-		-		456,389
Industrial Goods & Services		283,366		9,323		-		292,689
Finance		256,508		-		-		256,508
Other Industries		90,148		-		-		90,148
Health Care		17,785		-		-		17,785
Total Equities		2,013,740		136,299		20,000		2,170,039
Total Securities Lending Collateral		32,972		-		-		32,972
Total Short-Term Obligations		-		95,955		-		95,955
Total Investments	$	2,046,712	$	232,254	$	20,000	$	2,298,966

  The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sales price on the foreign exchange or market on which they trade. The Fund may use a systematic fair valuation model provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements. Securities acquired via private placement that have a holding period or an extended settlement period are valued at a discount to the same shares that are trading freely on the m arket. These discounts are determined by the adviser's experience with similar securities or situations. Factors may include, but are not limited to, trade volume, shares outstanding and stock price. Warrants which do not trade are valued as a percentage of the actively trading common stocks using a model based on Black Scholes.

  Certain short-term obligations may be valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  The Fund's assets assigned to the Level 3 input category are valued at fair value as determined in good faith under consistently applied procedures established by and under the general supervision of the Board of Trustees. To determine fair value, management will utilize the valuation technique that they deem the most appropriate in the circumstances. Securities acquired via private placement that are not yet trading are valued using a market approach for which management has determined that the original transaction price is the best representation of fair value. The original cost may be adjusted for the market movement in an index, ETF or similar security during the period it does not trade.

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

The following table reconciles asset balances for the year ending December 31, 2010, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2009		Realized Gain/ (Loss)			Change in Unrealized Appreciation (Depreciation)		Purchases		Sales			Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2010
Equities
Consumer Goods & Services	$	181	$	(20,560	)	$	20,380	$	-	$	(1	)	$	-	$	-	$	-
Energy & Minerals		-		-			-		20,000		-			-		-		20,000
	$	181	$	(20,560	)	$	20,380	$	20,000	$	(1	)	$	-	$	-	$	20,000

  The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

  The change in unrealized appreciation attributed to securities owned at December 31, 2010, which were valued using significant unobservable inputs (Level 3) amounted to $20,380. This amount is included in net change in unrealized appreciation (depreciation) on the Statements of Changes in Net Assets.

  For more information on valuation inputs, and their aggregation into the levels used in the tables above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

71

Columbia Thermostat Fund

Statement of Investments, December 31, 2010

Number of Shares			Value (000)
		> Affiliated Stock Funds: 59.7%
	388	Columbia Acorn International, Class I	$	15,884
	1,204	Columbia Dividend Income Fund, Class I		15,741
	563	Columbia Marsico Growth Fund, Class I		11,638
	385	Columbia Acorn Fund, Class I		11,623
	547	Columbia Contrarian Core Fund, Class I		7,837
	272	Columbia Acorn Select, Class I		7,829
	650	Columbia Large Cap Enhanced Core Fund, Class I		7,816
Total Stock Funds (Cost: $59,637)				78,368
		> Affiliated Bond Funds: 39.7%
	2,874	Columbia Intermediate Bond Fund, Class I		26,035
	1,402	Columbia U.S. Treasury Index Fund, Class I		15,604
	1,334	Columbia Conservative High Yield Fund, Class Z		10,470
Total Bond Funds (Cost: $52,047)				52,109

Principal Amount (000)			Value (000)
Short-Term Obligation: 0.5%
		> Repurchase Agreement: 0.5%
$	705	Repurchase Agreement with Fixed Income Clearing Corp., dated 12/31/10, due 1/03/11 at 0.16%, collateralized by a U.S. Government Agency obligation maturing 9/08/14, market value $722 (repurchase proceeds $705)	$	705
Total Short-Term Obligation (Cost: $705)				705
Total Investments: 99.9% (Cost: $112,389)(a)				131,182
Cash and Other Assets Less Liabilities: 0.1%				93
Total Net Assets: 100.0%			$	131,275

> Notes to Statement of Investments (dollar values in thousands)

(a)  At December 31, 2010, for federal income tax purposes, the cost of investments was $112,602 and net unrealized appreciation was $18,580, consisting of gross unrealized appreciation of $19,312 and gross unrealized depreciation of $732.

The following table summarizes the inputs used, as of December 31, 2010, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Total Stock Funds	$	78,368	$	-	$	-	$	78,368
Total Bond Funds		52,109		-		-		52,109
Total Short-Term Obligation		-		705		-		705
Total Investments	$	130,477	$	705	$	-	$	131,182

  The Fund's assets assigned to the Level 2 category include certain short-term obligations generally valued using amortized cost, an income approach which converts future cash flows to a present value based upon the discount or premium at purchase.

  There were no significant transfers of financial assets between levels 1 and 2 during the period.

  For more information on valuation inputs, and their aggregation into the levels used in the table above, please refer to the Security Valuation section in the accompanying Notes to Financial Statements.

See accompanying notes to financial statements.

72

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73

Columbia Acorn Family of Funds

Statements of Assets and Liabilities

December 31, 2010	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select			Columbia Acorn Select			Columbia Thermostat Fund
(in thousands)
Assets:
Unaffiliated investments, at cost	$	9,605,670		$	4,209,981		$	1,206,929		$	330,690		$	1,255,601		$	705
Affiliated investments, at cost (See Note 4)		2,324,758			97,243			4,479			—			395,668			111,684
Unaffiliated investments, at value (including securities on loan: Columbia Acorn Fund $363,573; Columbia Acorn International $51,194; Columbia Acorn USA $15,262; Columbia Acorn International Select $–; Columbia Acorn Select $31,854; Columbia Thermostat Fund $–)	$	15,053,040		$	5,997,341		$	1,722,280		$	450,548		$	1,896,140		$	705
Affiliated investments, at value (See Note 4)		3,446,513			114,116			3,294			—			402,826			130,477
Cash		1,627			5,195			14			687			509			—	*
Foreign currency (cost: Columbia Acorn Fund $28;		29			23,259			—			21			151			—
Columbia Acorn International $22,292; Columbia Acorn International Select $21; Columbia Acorn Select $151)
Net unrealized appreciation on forward foreign currency exchange contracts		—			11,287			—			—			—			—
Receivable for:
Investments sold		33,520			799			98			2,318			26,550			—
Fund shares sold		18,452			41,702			1,308			442			8,550			364
Dividends and interest		8,519			6,392			821			642			1,230			—	*
Securities lending income		372			142			16			14			34			—
Foreign tax reclaims		144			924			—			50			—			—
Expense reimbursement due from Adviser		—			—			—			—			—			12
Trustees' Deferred Compensation Investments		3,047			802			238			—			309			—
Other assets		216			71			20			6			29			1
Total Assets		18,565,479			6,202,030			1,728,089			454,728			2,336,328			131,559
Liabilities:
Collateral on securities loaned		375,541			53,018			15,768			—			32,972			—
Expense reimbursement due to Adviser		—			—			—			—	*		—			—
Payable for:
Investments purchased		34,913			9,387			5,534			816			6,574			—
Fund shares redeemed		37,678			6,943			6,224			637			11,071			121
Management fee		9,717			3,815			1,218			353			1,538			11
Administration fee		605			200			56			15			76			4
12b-1 Service & Distribution fees		1,641			270			82			27			246			46
Reports to shareholders		620			300			78			40			165			33
Deferred Trustees' fees		3,047			802			238			44			309			29
Transfer agent fees		2,501			608			292			42			369			20
Trustees' fees		—	*		—	*		1			—	*		—	*		—	*
Professional fee		136			67			30			24			34			13
Custody fees		285			1,020			14			58			108			—
Chief compliance officer expenses		47			16			4			1			6			—	*
Foreign capital gains tax		—			507			—			—			—			—
Other liabilities		36			14			4			4			5			7
Total Liabilities		466,767			76,967			29,543			2,061			53,473			284
Net Assets	$	18,098,712		$	6,125,063		$	1,698,546		$	452,667		$	2,282,855		$	131,275
Composition of Net Assets:
Paid in capital	$	11,409,140		$	4,691,850		$	1,213,358		$	370,640		$	1,772,391		$	141,101
Undistributed/(overdistributed) net investment income (Accumulated net investment loss)		(48,598	)		5,502			(238	)		(1,132	)		(17,217	)		1,479
Accumulated net realized gain/(loss)		169,015			(388,458	)		(28,740	)		(36,711	)		(120,017	)		(30,098	)
Net unrealized appreciation/(depreciation) on:
Investments		6,569,125			1,804,233			514,166			119,858			647,697			18,793
Foreign capital gains tax		—			(507	)		—			—			—			—
Foreign currency translations		30			12,443			—			12			1			—
Net Assets	$	18,098,712		$	6,125,063		$	1,698,546		$	452,667		$	2,282,855		$	131,275
Net asset value per share – Class A (a)	$	29.24		$	40.87		$	27.54		$	28.01		$	27.94		$	12.58
(Net assets/shares)		($3,639,788/124,485)			($810,603/19,836)			($214,097/7,775)			($71,668/2,559)			($555,263/19,872)			($44,527/3,541)
Maximum offering price per share – Class A (b)	$	31.02		$	43.36		$	29.22		$	29.72		$	29.64		$	13.35
(Net asset value per share/front- end sales charge)		($29.24/0.9425)			($40.87/0.9425)			($27.54/0.9425)			($28.01/0.9425)			($27.94/0.9425)			($12.58/0.9425)
Net asset value and offering price per share – Class B (a)	$	27.14		$	39.96		$	25.60		$	26.72		$	26.06		$	12.64
(Net assets/shares)		($287,650/10,599)			($29,368/735)			($9,222/360)			($3,030/113)			($72,203/2,771)			($28,752/2,274)
Net asset value and offering price per share – Class C (a)	$	26.85		$	39.79		$	25.39		$	26.58		$	25.83		$	12.62
(Net assets/shares)		($829,181/30,882)			($110,931/2,788)			($36,101/1,422)			($11,885/447)			($98,445/3,811)			($21,866/1,733)
Net asset value and offering price per share – Class I (c)	$	30.19		$	40.92		$	28.56		$	28.33		$	28.74	(e)
(Net assets/shares)		($11,627/385)			($66,581/1,627)			($28,993/1,015)			($3/0**)			($7,832/273)
Net asset value and offering price per share – Class Z (d)	$	30.19		$	40.92		$	28.56		$	28.33		$	28.73		$	12.44
(Net assets/shares)		($13,330,466/441,587)			($5,107,580/124,833)			($1,410,133/49,379)			($366,081/12,923)			($1,549,112/53,914)			($36,130/2,904)

(a)  Redemption price per share is equal to net asset value less any applicable contingent deferred sales charge and redemption fee.

(b)  On sales of $50,000 or more the offering price is reduced.

(c)  Shares commenced operations on September 27, 2010.

(d)  Redemption price per share is equal to net asset value less any applicable redemption fee.

(e)  Due to rounding of shares outstanding.

*  Rounds to less than $500.

**  Rounds to less than 500 shares.

See accompanying notes to financial statements.

74

Columbia Acorn Family of Funds

Statements of Operations
For the Year Ended December 31, 2010

(in thousands)	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select			Columbia Acorn Select			Columbia Thermostat Fund
Investment Income:
Dividend income	$	109,440		$	102,078		$	9,549		$	8,419		$	10,990		$	—
Dividend income from affiliates (See Note 4)		19,561			2,570			—			—			—			—
Dividends from affiliated investment company shares (See Note 4)		—			—			—			—			—			2,653
Interest income		762			277			10			33			161			1
Securitites lending income, net		3,053			1,005			149			49			169			—
		132,816			105,930			9,708			8,501			11,320			2,654
Foreign taxes withheld		(1,906	)		(8,508	)		(15	)		(606	)		(101	)		—
Total Investment Income		130,910			97,422			9,693			7,895			11,219			2,654
Expenses:
Management fee		99,409			37,945			12,548			3,892			16,589			125
Administration fee		6,176			1,979			580			165			813			50
12b-1 Service and Distribution fees:
Class A		7,754			1,613			476			159			1,297			107
Class B		2,783			241			98			24			574			223
Class C		7,388			924			323			110			920			206
Transfer agent fees:
Class A		3,089			1,119			192			113			583			68
Class B		818			91			36			12			195			63
Class C		950			167			41			26			144			36
Class Z		4,362			1,992			681			99			689			17
Custody fees		1,081			3,963			57			233			267			—
Trustees' fees		835			276			83			34			113			13
Reports to shareholders		2,117			1,153			315			198			506			112
Professional fees		502			217			80			50			97			26
Chief compliance officer expenses (See Note 4)		510			159			48			14			69			4
Other expenses		511			244			107			101			147			65
Total expenses		138,285			52,083			15,665			5,230			23,003			1,115
Less custody fees paid indirectly		(1	)		(1	)		—	*		—	*		(1	)		—
Less reimbursement of expenses by Investment Adviser		—			—			—			(2	)		—			(267	)
Net Expenses		138,284			52,082			15,665			5,228			23,002			848
Net Investment Income/(Loss)		(7,374	)		45,340			(5,972	)		2,667			(11,783	)		1,806
Net Realized and Unrealized Gain (Loss) on Portfolio Positions:
Net realized gain/(loss) on:
Unaffiliated investments		972,387			241,838			96,553			42,552			59,857			(2,634	)
Affiliated investments (See Note 4)		139,546			5,786			(1,208	)		—			(38,281	)		—
Foreign currency transactions and forward foreign currency   exchange contracts		(1,053	)		34,536			—			(25	)		(185	)		—
Distributions from affiliated investment company shares		—			—			—			—			—			658
Net realized gain/(loss)		1,110,880			282,160			95,345			42,527			21,391			(1,976	)
Net change in net unrealized appreciation/(depreciation) on:
Unaffiliated investments		1,864,477			741,944			224,623			38,172			283,122			—
Affiliated investments (See Note 4)		758,959			6,050			4,434			—			123,090			19,741
Foreign currency translations and forward foreign currency   exchange contracts		(106	)		9,798			—			21			1			—
Foreign capital gains tax		200			710			—			—			—			—
Net change in unrealized appreciation/ (depreciation)		2,623,530			758,502			229,057			38,193			406,213			19,741
Net realized and unrealized gain		3,734,410			1,040,662			324,402			80,720			427,604			17,765
Net Increase in Net Assets resulting from Operations	$	3,727,036		$	1,086,002		$	318,430		$	83,387		$	415,821		$	19,571

*  Rounds to less than $500.

See accompanying notes to financial statements.

75

Columbia Acorn Family of Funds

Statements of Changes in Net Assets

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2010			2009			2010			2009			2010			2009
Operations:
Net investment income/(loss)	$	(7,374	)	$	2,492		$	45,340		$	39,229		$	(5,972	)	$	(4,927	)
Net realized gain/(loss) on investments, foreign currency transactions, forward foreign currency exchange contracts and foreign capital gains tax		971,334			(227,359	)		276,374			(246,346	)		96,553			(20,041	)
Net realized gain/(loss) on affiliated investments and distributions from affiliated investment companies and affiliated investment company shares		139,546			(100,539	)		5,786			(3,829	)		(1,208	)		(110	)
Net change in net unrealized appreciation/(depreciation) on investments, foreign currency translations, forward foreign currency exchange contracts and foreign capital gains tax		1,864,571			3,343,490			752,452			1,558,895			224,623			437,114
Net change in net unrealized appreciation/(depreciation) on affiliated investment companies and affiliated investment company shares		758,959			1,143,521			6,050			49,345			4,434			1,994
Net Increase from Operations		3,727,036			4,161,605			1,086,002			1,397,294			318,430			414,030
Distributions to Shareholders From:
Net investment income – Class A		(2,387	)		—			(12,578	)		(6,102	)		—			—
Net realized gain – Class A		(100,919	)		—			—			—			—			—
Net investment income – Class B		—			—			(290	)		(290	)		—			—
Net realized gain – Class B		(9,116	)		—			—			—			—			—
Net investment income – Class C		—			—			(714	)		(348	)		—			—
Net realized gain – Class C		(25,102	)		—			—			—			—			—
Net investment income – Class I		—	*		—			(9	)		—			—			—
Net realized gain – Class I		—	*		—			—			—			—			—
Net investment income – Class Z		(18,634	)		(20,981	)		(109,328	)		(53,467	)		—			—
Net realized gain – Class Z		(361,156	)		—			—			—			—			—
Total Distributions to Shareholders		(517,314	)		(20,981	)		(122,919	)		(60,207	)		—			—
Share Transactions:
Subscriptions – Class A		843,928			639,685			317,458			181,444			55,029			54,531
Distributions reinvested – Class A		94,158			—			10,862			5,737			—			—
Redemptions – Class A		(866,166	)		(744,769	)		(221,501	)		(140,626	)		(59,786	)		(66,724	)
Net Increase/(Decrease) – Class A		71,920			(105,084	)		106,819			46,555			(4,757	)		(12,193	)
Subscriptions – Class B		989			100			35			14			2			5
Distributions reinvested – Class B		7,325			—			260			264			—			—
Redemptions – Class B		(312,686	)		(224,032	)		(15,278	)		(14,833	)		(13,951	)		(9,892	)
Net Decrease – Class B		(304,372	)		(223,932	)		(14,983	)		(14,555	)		(13,949	)		(9,887	)
Subscriptions – Class C		76,903			58,069			24,476			14,494			1,669			2,513
Distributions reinvested – Class C		19,273			—			590			265			—			—
Redemptions – Class C		(145,469	)		(151,419	)		(17,799	)		(18,021	)		(4,671	)		(5,210	)
Net Increase/(Decrease) – Class C		(49,293	)		(93,350	)		7,267			(3,262	)		(3,002	)		(2,697	)
Subscriptions – Class I (a)(b)		13,063			—			66,675			—			28,852			—
Distributions reinvested – Class I		—			—			9			—			—			—
Redemptions – Class I		(1,538	)		—			(2,003	)		—			(293	)		—
Net Increase – Class I		11,525			—			64,681			—			28,559			—
Subscriptions – Class Z		2,077,687			1,484,719			1,216,447			671,256			260,284			246,578
Distributions reinvested – Class Z		324,149			17,690			76,344			38,426			—			—
Redemptions – Class Z		(1,969,778	)		(1,364,770	)		(726,019	)		(486,805	)		(276,628	)		(190,623	)
Net Increase/(Decrease) – Class Z		432,058			137,639			566,772			222,877			(16,344	)		55,955
Net Increase/(Decrease) from Share Transactions		161,838			(284,727	)		730,556			251,615			(9,493	)		31,178
Redemption Fees		—			—			239			259			—			—
Increase from regulatory settlements (See Note 9)		1			40			447			1,210			—			5
Total Increase/(Decrease) in Net Assets		3,371,561			3,855,937			1,694,325			1,590,171			308,937			445,213
Net Assets:
Beginning of period		14,727,151			10,871,214			4,430,738			2,840,567			1,389,609			944,396
End of period	$	18,098,712		$	14,727,151		$	6,125,063		$	4,430,738		$	1,698,546		$	1,389,609
Undistributed/(Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(48,598	)	$	(20,794	)	$	5,502		$	39,113		$	(238	)	$	(275	)

(a)  Shares commenced operations on September 27, 2010.

(b)  Shares reflect activity for the period September 27, 2010 through December 31, 2010.

*  Rounds to less than $500.

See accompanying notes to financial statements.

76

	Columbia Acorn International Select						Columbia Acorn Select						Columbia Thermostat Fund
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2010			2009			2010			2009			2010			2009
Operations:
Net investment income/(loss)	$	2,667		$	2,398		$	(11,783	)	$	(10,372	)	$	1,806		$	1,281
Net realized gain/(loss) on investments, foreign currency transactions, forward foreign currency exchange contracts and foreign capital gains tax		42,527			(31,407	)		59,672			31,689			—			—
Net realized gain/(loss) on affiliated investments and distributions from affiliated investment companies and affiliated investment company shares		—			—			(38,281	)		(71,935	)		(1,976	)		(18,231	)
Net change in net unrealized appreciation/(depreciation) on investments, foreign currency translations, forward foreign currency exchange contracts and foreign capital gains tax		38,193			127,633			283,123			521,770			—			—
Net change in net unrealized appreciation/(depreciation) on affiliated investment companies and affiliated investment company shares		—			—			123,090			316,510			19,741			51,494
Net Increase from Operations		83,387			98,624			415,821			787,662			19,571			34,544
Distributions to Shareholders From:
Net investment income – Class A		(776	)		(456	)		—			—			(678	)		(7	)
Net realized gain – Class A		—			—			—			—			—			—
Net investment income – Class B		(25	)		—			—			—			(239	)		—
Net realized gain – Class B		—			—			—			—			—			—
Net investment income – Class C		(65	)		—			—			—			(124	)		—
Net realized gain – Class C		—			—			—			—			—			—
Net investment income – Class I		—			—			—			—			—			—
Net realized gain – Class I		—			—			—			—			—			—
Net investment income – Class Z		(5,241	)		(3,077	)		—			—			(625	)		(115	)
Net realized gain – Class Z		—			—			—			—			—			—
Total Distributions to Shareholders		(6,107	)		(3,533	)		—			—			(1,666	)		(122	)
Share Transactions:
Subscriptions – Class A		18,214			30,670			115,498			98,691			8,937			5,619
Distributions reinvested – Class A		675			439			—			—			609			6
Redemptions – Class A		(23,778	)		(28,558	)		(187,411	)		(190,444	)		(13,847	)		(14,381	)
Net Increase/(Decrease) – Class A		(4,889	)		2,551			(71,913	)		(91,753	)		(4,301	)		(8,756	)
Subscriptions – Class B		—	*		—			34			39			4			—
Distributions reinvested – Class B		22			—			—			—			218			—
Redemptions – Class B		(1,418	)		(1,493	)		(30,406	)		(23,638	)		(8,516	)		(12,541	)
Net Decrease – Class B		(1,396	)		(1,493	)		(30,372	)		(23,599	)		(8,294	)		(12,541	)
Subscriptions – Class C		1,883			1,872			6,743			6,147			3,195			1,960
Distributions reinvested – Class C		55			—			—			—			109			—
Redemptions – Class C		(3,121	)		(3,109	)		(19,302	)		(21,888	)		(5,530	)		(10,176	)
Net Increase/(Decrease) – Class C		(1,183	)		(1,237	)		(12,559	)		(15,741	)		(2,226	)		(8,216	)
Subscriptions – Class I (a)(b)		3			—			8,577			—			—			—
Distributions reinvested – Class I		—			—			—			—			—			—
Redemptions – Class I		—			—			(931	)		—			—			—
Net Increase – Class I		3			—			7,646			—			—			—
Subscriptions – Class Z		67,172			127,520			358,116			278,829			7,895			2,684
Distributions reinvested – Class Z		1,451			833			—			—			560			106
Redemptions – Class Z		(96,502	)		(59,794	)		(328,729	)		(310,353	)		(18,853	)		(6,183	)
Net Increase/(Decrease) – Class Z		(27,879	)		68,559			29,387			(31,524	)		(10,398	)		(3,393	)
Net Increase/(Decrease) from Share Transactions		(35,344	)		68,380			(77,811	)		(162,617	)		(25,219	)		(32,906	)
Redemption Fees		10			33			—			—			—			—
Increase from regulatory settlements (See Note 9)		46			265			—			—			—			—
Total Increase/(Decrease) in Net Assets		41,992			163,769			338,010			625,045			(7,314	)		1,516
Net Assets:
Beginning of period		410,675			246,906			1,944,845			1,319,800			138,589			137,073
End of period	$	452,667		$	410,675		$	2,282,855		$	1,944,845		$	131,275		$	138,589
Undistributed/(Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(1,132	)	$	1,978		$	(17,217	)	$	(8,359	)	$	1,479		$	1,247

See accompanying notes to financial statements.

77

Columbia Acorn Family of Funds

Statements of Changes in Net Assets, continued

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA
Changes in Shares of Beneficial Interest:	Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2010			2009			2010			2009			2010			2009
Subscriptions – Class A		32,735			33,142			8,744			6,366			2,334			3,208
Shares issued in reinvestment – Class A		3,306			—			325			208			—			—
Less shares redeemed – Class A		(34,053	)		(39,655	)		(6,188	)		(5,549	)		(2,521	)		(3,839	)
Net Increase/(Decrease) – Class A		1,988			(6,513	)		2,881			1,025			(187	)		(631	)
Subscriptions – Class B		38			5			1			—	*		—	*		—	*
Shares issued in reinvestment – Class B		276			—			9			10			—			—
Less shares redeemed – Class B		(13,126	)		(12,472	)		(444	)		(588	)		(636	)		(582	)
Net Decrease – Class B		(12,812	)		(12,467	)		(434	)		(578	)		(636	)		(582	)
Subscriptions – Class C		3,197			3,215			700			497			76			148
Shares issued in reinvestment – Class C		733			—			19			10			—			—
Less shares redeemed – Class C		(6,190	)		(8,764	)		(519	)		(740	)		(214	)		(327	)
Net Increase/(Decrease) – Class C		(2,260	)		(5,549	)		200			(233	)		(138	)		(179	)
Subscriptions – Class I (a)(b)		436			—			1,677			—			1,025			—
Shares issued in reinvestment – Class I		—			—			—	*		—			—			—
Less shares redeemed – Class I		(51	)		—			(50	)		—			(10	)		—
Net Increase – Class I		385			—			1,627			—			1,015			—
Subscriptions – Class Z		78,950			75,517			33,971			23,146			10,643			14,152
Shares issued in reinvestment – Class Z		11,048			750			2,239			1,391			—			—
Less shares redeemed – Class Z		(74,926	)		(70,272	)		(20,195	)		(18,261	)		(11,173	)		(10,509	)
Net Increase/(Decrease) – Class Z		15,072			5,995			16,015			6,276			(530	)		3,643
Net Increase/(Decrease) in Shares of Beneficial Interest		2,373			(18,534	)		20,289			6,490			(476	)		2,251

(a)  Shares commenced operations on September 27, 2010.

(b)  Shares reflect activity for the period September 27, 2010 through December 31, 2010.

*  Rounds to less than 500.

See accompanying notes to financial statements.

78

	Columbia Acorn International Select						Columbia Acorn Select						Columbia Thermostat Fund
Changes in Shares of Beneficial Interest:	Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2010			2009			2010			2009			2010			2009
Subscriptions – Class A		746			1,653			4,815			5,917			765			646
Shares issued in reinvestment – Class A		31			22			—			—			56			1
Less shares redeemed – Class A		(982	)		(1,497	)		(7,851	)		(11,758	)		(1,223	)		(1,674	)
Net Increase/(Decrease) – Class A		(205	)		178			(3,036	)		(5,841	)		(402	)		(1,027	)
Subscriptions – Class B		—	*		—			2			2			—	*		—
Shares issued in reinvestment – Class B		1			—			—			—			21			—
Less shares redeemed – Class B		(62	)		(85	)		(1,342	)		(1,512	)		(744	)		(1,410	)
Net Decrease – Class B		(61	)		(85	)		(1,340	)		(1,510	)		(723	)		(1,410	)
Subscriptions – Class C		83			103			299			371			275			212
Shares issued in reinvestment – Class C		2			—			—			—			10			—
Less shares redeemed – Class C		(138	)		(174	)		(870	)		(1,474	)		(485	)		(1,207	)
Net Increase/(Decrease) – Class C		(53	)		(71	)		(571	)		(1,103	)		(200	)		(995	)
Subscriptions – Class I (a)(b)		—	*		—			305			—			—			—
Shares issued in reinvestment – Class I		—			—			—			—			—			—
Less shares redeemed – Class I		—			—			(32	)		—			—			—
Net Increase – Class I		—	*		—			273			—			—			—
Subscriptions – Class Z		2,699			6,808			14,221			15,845			697			307
Shares issued in reinvestment – Class Z		66			42			—			—			51			12
Less shares redeemed – Class Z		(3,845	)		(3,083	)		(13,400	)		(18,178	)		(1,710	)		(727	)
Net Increase/(Decrease) – Class Z		(1,080	)		3,767			821			(2,333	)		(962	)		(408	)
Net Increase/(Decrease) in Shares of Beneficial Interest		(1,399	)		3,789			(3,853	)		(10,787	)		(2,287	)		(3,840	)

See accompanying notes to financial statements.

79

Columbia Acorn Family of Funds

Financial Highlights

Columbia Acorn Fund

Class A Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	23.98		$	17.22		$	28.87		$	29.02		$	27.57
Income from Investment Operations
Net investment income/(loss) (a)		(0.06	)		(0.02	)		(0.01	)		0.05	(b)		0.05
Net realized and unrealized gain/(loss)		6.18			6.78			(10.98	)		2.13			3.82
Total from Investment Operations		6.12			6.76			(10.99	)		2.18			3.87
Less Distributions to Shareholders
From net investment income		(0.02	)		—			—			(0.03	)		(0.04	)
From net realized gains		(0.84	)		—			(0.66	)		(2.30	)		(2.38	)
Total Distributions to Shareholders		(0.86	)		—			(0.66	)		(2.33	)		(2.42	)
Increase from regulatory settlements		0.00	(c)		0.00	(c)		—			—			—
Net Asset Value, End of Period	$	29.24		$	23.98		$	17.22		$	28.87		$	29.02
Total Return (d)		25.61	%		39.26	%		(38.72	)%		7.39	%(e)(f)		14.13	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.07	%		1.07	%		1.05	%		1.02	%		1.02	%
Net investment income/(loss) (g)		(0.22	)%		(0.12	)%		(0.04	)%		0.17	%		0.17	%
Waiver/Reimbursement		—			—			—			0.01	%		0.02	%
Portfolio turnover rate		28	%		27	%		21	%		20	%		22	%
Net assets at end of period (000s)	$	3,639,788		$	2,937,761		$	2,221,100		$	4,300,920		$	4,067,868

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.03 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by less than 0.01% and less than $0.01, respectively.

(g)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

Class B Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	22.43		$	16.21		$	27.39		$	27.78		$	26.61
Income from Investment Operations
Net investment loss (a)		(0.21	)		(0.14	)		(0.15	)		(0.11	)(b)		(0.13	)
Net realized and unrealized gain/(loss)		5.76			6.36			(10.37	)		2.02			3.68
Total from Investment Operations		5.55			6.22			(10.52	)		1.91			3.55
Less Distributions to Shareholders
From net realized gains		(0.84	)		—			(0.66	)		(2.30	)		(2.38	)
Total Distributions to Shareholders		(0.84	)		—			(0.66	)		(2.30	)		(2.38	)
Increase from regulatory settlements		0.00	(c)		0.00	(c)		—			—			—
Net Asset Value, End of Period	$	27.14		$	22.43		$	16.21		$	27.39		$	27.78
Total Return (d)		24.81	%		38.37	%		(39.11	)%		6.76	%(e)(f)		13.43	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.69	%		1.74	%		1.65	%		1.59	%		1.66	%
Net investment loss (g)		(0.88	)%		(0.77	)%		(0.64	)%		(0.39	)%		(0.48	)%
Waiver/Reimbursement		—			—			—			0.01	%		0.02	%
Portfolio turnover rate		28	%		27	%		21	%		20	%		22	%
Net assets at end of period (000s)	$	287,650		$	525,072		$	581,587		$	1,270,292		$	1,404,165

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.03 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by less than 0.01% and less than $0.01, respectively.

(g)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

See accompanying notes to financial statements.

80

Columbia Acorn Fund

Class C Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	22.23		$	16.09		$	27.25		$	27.70		$	26.58
Income from Investment Operations
Net investment loss (a)		(0.24	)		(0.17	)		(0.19	)		(0.18	)(b)		(0.17	)
Net realized and unrealized gain/(loss)		5.70			6.31			(10.31	)		2.03			3.67
Total from Investment Operations		5.46			6.14			(10.50	)		1.85			3.50
Less Distributions to Shareholders
From net realized gains		(0.84	)		—			(0.66	)		(2.30	)		(2.38	)
Total Distributions to Shareholders		(0.84	)		—			(0.66	)		(2.30	)		(2.38	)
Increase from regulatory settlements		0.00	(c)		0.00	(c)		—			—			—
Net Asset Value, End of Period	$	26.85		$	22.23		$	16.09		$	27.25		$	27.70
Total Return (d)		24.63	%		38.16	%		(39.23	)%		6.56	%(e)(f)		13.25	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.85	%		1.89	%		1.83	%		1.79	%		1.80	%
Net investment loss (g)		(1.00	)%		(0.93	)%		(0.82	)%		(0.60	)%		(0.61	)%
Waiver/Reimbursement		—			—			—			0.00	%(h)		0.02	%
Portfolio turnover rate		28	%		27	%		21	%		20	%		22	%
Net assets at end of period (000s)	$	829,181		$	736,818		$	622,665		$	1,312,243		$	1,345,520

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.03 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by less than 0.01% and less than $0.01, respectively.

(g)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(h)  Rounds to less than 0.01%.

Class I Shares	Period Ended December 31,
Selected data for a share outstanding throughout the period	2010(a)
Net Asset Value, Beginning of Period	$	26.80
Income from Investment Operations
Net investment loss (b)		(0.01	)
Net realized and unrealized gain		4.26
Total from Investment Operations		4.25
Less Distributions to Shareholders
From net investment income		(0.02	)
From net realized gains		(0.84	)
Total Distributions to Shareholders		(0.86	)
Net Asset Value, End of Period	$	30.19
Total Return (c)(d)		15.94	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)(f)		0.71	%
Net investment income/(loss) (e)(f)		(0.13	)%
Portfolio turnover rate (d)		28	%
Net assets at end of period (000s)	$	11,627

(a)  Class I shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(b)  Per share data was calculated using the average shares outstanding during the period.

(c)  Total return at net asset value assuming all distributions reinvested.

(d)  Not annualized.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Annualized.

See accompanying notes to financial statements.

81

Columbia Acorn Family of Funds

Financial Highlights, continued

Columbia Acorn International

Class A Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	34.13		$	23.03		$	43.42		$	40.07		$	33.20
Income from Investment Operations
Net investment income (a)		0.22			0.23			0.47			0.27			0.23
Net realized and unrealized gain/(loss)		7.21			11.27			(20.20	)		6.52			10.87
Total from Investment Operations		7.43			11.50			(19.73	)		6.79			11.10
Less Distributions to Shareholders
From net investment income		(0.69	)		(0.41	)		(0.06	)		(0.08	)		(0.32	)
From net realized gains		—			—			(0.60	)		(3.36	)		(3.91	)
Total Distributions to Shareholders		(0.69	)		(0.41	)		(0.66	)		(3.44	)		(4.23	)
Redemption Fees
Redemption fees added to paid in capital (a)(b)		0.00			0.00			0.00			0.00			0.00
Increase from regulatory settlements		0.00	(b)		0.01			—			—			—
Net Asset Value, End of Period	$	40.87		$	34.13		$	23.03		$	43.42		$	40.07
Total Return (c)		22.23	%		50.40	%		(46.09	)%		16.90	%(d)		34.16	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.35	%		1.36	%		1.31	%		1.23	%		1.24	%
Net investment income (e)		0.62	%		0.85	%		1.36	%		0.60	%		0.61	%
Waiver/Reimbursement		—			—			—			0.00	%(f)		0.01	%
Portfolio turnover rate		25	%		31	%		38	%		28	%		31	%
Net assets at end of period (000s)	$	810,603		$	578,599		$	366,820		$	622,901		$	313,401

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Rounds to less than $0.01 per share.

(c)  Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Rounds to less than 0.01%.

Class B Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	33.22		$	22.41		$	42.46		$	39.39		$	32.71
Income from Investment Operations
Net investment income/(loss) (a)		0.03			0.08			0.27			0.04			(0.00	)(b)
Net realized and unrealized gain/(loss)		7.02			10.92			(19.72	)		6.39			10.66
Total from Investment Operations		7.05			11.00			(19.45	)		6.43			10.66
Less Distributions to Shareholders
From net investment income		(0.31	)		(0.20	)		—			(0.00	)(b)		(0.07	)
From net realized gains		—			—			(0.60	)		(3.36	)		(3.91	)
Total Distributions to Shareholders		(0.31	)		(0.20	)		(0.60	)		(3.36	)		(3.98	)
Redemption Fees
Redemption fees added to paid in capital (a)(b)		0.00			0.00			0.00			0.00			0.00
Increase from regulatory settlements		0.00	(b)		0.01			—			—			—
Net Asset Value, End of Period	$	39.96		$	33.22		$	22.41		$	42.46		$	39.39
Total Return (c)		21.49	%		49.36	%		(46.41	)%		16.25	%(d)		33.26	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.96	%		2.03	%		1.90	%		1.81	%		1.89	%
Net investment income/(loss) (e)		0.08	%		0.29	%		0.77	%		0.08	%		(0.01	)%
Waiver/Reimbursement		—			—			—			0.01	%		0.02	%
Portfolio turnover rate		25	%		31	%		38	%		28	%		31	%
Net assets at end of period (000s)	$	29,368		$	38,835		$	39,153		$	103,631		$	94,165

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Rounds to less than $0.01 per share.

(c)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

See accompanying notes to financial statements.

82

Columbia Acorn International

Class C Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	33.08		$	22.30		$	42.32		$	39.35		$	32.68
Income from Investment Operations
Net investment income/(loss) (a)		(0.05	)		0.02			0.21			(0.06	)		(0.05	)
Net realized and unrealized gain/(loss)		7.03			10.89			(19.63	)		6.39			10.66
Total from Investment Operations		6.98			10.91			(19.42	)		6.33			10.61
Less Distributions to Shareholders
From net investment income		(0.27	)		(0.14	)		—			(0.00	)(b)		(0.03	)
From net realized gains		—			—			(0.60	)		(3.36	)		(3.91	)
Total Distributions to Shareholders		(0.27	)		(0.14	)		(0.60	)		(3.36	)		(3.94	)
Redemption Fees
Redemption fees added to paid in capital (a)(b)		0.00			0.00			0.00			0.00			0.00
Increase from regulatory settlements		0.00	(b)		0.01			—			—			—
Net Asset Value, End of Period	$	39.79		$	33.08		$	22.30		$	42.32		$	39.35
Total Return (c)		21.34	%		49.12	%		(46.50	)%		16.01	%(d)		33.14	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		2.11	%		2.17	%		2.08	%		1.99	%		2.01	%
Net investment income/(loss) (e)		(0.13	)%		0.07	%		0.60	%		(0.14	)%		(0.14	)%
Waiver/Reimbursement		—			—			—			0.00	%(f)		0.01	%
Portfolio turnover rate		25	%		31	%		38	%		28	%		31	%
Net assets at end of period (000s)	$	110,931		$	85,625		$	62,906		$	153,416		$	99,425

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Rounds to less than $0.01 per share.

(c)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Rounds to less than 0.01%.

Class I Shares	Period ended December 31,
Selected data for a share outstanding throughout the period	2010(a)
Net Asset Value, Beginning of Period	$	37.69
Income from Investment Operations
Net investment income (b)		0.08
Net realized and unrealized gain		3.49
Total from Investment Operations		3.57
Less Distributions to Shareholders
From net investment income		(0.34	)
Redemption Fees
Redemption fees added to paid in capital (b)(c)		0.00
Net Asset Value, End of Period	$	40.92
Total Return (d)(e)		9.50	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)(g)		0.94	%
Net investment income (f)(g)		0.77	%
Portfolio turnover rate (e)		25	%
Net assets at end of period (000s)	$	66,581

(a)  Class I Shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(b)  Per share data was calculated using the average shares outstanding during the period.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested.

(e)  Not annualized.

(f)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(g)  Annualized.

See accompanying notes to financial statements.

83

Columbia Acorn Family of Funds

Financial Highlights, continued

Columbia Acorn USA

Class A Shares	Year Ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	22.43		$	15.90		$	27.23		$	28.02		$	26.52
Income from Investment Operations
Net investment loss (a)		(0.15	)		(0.11	)		(0.14	)		(0.09	)(b)		(0.10	)
Net realized and unrealized gain/(loss)		5.26			6.64			(10.23	)		1.01			2.21
Total from Investment Operations		5.11			6.53			(10.37	)		0.92			2.11
Less Distributions to Shareholders
From net realized gains		—			—			(0.96	)		(1.71	)		(0.61	)
Increase from regulatory settlements		—			0.00	(c)		—			—			—
Net Asset Value, End of Period	$	27.54		$	22.43		$	15.90		$	27.23		$	28.02
Total Return (d)		22.78	%		41.07	%		(39.38	)%		3.18	%(e)(f)		7.95	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.30	%		1.32	%		1.29	%		1.25	%		1.26	%
Net investment loss (g)		(0.64	)%		(0.64	)%		(0.60	)%		(0.29	)%		(0.35	)%
Waiver/Reimbursement		—			—			—			0.00	%(h)		0.01	%
Portfolio turnover rate		32	%		28	%		23	%		21	%		13	%
Net assets at end of period (000s)	$	214,097		$	178,605		$	136,597		$	245,085		$	245,552

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.09 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by less than 0.01% and less than $0.01, respectively.

(g)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(h)  Rounds to less than 0.01%.

Class B Shares	Year Ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	20.99		$	14.98		$	25.87		$	26.87		$	25.61
Income from Investment Operations
Net investment loss (a)		(0.30	)		(0.22	)		(0.27	)		(0.25	)(b)		(0.27	)
Net realized and unrealized gain/(loss)		4.91			6.23			(9.66	)		0.96			2.14
Total from Investment Operations		4.61			6.01			(9.93	)		0.71			1.87
Less Distributions to Shareholders
From net realized gains		—			—			(0.96	)		(1.71	)		(0.61	)
Increase from regulatory settlements		—			0.00	(c)		—			—			—
Net Asset Value, End of Period	$	25.60		$	20.99		$	14.98		$	25.87		$	26.87
Total Return (d)		21.96	%		40.12	%		(39.75	)%		2.53	%(e)(f)		7.29	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.98	%		2.02	%		1.92	%		1.85	%		1.93	%
Net investment loss (g)		(1.37	)%		(1.33	)%		(1.24	)%		(0.87	)%		(1.01	)%
Waiver/Reimbursement		—			—			—			0.01	%		0.02	%
Portfolio turnover rate		32	%		28	%		23	%		21	%		13	%
Net assets at end of period (000s)	$	9,222		$	20,903		$	23,633		$	53,820		$	65,040

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.09 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by less than 0.01% and less than $0.01, respectively.

(g)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

See accompanying notes to financial statements.

84

Columbia Acorn USA

Class C Shares	Year Ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	20.84		$	14.89		$	25.77		$	26.81		$	25.59
Income from Investment Operations
Net investment loss (a)		(0.31	)		(0.24	)		(0.30	)		(0.30	)(b)		(0.30	)
Net realized and unrealized gain/(loss)		4.86			6.19			(9.62	)		0.97			2.13
Total from Investment Operations		4.55			5.95			(9.92	)		0.67			1.83
Less Distributions to Shareholders
From net realized gains		—			—			(0.96	)		(1.71	)		(0.61	)
Increase from regulatory settlements		—			0.00	(c)		—			—			—
Net Asset Value, End of Period	$	25.39		$	20.84		$	14.89		$	25.77		$	26.81
Total Return (d)		21.83	%		39.96	%		(39.87	)%		2.39	%(e)(f)		7.14	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		2.08	)%		2.13	%		2.08	%		2.03	%		2.05	%
Net investment loss (g)		(1.41	)%		(1.45	)%		(1.39	)%		(1.07	)%		(1.14	)%
Waiver/Reimbursement		—			—			—			0.00	%(h)		0.01	%
Portfolio turnover rate		32	%		28	%		23	%		21	%		13	%
Net assets at end of period (000s)	$	36,101		$	32,508		$	25,899		$	50,743		$	55,306

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.09 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by less than 0.01% and less than $0.01, respectively.

(g)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(h)  Rounds to less than 0.01%.

Class I Shares	Period Ended December 31,
Selected data for a share outstanding throughout the period	2010(a)
Net Asset Value, Beginning of Period	$	24.24
Income from Investment Operations
Net investment income (b)		(0.03	)
Net realized and unrealized gain/(loss)		4.35
Total from Investment Operations		4.32
Net Asset Value, End of Period	$	28.56
Total Return (c)(d)		17.82	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)(f)		0.94	%
Net investment income (e)(f)		(0.35	)%
Portfolio turnover rate (d)		32	%
Net assets at end of period (000s)	$	28,993

(a)  Class I shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(b)  Per share data was calculated using the average shares outstanding during the period.

(c)  Total return at net asset value assuming all distributions reinvested.

(d)  Not annualized.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Annualized.

See accompanying notes to financial statements.

85

Columbia Acorn Family of Funds

Financial Highlights, continued

Columbia Acorn International Select

Class A Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	23.39		$	17.99		$	31.74		$	27.68		$	20.36
Income from Investment Operations
Net investment income (a)		0.08			0.10			0.20			0.04	(b)		0.03
Net realized and unrealized gain/(loss)		4.84			5.43			(13.41	)		5.91			7.29
Total from Investment Operations		4.92			5.53			(13.21	)		5.95			7.32
Less Distributions to Shareholders
From net investment income		(0.30	)		(0.15	)		—			(0.12	)		—
From net realized gains		—			—			(0.54	)		(1.77	)		—
Total Distributions to Shareholders		(0.30	)		(0.15	)		(0.54	)		(1.89	)		—
Redemption Fees
Redemption fees added to paid in capital (a)(c)		0.00			0.00			0.00			0.00			0.00
Increase from regulatory settlements		0.00	(c)		0.02			—			—			—
Net Asset Value, End of Period	$	28.01		$	23.39		$	17.99		$	31.74		$	27.68
Total Return (d)		21.41	%		31.01	%		(42.30	)%		21.50	%(e)		35.97	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		1.56	%		1.56	%		1.54	%		1.49	%		1.58	%
Net investment income (f)		0.33	%		0.53	%		0.78	%		0.11	%		0.11	%
Waiver/Reimbursement		—			—			—			0.00	%(g)		0.02	%
Portfolio turnover rate		42	%		56	%		68	%		57	%		47	%
Net assets at end of period (000s)	$	71,668		$	64,664		$	46,522		$	48,538		$	22,599

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.07 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(g)  Rounds to less than 0.01%.

Class B Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	22.34		$	17.16		$	30.50		$	26.73		$	19.80
Income from Investment Operations
Net investment income/(loss) (a)		(0.06	)		(0.01	)		0.04			(0.13	)(b)		(0.12	)
Net realized and unrealized gain/(loss)		4.62			5.17			(12.84	)		5.67			7.05
Total from Investment Operations		4.56			5.16			(12.80	)		5.54			6.93
Less Distributions to Shareholders
From net investment income		(0.18	)		—			—			—			—
From net realized gains		—			—			(0.54	)		(1.77	)		—
Total Distributions to Shareholders		(0.18	)		—			(0.54	)		(1.77	)		—
Redemption Fees
Redemption fees added to paid in capital (a)(c)		0.00			0.00			0.00			0.00			0.00
Increase from regulatory settlements		0.00	(c)		0.02			—			—			—
Net Asset Value, End of Period	$	26.72		$	22.34		$	17.16		$	30.50		$	26.73
Total Return (d)		20.63	%(e)		30.19	%(e)		(42.68	)%		20.69	%(e)		35.00	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		2.20	%		2.20	%		2.17	%		2.10	%		2.25	%
Net investment income/(loss) (f)		(0.27	)%		(0.05	)%		0.16	%		(0.45	)%		(0.53	)%
Waiver/Reimbursement		0.04	%		0.12	%		—			0.01	%		0.04	%
Portfolio turnover rate		42	%		56	%		68	%		57	%		47	%
Net assets at end of period (000s)	$	3,030		$	3,887		$	4,444		$	11,941		$	9,787

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.07 per share.

(c)  Rounds to less than $0.01 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

See accompanying notes to financial statements.

86

Columbia Acorn International Select

Class C Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	22.21		$	17.08		$	30.42		$	26.70		$	19.80
Net investment income/(loss) (a)		(0.10	)		(0.06	)		0.00	(b)		(0.20	)(c)		(0.15	)
Net realized and unrealized gain/(loss)		4.60			5.17			(12.80	)		5.69			7.05
Total from Investment Operations		4.50			5.11			(12.80	)		5.49			6.90
Less Distributions to Shareholders
From net investment income		(0.13	)		—			—			—			—
From net realized gains		—			—			(0.54	)		(1.77	)		—
Total Distributions to Shareholders		(0.13	)		—			(0.54	)		(1.77	)		—
Redemption Fees
Redemption fees added to paid in capital (a)(b)		0.00			0.00			0.00			0.00			0.00
Increase from regulatory settlements		0.00	(b)		0.02			—			—			—
Net Asset Value, End of Period	$	26.58		$	22.21		$	17.08		$	30.42		$	26.70
Total Return (d)		20.45	%		30.04	%		(42.79	)%		20.53	%(e)		34.85	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		2.36	%		2.42	%		2.34	%		2.29	%		2.38	%
Net investment income/(loss) (f)		(0.45	)%		(0.30	)%		0.01	%		(0.68	)%		(0.67	)%
Waiver/Reimbursement		—			—			—			0.01	%		0.02	%
Portfolio turnover rate		42	%		56	%		68	%		57	%		47	%
Net assets at end of period (000s)	$	11,885		$	11,096		$	9,747		$	13,023		$	7,060

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Rounds to less than $0.01 per share.

(c)  Net investment income per share includes special dividends. The effect of these dividends amounted to $0.07 per share.

(d)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(e)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(f)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

Class I Shares	Period ended December 31,
Selected data for a share outstanding throughout the period	2010(a)
Net Asset Value, Beginning of Period	$	26.11
Income from Investment Operations
Net investment income (b)		0.03
Net realized and unrealized gain		2.19
Total from Investment Operations		2.22
Net Asset Value, End of Period	$	28.33
Total Return (c)(d)		8.50	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)(f)		1.14	%
Net investment income (e)(f)		0.44	%
Portfolio turnover rate (d)		42	%
Net assets at end of period (000s)	$	3

(a)  Class I shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(b)  Per share data was calculated using the average shares outstanding during the period.

(c)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(d)  Not annualized.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Annualized.

See accompanying notes to financial statements.

87

Columbia Acorn Family of Funds

Financial Highlights, continued

Columbia Acorn Select

Class A Shares	Year Ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	22.81		$	13.77		$	27.89		$	26.18		$	22.47
Income from Investment Operations
Net investment loss (a)		(0.18	)		(0.14	)		(0.18	)		(0.15	)		(0.13	)
Net realized and unrealized gain/(loss)		5.31			9.18			(13.25	)		2.50			4.45
Total from Investment Operations		5.13			9.04			(13.43	)		2.35			4.32
Less Distributions to Shareholders
From net investment income		—			—			—			—			(0.02	)
From net realized gains		—			—			(0.69	)		(0.64	)		(0.59	)
Total Distributions to Shareholders		—			—			(0.69	)		(0.64	)		(0.61	)
Net Asset Value, End of Period	$	27.94		$	22.81		$	13.77		$	27.89		$	26.18
Total Return (b)		22.49	%		65.65	%		(49.31	)%(c)		8.92	%(d)		19.32	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.28	%		1.30	%		1.24	%		1.19	%		1.24	%
Net investment loss (e)		(0.73	)%		(0.78	)%		(0.80	)%		(0.52	)%		(0.54	)%
Waiver/Reimbursement		—			—			—			0.00	%(f)		0.03	%
Portfolio turnover rate		28	%		19	%		28	%		14	%		21	%
Net assets at end of period (000s)	$	555,263		$	522,443		$	395,794		$	1,117,941		$	940,857

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by 0.101% and $0.01, respectively.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Rounds to less than 0.01%.

Class B Shares	Year Ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	21.41		$	13.02		$	26.57		$	25.13		$	21.71
Income from Investment Operations
Net investment loss (a)		(0.31	)		(0.24	)		(0.31	)		(0.31	)		(0.28	)
Net realized and unrealized gain/(loss)		4.96			8.63			(12.55	)		2.39			4.29
Total from Investment Operations		4.65			8.39			(12.86	)		2.08			4.01
Less Distributions to Shareholders
From net realized gains		—			—			(0.69	)		(0.64	)		(0.59	)
Net Asset Value, End of Period	$	26.06		$	21.41		$	13.02		$	26.57		$	25.13
Total Return (b)		21.72	%		64.44	%		(49.62	)%(c)		8.22	%(d)		18.54	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.92	%		2.01	%		1.87	%		1.79	%		1.91	%
Net investment loss (e)		(1.39	)%		(1.49	)%		(1.43	)%		(1.12	)%		(1.21	)%
Waiver/Reimbursement		—			—			—			0.01	%		0.03	%
Portfolio turnover rate		28	%		19	%		28	%		14	%		21	%
Net assets at end of period (000s)	$	72,203		$	88,004		$	73,152		$	199,182		$	214,260

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(c)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by 0.101% and $0.01, respectively.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

See accompanying notes to financial statements.

88

Columbia Acorn Select

Class C Shares	Year Ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	21.25		$	12.94		$	26.46		$	25.07		$	21.69
Income from Investment Operations
Net investment loss (a)		(0.34	)		(0.26	)		(0.34	)		(0.36	)		(0.31	)
Net realized and unrealized gain/(loss)		4.92			8.57			(12.49	)		2.39			4.28
Total from Investment Operations		4.58			8.31			(12.83	)		2.03			3.97
Less Distributions to Shareholders
From net realized gains		—			—			(0.69	)		(0.64	)		(0.59	)
Net Asset Value, End of Period	$	25.83		$	21.25		$	12.94		$	26.46		$	25.07
Total Return (b)		21.55	%		64.22	%		(49.71	)%(c)		8.04	%(d)		18.37	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		2.07	%		2.14	%		2.04	%		1.98	%		2.04	%
Net investment loss (e)		(1.52	)%		(1.62	)%		(1.60	)%		(1.31	)%		(1.34	)%
Waiver/Reimbursement		—			—			—			0.00	%(f)		0.03	%
Portfolio turnover rate		28	%		19	%		28	%		14	%		21	%
Net assets at end of period (000s)	$	98,445		$	93,121		$	70,962		$	197,100		$	173,152

(a)  Per share data was calculated using the average shares outstanding during the period.

(b)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(c)  Total return includes a voluntary reimbursement by the Adviser for a realized investment loss due to a trading error. This reimbursement increased total return and net asset value per share by 0.101% and $0.01, respectively.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Rounds to less than 0.01%.

Class I Shares	Period Ended December 31,
Selected data for a share outstanding throughout the period	2010(a)
Net Asset Value, Beginning of Period	$	24.74
Income from Investment Operations
Net investment income (b)		0.01
Net realized and unrealized gain		3.99
Total from Investment Operations		4.00
Net Asset Value, End of Period	$	28.74
Total Return (c)(d)		16.17	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)(f)		0.91	%
Net investment income (e)(f)		0.18	%
Portfolio turnover rate (d)		28	%
Net assets at end of period (000s)	$	7,832

(a)  Class I Shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(b)  Per share data was calculated using the average shares outstanding during the period.

(c)  Total return at net asset value assuming all distributions reinvested.

(d)  Not annualized.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(f)  Annualized.

See accompanying notes to financial statements.

89

Columbia Acorn Family of Funds

Financial Highlights, continued

Columbia Thermostat Fund

Class A Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	10.90		$	8.26		$	12.31		$	12.59		$	12.49
Income from Investment Operations
Net investment income (a)		0.19			0.11			0.22			0.49			0.45
Net realized and unrealized gain/(loss)		1.67			2.53			(3.98	)		0.53			0.84
Total from Investment Operations		1.86			2.64			(3.76	)		1.02			1.29
Less Distributions to Shareholders
From net investment income		(0.18	)		(0.00	)(b)		(0.22	)		(0.51	)		(0.47	)
From net realized gains		—			—			(0.07	)		(0.79	)		(0.72	)
Total Distributions to Shareholders		(0.18	)		(0.00	)(b)		(0.29	)		(1.30	)		(1.19	)
Net Asset Value, End of Period	$	12.58		$	10.90		$	8.26		$	12.31		$	12.59
Total Return (c)(d)		17.28	%		31.98	%		(30.67	)%		8.19	%		10.56	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)(f)		0.50	%		0.50	%		0.50	%		0.50	%		0.50	%
Net investment income (f)		1.64	%		1.17	%		1.99	%		3.75	%		3.53	%
Waiver/Reimbursement		0.22	%		0.28	%		0.18	%		0.18	%		0.20	%
Portfolio turnover rate		118	%		17	%		130	%		128	%		66	%
Net assets at end of period (000s)	$	44,527		$	42,976		$	41,032		$	53,246		$	58,013

(a)  Per share data was calculated using the average shares outstanding during the period. Recognition of net investment income by the Fund is affected by the timing of the declaration of dividends by the underlying investment companies in which the Fund invests.

(b)  Rounds to less than $(0.01) per share.

(c)  Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(d)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)  Does not include expenses of the investment companies in which the Fund invests.

(f)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

Class B Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	10.93		$	8.32		$	12.38		$	12.62		$	12.51
Income from Investment Operations
Net investment income (a)		0.13			0.06			0.16			0.42			0.38
Net realized and unrealized gain/(loss)		1.67			2.55			(4.00	)		0.54			0.84
Total from Investment Operations		1.80			2.61			(3.84	)		0.96			1.22
Less Distributions to Shareholders
From net investment income		(0.09	)		—			(0.15	)		(0.41	)		(0.39	)
From net realized gains		—			—			(0.07	)		(0.79	)		(0.72	)
Total Distributions to Shareholders		(0.09	)		—			(0.22	)		(1.20	)		(1.11	)
Net Asset Value, End of Period	$	12.64		$	10.93		$	8.32		$	12.38		$	12.62
Total Return (b)(c)		16.64	%		31.37	%		(31.10	)%		7.71	%		9.91	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (d)(e)		1.00	%		1.00	%		1.00	%		1.00	%		1.06	%
Net investment income (e)		1.10	%		0.64	%		1.45	%		3.25	%		2.99	%
Waiver/Reimbursement		0.28	%		0.32	%		0.20	%		0.19	%		0.23	%
Portfolio turnover rate		118	%		17	%		130	%		128	%		66	%
Net assets at end of period (000s)	$	28,752		$	32,758		$	36,673		$	67,709		$	72,367

(a)  Per share data was calculated using the average shares outstanding during the period. Recognition of net investment income by the Fund is affected by the timing of the declaration of dividends by the underlying investment companies in which the Fund invests.

(b)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(c)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(d)  Does not include expenses of the investment companies in which the Fund invests.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

See accompanying notes to financial statements.

90

Columbia Thermostat Fund

Class C Shares	Year ended December 31,
Selected data for a share outstanding throughout each period	2010			2009			2008			2007			2006
Net Asset Value, Beginning of Period	$	10.91		$	8.33		$	12.37		$	12.62		$	12.51
Income from Investment Operations
Net investment income (a)		0.10			0.03			0.13			0.39			0.36
Net realized and unrealized gain/(loss)		1.68			2.55			(3.97	)		0.53			0.84
Total from Investment Operations		1.78			2.58			(3.84	)		0.92			1.20
Less Distributions to Shareholders
From net investment income		(0.07	)		—			(0.13	)		(0.38	)		(0.37	)
From net realized gains		—			—			(0.07	)		(0.79	)		(0.72	)
Total Distributions to Shareholders		(0.07	)		—			(0.20	)		(1.17	)		(1.09	)
Net Asset Value, End of Period	$	12.62		$	10.91		$	8.33		$	12.37		$	12.62
Total Return (b)(c)		16.43	%		30.97	%		(31.20	)%		7.36	%		9.72	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (d)(e)		1.25	%		1.25	%		1.25	%		1.25	%		1.25	%
Net investment income (e)		0.88	%		0.39	%		1.23	%		3.02	%		2.81	%
Waiver/Reimbursement		0.24	%		0.30	%		0.20	%		0.19	%		0.23	%
Portfolio turnover rate		118	%		17	%		130	%		128	%		66	%
Net assets at end of period (000s)	$	21,866		$	21,090		$	24,383		$	26,908		$	27,375

(a)  Per share data was calculated using the average shares outstanding during the period. Recognition of net investment income by the Fund is affected by the timing of the declaration of dividends by the underlying investment companies in which the Fund invests.

(b)  Total return at net asset value assuming all distributions reinvested and no contingent deferred sales charge.

(c)  Had the Adviser and/or Transfer Agent not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(d)  Does not include expenses of the investment companies in which the Fund invests.

(e)  The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

See accompanying notes to financial statements.

91

Columbia Acorn Family of Funds

Notes to Financial Statements

1.  Nature of Operations

Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select and Columbia Thermostat Fund (the Funds) are each a series of Columbia Acorn Trust (the Trust), an open-end management investment company organized as a Massachusetts business trust. The investment objective of each Fund is to seek long-term capital appreciation.

Columbia Thermostat Fund pursues its investment objective by investing in shares of other mutual funds. As a "fund of funds" under normal circumstances, the Fund allocates at least 95% of its net assets among a selected group of stock and bond mutual funds (portfolio funds) according to the current level of the Standard & Poor's (S&P) 500 Index in relation to predetermined ranges set by Columbia Wanger Asset Management, LLC (the Adviser). The Fund may invest up to 5% of its net assets plus any cash received that day in cash, repurchase agreements, high quality short-term paper and government securities.

Each Fund may issue an unlimited number of shares. Each Fund currently has five classes of shares: – Class A, Class B, Class C, Class I and Class Z – except Columbia Thermostat Fund, which does not have Class I shares. Effective February 29, 2008, the Funds no longer offer Class B shares (other than through dividend reinvestment).

Class A shares are sold with a front-end sales charge. Class A shares bought without an initial sales charge in accounts aggregating $1 million up to $50 million at the time of purchase are subject to a 1.00% contingent deferred sales charge (CDSC) if the shares are redeemed within 12 months of the date of purchase.

Class B shares are subject to a CDSC if redeemed within six years of purchase. Class B shares will convert to Class A shares automatically eight years after purchase.

Class C shares are offered at net asset value but are subject to a CDSC on redemptions made within one year after purchase.

Class I shares are offered continuously at net asset value. There are certain restrictions on the purchase of Class I shares.

Class Z shares are offered at net asset value. There are certain restrictions on who may purchase Class Z shares. Generally, Class Z shares of a Fund may be exchanged for shares of another fund distributed by Columbia Management Distributors, Inc. at no additional charge.

The financial highlights for the Fund's Class Z shares are presented in a separate annual report.

Investment income, realized and unrealized gains and losses, and certain fund-level expenses are allocated pro rata on the basis of the relative net assets of all classes, except that each class bears certain expenses specific to that class such as distribution services, transfer agency, and certain other class specific expenses. Differences in class expenses may result in payment of different dividend distributions for each class. All of the Funds' share classes have equal rights with respect to voting, subject to Fund or class specific matters.

2.  Significant Accounting Policies

The preparation of financial statements in accordance with accounting principles generally accepted in the United States of America (GAAP) requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.

>Security valuation

Securities of the Funds are valued at market value or, if a market quotation for a security is not readily available or is deemed not to be reliable because of events or circumstances that have occurred between the market quotation and the time as of which the security is to be valued, the security is valued at a fair value determined in good faith under consistently applied procedures established by the Board of Trustees. With respect to Columbia Thermostat Fund, investments in portfolio funds are valued at their net asset values as reported by the portfolio funds. A security traded on a securities exchange or in an over-the-counter market in which transaction prices are reported is valued at the last sales price at the time of valuation. A security traded principally on NASDAQ is valued at the NASDAQ official closing price. Mutual Funds and Exchange Traded Funds are valued at their closing net asset value as reported to NASDAQ. A security for which there is no reported sale on the valuation date is valued at the latest bid quotation. Short-term investments maturing in 60 days or less are valued at amortized cost, which approximates market value. A security for which a market quotation is not readily available and any other assets are valued at their fair value determined in good faith under consistently applied procedures established by the Board of Trustees. The Funds have retained an independent statistical fair value pricing service that employs a systematic methodology to assist in the fair valuation process for securities principally traded in a foreign market in order to adjust for possible changes in value that may occur between the close of

92

the foreign exchange and the time as of which the securities are to be valued. If a security is valued at fair value, that value may be different from the last quoted market price for the security.

Various inputs are used in determining the value of each Fund's investments, following the input prioritization hierarchy established by GAAP. These inputs are summarized in the three broad levels listed below:

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

• Level 3 – prices determined using significant unobservable inputs where quoted prices or observable inputs are unavailable or less reliable (including management's own assumptions about the factors market participants would use in pricing an investment)

The inputs or methodologies used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Examples of the types of securities in which the Funds would typically invest and how they are classified within this hierarchy are as follows. Typical Level 1 securities include exchange traded domestic equities, mutual funds whose NAVs are published each day and exchange traded foreign equities that are not statistically fair valued. Typical Level 2 securities include exchange traded foreign equities that are statistically fair valued, forward foreign currency exchange contracts and short-term investments valued at amortized cost. Additionally, securities fair valued by the Fund's Valuation Committee that rely on significant observable inputs are also included in Level 2. Typical Level 3 securities include any security fair valued by the Funds' Valuation Committee that relies on significant unobservable inputs.

>Repurchase agreements

Each Fund may engage in repurchase agreement transactions. Each Fund, through its custodian, receives delivery of underlying securities collateralizing repurchase agreements. The counterparty is required to maintain collateral that is at all times at least equal to the repurchase price including interest. In the event of default or bankruptcy by the counterparty to the agreement, realization and/or retention of the collateral may be subject to legal proceedings.

>Foreign currency translations

Values of investments denominated in foreign currencies are converted into U.S. dollars using the New York spot market rate of exchange at the time of valuation. Purchases and sales of investments and dividend and interest income are translated into U.S. dollars using the spot market rate of exchange prevailing on the respective dates of such transactions. The gain or loss resulting from changes in foreign exchange rates is included with net realized and unrealized gain or loss from investments, as appropriate.

>Forward foreign currency exchange contracts

Columbia Acorn International may enter into forward foreign currency exchange contracts in order to seek to minimize the risk from adverse changes in the relationship between the U.S. dollar and foreign currencies. A forward foreign currency exchange contract is a commitment to purchase or sell a foreign currency at a future date at a negotiated forward rate. Forward foreign currency exchange contracts are valued at the interpolated forward exchange rate of the underlying currencies and any market gain or loss, arising from the difference between the original value and the current value of such contract, is included as a component of unrealized gain/(loss) on the Statements of Operations. Open forward foreign currency exchange contracts, if any, are disclosed in the Notes to the Statement of Investments. As forward foreign currency exchange contracts are closed the resulting gain or loss, arising from the difference between the original val ue of the contract and the closing value of such contract, is included as a component of realized gain/(loss) on the Statements of Operations.

A forward foreign currency exchange contract would limit the risk of loss due to a decline in the value of a particular currency; however, it also would limit any potential gain that might result should the value of the currency increase instead of decrease. These contracts may involve market risk in excess of the unrealized gain or loss reflected on the Statements of Assets and Liabilities. In addition, a Fund could be exposed to counterparty risks if counterparties to the contracts are unable to meet the terms of their contracts. The counterparty risk exposure is, therefore, closely monitored and contracts are only executed with high credit quality financial institutions.

A Fund may use forward foreign currency exchange contracts to buy or sell a foreign currency when the Adviser believes it has exposure to a foreign currency which may suffer or enjoy a movement against another foreign currency to which

93

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

the Fund has exposure. A Fund will not attempt to hedge all of its foreign portfolio positions.

For additional information on derivative instruments, please see Note 5.

>Securities lending

Each Fund, except Columbia Thermostat Fund, may lend securities up to one-third of the value of its total assets to certain approved brokers, dealers and other financial institutions to earn additional income. In lending its securities, the Fund retains the benefits of owning the securities, including receipt of dividends or interest generated by the security. Each Fund also receives a fee for the loan. Each Fund has the ability to recall the loans at any time and could do so in order to vote proxies or to sell the loaned securities. Each loan is collateralized by cash that exceeds the value of the securities on loan. The market value of the loaned securities is determined daily at the close of business of each Fund and any additional required collateral is delivered to each Fund on the next business day. Each Fund has elected to invest the cash collateral in the Dreyfus Government Cash Management Fund, and the income earned is paid to each Fund, net of any fees remitted to Goldman Sachs Agency Lending as the lending agent and net of any borrower rebates. The Adviser does not retain any fees earned by the lending program. Generally, in the event of borrower default, a Fund has the right to use the collateral to offset any losses incurred. In the event a Fund is delayed or prevented from exercising its right to dispose of the collateral, there may be a potential loss to a Fund. Some of these losses may be indemnified by the lending agent. Each Fund bears the risk of loss with respect to the investment of collateral.

The net lending income earned in 2010 by each Fund is included in the Statements of Operations.

>Security transactions and investment income

Security transactions, investment income and shareholder fund transactions are accounted for on the trade date (date the order to buy or sell is executed) and dividend income and realized gain distributions from other funds are recorded on the ex-dividend date, except that certain dividends from foreign securities are recorded as soon as the information is available to the Funds. Interest income is recorded on the accrual basis and includes amortization of discounts on debt obligations when required for federal income tax purposes. Realized gains and losses from security transactions are recorded on an identified cost basis.

Awards, if any, from class action litigation related to securities owned may be recorded as a reduction of cost of those securities. If the applicable securities are no longer owned, the proceeds are recorded as realized gains.

The Funds estimate the tax character of distributions from real estate investment trusts (REITs). Distributions received in excess of income are recorded as a reduction of the cost of the related investments. If the applicable securities are no longer owned, any distributions received in excess of income are recorded as realized gains.

>Restricted securities

Restricted securities are securities that may only be resold upon registration under federal securities laws or in transactions exempt from registration. In some cases, the issuer of restricted securities has agreed to register such securities for resale at the issuer's expense either upon demand by the Funds or in connection with another registered offering of the securities. Many restricted securities may be resold in the secondary market in transactions exempt from registration. Such restricted securities may be determined to be liquid under criteria established by the Board of Trustees.

>Fund share valuation

Fund shares are sold and redeemed on a daily basis at net asset value, subject to any applicable sales charge. Net asset value per share is determined daily as of the close of trading on the New York Stock Exchange (NYSE) on each day the NYSE is open for trading. Generally, income, expenses and realized and unrealized gain/(losses) of a Fund are allocated to each class proportionately on a daily basis for purposes of determining the net asset value of each class. The Rule 12b-1 service and distribution fees and transfer agency fees are charged to each specific class as expenses are incurred. Redemption fees are accounted for as an addition to paid in capital for purposes of determining the net asset value of each class.

>Custody fees/credits

Custody fees are reduced based on each Fund's cash balances maintained with the custodian. The amount is disclosed as a reduction of total expenses on the Statements of Operations.

>Federal income taxes

It is each Fund's policy to comply with the provisions of the Internal Revenue Code available to regulated investment companies and, in the manner provided therein, distribute substantially all their taxable income, as well as any net realized gain on sales of investments and foreign currency transactions reportable for federal income tax purposes. Columbia Thermostat Fund distributes all of its taxable income, as well as any net realized gain on sales of portfolio fund shares and any distributions of net realized gains received by

94

the Fund from its portfolio funds, reportable for federal income tax purposes. Accordingly, the Funds paid no federal income taxes and no federal income tax provision was required.

>Foreign capital gains taxes

Realized gains in certain countries may be subject to foreign taxes at the fund level, at rates ranging from approximately 10% to 15%. The Funds accrue for such foreign taxes on net realized and unrealized gains at the appropriate rate for each jurisdiction.

>Distributions to Shareholders

Distributions to shareholders are recorded on the ex-dividend date.

>Indemnification

In the normal course of business, the Trust on behalf of the Funds enters into contracts that contain a variety of representations and warranties and that provide general indemnities. A Fund's maximum exposure under these arrangements is unknown, as this would involve future claims against the Fund. Also, under the Trust's organizational documents, the trustees and officers of the Trust are indemnified against certain liabilities that may arise out of their duties to the Trust. However, based on experience, the Funds expect the risk of loss due to these warranties and indemnities to be remote.

3.  Federal Tax Information

The timing and character of income and capital gain distributions are determined in accordance with income tax regulations, which may differ from GAAP. Reclassifications are made to the Funds' capital accounts for permanent tax differences to reflect income and gains available for distribution (or available capital loss carryforwards) under income tax regulations.

For the year ended December 31, 2010, permanent book and tax basis differences resulting primarily from differing treatments for net operating losses, foreign currency transactions, passive foreign investment company (PFIC) adjustments, short-term capital gain distributions from investments in mutual funds and proceeds from litigation settlements were identified and reclassified among the components of each Fund's net assets as follows:

	Undistributed/ (Overdistributed) or (Accumulated) Net Investment Income (Loss)		Accumulated Net Realized Gain/(Loss)			Paid-in Capital
(in thousands)
Columbia Acorn Fund	$	590	$	(589	)	$	(1	)
Columbia Acorn International		43,968		(42,361	)		(1,607	)
Columbia Acorn USA		6,009		—			(6,009	)
Columbia Acorn International Select		330		(284	)		(46	)
Columbia Acorn Select		2,926		(2,926	)		—
Columbia Thermostat Fund		92		(92	)		—

Net investment income/(loss) and net realized gains/(losses), as disclosed on the Statements of Operations, and net assets were not affected by these reclassifications.

The tax character of distributions paid during the years ended December 31, 2010 and December 31, 2009 was as follows:

	December 31, 2010				December 31, 2009
	Ordinary Income*		Long-Term Capital Gains		Ordinary Income*		Long-Term Capital Gains
(in thousands)
Columbia Acorn Fund	$	21,020	$	496,293	$	20,981	$	—
Columbia Acorn International		122,919		—		60,207		—
Columbia Acorn USA		—		—		—		—
Columbia Acorn International Select		6,107		—		3,533		—
Columbia Acorn Select		—		—		—		—
Columbia Thermostat Fund		1,666		—		122		—

*For tax purposes short-term capital gain distributions, if any, are considered ordinary income distributions.

As of December 31, 2010, the components of distributable earnings on a tax basis were as follows:

	Undistributed Ordinary Income		Undistributed Long-Term Capital Gains		Net Unrealized Appreciation*
(in thousands)
Columbia Acorn Fund	$	38,838	$	183,753	$	6,469,997
Columbia Acorn International		156,914		—		1,662,843
Columbia Acorn USA		—		—		513,833
Columbia Acorn International Select		5,840		—		112,829
Columbia Acorn Select		31,148		—		598,661
Columbia Thermostat Fund		1,509		—		18,580

*The differences between book-basis and tax-basis net unrealized appreciation/(depreciation) are primarily due to deferral of losses from wash sales and PFIC adjustments.

The following capital loss carryforwards, determined as of December 31, 2010, may be available to reduce taxable income arising from future net realized gains on investments, if any, to the extent permitted by the Internal Revenue Code:

	Year of Expiration
	2011- 2015		2016		2017		2018		Total
(in thousands)
Columbia Acorn International	$	—	$	—	$	386,385	$	—	$	386,385
Columbia Acorn USA		—		—		28,408		—		28,408
Columbia Acorn International Select		—		—		36,610		—		36,610
Columbia Acorn Select		—		3,592		115,445		—		119,037
Columbia Thermostat Fund		—		5,193		21,738		2,954		29,885

Capital loss carryforwards that were utilized for the Funds during the year ended December 31, 2010 were as follows:

(in thousands)
Columbia Acorn Fund	$	409,911
Columbia Acorn International		238,546
Columbia Acorn USA		85,334
Columbia Acorn International Select		40,289
Columbia Acorn Select		8,679

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Columbia Acorn Family of Funds

Notes to Financial Statements, continued

Management is required to determine whether a tax position of the Funds is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any related appeals or litigation processes, based on the technical merits of the position. The tax benefit to be recognized by the Funds is measured as the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. Management is not aware of any tax positions for which it is reasonably possible that the total amounts of unrecognized tax benefits will significantly change in the next twelve months. However, management's conclusions may be subject to review and adjustment at a later date based on factors including, but not limited to, new tax laws, regulations, and administrative interpretations (including relevant court decisions). The Funds' federal tax returns for the prior three fiscal years remain s ubject to examination by the Internal Revenue Service.

4.  Transactions with Affiliates

CWAM is a wholly owned subsidiary of Columbia Management Investment Advisors, LLC (CMIA), (formerly, Riversource Investments, LLC), which in turn is a, wholly owned subsidiary of Ameriprise Financial, Inc. (Ameriprise Financial). CWAM furnishes continuing investment supervision to the Funds and is responsible for the overall management of the Funds' business affairs.

After the close of business on April 30, 2010 (the Closing), Ameriprise Financial acquired from Bank of America Corporation (BoA), a portion of the asset management business of Columbia Management Group, LLC, including 100% of CWAM. On May 27, 2010, the shareholders of the Funds approved a new investment advisory agreement with CWAM to provide advisory services to the Funds. There were no changes to the Funds' advisory fee rate under the new agreement.

CWAM receives a monthly advisory fee based on each Fund's average daily net assets at the following annual rates:

Columbia Acorn Fund

Average Daily Net Assets	Annual Fee Rate
Up to $700 million		0.74	%
$700 million to $2 billion		0.69	%
$2 billion to $6 billion		0.64	%
$6 billion and over		0.63	%

Columbia Acorn International

Average Daily Net Assets	Annual Fee Rate
Up to $100 million		1.19	%
$100 million to $500 million		0.94	%
$500 million and over		0.74	%

Columbia Acorn USA

Average Daily Net Assets	Annual Fee Rate
Up to $200 million		0.94	%
$200 million to $500 million		0.89	%
$500 million to $2 billion		0.84	%
$2 billion to $3 billion		0.80	%
$3 billion and over		0.70	%

Columbia Acorn International Select

Average Daily Net Assets	Annual Fee Rate
Up to $500 million		0.94	%
$500 million and over		0.90	%

Columbia Acorn Select

Average Daily Net Assets	Annual Fee Rate
Up to $700 million		0.85	%
$700 million to $2 billion		0.80	%
$2 billion to $3 billion		0.75	%
$3 billion and over		0.70	%

Columbia Thermostat Fund

	Annual Fee Rate
All Average Daily Net Assets		0.10	%

For the year ended December 31, 2010, the Funds' effective investment advisory fee rates were as follows:

Columbia Acorn Fund	0.64	%
Columbia Acorn International	0.77	%
Columbia Acorn USA	0.86	%
Columbia Acorn International Select	0.94	%
Columbia Acorn Select	0.82	%
Columbia Thermostat Fund	0.10	%

>Expense Limit

CWAM has voluntarily agreed to reimburse the ordinary operating expenses (exclusive of brokerage commissions, interest, taxes and extraordinary expenses, but inclusive of custodial charges relating to overdrafts, if any) after giving effect to any balance credits from the Funds' custodian, exceeding annually the average daily net assets of the Funds as follows:

Fund	Class A			Class B			Class C			Class I
Columbia Acorn International Select		1.70	%		2.20	%		2.45	%		1.30	%
Columbia Acorn Select		1.60	%		2.10	%		2.35	%		1.25	%

This arrangement may be modified or terminated by either the Funds or CWAM on 30 days notice.

CWAM has contractually agreed to waive fees and/or reimburse expenses of Columbia Thermostat Fund so that the ordinary operating expenses (exclusive of distribution and service fees, interest and fees on borrowings, and expenses

96

associated with the Fund's investment in other investment companies, but including custodian charges relating to overdrafts, if any), after giving effect to any balance credits from the Fund's custodian, will not exceed 0.25% annually of the Fund's average daily net assets through April 30, 2011. There is no guarantee that this arrangement will continue thereafter.

Expenses reimbursed by CWAM to Columbia Acorn International Select and Columbia Thermostat Fund for the year ended December 31, 2010, were $1,817 and $266,413, respectively.

CWAM provides administrative services and receives an administration fee from the Funds at the following annual rates:

Columbia Acorn Trust

Aggregate Average Daily Net Assets of the Trust:	Annual Fee Rate
Up to $8 billion		0.050	%
$8 billion to $16 billion		0.040	%
$16 billion to $35 billion		0.030	%
$35 billion to $45 billion		0.025	%
$45 billion and over		0.015	%

For the year ended December 31, 2010, each Fund's effective administration fee rate was 0.04% of average daily net assets. Prior to the Closing, CWAM had delegated to Columbia Management Advisors, LLC (CMA) an indirect, wholly owned subsidiary of Bank of America Corporation (BOA), responsibility to provide certain sub-administrative services to the Funds. Following the Closing, Columbia Management succeeded CMA as sub-administrator and continued providing certain sub-administrative services to the Funds.

Prior to the Closing, Columbia Management Distributors, Inc., an indirect subsidiary of BOA, served as the Funds' distributor and principal underwriter. In connection with the Closing, Columbia Management Investment Distributors, Inc., (formerly, Riversource Fund Distributors, Inc.) (CMID) a wholly owned subsidiary of Ameriprise Financial, became the distributor of the Funds. There were no changes to the underwriting discount structure of the Funds or the service or distribution fee rates paid by the Funds as a result of the Closing.

For the year ended December 31, 2010, Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select and Columbia Thermostat Fund have been advised that CMDI retained $420,069 in underwriting discounts in connection with redemptions of Class A shares and received CDSCs of $4,038, $213,466 and $48,376, in connection with Class A, Class B and Class C share redemptions, respectively.

Each Fund has adopted a Rule 12b-1 (distribution and service) plan which requires it to pay CMID a monthly service fee equal to 0.25% annually of the average daily net assets attributable to Class A, Class B and Class C shares and a monthly distribution fee equal to 0.50% and 0.75%, annually, of the average daily net assets attributable to Class B and Class C shares, respectively. CMID receives no compensation with respect to Class Z shares.

Prior to the Closing, Columbia Management Services, Inc., an indirect, wholly owned subsidiary of BOA, provided shareholder services to the Funds and contracted with Boston Financial Data Services (BFDS) to serve as sub-transfer agent. Following the Closing, Columbia Management Investment Services Corp. (CMIS), (formerly, Riversource Service Corporation), a wholly owned subsidiary of Ameriprise Financial, became the transfer agent of the Funds. The transfer agent fee rates paid by the Funds did not change as a result of the change in transfer agent. For its services, each Fund pays CMIS a monthly fee at the annual rate of $17.00 per open account. CMIS also receives reimbursement for certain out-of-pocket expenses. The arrangement with BFDS has been continued by CMIS.

Class I shares do not pay transfer agent fees.

Certain officers and trustees of the Trust are also officers of CWAM. The Trust makes no direct payments to its officers and trustees who are affiliated with CWAM.

The Board of Trustees appointed a Chief Compliance Officer of the Trust in accordance with federal securities regulations. The Funds, along with other affiliated funds, pay their pro-rata share of the expenses associated with the Office of the Chief Compliance Officer. Those expenses are disclosed separately as "Chief compliance officer expenses" in the Statements of Operations.

The Trust offers a deferred compensation plan for its independent trustees. Under that plan, a trustee may elect to defer all or a portion of his or her compensation. Amounts deferred are retained by the Trust and may represent an unfunded obligation of the Trust. The value of amounts deferred is determined by reference to the change in value of Class Z shares of one or more series of the Trust or a money market fund specified by the trustee. Benefits under the deferred compensation plan are payable when the trustee ceases to be a member of the Board of Trustees.

An affiliated person of a Fund may include any company in which a Fund owns five percent or more of its outstanding voting shares. On December 31, 2010, Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA and

97

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

Columbia Acorn Select each held five percent or more of the outstanding voting securities of one or more companies. Details of investments in those affiliated companies are presented on pages 35, 36, 47, 58 and 70, respectively.

During the year ended December 31, 2010, the Funds engaged in purchase and sale transactions with funds that have a common investment adviser (or affiliated investment advisers), common directors/trustees, and/or common officers. Those transactions complied with Rule 17a-7 under the Investment Company Act of 1940 and were as follows:

	Purchases		Sales
(in thousands)
Columbia Acorn Fund	$	12,585	$	683
Columbia Acorn International		7,383		1,715
Columbia Acorn USA		704		1,016
Columbia Acorn International Select		334		381
Columbia Acorn Select		1,350		12,647

5.  Objectives and Strategies for Investing in Derivative Instruments

Columbia Acorn International uses derivative instruments including forward foreign currency exchange contracts in order to meet its investment objectives. The Fund employs strategies in differing combinations to permit it to increase, decrease or change the level of exposure to market risk factors. The achievement of any strategy involving derivatives depends on analysis of various risk factors, and if the strategies for the use of derivatives do not work as intended, the Fund may not achieve its investment objectives.

In pursuit of its investment objectives, the Fund is exposed to the following market risks:

Foreign Exchange Rate Risk: Foreign exchange rate risk relates to the change in the U.S. dollar value of a security held that is denominated in a foreign currency. The U.S. dollar value of a foreign-currency-denominated security will decrease as the dollar appreciates against the currency, while the U.S. dollar value will increase as the dollar depreciates against the currency.

The following note provides more detailed information about the derivative type held by the Columbia Acorn International:

Forward Foreign Currency Exchange Contracts

• The Fund entered into forward foreign currency exchange contracts to shift its investment exposure from one currency to another.

• The Fund used forward foreign currency exchange contracts to shift its U.S. dollar exposure in order to achieve a representative weighted mix of major currencies relative to its benchmark and/or to recover an underweight country exposure in its portfolio relative to its benchmark.

Forward foreign currency exchange contracts are agreements to exchange one currency for another at a future date at a specified price. These contracts are used to seek to minimize the exposure to foreign exchange rate fluctuations during the period between the trade and settlement dates of the contract. The Fund may utilize forward foreign currency exchange contracts in connection with the settlement of purchases and sales of securities. The Fund may also enter into these contracts to seek to reduce the exposure to adverse price movements in certain other foreign-currency-denominated assets. Contracts to buy are used to acquire exposure to foreign currencies, while contracts to sell are used to reduce the exposure to foreign exchange rate fluctuations. Forward foreign currency exchange contracts are valued daily at the current exchange rate of the underlying currency, resulting in unrealized gains (losses) which become realized at the time the forward foreign currency exchange contracts are closed or mature. Realized and unrealized gains (losses) arising from such transactions are included in net realized and unrealized gains (losses) on foreign currency transactions. The use of forward foreign currency exchange contracts does not eliminate fluctuations in the prices of the Fund's portfolio securities. While the maximum potential loss from such contracts is the aggregate face value in U.S. dollars at the time the contract was opened, exposure is typically limited to the change in value of the contract (in U.S. dollars) over the period it remains open. The Fund could also be exposed to risk that counterparties of the contracts may be unable to fulfill the terms of the contracts.

During the year ended December 31, 2010, Columbia Acorn International entered into 146 forward foreign currency exchange contracts.

The following table is a summary of the value of Columbia Acorn International's derivative instruments as of December 31, 2010.

Fair Value of Derivative Instruments

	Asset
	Statement of Assets and Liabilities	Fair Value
(in thousands)
	Unrealized appreciation on forward foreign currency exchange contracts	$11,287

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The effect of derivative instruments on Columbia Acorn International's Statement of Operations for the year ended December 31, 2010 was as follows:

Amount of Realized Gain or (Loss) and Change in Unrealized Appreciation or (Depreciation)
on Derivatives Recognized in Income

	Risk Exposure	Realized Gain/(Loss)		Change in Unrealized Appreciation/ (Depreciation)
(in thousands)
Forward foreign currency exchange contracts	Foreign Exchange Rate Risk	$	34,627	$	8,803

6.  Borrowing Arrangements

The Trust participates in a $150 million credit facility, along with another Trust managed by CWAM, which was entered into to facilitate portfolio liquidity. Under the facility, interest is charged to each participating fund based on its borrowings at a rate per annum equal to the higher of Federal Funds Rate or Overnight LIBOR plus 1.25%. In addition, a commitment fee of 0.15% per annum of the unutilized line of credit was accrued and apportioned among the participating funds based on their relative net assets. The commitment fee is included in "Other expenses" in the Statements of Operations. No amounts were borrowed by any Fund under this facility for the year ended December 31, 2010. The Trust enters into this line of credit for one year durations. The Trust has secured the line of credit for the entire year of 2011.

7.  Investment Transactions

The aggregate cost of purchases and proceeds from sales, other than short-term obligations, for the year ended December 31, 2010, were:

Columbia Acorn Fund

(in thousands)
Investment securities
Purchases	$	4,129,651
Proceeds from sales		4,459,270

Columbia Acorn International

(in thousands)
Investment securities
Purchases	$	1,668,861
Proceeds from sales		1,164,147

Columbia Acorn USA

(in thousands)
Investment securities
Purchases	$	454,468
Proceeds from sales		469,161

Columbia Acorn International Select

(in thousands)
Investment securities
Purchases	$	163,811
Proceeds from sales		204,032

Columbia Acorn Select

(in thousands)
Investment securities
Purchases	$	580,228
Proceeds from sales		529,594

Columbia Thermostat Fund

(in thousands)
Investment securities
Purchases	$	146,478
Proceeds from sales		174,366

8.  Redemption Fees

For the year ended December 31, 2010, the redemption fees imposed by Columbia Acorn International and Columbia Acorn International Select amounted to approximately $239,708 and $10,223, respectively, and are accounted for as additions to paid in capital. Effective September 1, 2010, Columbia Acorn International and Columbia Acorn International Select ceased to impose redemption fees.

9.  Regulatory Settlements with Third Parties

During the year ended December 31, 2010, Columbia Acorn International and Columbia Acorn International Select received payments totaling $446,565 and $46,265, respectively, representing distributions from a fair fund established in connection with a regulatory settlement between the Securities and Exchange Commission and a third party broker dealer relating to alleged market timing and late trading in mutual funds, including the Funds. The payments have been included in "Increase from regulatory settlements" in the Statements of Changes in Net Assets.

10.  Information Regarding Pending and Settled Legal Proceedings

In June 2004, an action captioned John E. Gallus et al. v. American Express Financial Corp. and American Express Financial Advisors Inc. was filed in the United States District Court for the District of Arizona. The plaintiffs allege that they are investors in several American Express Company (now known as legacy RiverSource) mutual funds and they purport to bring the action derivatively on behalf of those funds under the Investment Company Act of 1940. The plaintiffs allege that fees allegedly paid to the defendants by the funds for investment advisory and administrative services are excessive. The plaintiffs seek remedies including restitution and rescission of

99

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

investment advisory and distribution agreements. The plaintiffs voluntarily agreed to transfer this case to the United States District Court for the District of Minnesota (the District Court). In response to defendants' motion to dismiss the complaint, the District Court dismissed one of plaintiffs' four claims and granted plaintiffs limited discovery. Defendants moved for summary judgment in April 2007. Summary judgment was granted in the defendants' favor on July 9, 2007. The plaintiffs filed a notice of appeal with the Eighth Circuit Court of Appeals (the Eighth Circuit) on August 8, 2007. On April 8, 2009, the Eighth Circuit reversed summary judgment and remanded to the District Court for further proceedings. On August 6, 2009, defendants filed a writ of certiorari with the U.S. Supreme Court (the Supreme Court), asking the Supreme Court to stay the District Court proceedings while the Supreme Court considers and rules in a case caption ed Jones v. Harris Associates, which involves issues of law similar to those presented in the Gallus case. On March 30, 2010, the Supreme Court issued its ruling in Jones v. Harris Associates, and on April 5, 2010, the Supreme Court vacated the Eighth Circuit's decision in the Gallus case and remanded the case to the Eighth Circuit for further consideration in light of the Supreme Court's decision in Jones v. Harris Associates. On June 4, 2010, the Eighth Circuit remanded the Gallus case to the District Court for further consideration in light of the Supreme Court's decision in Jones v. Harris Associates. On December 9, 2010, the District Court reinstated its July 9, 2007 summary judgment order in favor of the defendants. On January 10, 2011, plaintiffs filed a notice of appeal with the Eighth Circuit.

In December 2005, without admitting or denying the allegations, American Express Financial Corporation (AEFC, which is now known as Ameriprise Financial, Inc. (Ameriprise Financial)), entered into settlement agreements with the Securities and Exchange Commission (SEC) and Minnesota Department of Commerce (MDOC) related to market timing activities. As a result, AEFC was censured and ordered to cease and desist from committing or causing any violations of certain provisions of the Investment Advisers Act of 1940, the Investment Company Act of 1940, and various Minnesota laws. AEFC agreed to pay disgorgement of $10 million and civil money penalties of $7 million. AEFC also agreed to retain an independent distribution consultant to assist in developing a plan for distribution of all disgorgement and civil penalties ordered by the SEC in accordance with various undertakings detailed at http://www.sec.gov/litigation/admin/ia-2451.pdf. Ameriprise Financial and its affiliates have cooperated with the SEC and the MDOC in these legal proceedings, and have made regular reports to the RiverSource, Seligman and Threadneedle funds' Boards of Directors/Trustees.

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Funds are not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Funds or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Funds. Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.s ec.gov.

There can be no assurance that these matters, or the adverse publicity associated with them, will not result in increased fund redemptions, reduced sale of fund shares or other adverse consequences to the Funds. Further, although we believe proceedings are not likely to have a material adverse effect on the Funds or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Funds, these proceedings are subject to uncertainties and, as such, we are unable to estimate the possible loss or range of loss that may result. An adverse outcome in one or more of these proceedings could result in adverse judgments, settlements, fines, penalties or other relief that could have a material adverse effect on the consolidated financial condition or results of operations of Ameriprise Financial.

**********

CWAM and the Trustees of the Trust (collectively, the Columbia defendants) were named as defendants in class and derivative complaints that were consolidated in a Multi-District Action (the MDL Action) in the federal district court of Maryland. These lawsuits contend that defendants permitted certain investors to market time their trades in certain Columbia Acorn Funds. The MDL Action is ongoing. However, all claims against the Trust and the Independent Trustees of the Trust have been dismissed.

Columbia Acorn Trust and CWAM are also defendants in a state court class action lawsuit that alleges, in summary, that the Trust and CWAM exposed shareholders of Columbia Acorn International to trading by market timers by allegedly: (a) failing to properly evaluate daily whether a significant event affecting

100

the value of the Fund's securities had occurred after foreign markets had closed but before the calculation of the Fund's net asset value (NAV); (b) failing to implement the Fund's portfolio valuation and share pricing policies and procedures; and (c) failing to know and implement applicable rules and regulations concerning the calculation of NAV (the Fair Valuation Lawsuit). The United States Court of Appeals for the Seventh Circuit ruled that the plaintiffs' state law claims were preempted under federal law, resulting in the dismissal of plaintiffs' complaint. Plaintiffs appealed the Seventh Circuit's ruling to the United States Supreme Court. The Supreme Court reversed the Seventh Circuit's ruling on jurisdictional grounds and the case was remanded to the state court.

On March 21, 2005, a class action complaint was filed against the Trust and CWAM seeking to rescind the contingent deferred sales charge (CDSC) assessed upon redemption of Class B shares of the Columbia Acorn Funds (the CDSC Lawsuit). In addition to the rescission of sales charges, plaintiffs seek recovery of actual damages, attorneys' fees and costs. The case was transferred to the MDL Action in the federal district court of Maryland.

On September 14, 2007, the plaintiffs and the Columbia defendants named in the MDL Action, including the Columbia family of funds, entered into a stipulation of settlement with respect to all Columbia-related claims in the MDL Action described above, including the CDSC and Fair Valuation Lawsuits.

On April 23, 2010, the parties to the MDL Action filed a motion seeking: (a) preliminary approval of the MDL settlements; (b) the conditional certification of the plaintiff class for purposes of settlement; (c) approval of the form and manner of giving notice to the plaintiff class of the proposed settlements; and, (d) approval of the proposed schedule for various deadlines in connection with the final settlement hearing. The motion was presented to and approved by the court on May 7, 2010.

On October 21, 2010, the court held a final hearing regarding the MDL settlements and on October 25, 2010 issued a final judgment and related orders that: (a) approved the settlements as fair, reasonable and adequate, and in the best interests of members of both the plaintiff class and current shareholders of the Columbia funds, including the Columbia Acorn Funds; (b) dismissed with prejudice all complaints against the Columbia defendants; and (c) approved a plan of distribution for the amounts due to the plaintiff class as established in the settlements. The orders of settlement do not create any liability for the Columbia Acorn Funds.

CWAM believes that the lawsuits described in the four preceding paragraphs are not likely to materially affect its ability to provide investment management services to the Funds.

101

Report of Independent Registered Public Accounting Firm

To the Board of Trustees and Shareholders of
Columbia Acorn Trust:

In our opinion, the accompanying statement of assets and liabilities, including the statement of investments, and the related statements of operations and of changes in net assets and the financial highlights present fairly, in all material respects, the financial position of Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select and Columbia Thermostat Fund (each a series of the Columbia Acorn Trust, hereinafter referred to as the "Funds") at December 31, 2010, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended and the financial highlights for each of the five years in the period then ended, in conformity with accounting principles generally accepted in the United States of America. These financial statements and financial highlights (hereafter referred to as "financial statements") are the responsibility of the Funds' management; our responsibility is to express an opinion on these financial statements based on our audits. We conducted our audits of these financial statements in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits, which included confirmation of securities at December 31, 2010 by correspondence with the custodian, brokers and transfer agent, provide a reasonable basis for our opinion.

PricewaterhouseCoopers LLP
Chicago, Illinois
February 16, 2011

102

Columbia Acorn Family of Funds

Federal Income Tax Information (in thousands) (Unaudited) — Class A, B, C, I and Z shares

Columbia Acorn Fund

The Fund hereby designates as a capital gain dividend with respect to the fiscal year ended December 31, 2010 $714,049, or, if subsequently determined to be different, the net capital gain of such year.

100.00% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2010 qualified for the corporate dividends received deduction.

For non-corporate shareholders 100.00%, or the maximum amount allowable under the Jobs and Growth Tax Relief Reconciliation Act of 2003, of ordinary income distributed by the Fund for the fiscal year ended December 31, 2010 may represent qualified dividend income.

Columbia Acorn International

Foreign taxes paid during the fiscal years ended December 31, 2010 and 2009 of $7,871 and $1,789, respectively, are being passed through to shareholders. These represent $0.05 and $0.01 per share, respectively. Eligible shareholders may claim these amounts as a foreign tax credit.

Gross income derived from sources within foreign countries was $104,523 ($0.70 per share) for the fiscal year ended December 31, 2010.

For non-corporate shareholders, 100.00% or the maximum amount allowable under the Jobs and Growth Tax Relief Reconciliation Act of 2003, of the ordinary income distributed by the Fund for the fiscal year ended December 31, 2010 may represent qualified dividend income.

Columbia Acorn International Select

Foreign taxes paid during the fiscal year ended December 31, 2010, of $516 are being passed through to shareholders. This represents $0.03 per share. Eligible shareholders may claim this amount as a foreign tax credit.

Gross income derived from sources within foreign countries was $8,297 ($0.52 per share) for the fiscal year ended December 31, 2010.

For non-corporate shareholders, 100.00% or the maximum amount allowable under the Jobs and Growth Tax Relief Reconciliation Act of 2003, of the ordinary income distributed by the Fund for the fiscal year ended December 31, 2010 may represent qualified dividend income.

Columbia Thermostat Fund

For non-corporate shareholders, 100.00% or the maximum amount allowable under the Jobs and Growth Tax Relief Reconciliation Act of 2003, of the ordinary income distributed by the Fund for the fiscal year ended December 31, 2010 may represent qualified dividend income.

100.00% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2010 qualified for the corporate dividends received deduction.

103

Board of Trustees and Management of
Columbia Acorn Funds

Each trustee may serve a term of unlimited duration. The Trust's By-laws generally require that a trustee retire at the end of the calendar year in which the trustee attains the age of 75 years. The trustees appoint their own successors, provided that at least two-thirds of the trustees, after such appointment, have been elected by shareholders. Shareholders may remove a trustee, with or without cause, upon the vote of two-thirds of the Trust's outstanding shares at any meeting called for that purpose. A trustee may be removed, with or without cause, upon the vote of a majority of the trustees. The names of the trustees and officers of the Trust, the date each was first elected or appointed to office, their principal business occupations during at least the last five years, number of portfolios in the fund complex they oversee, and other directorships they hold, are shown below. Each trustee serves in such capacity for each of the six serie s of Columbia Acorn Trust and for each of the four series of Wanger Advisors Trust.

The address for the trustees and officers of the Trust is Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. The Funds' Statement of Additional Information includes additional information about the Funds' trustees and officers. You may obtain a free copy of the Statement of Additional Information by writing or calling toll-free:

Columbia Wanger Asset Management, LLC
Shareholder Services Group
227 W. Monroe, Suite 3000
Chicago IL 60606
1-800-922-6769

Name, Position(s) with Columbia Acorn Trust and Age at December 31, 2010	Year First Elected or Appointed to Office*		Principal Occupation(s) during Past Five Years	Number of Portfolios in Fund Complex Overseen by Trustee/Officer		Other Directorships in addition to Columbia Acorn Trust
Trustees who are not interested persons of Columbia Acorn Trust:
Laura M. Born, 45, Trustee		2007	Adjunct Assistant Professor of Finance, University of Chicago Booth School of Business; formerly, Managing Director – Investment Banking, JP Morgan Chase & Co. (broker/dealer) 2002-2007; prior thereto, associated with JP Morgan as an investment professional since 1991.		10	Wanger Advisors Trust
Michelle L. Collins, 50, Trustee		2008	President, Cambium LLC (financial advisory firm) since 2007; Advisory Board Member, Svoboda Capital Partners LLC (private equity firm) since 2007; Managing Director Svoboda Capital Partners LLC, 1998-2006.		10	Wanger Advisors Trust; Bucyrus International, Inc. (mining equipment manufacturer); Molex, Inc. (electronics components manufacturer); CDW Corporation (electronics components manufacturer) (until October 2007).
Maureen M. Culhane, 62, Trustee		2007	Retired. Formerly, Vice President, Goldman Sachs Asset Management, L.P. (investment adviser), 2005-2007, and Vice President (Consultant) – Strategic Relationship Management, Goldman Sachs & Co., 1999-2005.		10	Wanger Advisors Trust
Margaret M. Eisen, 57, Trustee		2002	Chief Investment Officer, EAM International LLC (corporate finance and asset management) since 2003; Managing Director, CFA Institute, 2005-2008.		10	Wanger Advisors Trust; Antigenics, Inc. (biotechnology and pharmaceuticals) (until June 2009).
John C. Heaton, 51, Trustee		2010	Joseph L. Gidwitz Professor of Finance, University of Chicago Booth School of Business; financial consultant.		10	Wanger Advisors Trust
Steven N. Kaplan, 51, Trustee and Vice Chairman of the Board		1999	Neubauer Family Professor of Entrepreneurship and Finance, University of Chicago Booth School of Business.		10	Wanger Advisors Trust; Accretive Health, Inc. (healthcare management services provider); Morningstar, Inc. (provider of independent investment research).
David C. Kleinman, 75, Trustee(1)		1972	Adjunct Professor of Strategic Management, University of Chicago Booth School of Business; business consultant.		10	Wanger Advisors Trust; Sonic Foundry, Inc. (rich media systems and software).
Allan B. Muchin, 74, Trustee		1998	Chairman Emeritus, Katten Muchin Rosenman LLP (law firm).		10	Wanger Advisors Trust
David B. Small, 54, Trustee		2010	Managing Director, Chairman of Investment Committee, Grosvenor Capital Management, L.P. (investment adviser).		10	Wanger Advisors Trust

104

Name, Position(s) with Columbia Acorn Trust and Age at December 31, 2010	Year First Elected or Appointed to Office*		Principal Occupation(s) during Past Five Years	Number of Portfolios in Fund Complex Overseen by Trustee/Officer		Other Directorships in addition to Columbia Acorn Trust
Trustees who are not interested persons of Columbia Acorn Trust: (continued)
James A. Star, 49, Trustee and Chairman of the Board		2006	President, Longview Asset Management LLC (investment adviser) since 2003; associated with Longview or its predecessors and affiliates since 1994.		10	Wanger Advisors Trust
Trustees who are interested persons of Columbia Acorn Trust:
Charles P. McQuaid, 57, Trustee and President(2)		1992	President and Chief Investment Officer, CWAM or its predecessors, since October 2003; associated with CWAM or its predecessors as an investment professional since 1978.		10	Wanger Advisors Trust
David J. Rudis, 57, Trustee(3)		2010	National Checking and Debit Executive, and Illinois President, Bank of America, 2007 to 2009; President, Consumer Banking Group, LaSalle National Bank, 2004 to 2007.		10	Wanger Advisors Trust
Trustee Emeritus
Ralph Wanger, 76, Trustee Emeritus(4)		1970	Founder, CWAM. Formerly, President, Chief Investment Officer and portfolio manager, CWAM or its predecessors, July 1992 – September 2003; Director, Wanger Investment Company PLC; Consultant, CWAM or its predecessors, September 2003 – September 2005.		10	Wanger Advisors Trust
Officers of Columbia Acorn Trust:
Ben Andrews, 44, Vice President		2004	Portfolio manager and analyst, CWAM or its predecessors, since 1998; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2004.		10	None
Michael G. Clarke, 41, Assistant Treasurer		2004	Vice President, Columbia Management Investment Advisers, LLC since May 2010; Managing Director of Fund Administration, Columbia Management Advisors, LLC, from September 2004 to April 2010; senior officer of Columbia Family of Funds and affiliated funds since 2002.		10	None
Joseph F. DiMaria, 43, Assistant Treasurer		2010	Vice President, Mutual Fund Administration, Columbia Management Investment Advisers, LLC, since May 2010; Director of Fund Administration, Columbia Management Advisors, LLC from January 2006 to April 2010; Head of Tax/Compliance and Assistant Treasurer, Columbia Management Advisors, LLC, from November 2004 to December 2005.		10	None
P. Zachary Egan, 42, Vice President		2003	Director of International Research, CWAM or its predecessors, since December 2004; Vice President, Columbia Acorn Trust since 2003 and Wanger Advisors Trust since 2007; portfolio manager and analyst, CWAM or its predecessors, since 1999.		10	None
John Kunka, 40, Assistant Treasurer		2006	Director of Accounting and Operations, CWAM or its predecessors, since May 2006; Manager of Mutual Fund Operations, Calamos Advisors, Inc. (investment advisor), September 2005 – May 2006; prior thereto, Manager of Mutual Fund Administration, Van Kampen Investments.		10	None
Joseph C. LaPalm, 41, Vice President		2006	Chief Compliance Officer, CWAM since 2005; prior thereto, compliance officer, William Blair & Company (investment firm).		10	None

105

Name, Position(s) with Columbia Acorn Trust and Age at December 31, 2010	Year First Elected or Appointed to Office*		Principal Occupation(s) during Past Five Years	Number of Portfolios in Fund Complex Overseen by Trustee/Officer		Other Directorships in addition to Columbia Acorn Trust
Officers of Columbia Acorn Trust: (continued)
Bruce H. Lauer, 53, Vice President, Secretary and Treasurer		1995	Chief Operating Officer, CWAM or its predecessors, since April 2000; Vice President, Secretary and Treasurer, Columbia Acorn Trust and Wanger Advisors Trust, since 1995; Director, Wanger Investment Company PLC; formerly, Director, Banc of America Capital Management (Ireland) Ltd.; and formerly, Director, Bank of America Global Liquidity Funds, PLC.		10	None
Louis J. Mendes III, 46, Vice President		2003	Portfolio manager and analyst, CWAM or its predecessors, since 2001; Vice President, Columbia Acorn Trust since 2003 and Wanger Advisors Trust since 2005.		10	None
Robert A. Mohn, 49, Vice President		1997	Director of Domestic Research, CWAM or its predecessors, since March 2004; Vice President, Columbia Acorn Trust and Wanger Advisors Trust, since 1997; portfolio manager and analyst, CWAM or its predecessors, since August 1992.		10	None
Christopher J. Olson, 46, Vice President		2001	Portfolio manager and analyst, CWAM or its predecessors, since January 2001; Vice President, Columbia Acorn Trust and Wanger Advisors Trust, since 2001.		10	None
Scott R. Plummer, 51 Assistant Secretary		2010	Chief Legal Officer and Assistant Secretary, Columbia Management Investment Advisers, LLC (or its predecessor) since June 2005; Vice President and Lead Chief Counsel – Asset Management, Ameriprise Financial since May 2010 (previously Vice President and Chief Counsel – Asset Management, from 2005 to April 2010, and Vice President – Asset Management Compliance from 2004 to 2005); Vice President, Chief Counsel and Assistant Secretary, Columbia Management Investment Distributors, Inc. (or its predecessor) since 2008; Vice President, General Counsel and Secretary, Ameriprise Certificate Company since 2005; Chief Counsel, RiverSource Distributors, Inc. from 2006 to 2010; Vice President, General Counsel and Secretary, RiverSource Funds, since December 2006; Senior Vice President, Secretary and Chief Legal Officer, Columbia Family of Funds since May 2010.		10	None
Christopher O. Petersen, 41 Assistant Secretary		2010	Vice President and Chief Counsel, Ameriprise Financial since January 2010 (formerly Vice President and Group Counsel or Counsel from April 2004 to January 2010); Assistant Secretary of RiverSource Funds since January 2007.		10	None
Robert P. Scales, 58, Chief Compliance Officer, Chief Legal Officer, Senior Vice President and General Counsel		2004	Chief Compliance Officer, Chief Legal Officer, Senior Vice President and General Counsel, Columbia Acorn Trust and Wanger Advisors Trust, since 2004.		10	None
Linda Roth-Wiszowaty, 41, Assistant Secretary		2006	Business support analyst, CWAM, since April 2007; prior thereto executive administrator, CWAM or its predecessors, and executive assistant to the Chief Operating Officer of CWAM or its predecessors.		10	None

*  Dates prior to April 1992 correspond to the date of first election or appointment as a trustee or officers of The Acorn Fund, Inc., the predecessor trust to Columbia Acorn Trust.

(1)  Mr. Kleinman retired at the end of calendar year 2010.

(2)  Mr. McQuaid is an "interested person" of Columbia Acorn Trust and of CWAM, as defined in the Investment Company Act of 1940 because he is an officer of the Trust and of CWAM.

(3)  Mr. Rudis commenced service as a Trustee on January 1, 2011. Mr. Rudis is an "interested person" of Columbia Acorn Trust, as defined in the New York Attorney General's Assurance of Discontinuance ("Order") entered into in February 2005 by Columbia Management Advisors, LLC (an indirect subsidiary of Bank of America Corporate ("BOA")) and Columbia Management Distributors, Inc. (an indirect subsidiary of BOA), because of his former employment as a BOA executive.

(4)  As permitted under the Columbia Acorn Trust's By-Laws, Mr. Wanger serves as a non-voting Trustee Emeritus of the Trust.

106

Columbia Acorn Family of Funds

Fourth Quarter Class A, B, C and I Share Information (Unaudited)

Minimum Initial Investment in all Funds	$2,000 for most Investors $1,000 for an IRA
Minimum Subsequent Investment in all Funds	$100
Exchange Fee	None

Columbia Acorn Fund	Class A			Class B*			Class C			Class I**
Management Fees		0.64	%		0.64	%		0.64	%		0.64	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%
Other Expenses		0.18	%		0.30	%		0.21	%		0.07	%
Net Expense Ratio		1.07	%		1.69	%		1.85	%		0.71	%
Columbia Acorn International	Class A			Class B*			Class C			Class I**
Management Fees		0.77	%		0.77	%		0.77	%		0.77	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%
Other Expenses		0.33	%		0.44	%		0.34	%		0.17	%
Net Expense Ratio		1.35	%		1.96	%		2.11	%		0.94	%
Columbia Acorn USA	Class A			Class B*			Class C			Class I**
Management Fees		0.86	%		0.86	%		0.86	%		0.86	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%
Other Expenses		0.19	%		0.37	%		0.22	%		0.08	%
Net Expense Ratio		1.30	%		1.98	%		2.08	%		0.94	%
Columbia Acorn International Select	Class A			Class B*			Class C			Class I**
Management Fees		0.94	%		0.94	%		0.94	%		0.94	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%
Other Expenses		0.37	%		0.51	%		0.42	%		0.20	%
Net Expense Ratio		1.56	%		2.20	%		2.36	%		1.14	%
Columbia Acorn Select	Class A			Class B*			Class C			Class I**
Management Fees		0.82	%		0.82	%		0.82	%		0.82	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%
Other Expenses		0.21	%		0.35	%		0.25	%		0.09	%
Net Expense Ratio		1.28	%		1.92	%		2.07	%		0.91	%
Columbia Thermostat Fund	Class A			Class B*			Class C
Management Fees		0.10	%		0.10	%		0.10	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%
Other Expenses***		0.15	%		0.15	%		0.15	%
Net Expense Ratio		0.50	%		1.00	%		1.25	%

    Fees and expenses are for the year ended December 31, 2010. Some share classes of Columbia Acorn Select and Columbia Acorn International Select include the effect of the contractual undertaking by Columbia Wanger Asset Management, LLC (CWAM) to waive fees and/or reimburse the Funds for any ordinary operating expenses (exclusive of brokerage commissions, interest, taxes and extraordinary expenses, but inclusive of custodian charges relating to overdrafts, if any), after giving effect to any balance credits from the Funds' custodian, in excess of the annual rate of the Funds as follows:

Fund	Class A			Class B			Class C			Class I
Columbia Acorn International Select		1.70	%		2.20	%		2.45	%		1.30	%
Columbia Acorn Select		1.60	%		2.10	%		2.35	%		1.25	%

    These arrangements may be modified or terminated by either the Funds or CWAM upon 30 days notice. Columbia Thermostat Fund's fees and expenses include the effect of CWAM's contractual undertaking to waive fees and/or reimburse the Fund for any ordinary operating expenses (exclusive of distribution and service fees, interest and fees on borrowings and expenses associated with the Fund's investments in other investment companies, but including custodian charges relating to overdrafts, if any), after giving effect to any balance credits from the Fund's custodian, in excess of the annual rate of 0.25% of the average daily net assets. Columbia Thermostat Fund's waiver/reimbursement arrangement is contractual through April 30, 2011. There is no guarantee that this arrangement will continue thereafter.

  *  The Funds no longer offer Class B shares (other than through dividend reinvestment).

  **  Class I shares were initially offered by the Funds on September 27, 2010.

  ***  Does not include estimated fees and expenses of 0.79% incurred by the Fund from the underlying portfolio funds in which it invests.

107

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109

Columbia Acorn Family of Funds

Investment Adviser

Columbia Wanger Asset Management, LLC
227 West Monroe Street, Suite 3000
Chicago, Illinois 60606

1-800-922-6769

Distributor*

Columbia Management Investment Distributors, Inc.
One Financial Center
Boston, Massachusetts 02111-2621

Transfer Agent, Dividend Disbursing Agent*

Columbia Management Investment Services Corp.
P. O. Box 8081
Boston, Massachusetts 02266-8081

1-800-345-6611

Legal Counsel to the Funds

Perkins Coie LLP
Washington, DC

Legal Counsel to the Independent Trustees

Drinker Biddle & Reath LLP
Philadelphia, Pennsylvania

Independent Registered Public Accounting Firm

PricewaterhouseCoopers LLP
Chicago, Illinois

*As of May 1, 2010

This report, including the schedules of investments, is submitted for the general information of the shareholders of Columbia Acorn Trust.

A description of the policies and procedures that the Funds use to determine how to vote proxies and a copy of the Funds' voting record are available (i) without charge, upon request, by calling 800-922-6769 and (ii) on the Securities and Exchange Commission's website at www.sec.gov. Information regarding how the Funds voted proxies relating to portfolio securities during the 12-month period ended June 30, is available from the SEC's website. Information regarding how the Funds voted proxies relating to portfolio securities is also available at http://institutional.columbiamanagement.com.

The Funds file a complete schedule of portfolio holdings with the SEC for the first and third quarters of each fiscal year on Form N-Q. The Funds' Form N-Q is available on the SEC's website at www.sec.gov and may be reviewed and copied at the SEC's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330.

Investors should consider the investment objectives, risks, charges and expenses of a mutual fund carefully before investing. For a free prospectus, which contains this and other important information about the funds, visit www.columbiamanagement.com. Read the prospectus carefully before investing.

Columbia Acorn Funds are distributed by Columbia Management Investment Distributors, Inc., member FINRA and managed by Columbia Wanger Asset Management, LLC.

Find out what's new – visit our web site at:

www.columbiamanagement.com

Our e-mail address is:

ServiceInquiries@ColumbiaManagement.com

Shareholders should not include personal information such as account numbers, Social Security numbers or taxpayer identification numbers in e-mail. We are unable to accept account transactions sent via e-mail.

110

PRESORTED

FIRST-CLASS MAIL

U.S. POSTAGE PAID

HOLLISTON, MA

PERMIT NO. 20

Columbia Management^®

Columbia Acorn Family of Funds
Class A, B, C and I Shares

Annual Report, December 31, 2010

For More Information

You'll find more information about the Columbia Acorn Family of Funds in the documents described below. Contact Columbia Funds as follows to obtain these documents free of charge:

By Mail:  Columbia Funds
c/o Columbia Management Investment Services Corp.
P.O. Box 8081
Boston, MA 02266-8081

By Telephone: 800.345.6611

Online: www.columbiamanagement.com

Shareholder Communications with the Board

The Funds' Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Prospectuses and the Statement of Additional Information (SAI)

The prospectuses and the SAI provide more detailed information about the Funds and their policies. The SAI is legally part of each prospectus (it's incorporated by reference). A copy of each has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Funds (including their prospectuses, the SAI and shareholder reports) at the SEC's Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC's website at http://www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov. You can also obtain copies of this information by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-0102.

The investment company registration number of Columbia Acorn Trust, of which each of these Funds is a series, is 811-01829.

© 2011 Columbia Management Investment Advisers, LLC. All rights reserved.

One Financial Center, Boston, MA 02111-2621

800.345.6611 www.columbiamanagement.com

C-1446 A (2/11) 113563

Columbia Management^®

Columbia Acorn Family of Funds
Class A, B, C and I Shares

Annual Report, December 31, 2010

For More Information

You'll find more information about the Columbia Acorn Family of Funds in the documents described below. Contact Columbia Funds as follows to obtain these documents free of charge:

By Mail:  Columbia Funds
c/o Columbia Management Investment Services Corp.
P.O. Box 8081
Boston, MA 02266-8081

By Telephone: 800.345.6611

Online: www.columbiamanagement.com

Shareholder Communications with the Board

The Funds' Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Prospectuses and the Statement of Additional Information (SAI)

The prospectuses and the SAI provide more detailed information about the Funds and their policies. The SAI is legally part of each prospectus (it's incorporated by reference). A copy of each has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Funds (including their prospectuses, the SAI and shareholder reports) at the SEC's Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC's website at http://www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov. You can also obtain copies of this information by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-0102.

The investment company registration number of Columbia Acorn Trust, of which each of these Funds is a series, is 811-01829.

© 2011 Columbia Management Investment Advisers, LLC. All rights reserved.

One Financial Center, Boston, MA 02111-2621

800.345.6611 www.columbiamanagement.com

C-1446 A (2/11) 113563

Columbia Management^®

Columbia Acorn Family of Funds
Class A, B, C and I Shares

Annual Report, December 31, 2010

For More Information

You'll find more information about the Columbia Acorn Family of Funds in the documents described below. Contact Columbia Funds as follows to obtain these documents free of charge:

By Mail:  Columbia Funds
c/o Columbia Management Investment Services Corp.
P.O. Box 8081
Boston, MA 02266-8081

By Telephone: 800.345.6611

Online: www.columbiamanagement.com

Shareholder Communications with the Board

The Funds' Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Prospectuses and the Statement of Additional Information (SAI)

The prospectuses and the SAI provide more detailed information about the Funds and their policies. The SAI is legally part of each prospectus (it's incorporated by reference). A copy of each has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Funds (including their prospectuses, the SAI and shareholder reports) at the SEC's Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC's website at http://www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov. You can also obtain copies of this information by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-0102.

The investment company registration number of Columbia Acorn Trust, of which each of these Funds is a series, is 811-01829.

C-1446 A (2/11) 113563

Item 2. Code of Ethics.

(a)The registrant has adopted a code of ethics that applies to the registrant’s principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party.

(b)During the period covered by this report, there were not any amendments to a provision of the code of ethics adopted in 2(a) above.

(c)During the period covered by this report, there were no waivers, including any implicit waivers, from a provision of the code of ethics described in 2(a) above that relates to one or more of the items set forth in paragraph (b) of this item’s instructions.

Item 3. Audit Committee Financial Expert.

The registrant’s Board of Trustees has determined that Laura M. Born, Michelle L. Collins and David C. Kleinman, each of whom are members of the registrant’s Board of Trustees and Audit Committee, each qualify as an audit committee financial expert.  Ms. Born, Ms. Collins and Mr. Kleinman are each independent trustees, as defined in paragraph (a)(2) of this item’s instructions.

Item 4. Principal Accountant Fees and Services.

(a) Audit Fees. Aggregate Audit Fees billed by the principal accountant for professional services rendered during the fiscal years ended December 31, 2010 and December 31, 2009 are approximately as follows:

2010		2009
$	219,500	$	215,300

Audit Fees include amounts related to the audit of the registrant’s annual financial statements or services that are normally provided by the accountant in connection with statutory and regulatory filings or engagements for those fiscal years.

(b) Audit-Related Fees. Aggregate Audit-Related Fees billed to the registrant by the principal accountant for professional services rendered during the fiscal years ended December 31, 2010 and December 31, 2009 are approximately as follows:

2010		2009
$	15,800	$	11,000

Audit-Related Fees include amounts for assurance and related services by the principal accountant that are reasonably related to the performance of the audit of the registrant’s financial statements and are not reported in Audit Fees above.  In fiscal years 2010 and 2009, Audit-Related Fees consist of agreed-upon procedures performed for other audit-related additional testing. Fiscal year 2010 also includes Audit-Related Fees for agreed-upon procedures related to a fund merger.

During the fiscal years ended December 31, 2010 and December 31, 2009, there were no Audit-Related Fees billed by the registrant’s principal accountant to the registrant’s investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser) and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant for an engagement that related directly to the operations and financial reporting of the registrant.

(c) Tax Fees. Aggregate Tax Fees billed by the principal accountant to the registrant for professional services rendered during the fiscal years ended December 31, 2010 and December 31, 2009 are approximately as follows:

2010		2009
$	41,500	$	40,600

Tax Fees incurred in both fiscal years 2010 and 2009 relate to the review of annual tax returns, the review of required shareholder distribution calculations and include amounts for professional services by the principal accountant for tax compliance, tax advice and tax planning.

During the fiscal years ended December 31, 2010 and December 31, 2009, there were no Tax Fees billed by the registrant’s principal accountant to the registrant’s investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser) and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant for an engagement that related directly to the operations and financial reporting of the registrant.

(d) All Other Fees. Aggregate All Other Fees billed by the principal accountant to the registrant for professional services rendered during the fiscal years ended December 31, 2010 and December 31, 2009 are as follows:

2010		2009
$	0	$	0

All Other Fees include amounts for products and services provided by the principal accountant, other than the services reported in paragraphs (a) through (c) above.

Aggregate All Other Fees billed by the registrant’s principal accountant to the registrant’s investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser) and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant for an engagement that related directly to the operations and financial reporting of the registrant during the fiscal years ended December 31, 2010 and December 31, 2009 are approximately as follows:

2010		2009
$	135,000	$	136,200

In both fiscal years 2010 and 2009, All Other Fees consist of professional services rendered for internal control reviews of the registrant’s transfer agent.

(e)(1) Audit Committee Pre-Approval Policies and Procedures

The policy of the registrant’s Audit Committee is to specifically pre-approve (i) all audit and non-audit (including audit related, tax and all other) services provided by the registrant’s independent auditor to the registrant and individual funds (collectively “Fund Services”) and (ii) all non-audit services provided by the registrant’s independent auditor to the funds’ adviser or a control affiliate of the adviser, that relate directly to the funds’ operations and financial reporting (collectively “Fund-related Adviser Services”).  A “control affiliate” is an entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the funds, and the term “adviser” is deemed to exclude any unaffiliated sub-adviser whose role is primarily portfolio management and is sub-contracted or overseen by another investment adviser.

If such Fund Services or Fund-related Adviser Services are required during the period between the Audit Committee’s regularly scheduled meetings, the Chairman of the Audit Committee has the authority to pre-approve the service, with reporting to the full Audit Committee at the next regularly scheduled meeting.

The Audit Committee will waive pre-approval of Fund Services or Fund-related Adviser Services provided that the requirements under paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X are met.

(e)(2) The percentage of services described in paragraphs (b) through (d) of this Item approved pursuant to the “de minimis” exception under paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X during both fiscal years ended December 31, 2010 and December 31, 2009 was zero.

(f) Not applicable.

(g) The aggregate non-audit fees billed by the registrant’s accountant for services rendered to the registrant, and rendered to the registrant’s investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant for the fiscal years ended December 31, 2010 and December 31, 2009 are approximately as follows:

2010		2009
$	192,300	$	187,800

(h) The registrant’s Audit Committee of the Board of Directors has considered whether the provision of non-audit services that were rendered to the registrant’s adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X, is compatible with maintaining the principal accountant’s independence.

Item 5. Audit Committee of Listed Registrants.

Not applicable.

Item 6. Investments

(a)The registrant’s “Schedule I – Investments in securities of unaffiliated issuers” (as set forth in 17 CFR 210.12-12) is included in Item 1 of this Form N-CSR.

(b)Not applicable

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies.

Not applicable.

Item 8. Portfolio Managers of Closed-End Management Investment Companies.

Not applicable.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

Not applicable.

Item 10. Submission of Matters to a Vote of Security Holders.

There were no material changes to the procedures by which shareholders may recommend nominees to the registrant’s board of directors.

Item 11. Controls and Procedures.

(a)The registrant’s principal executive officer and principal financial officers, based on their evaluation of the registrant’s disclosure controls and procedures as of a date within 90 days of the filing of this report, have concluded that such controls and procedures are adequately designed to ensure that material information required to be disclosed by the registrant in Form N-CSR is accumulated and communicated to the registrant’s management, including the principal executive officer and principal financial officer, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure.

(b)There was no change in the registrant’s internal control over financial reporting that occurred during the registrant’s second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12. Exhibits.

(a)(1) Code of ethics required to be disclosed under Item 2 of Form N-CSR attached hereto as Exhibit 99.CODE ETH.

(a)(2) Certifications pursuant to Rule 30a-2(a) under the Investment Company Act of 1940 (17 CFR 270.30a-2(a)) attached hereto as Exhibit 99.CERT.

(a)(3) Not applicable.

(b) Certification pursuant to Rule 30a-2(b) under the Investment Company Act of 1940 (17 CFR 270.30a-2(b)) attached hereto as Exhibit 99.906CERT.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(registrant)	Columbia Acorn Trust
By (Signature and Title)	/s/Robert Mohn
	Robert Mohn, Principal Executive Officer
Date	February 18, 2011

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)	/s/Robert Mohn
	Robert Mohn, Principal Executive Officer
Date	February 18, 2011
By (Signature and Title)	/s/Bruce H. Lauer
	Bruce H. Lauer, Treasurer
Date	February 18, 2011