Columbia Thermostat Fund NCSR 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)

225 Franklin Street, Boston, Massachusetts					02110
(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, 2011

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 2011

Columbia Acorn Family of Funds

Class Z Shares

Managed by Columbia Wanger Asset Management, LLC

Annual Report

December 31, 2011

n Columbia
Acorn® Fund

n Columbia
Acorn International®

n Columbia
Acorn USA®

n Columbia
Acorn International Select^SM

n Columbia
Acorn Select^SM

n Columbia
Thermostat Fund^SM

n Columbia
Acorn Emerging Markets Fund^SM

n Columbia
Acorn European Fund^SM

Not FDIC insured • No bank guarantee • May lose value

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.

• HSBC Smaller European Companies (inc UK) Index is a weighted combination of two indexes: the HSBC Smaller Europe (ex UK) Index and the HSBC Smaller UK Index. The index is rebalanced on a quarterly basis.

• Lipper Indexes include the largest funds tracked by Lipper, Inc. in the named category. 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 Flexible Portfolio Funds Index, an equal-weighted index of the 30 largest mutual funds within the Flexible Portfolio fund classification, as defined by Lipper. Lipper Emerging Markets Index, 30 largest emerging markets funds; Lipper European Region Index, 10 largest European funds.

• Morgan Stanley Capital International Europe, Australasia, Far East (MSCI EAFE) Index (Net) 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 (Net) are presented net of the withholding tax rate applicable to foreign non-resident institutional investors in the foreign companies included in the index who do not benefit from double taxation treaties.

• MSCI Emerging Markets Small Cap Index, a widely recognized international benchmark, is a free float-adjusted market capitalization index that is designed to measure small-cap emerging market equity performance. The MSCI Emerging Markets Small Cap Index currently consists of the following 21 emerging market country indexes: Brazil, Chile, China, Colombia, Czech Republic, Egypt, Hungary, India, Indonesia, Korea, Malaysia, Mexico, Morocco, Peru, Philippines, Poland, Russia, South Africa, Taiwan, Thailand and Turkey.

• 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 Emerging Markets Between $500M and $5B Index represents the institutionally investable capital of emerging market countries with market caps ranging between $500 million to $5 billion, as selected by S&P. The index currently consists of the following 21 emerging market country indexes: Brazil, Chile, China, Colombia, Czech Republic, Egypt, Hungary, India, Indonesia, Korea, Malaysia, Mexico, Morocco, Peru, Philippines, Poland, Russia, South Africa, Taiwan, Thailand and Turkey.

• S&P Europe Between $500M and $5B Index represents the institutionally investable capital of European countries with market caps ranging between $500 million to $5 billion, as selected by S&P. The index currently consists of the following 17 developed market country indexes: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.

• S&P Global Ex-U.S. SmallCap Index consists of the bottom 20% of institutionally investable capital of developed and emerging countries, excluding the United States.

• 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.

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.

Acorn®, Acorn USA® and Acorn International® are service marks owned and registered by Columbia Acorn Trust. Columbia^SM, Columbia Management®, and the Columbia Management Logo® are service marks owned and/or registered by Ameriprise Financial, Inc.

Letter to Shareholders from the
Columbia Acorn Board of Trustees

Stewardship and Growth

Fellow Shareholders:

Last June, I was elected the independent Chair of the Columbia Acorn Trust Board of Trustees. I am honored to continue a long and distinguished tradition of stewardship and advocacy for our shareholders. Stewardship is defined as the careful and responsible management of those things entrusted to one's care. While Trustees cannot influence the volatility of markets, they can maintain standards of excellence in stewardship and take steps to foster the continued vitality of the adviser that manages the Funds' investments, Columbia Wanger Asset Management (CWAM). I am pleased to report that your Board has worked hard towards both this year.

Stewardship requires that we maintain our independence. It also requires that we promote a culture at CWAM that places investment results ahead of all other considerations, that retains and motivates talented individuals, and that continues to employ the investment philosophy established by Ralph Wanger over 40 years ago. Our Board is composed entirely of Trustees who are independent of CWAM, with the exception of Chuck McQuaid, CWAM's Chief Investment Officer.¹ The CWAM team serves our shareholders under the ownership of Columbia Management Investment Advisers, LLC (Columbia Management), a subsidiary of Ameriprise Financial, Inc. The Board has taken the steps necessary to ensure CWAM's autonomy in managing the Acorn Funds, while securing the advantages of the larger Ameriprise organization. On February 15, 2012, the president of Columbia Management, to whom CWAM reported, resigned. Columbia Management has assured the Board that this departure will not impact CWAM's independence.

One important signpost for stewardship is the willingness to have "skin in the game." All of our Trustees are investors in the Acorn Funds. Moreover, your portfolio managers have significant personal investments in the Acorn Funds and CWAM continues to compensate its professionals using incentives that reward investment performance. At present, five CWAM portfolio managers each have over $1 million of their own money invested in the Funds they manage. These five Funds represent approximately 85% of the assets currently under management at CWAM. As a result, your portfolio managers are motivated to achieve outstanding investment results for you.

For the first time since 2002, the Board approved the launch of two new Acorn Funds: Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund. Both Funds are managed by experienced professionals who have established track records as CWAM analysts, and both invest using the "growth at a reasonable price" philosophy that guides the other Acorn Funds. The new Funds were primarily seeded with the personal investments of their portfolio managers and other CWAM professionals. The launch of these Funds demonstrates the Board's commitment to encouraging growth through developing and retaining investment talent while maintaining our investment principles and furthering the stewardship values that protect our shareholders. We are confident that these two new Funds will be outstanding additions to the Acorn Fund family.

Thank you for your continued confidence in the Acorn Funds.

Laura M. Born
Independent Chair of the Board of Trustees
Columbia Acorn Trust

¹ Mr. David Rudis became a disinterested Trustee on January 1, 2012. Ralph Wanger, CWAM's founder, serves as non-voting Trustee Emeritus.

Columbia Acorn Family of Funds

Table of Contents

Performance At A Glance					1
Squirrel Chatter II: Vaccines, Medicine's Greatest Lifesaver					2
Understanding Your Expenses					6
Columbia Acorn Fund
In a Nutshell					8
At a Glance					9
Major Portfolio Changes					24
Statement of Investments					26
Columbia Acorn International
In a Nutshell					10
At a Glance					11
Major Portfolio Changes					39
Statement of Investments					41
Portfolio Diversification					50
Columbia Acorn USA
In a Nutshell					12
At a Glance					13
Major Portfolio Changes					51
Statement of Investments					52
Columbia Acorn International Select
In a Nutshell					14
At a Glance					15
Major Portfolio Changes					59
Statement of Investments					60
Portfolio Diversification					64
Columbia Acorn Select
In a Nutshell					16
At a Glance					17
Major Portfolio Changes					65
Statement of Investments					66
Columbia Thermostat Fund
In a Nutshell					18
At a Glance					19
Statement of Investments					71
Columbia Acorn Emerging Markets Fund
In a Nutshell					20
At a Glance					21
Major Portfolio Changes					72
Statement of Investments					73
Portfolio Diversification					76
Columbia Acorn European Fund
In a Nutshell					22
At a Glance					23
Major Portfolio Changes					77
Statement of Investments					78
Portfolio Diversification					81
Columbia Acorn Family of Funds
Statements of Assets and Liabilities					82
Statements of Operations					84
Statements of Changes in Net Assets					86
Financial Highlights					92
Notes to Financial Statements					96
Report of Independent Registered Public Accounting Firm					107
Federal Income Tax Information					108
Board of Trustees and Management of Columbia Acorn Funds					109
Columbia Acorn Family of Funds Information					113

2011 Year-end Distributions

The following table details the year-end distributions for the Columbia Acorn Funds. For all Funds except Columbia Thermostat Fund, the record date was December 6, 2011, and the ex-dividend and payable date was December 7, 2011. For Columbia Thermostat Fund, the record date was December 21, 2011, and the ex-dividend and payable date was December 22, 2011.

	Short-term Capital Gains		Long-term Capital Gains		Ordinary Income		Reinvestment Price
Columbia Acorn Fund		None	$	0.88962		None	$	27.98
Columbia Acorn International		None		None		None		N/A
Columbia Acorn USA		None	$	0.16883		None	$	27.45
Columbia Acorn International Select		None	$	0.39302	$	0.37430	$	25.10
Columbia Acorn Select		None		None		None		N/A
Columbia Thermostat Fund		None		None	$	0.21327	$	12.60
Columbia Acorn Emerging Markets Fund		None		None		None		N/A
Columbia Acorn European Fund	$	0.01544		None	$	0.06861	$	9.67

Columbia Acorn Family of Funds

Performance At A Glance Class Z Average Annual Total Returns through 12/31/11

	NAV on 12/31/11		4th quarter*			1 year			5 years			10 years			Life of Fund
Columbia Acorn Fund (ACRNX) (6/10/70)	$	27.56		10.78	%		-4.61	%		2.12	%		8.24	%		14.50	%
Russell 2500 Index				14.52	%		-2.51	%		1.24	%		6.57	%		N/A
S&P 500 Index**				11.82	%		2.11	%		-0.25	%		2.92	%		10.44	%
Lipper Mid-Cap Growth Funds Index				10.30	%		-5.30	%		2.89	%		4.48	%		N/A
Columbia Acorn International (ACINX) (9/23/92)	$	34.31		2.02	%		-14.06	%		0.20	%		10.27	%		10.63	%
S&P Global Ex-U.S. Between $500M and $5B Index				0.75	%		-16.94	%		-0.58	%		11.10	%		7.90	%
S&P Global Ex-U.S. SmallCap Index				1.15	%		-17.40	%		-2.14	%		10.33	%		7.10	%
Lipper International Small/Mid Growth Funds Index				2.88	%		-14.22	%		-1.73	%		8.98	%		N/A
Columbia Acorn USA (AUSAX) (9/4/96)	$	26.98		11.94	%		-4.95	%		0.82	%		6.30	%		9.49	%
Russell 2000 Index				15.47	%		-4.18	%		0.15	%		5.62	%		6.74	%
Russell 2500 Index				14.52	%		-2.51	%		1.24	%		6.57	%		8.34	%
Lipper Small-Cap Growth Funds Index				12.88	%		-3.40	%		1.14	%		3.65	%		5.21	%
Columbia Acorn Int'l Select (ACFFX) (11/23/98)	$	24.46		1.93	%		-9.76	%		0.41	%		9.22	%		8.65	%
S&P Developed Ex-U.S. Between $2B and $10B Index				0.99	%		-14.01	%		-3.06	%		8.41	%		6.47	%
MSCI EAFE Index				3.33	%		-12.14	%		-4.72	%		4.67	%		2.64	%
Lipper International Small/Mid Growth Funds Index				2.88	%		-14.22	%		-1.73	%		8.98	%		9.15	%
Columbia Acorn Select (ACTWX) (11/23/98)	$	23.62		9.35	%		-16.37	%		-1.07	%		6.05	%		8.76	%
S&P MidCap 400 Index				12.98	%		-1.73	%		3.32	%		7.04	%		8.57	%
S&P 500 Index**				11.82	%		2.11	%		-0.25	%		2.92	%		2.42	%
Lipper Mid-Cap Growth Funds Index				10.30	%		-5.30	%		2.89	%		4.48	%		5.55	%
Columbia Thermostat Fund (COTZX) (9/25/02)†	$	12.67		7.64	%		4.85	%		4.21	%		—			7.51	%
S&P 500 Index				11.82	%		2.11	%		-0.25	%		—			6.85	%
Barclays Capital U.S. Aggregate Bond Index				1.12	%		7.84	%		6.50	%		—			5.33	%
Lipper Flexible Portfolio Funds Index				6.28	%		-1.16	%		2.02	%		—			7.10	%
50/50 Blended Benchmark				6.47	%		5.28	%		3.54	%		—			6.43	%
Columbia Acorn Emerging Markets Fund (CEFZX) (8/19/11)		$9.28		4.98	%		—			—			—			-7.20	%*
S&P Emerging Markets Between $500M and $5B Index				0.96	%		—			—			—			-13.46	%*
MSCI Emerging Markets Small Cap Index				-0.66	%		—			—			—			-16.65	%*
Lipper Emerging Markets Index				5.09	%		—			—			—			-6.81	%*
Columbia Acorn European Fund (CAEZX) (8/19/11)	$	9.44		1.19	%		—			—			—			-4.78	%*
S&P Europe Between $500M and $5B Index				0.41	%		—			—			—			-7.17	%*
HSBC Smaller European Companies Index				-0.94	%		—			—			—			-9.54	%*
Lipper European Region Index				5.89	%		—			—			—			-1.24	%*

*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. Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser (Columbia Wanger Asset Management, LLC ("CWAM")) and/or any of its affiliates. Absent these fee waivers or expense reimbursement arrangements, performance results would have been lower. 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.

Annual operating expense ratios are stated as of each Fund's current prospectus and differences in expense ratios disclosed elsewhere in this report may result from including fee waivers and expense reimbursements as well as different time periods used in calculating the ratios for Class Z shares. Columbia Acorn Fund: 0.76%. Columbia Acorn International: 0.98%. Columbia Acorn USA: 1.01%. Columbia Acorn International Select: 1.16%. Columbia Acorn Select: 0.97%. Columbia Thermostat Fund has a contractual fee waiver and expense reimbursement agreement with CWAM that expires April 30, 2012; expense ratios without and with the contractual waiver/reimbursement, including fees and expenses associated with the Fund's investments in other investment companies (underlying funds), are 1.16% and 1.04%, respectively. Columbia Acorn Emerging Markets Fund has a contractual fee waiver and expense reimbursement agreement with CWAM that expires April 30, 2013; expense ratios without and with the contractual waiver/reimbursement are 1.58%. Columbia Acorn European Fund has a contractual fee waiver and expense reimbursement agreement with CWAM that expires April 30, 2013; expense ratios without and with the contractual waiver/reimbursement are 1.51% and 1.50%, respectively. See Page 101 for more information about the Funds' fees and expenses.

†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. 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.

Squirrel Chatter II: Vaccines, Medicine's Greatest Lifesaver

I recently read several books on the history of vaccines. As one of the authors put it, "Of all of the benefits of medical science, vaccination is at or near the summit."¹

Deadly Diseases

"Bring out your dead!" cries a wretched man pulling a cart of bodies in Monty Python and the Holy Grail. Set in the middle ages, the movie makes fun of the impact of communicable disease at that time. In reality, such diseases were no laughing matter. Once mankind transitioned from isolated bands of nomadic hunter-gatherers to more densely populated groups of farmers, epidemic diseases began to ravage civilization.

Remarkable progress has been made as fatal, communicable disease has now become rare in the developed world. Clearly, improved sanitation and nutrition have helped, but much of the credit goes to the development of vaccines.

The First Vaccine

Dating back to at least the time of the Pharaohs, waves of smallpox epidemics ravaged mankind. In populations previously subject to the disease, mortality rates for those infected could be more than 30% and, for other populations, much more.² North American Indians had little immunity to the disease. Their population decreased 99% between Columbus's voyage in 1492 and the year 1800, and smallpox was the largest killer.³

People observed that the disease was communicable and one who survived a smallpox infection became immune to the next epidemic of the disease. In ancient China and more recently in Asia and Africa, a crude form of vaccination called variolation developed whereby fluid from a smallpox pustule or parts of smallpox scabs were scraped into the skin of a healthy person. In most cases, immunity would build up before the disease reached a vital organ and the individual would survive.

In 1790, Lady Montague, the wife of the British ambassador to the Ottoman Empire, introduced variolation to Britain. The process was far riskier than vaccines today; most people suffered severe side effects and up to about 3% of those treated died as a result.⁴ But these were much better odds than for those infected with smallpox.

Edward Jenner, a pharmacist in England, learned that milkmaids were immune to smallpox because they often suffered blisters from cowpox, a related disease. In 1796, Jenner began experimenting with variolating using fluid from a milkmaid's cowpox blisters, rather than smallpox sores. When his subjects were later variolated with smallpox fluid, no reaction occurred, indicating that they were immune from smallpox. Immunization using cowpox fluids rose rapidly and protected millions of people.⁵

A cowpox-derived vaccine for smallpox continued to be used well into the 20th century, including use by six million New Yorkers who were inoculated during a smallpox scare in 1947. Smallpox was eradicated from nature; the last case occurred in India in 1975.⁶ Smallpox immunizations ended when health authorities judged the risk of side effects from the vaccine exceeded the risk of the disease returning.

The Golden Age of Vaccines

Beginning in the 1860s, tremendous scientific advances were made. Robert Koch's laboratory in Germany identified bacteria as the source of many diseases and proved that bacteria grown in a lab could cause disease.⁷ Koch's lab created some vaccines, including those for diphtheria and tetanus.

In France, Louis Pasteur stunned the world by developing the first rabies vaccine in 1885; until then rabies infections resulted in horrible deaths. His mantra was to "isolate, attenuate and vaccinate" the pathogen causing a disease.⁸ He attenuated a germ by having it reproduce in petri dishes or animal cells where it would evolve in order to optimize in its new environment. Once it evolved to the point it would no longer thrive in and harm humans, it was injected into humans with the hope that the subject would build immunity to full power germs. The Goldilocks' trick, of course, was to make the attenuated germ weak enough so as not to cause harm, but strong enough to create immunity.

While scientific understanding of disease increased rapidly, it was primitive compared to modern times. Diagnostic tools were poor. Bacteria could be seen by optical microscopes, but viruses were unseen until the development of the electron microscope in the 1930s. Viruses were inferred to exist as a result of an 1898 experiment by Danish professor Martinus Beijerinck, who filtered bacteria out through unglazed porcelain containers, but observed remaining, and much smaller, disease-causing elements. Scientists learned how to grow viruses in laboratories only in the late 1940s.⁹

Early vaccines were dangerous and unreliable by today's standards, though far less dangerous than the underlying diseases they prevented. Vaccines did not stop the great influenza epidemic of 1918-1919. Of a worldwide population of one billion, an estimated 500 million were infected and more than 50 million people died.¹⁰ This virus was unusual in that it had high mortality among young, healthy people.

Vaccines continued to progress. During World War II, all 11 million U.S. soldiers were vaccinated for typhoid, tetanus, smallpox, cholera and plague. Vaccines, coupled with antibiotics, drastically improved their health. Disease deaths outnumbered battle deaths by 13:1 in the Spanish American War, matched them in World War I and were outnumbered by 1:85 in World War II.¹¹

Maurice Hilleman's Mission

Maurice Hilleman had a role in creating more vaccines than anyone else in history, some three dozen. As noted by Arthur Allen, author of Vaccine, The Controversial Story of Medicine's Greatest Lifesaver, "...his products undoubtedly saved more lives than those of any other individual in the past half-century."¹²

Hilleman grew up in Montana and earned a Ph.D. in microbiology at the University of Chicago, where he discovered that chlamydia is a tiny bacteria rather than a virus. He then stunned his mentors by departing academia to work in industry. At Squibb, he developed a vaccine against Japanese B encephalitis to protect American Pacific troops during World War II. In 1948, he joined the Walter Reed Army Medical Center, then a hub of vaccine development.

In 1957, Hilleman moved to Merck, where he continued to develop vaccines well past his official retirement in 1984. He had a tremendous work ethic, often working seven days a week and expecting the same from his staff. He and his team were on a mission to rid the world of disease. They developed eight of 14 now common vaccines for measles, mumps, hepatitis A and B, chickenpox, meningitis, pneumonia and Hib (hemophilus influenza, which harms infants and young children).¹³ One of his accomplishments was the combination MMR (measles, mumps and rubella) vaccine.

Hilleman discovered that the influenza virus is particularly difficult to deal with due to frequent minor drifts in its surface, which each year makes the last year's vaccine obsolete. Periodically, the virus shifts its surface characteristics substantially, becoming much more virulent. Hilleman inferred that a shift occurred in Hong Kong in 1957 and, by having Merck produce 40 million doses of vaccine, saved thousands of lives in America. Potential future shifts keep virologists up at night.

Hilleman helped develop the first two anti-cancer vaccines. One vaccine prevents hepatitis B, the third most common known cause of cancer in the world (after sunlight and smoking).¹⁴ It was the first vaccine utilizing recombinant technology and the first made by a single protein. His innovations helped create a vaccine to prevent HPV (human papillomavirus), the cause of cervical cancer. Hilleman had high integrity, as he refused to risk changes in manufacturing processes in order to enhance yields and profits.¹⁵ He died in 2005 at age 85.

Vaccine Scares

Two notable scares set back progress on vaccine usage.

In 1982, a TV station in Washington D.C. aired "Vaccine Roulette," a story highlighting risks of the DTP (diphtheria, tetanus and pertussis) vaccine. It showed reactions well known to physicians, including cases of seizures, high fevers and fainting. In a case of ambush journalism, it edited doctors' comments out of context and failed to mention that none of the victims portrayed suffered permanent damage. Other media quoted the story further out of context, claiming permanent damage. The media also failed to mention the consequences of contracting the underlying diseases.¹⁶

In 1998, the British medical journal The Lancet published a paper alleging a link between the MMR vaccine

and autism.¹⁷ It claimed that, in some cases, the vaccine caused the measles virus to lodge in the intestines and create leakage, allowing opioid peptides to escape and penetrate the brain, causing autism. The paper was under fire by scientists immediately. The opioid causation theory had already been widely discredited, the findings of measles in intestines could not be duplicated by other scientists and there was no comparison between autism rates of children who got the vaccine and those who did not. A review by 37 experts found that the theories were "biologically implausible," and the conclusions essentially worthless.¹⁸

Fourteen separate groups of investigators did statistical studies that also refuted the link.¹⁹ One notable study covered 530,000 children in Denmark from 1991-1998, comparing vaccinated and unvaccinated children. It showed "strong evidence against the hypothesis that MMR vaccination causes autism."²⁰ By 2004, 10 of the original 12 authors of The Lancet article withdrew their support of the paper.²¹ The Lancet formally retracted the paper in 2010 and, that same year, the primary author of the paper had his U.K. medical license revoked.

Once the MMR-autism link was largely discredited, vaccine opponents claimed a link between mercury in vaccines and autism. Minute amounts of ethyl mercury were utilized in vaccines, usually less than the more toxic methyl mercury infants get exposed to from the environment. Combined, in some cases, the dosage did exceed government guidelines, so the mercury was removed. Studies showed that reported rates of autism continued to climb once mercury was removed from vaccines.²² "In spite of all the concern...there has not been a single case of proven mercury toxicity from vaccines...," writes Kurt Link, author of The Vaccine Controversy: The History, Use, and Safety of Vaccinations.²³

Unfortunately, many people appear to rely on one-sided scares and opinions expressed in talk shows and by celebrity activists, rather than on scientific evidence. Immunization rates around the world have fluctuated with publicity, funding for inoculations, public policy and legal requirements. Where immunizations have dropped, outbreaks have occurred. A diphtheria epidemic hit the former Soviet Union in 1993, causing 4,000 deaths.²⁴ In Japan, where pertussis immunizations fell from 80% in 1974 to 10% in 1976, a 1979 epidemic of that disease resulted in 13,000 infections and 41 deaths.²⁵ In the United States, where pockets of low immunization rates exist, outbreaks occur. Some of the Chicago suburbs are currently experiencing a whooping cough outbreak.²⁶

Perspectives on Risks

There have been mistakes in vaccine development, production and use that have resulted in injuries and deaths. However, those numbers pale in comparison to the injuries and deaths caused by the underlying diseases that are being conquered by vaccines. While rare vaccine side effects continue to exist, drugs and vaccines come with disclosures of the known side effects and risks, however unlikely. Diseases don't.

Many people believe some vaccine-preventable diseases to be fairly benign and some are, in most cases. Yet measles is one of the most contagious viruses and has killed more children than any other disease in history.²⁷ It hospitalized 48,000 Americans yearly in the 1960s and killed 400 during a 1964 epidemic.²⁸

Chickenpox is perceived to be a mild disease and it usually is. Acquiring chickenpox creates lifetime immunity to the disease (though susceptibility to shingles) so some question the usefulness of the vaccine. However, Paul Offit, author of Vaccinated, One Man's Quest to Defeat the World's Deadliest Diseases, points out that chickenpox creates risk of encephalitis, hepatitis, pneumonia and Group A streptococci, the "flesh-eating bacteria." He notes that, before the vaccine, some 10,000 people a year were hospitalized and 100 died annually in the United States due to the disease or related illnesses.²⁹

German measles (rubella) was considered a benign illness featuring a rash and a low fever until Australian ophthalmologist Sir Norman McAllister Gregg discovered a link to birth defects. When striking a mother in her first trimester, rubella causes fetal anomalies in 90% of pregnancies. In 1964-65, prior to the rubella vaccine, the last major epidemic in the United States caused thousands of birth defects.³⁰ Hilleman's MMR vaccine was approved in

1971 and the number dropped to seven U.S. cases in 1983.³¹

Whooping cough (pertussis) is a horrible disease for babies and small children. Babies have died because of outbreaks when vaccination rates declined as a result of scares. The underlying vaccine has changed since the "Vaccine Roulette" television program, to an acellular version with fewer side effects.³² That is why the combination vaccine is now called DTaP rather than DTP.

While no vaccine is 100% effective, the fact remains that if the vast majority of people are vaccinated, a disease cannot infect enough victims to spread. Link writes, "In the prevaccine era, every family lost a child or knew of one so lost due to vaccine-preventable diseases. Today in the USA, the death of a child is an unexpected tragedy; in the past it was an expected sorrow."³³ American life expectancies increased 30 years during the 20th century, largely due to vaccines.³⁴

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 2-5 of this report is unaudited.

¹ Link, M.D., Kurt, The Vaccine Controversy, The History, Use, And Safety of Vaccinations, (Westport, Connecticut, Praeger Publishers 2005) p. 38.

²Mnookin, Seth, The Panic Virus, A True Story of Medicine, Science, and Fear, (New York, New York, Simon & Schuster 2011) p. 30.

³Offit, M.D., Paul A., Vaccinated, One Man's Quest to Defeat the World's Deadliest Diseases, (New York, New York, HarperCollins Publishers 2007) pg. 32.

⁴Link, M.D., Kurt, op. cit., p. 12.

⁵Allen, Arthur, Vaccine, The Controversial Story of Medicines Greatest Lifesaver, (New York, New York, W. W. Norton & Company 2007) p. 49-50.

⁶Ibid., p. 115, 303.

⁷Offit, M.D., Paul A., op. cit., p. 144.

⁸Allen, Arthur, op. cit., p. 65, 121.

⁹Offit, M.D., Paul A., op. cit., p. 37, 41-42.

¹⁰ Ibid., p. 2-3.

¹¹Allen, Arthur, op. cit., p. 119, 159.

¹²Ibid., p. 221.

¹³Link, M.D., Kurt, op. cit., p. 101.

¹⁴Offit, M.D., Paul A., op. cit., p. 115.

¹⁵Ibid., p. 130, 156.

¹⁶Allen, Arthur, op. cit., p. 251-256.

¹⁷Wakefield, Andrew J., et al., "Ileal-lymphoid-nodular Hyperplasia, Non-Specific Colitis, and Pervasive Developmental Disorders in Children," The Lancet 351, Issue 9103 (1998), p. 637-41.

¹⁸Mnookin, Seth, op. cit., p. 106-107, 114.

¹⁹Offit, M.D., Paul A., op. cit., p. 167.

²⁰Mnookin, Seth, op. cit., p. 163.

²¹Murch, Simon H., et al., "Retraction of an Interpretation," The Lancet 363, Issue 9411 (2004), p. 750.

²²Mnookin, Seth, op. cit., p. 167.

²³Link, M.D., Kurt, op. cit., p. 21.

²⁴Ibid., p. 57.

²⁵Mnookin, Seth, op. cit., p. 277.

²⁶Synett, Lawerence, "Whooping Cough Strikes Collar Counties," Chicago Tribune, December 6, 2011.

²⁷Mnookin, Seth, op. cit., p. 19.

²⁸Allen, Arthur, op. cit., p. 217.

²⁹Offit, M.D., Paul A., op. cit., p. 102.

³⁰Link, M.D., Kurt, op. cit., p. 82-84.

³¹Allen, Arthur, op. cit., p. 240.

³²Ibid., p. 352, 286.

³³Link, M.D., Kurt, op. cit., p. 163.

³⁴Offit, M.D., Paul A., op. cit., p. xiv.

Understanding Your Expenses

As a shareholder, you incur two types of costs. There are transaction costs, which generally include sales charges on purchases and may include redemption fees. There are also ongoing costs, which generally include management fees, distribution and service (Rule 12b-1) fees, and other Fund expenses. The following information is intended to help you understand your ongoing costs (in dollars) of investing in the Fund and to help you 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 Class Z shares of the Funds during the period. The actual and hypothetical information in the tables is based on an initial investment of $1,000 at the beginning of the period indicated 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 the Funds' actual operating expenses and total return for the period. You may use the Actual information, together with the amount invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the results by the expenses paid during the period under the Actual column. The amount listed in the "Hypothetical" column assumes a 5% annual rate of return before expenses (which is not the Funds' actual return) and then applies the Funds' 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 period. See "Compare With Other Funds" below for details on how to use the hypothetical data.

In addition to the ongoing expenses which the Funds bear directly, Columbia Thermostat Fund's shareholders indirectly bear the Fund's allocable share of the costs and expenses of each underlying fund in which the Fund invests. You can also estimate the effective expenses paid during the period, which includes the indirect fees associated with investing in the underlying funds, by using the amounts listed in the effective expenses paid during the period column in the "Fund of Funds" table below.

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 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 ongoing costs of investing in a fund only and do not reflect any transaction costs, such as sales charges, or redemption or exchange fees. Therefore, the hypothetical calculations are useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. If transaction costs were included in these calculations, your costs would be higher.

July 1, 2011 – December 31, 2011

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during 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		890.00		1,021.26		3.60		3.85		0.76
Columbia Acorn International		1,000.00		1,000.00		834.20		1,020.41		4.28		4.71		0.93
Columbia Acorn USA		1,000.00		1,000.00		870.90		1,020.00		4.74		5.11		1.01
Columbia Acorn International Select		1,000.00		1,000.00		869.80		1,019.35		5.34		5.77		1.14
Columbia Acorn Select		1,000.00		1,000.00		836.10		1,020.21		4.46		4.91		0.97
Columbia Acorn Emerging Markets Fund		1,000.00		1,000.00		928.00		1,013.00		5.17		7.37		1.46
Columbia Acorn European Fund		1,000.00		1,000.00		952.20		1,013.33		4.91		6.91		1.37

Expenses do not include fees and expenses incurred indirectly by the Fund from the underlying funds in which the Fund may invest (also referred to as "acquired funds"), including affiliated and non-affiliated pooled investments vehicles (including mutual funds and exchange traded funds).

Fund of Funds—Columbia Thermostat Fund

July 1, 2011 – December 31, 2011

Account value at
the beginning of
the period ($)

Account value at
the end of
the period ($)

Expenses paid
during period ($)

Fund's
annualized
expense
ratio (%)

Effective
expenses
paid during
the period

Fund's
effective
annualized
expense
ratio (%)

Actual

Hypothetical

Actual

Hypothetical

Actual

Hypothetical

Actual

Hypothetical

Actual

Class Z Shares

Columbia
Thermostat Fund

1,000.00

1,001.90

1,023.82

1.25

1.27

0.25

4.52

4.57

0.90

Expenses paid during the period are equal to the 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.

In the case of Columbia Thermostat Fund, effective expenses paid during the period and the Fund's effective annualized expense ratio include expenses borne directly to the class plus the Fund's pro rata portion of the ongoing expenses charged by the underlying funds using the expense ratio of each class of the underlying funds as of the underlying fund's most recent shareholder report.

Had the investment adviser and/or certain of its affiliates not waived/reimbursed certain fees and expenses, account value at the end of the period would have been reduced.

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 12/31/11

FMC Technologies	1.9	%
Donaldson	1.8	%
Ametek	1.7	%
lululemon athletica	1.6	%
Alexion Pharmaceuticals	1.4	%
tw telecom	1.1	%
Abercrombie & Fitch	1.0	%
SBA Communications	1.0	%
Fugro	0.7	%
Pall	0.6	%
Pacific Rubiales Energy	0.5	%
Shutterfly	0.4	%
Delphi Financial Group	0.3	%
True Religion Apparel	0.3	%
InterMune	0.2	%
Diamond Foods	0.2	%

Columbia Acorn Fund rose 10.78% in the fourth quarter of 2011, but ended the year down 4.61%. The Fund underperformed its primary benchmark, the Russell 2500 Index, by 3.74% during the quarter and 2.10% for the year. Performance was hurt by the underperformance of the Fund's international stocks. During both periods, Columbia Acorn Fund slightly beat its peers, as measured by the Lipper Mid-Cap Growth Funds Index.

Telecom stocks called in good gains during both periods. Tower company SBA Communications appreciated 25% in the quarter and 5% for the year as demand improved and the AT&T/T-Mobile merger was abandoned. Fiber optic voice and data services provider tw telecom accelerated growth; its stock rose 17% during the quarter and 14% for the year. PAETEC, a provider of telephone and data services, jumped 49% from the start of the year until its takeover by Windstream was completed on December 1.

Industrial stocks provided fine absolute returns during the quarter. Filter makers Donaldson and Pall rose 25% and 35%, respectively, on better than expected earnings. Instrument maker Ametek also posted fine results and its stock rose 28% in the quarter.

Energy stocks were mixed, providing generally good returns for the quarter but poor returns for the year. Oil and gas wellhead manufacturer FMC Technologies was one exception, rising 39% for the quarter and 18% for the year on improving demand for its products. Pacific Rubiales Energy was another exception, down 13% for the quarter and 45% for the year on substantial, but less than expected, progress on oil production and exploration in Colombia. Netherlands-based Fugro, a provider of sub-sea oilfield services, was up 14% for the quarter but off 27% for the year. Higher oil prices in the quarter improved expectations with respect to demand and earnings growth.

Consumer discretionary stocks were also mixed. Premium activewear retailer lululemon athletica reported excellent growth for both periods, but corrected 4% in the quarter on concerns about inventory levels, reducing its yearly gain to 38%. Internet photo-centric retailer Shutterfly plunged 45% in the quarter and 35% during the year as apparently desperate competitors cut prices. Teen apparel retailer Abercrombie & Fitch was discounted 20% in the quarter and 14% for the year as profits fell short of expectations due to weak margins in the United States and disappointing European sales. True Religion Apparel jumped 55% for the year on excellent sales gains.

Looking at stocks outside of the above sectors, Delphi Financial Group surged 108% in the quarter and 56% for the year on a takeover by Tokio Marine. Snack food distributor Diamond Foods turned bad in the quarter on an accounting controversy, plunging 60%. For the year, Alexion Pharmaceuticals, a biotech company, was the Fund's largest dollar winner, jumping 77% as its drug Soliris appeared effective for treating a neurological condition. However, another biotech company, InterMune, plunged 40% during the quarter and 67% for the year as Germany set disappointing reimbursement rates for the company's pulmonary fibrosis drug.

Columbia Acorn Fund's international stocks rose just 3.22% in the quarter and were off 23.71% for the year. Besides Pacific Rubiales Energy and Fugro, mentioned above, a number of small international energy and materials stocks performed poorly. Foreign stocks accounted for 12.6% of the Fund's assets at the beginning of 2011 and 9.2% of assets at year end.

Stocks were highly correlated with each other in 2011, suggesting to us that good company fundamentals were not adequately rewarded. We continue to believe that buying good companies at reasonable prices will result in long-term outperformance.

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.

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, 2011

*Inception 6/10/70*	1 year			5 years			10 years
Returns before taxes		-4.61	%		2.12	%		8.24	%
Returns after taxes on distributions		-5.23			1.58			7.66
Returns after taxes on distributions and sale of fund shares		-2.13			1.81			7.25
Russell 2500 Index (pretax)*		-2.51			1.24			6.57

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.

The Fund's Class Z annual operating expense ratio, as stated in the current prospectus, is 0.76%.

Columbia Acorn Fund Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn Fund Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	FMC Technologies Oil & Gas Wellhead Manufacturer	1.9	%
2.	Donaldson Industrial Air Filtration	1.8	%
3.	Ametek Aerospace/Industrial Instruments	1.7	%
4.	lululemon athletica Premium Active Apparel Retailer	1.6	%
5.	Mettler Toledo Laboratory Equipment	1.4	%
6.	Alexion Pharmaceuticals Biotech Focused on Orphan Diseases	1.4	%
7.	Crown Castle International Communications Towers	1.3	%
8.	tw telecom Fiber Optic Telephone/Data Services	1.1	%
9.	Informatica Enterprise Data Integration Software	1.1	%
10.	Abercrombie & Fitch Teen Apparel Retailer	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, 2011

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: $16.3 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.

Columbia Acorn International

In a Nutshell



P. Zachary Egan				Louis J. Mendes III

Co-Portfolio Manager				Co-Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Novozymes	0.9	%
Gree	0.7	%
Rheinmetall	0.6	%
Start Today	0.2	%

Columbia Acorn International returned 2.02% in the fourth quarter of 2011, 1.27% ahead of its primary benchmark, the S&P Global Ex-U.S. Between $500M and $5B Index. For 2011, the Fund fell 14.06%, which was 2.88% ahead of its benchmark. International small-cap stocks underperformed larger-cap stocks in a year marked by extreme volatility and high correlation among most risk assets. For comparison, the large-cap developed international market, as tracked by the MSCI EAFE Index, declined 12.14% during the year.

In 2010, the economic schism between stagnant, deflating developed economies and the high-growth inflationary emerging economies bore out in the strong performance of emerging market stocks. In 2011, fears of a renewed global recession dragged down all markets tied to economic growth, especially those of Europe and the emerging markets. Although early concerns over inflation in China, India and Brazil abated as the year progressed, they were replaced by the far greater concerns of potential sovereign debt defaults in Europe. European banks are important lenders in Asia and Latin America. Investors worried that the banks could serve as a transmission mechanism of European credit contraction.

Notwithstanding the horrific news related to the Japanese tsunami and associated nuclear catastrophe in the spring, Japanese equities proved to be among the best performers globally in 2011. The Fund's Japanese holdings, which represented on average 18% of the portfolio, fell less than 1% in U.S. dollar terms, buoyed in part by an appreciating yen. Internet-related companies Gree (a social networking game developer) and Start Today (an online apparel retailer) posted 182% and 82% gains, respectively, for the year and both were up roughly 12% in the fourth quarter. Investors became enthusiastic about their innovative business models, prospective near-term earnings growth in excess of 50% and high valuations assigned in transactions involving internet-related companies elsewhere in the world. We like these businesses and remain invested, but took some money off the table in both cases to fund more attractively valued new ideas.

As mentioned above, the European debt crisis became the overriding political and economic development affecting global risk premiums in the year and did take a toll on the Fund's equity holdings. Continental European holdings were off over 17%. Danish enzyme manufacturer Novozymes was an exception and up almost 12% for the year and 9% in the fourth quarter. On the downside, German auto supplier and defense contractor Rheinmetall was off more than 40% for the year and 6% in the fourth quarter despite solid improvements and respectable growth in its exhaust-system business, where fuel efficiency and tightening emission standards are creating opportunity. In the age of European austerity, however, the outlook for defense spending has soured, which explains the disappointing share price movement as earnings multiples of European defense stocks contracted.

Emerging market small-cap stocks, strong performers in 2010, were the worst performing equity class in 2011. The Fund's Brazilian holdings declined more than 30%, Chinese holdings more than 35% and Indian holdings more than 53%. At the end of the year, emerging market stocks represented about 24% of the Fund's assets, which compares with a benchmark weight of 25%. Our full weight here reflects our conviction in the long-term underlying opportunities offered by emerging market small-cap stocks as these emerging societies continue to negotiate the transition from informal to formal economies and raise the purchasing power and living standards of millions of people.

2012 has several major catalysts that we believe will affect global risk and the opportunity for continued growth in international small-cap equities. In the beginning of the year, all eyes will continue to look toward Europe for a resolution on the euro debt crisis. This is expected to be resolved before the high rhetoric associated with major elections of new governments in both China and the United States in the fall. As always, we will continue to work hard to find and invest in dynamic growth companies for you, our shareholders. Thank you for your continued investment in the Fund.

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.

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, 2011

*Inception 9/23/92*	1 year			5 years			10 years
Returns before taxes		-14.06	%		0.20	%		10.27	%
Returns after taxes on distributions		-14.63			-0.32			9.71
Returns after taxes on distributions and sale of fund shares		-8.88			0.20			9.18
S&P Global Ex-U.S. Between $500M and $5B Index*		-16.94			-0.58			11.10

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

The Fund's Class Z shares annual operating expense ratio, as stated in the current prospectus, is 0.98%.

Columbia Acorn International Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn International Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Far Eastone Telecom (Taiwan) Taiwan's Third Largest Mobile Operator	1.3	%
2.	Melco Crown Entertainment - ADR (Hong Kong) Macau Casino Operator	1.2	%
3.	Kansai Paint (Japan) Paint Producer in Japan, India, China & Southeast Asia	1.2	%
4.	Hexagon (Sweden) Design, Measurement & Visualization Software & Equipment	1.1	%
5.	Gemalto (France) Digital Security Solutions	1.1	%
6.	Zhaojin Mining Industry (China) Gold Mining & Refining in China	1.0	%
7.	Localiza Rent A Car (Brazil) Car Rental	1.0	%
8.	Olam International (Singapore) Agriculture Supply Chain Manager	1.0	%
9.	Naspers (South Africa) Media in Africa, China, Russia & Other Emerging Markets	0.9	%
10.	Novozymes (Denmark) Industrial Enzymes	0.9	%

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, 2011

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: $5.4 billion

Columbia Acorn USA

In a Nutshell



Robert A. Mohn

Lead Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

FMC Technologies	2.8	%
Ametek	2.5	%
lululemon athletica	2.2	%
Donaldson	1.9	%
Bally Technologies	1.7	%
World Acceptance	1.6	%
Abercrombie & Fitch	1.5	%
Extra Space Storage	1.4	%
Gaylord Entertainment	1.3	%
Alexion Pharmaceuticals	1.3	%
IPG Photonics	1.1	%
Atmel	1.0	%
Acuity Brands	1.0	%
Finisar	0.8	%
Shutterfly	0.4	%
Quicksilver Resources	0.3	%
TriQuint Semiconductor	0.3	%
InterMune	0.3	%
Diamond Foods	0.1	%

Columbia Acorn USA ended the fourth quarter of 2011 up 11.94%, underperforming the 15.47% return of its primary benchmark, the Russell 2000 Index. For the annual period, Fund performance was more in line with the benchmark, though still below it, with the Fund down 4.95% vs. the Russell 2000's 4.18% decline. Relative Fund performance was strong through the end of October, but returns for the final two months of the year were hard hit by the poor performance of the Fund's consumer stocks.

Winners for the quarter included three industrial names: instrument maker Ametek, industrial air filtration manufacturer Donaldson and commercial lighting manufacturer Acuity Brands. All three companies experienced market share gains and rapid earnings growth, leading to returns between 25% and 47%.

Other winners included FMC Technologies, up 39% for the quarter. FMC benefited from higher oil prices and strong demand for its sub-sea wellhead systems. Bally Technologies, a slot machine manufacturer, gained 47% in the quarter on strong sales of newly released games. Up 31%, lender World Acceptance was boosted by double-digit loan growth and a significant stock buyback. Extra Space Storage, a self-storage facility, gained 31% in the quarter on increasing occupancy and rent hikes.

For the year, Alexion Pharmaceuticals, a biotech company focused on orphan diseases, rose 77% as its primary drug, Soliris, was approved for treating a severe neurological condition. lululemon athletica suffered from a perceived surplus of inventory during the fourth quarter, but still ended the year up 36% in Columbia Acorn USA on strong sales growth driven by increased awareness of its yoga-inspired athletic apparel. FMC Technologies, World Acceptance and Extra Space Storage were also among the Fund's annual winners with gains ranging from 17% to 43% in 2011.

The quarter's primary laggards were consumer stocks. Teen apparel retailer Abercrombie & Fitch dropped 20%, as profits fell short of expectations due to weak margins in the United States and disappointing European sales. Internet photo-centric retailer Shutterfly fell victim to a fierce price war waged by all the internet photo book and photo card companies this holiday season, resulting in a steep stock drop of 45% in the quarter. Down nearly 60%, snack food distributor Diamond Foods was crushed on news of an accounting controversy regarding the timing of payments made to its walnut suppliers.

Outside the consumer sector, IPG Photonics, a manufacturer of fiber lasers, fell 22% during the quarter on decreased orders for low-powered lasers from its Chinese customers. Biotech company InterMune fell more than 40% after receiving a negative ruling from a drug reimbursement board in Germany.

For the annual period, laggards included Gaylord Entertainment, an operator of convention hotels. Its stock fell 33% on poor results at its D.C. and Orlando properties. Quicksilver Resources, a natural gas producer, sank 54% as plans to take the company private fell through and natural gas prices declined. Technology companies Finisar, a manufacturer of telecom equipment, and two semiconductor and related equipment manufacturers, TriQuint Semiconductor and Atmel, saw losses ranging from 34% to 60%. The three stocks soared in 2010, but as sales plateaued in early 2011, the stocks retraced much (and in the case of TriQuint, all) of their prior gains.

Investors spent much of 2011 focused on what could go wrong at home and abroad. Concern is certainly warranted, but we believe that consideration should also be given to the many things that could go right. U.S. economic indicators could keep improving, the unemployment rate could keep dropping, European sovereign debt yields could retreat, and low stock market valuation multiples could jump higher. Last year, it paid to be a pessimist. We believe that sometime soon, the optimists will reign.

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 (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, 2011

*Inception 9/4/96*	1 year			5 years			10 years
Returns before taxes		-4.95	%		0.82	%		6.30	%
Returns after taxes on distributions		-5.04			0.52			6.02
Returns after taxes on distributions and sale of fund shares		-3.10			0.69			5.54
Russell 2000 Index (pretax)*		-4.18			0.15			5.62

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

The Fund's Class Z shares annual operating expense ratio, as stated in the current prospectus, is 1.01%.

Columbia Acorn USA Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn USA Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	FMC Technologies Oil & Gas Wellhead Manufacturer	2.8	%
2.	Ametek Aerospace/Industrial Instruments	2.5	%
3.	lululemon athletica Premium Active Apparel Retailer	2.2	%
4.	Informatica Enterprise Data Integration Software	2.2	%
5.	Micros Systems Information Systems for Hotels, Restaurants & Retailers	2.1	%
6.	Nordson Dispensing Systems for Adhesives & Coatings	2.0	%
7.	Donaldson Industrial Air Filtration	1.9	%
8.	Atwood Oceanics Offshore Drilling Contractor	1.8	%
9.	tw telecom Fiber Optic Telephone/Data Services	1.8	%
10.	Mettler Toledo Laboratory Equipment	1.7	%

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, 2011

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: $1.6 billion

Columbia Acorn International Select

In a Nutshell

Christopher J. Olson

Lead Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Far Eastone Telecom	6.4	%
Wirecard	3.1	%
Intertek Group	2.0	%
Asahi Diamond Industrial	1.9	%
Gree	1.9	%
Ain Pharmaciez	1.5	%
Chemring	1.5	%
Rheinmetall	1.5	%
Israel Chemicals	1.5	%

Columbia Acorn International Select ended the fourth quarter of 2011 up 1.93%, outperforming the 0.99% gain of its primary benchmark, the S&P Developed Ex-U.S. Between $2B and $10B Index. For the year, the Fund was down 9.76%, holding up better than the benchmark's 14.01% decline. Fears of a global recession and continuing financial crisis plagued international market performance throughout the year.

Taiwan's Far Eastone Telecom was a top contributor to Fund gains for both the fourth quarter and the year, up roughly 26% for both periods. Far Eastone is Taiwan's third largest mobile operator and is seeing strong data growth and rising revenue due to the increasing use of smartphones. A 6% yield and strong cash position also made it an attractive investment option during a weak market. Another winner in the mobile communication industry was Japanese mobile social networking game developer Gree. The company's higher than expected growth was reflected in its stock gain of 173% for the year and 13% for the fourth quarter in Columbia Acorn International Select. It too is benefiting from the increased use of smartphones, which has helped to drive its outperformance. Japanese drugstore operator Ain Pharmaciez gained 9% in the fourth quarter, contributing to the stock's annual gain of 39%. Good acquisitions and better than expected cost cutting helped it beat earnings estimates. UK testing, inspection and certification services provider Intertek Group gained 10% in the fourth quarter, ending the year up 15%. Increasing regulations and a focus on product quality has made the testing and inspection business highly resilient in tough economic times. German online payment processor and risk manager Wirecard was up 18% for the year and gained 5% in the fourth quarter. The company has been growing revenues due to strong growth in e-commerce as well as the popularity of a newly introduced prepaid cash card.

Laggards included UK defense contractor Chemring, down 33% in the fourth quarter and 38% for the year as fears of cuts in defense spending dampened the prospects for the company. Germany's Rheinmetall was also impacted by defense spending concerns, falling 43% for the annual period and down 5% in the fourth quarter in the Fund. Israel Chemicals, an Israeli chemical producer, ended the year down 34% and the quarter off 7% due, in part, to fears of political risk in that country and remediation costs associated with clean-up near the company's evaporation pools. Japanese manufacturer of consumable diamond tools, Asahi Diamond Industrial, continued its downward trend from last quarter, falling another 13% in the fourth quarter and ending the year down 35%. Its business has suffered from fears of slowing global growth.

I remain cautious about the global financial markets given the magnitude and multitude of issues that need to be addressed. The Fund will continue to focus on companies with strong cash flow and dividend yield characteristics, solid balance sheets and above-average earnings visibility.

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

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, 2011

*Inception 11/23/98*	1 year			5 years			10 years
Returns before taxes		-9.76	%		0.41	%		9.22	%
Returns after taxes on distributions		-10.24			0.01			9.02
Returns after taxes on distributions and sale of fund shares		-5.37			0.45			8.31
S&P Developed Ex-U.S. Between $2B and $10B Index (pretax)*		-14.01			-3.06			8.41

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

The Fund's Class Z shares annual operating expense ratio, as stated in the current prospectus, is 1.16%.

Columbia Acorn International Select Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn International Select
Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Far Eastone Telecom (Taiwan) Taiwan's Third Largest Mobile Operator	6.4	%
2.	Kansai Paint (Japan) Paint Producer in Japan, India, China & Southeast Asia	5.7	%
3.	Ascendas REIT (Singapore) Singapore Industrial Property Landlord	5.7	%
4.	Mapletree Industrial Trust (Singapore) Singapore Industrial Property Landlord	5.2	%
5.	Seven Bank (Japan) ATM Processing Services	4.0	%
6.	Rand Merchant Insurance (South Africa) Directly Sold Property & Casualty Insurance; Holdings in Other Insurers	3.8	%
7.	Wirecard (Germany) Online Payment Processing & Risk Management	3.1	%
8.	Hexagon (Sweden) Design, Measurement & Visualization Software & Equipment	3.0	%
9.	Archipelago Resources (Indonesia) Gold Mining Projects in Indonesia, Vietnam & the Philippines	2.9	%
10.	Adcock Ingram Holdings (South Africa) Manufacturer of Pharmaceuticals & Medical Supplies	2.9	%

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, 2011

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: $326.4 million

Columbia Acorn Select

In a Nutshell



Ben Andrews				Robert A. Chalupnik

Lead Portfolio Manager				Co-Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Hertz	6.0	%
CNO Financial Group	4.4	%
Sanmina-SCI	4.4	%
Pacific Rubiales Energy	3.1	%

Diversification Status Change

Effective January 31, 2012, Columbia Acorn Select changed its classification to a diversified investment company. This is a change in classification only. The Fund's investment style remains the same. Diversified funds have greater flexibility in allocating investments than non-diversified funds. The Fund was previously registered as a non-diversified investment company, which required more concentrated holdings with a relatively large percentage of portfolio assets invested in a single issuer or a small number of issuers. The Fund will not be able to become non-diversified unless it seeks and obtains the approval of shareholders.

Columbia Acorn Select gained 9.35% in the fourth quarter of 2011 but fell 16.37% for the year. The S&P MidCap 400 Index, the Fund's primary benchmark, was up 12.98% in the fourth quarter and off 1.73% for the annual period. The large-cap S&P 500 Index gained 11.82% in the quarter and was up 2.11% for the year.

The loss and the performance lag were disappointments to us as Fund managers. So, what happened? What changes have we made to improve this performance?

Last quarter, we spoke about big valuation disparities between different types of companies likely due to investors' beliefs that the world was going to experience another 2008-type crisis. The Fund owned, and still does own, a handful of stocks that we believe have underperformed due to this phenomenon, and which contributed significantly to the Fund's underperformance in 2011. However, many of these companies have strong operational fundamentals, which is the reason that we continue to own them in the Fund. Some examples include: rental car company Hertz, down 20% in 2011 while its adjusted earnings are expected to be up 80% year over year (according to stock market analysts' earnings estimates); Colombian oil producer Pacific Rubiales Energy, down 45% for the year but with earnings up 125% year over year; insurance company CNO Financial Group, down 7% in 2011 but showing adjusted earnings up 80% year over year; and electronic manufacturing services provider Sanmina-SCI, down 19% in 2011 while its adjusted year-over-year earnings rose 25%.

We firmly believe that if a company continues to grow its earnings, its stock price will go up over time. We believe that the 2012 outlook for the companies mentioned above appears relatively strong. Though not visible in the Fund's fourth quarter performance, most of these stocks started to perform better late in the year. We believe that investors may be starting to realize that certain stocks are too cheap at current levels.

In prior shareholder reports, we've mentioned the two types of businesses held by the Fund: (1) core holdings, or companies with sustainable competitive advantages, pricing power, dominant market share and strong cash generation, and (2) opportunistic holdings, or companies going through a turnaround or that are misunderstood by Wall Street for various reasons. Midyear, the Fund began executing on its plan to structure the portfolio with fewer opportunistic holdings (like the stocks mentioned above) and more core holdings. In May 2011, we added Rob Chalupnik as co-portfolio manager to assist in this focus. However, we are deliberately making this transition slowly because we believe many of the Fund's opportunistic holdings are quite cheap and exhibit strong operational fundamentals. We anticipate opportunistic holdings will continue to be part of the portfolio, though a smaller percentage than the Fund has owned in recent years, especially in times of global uncertainty. We expect to vary the percentage when we believe we are being paid to take risk.

Due to the 2012 elections both here and in Europe, we wouldn't be surprised to see positive market results for this country, and some countries in Europe and Asia, in the new year. However, we do anticipate continued stock market volatility as we see little to no improvement in the over-leveraged status of the western world governments.

Thank you for your continued investment in Columbia Acorn Select.

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. 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.

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, 2011

*Inception 11/23/98*	1 year			5 years			10 years
Returns before taxes		-16.37	%		-1.07	%		6.05	%
Returns after taxes on distributions		-16.87			-1.33			5.77
Returns after taxes on distributions and sale of fund shares		-10.60			-0.95			5.27
S&P MidCap 400 Index (pretax)*		-1.73			3.32			7.04

All results shown assume reinvestment of distributions.

*The Fund's primary benchmark.

The Fund's Class Z shares annual operating expense ratio, as stated in the current prospectus, is 0.97%.

Columbia Acorn Select Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn Select Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Hertz Largest U.S. Rental Car Operator	6.0	%
2.	Discover Financial Services Credit Card Company	6.0	%
3.	Ametek Aerospace/Industrial Instruments	5.1	%
4.	CNO Financial Group Life, Long-term Care & Medical Supplement Insurance	4.4	%
5.	Sanmina-SCI Electronic Manufacturing Services	4.4	%
6.	Donaldson Industrial Air Filtration	3.7	%
7.	SBA Communications Communications Towers	3.7	%
8.	Pall Filtration & Fluids Clarification	3.3	%
9.	Safeway Supermarkets	3.3	%
10.	Abercrombie & Fitch Teen Apparel Retailer	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 Select (Class Z)

November 23, 1998 through December 31, 2011

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: $1.3 billion

Columbia Thermostat Fund

In a Nutshell

Charles P. McQuaid

Lead Portfolio Manager

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 ended the fourth quarter of 2011 up 7.64% and had a 4.85% gain for the annual period. This compares to an 11.82% fourth quarter return for its primary equity benchmark, the S&P 500 Index, and a 2.11% gain in the equity benchmark for the full year. The Fund's primary debt benchmark, the Barclays Capital U.S. Aggregate Bond Index, had a 1.12% return in the fourth quarter and ended the year up 7.84%.

The Fund hit three reallocation triggers in the fourth quarter. Stock exposure was reduced to 60% in October, increased to 70% in November and, in December, reduced back to 60%. The equity portion of the portfolio provided a strong return for the fourth quarter, with Columbia Dividend Income Fund providing top gains. For the year, the bond portion of the portfolio posted the higher weighted average gain, up 7.67% fueled by the 9.46% annual return of Columbia U.S. Treasury Index Fund.

As a result of the periodic review of underlying funds called for by Columbia Thermostat Fund's prospectus, effective December 12, 2011, the following changes were made to Columbia Thermostat Fund:

• Columbia Marsico Growth Fund, which comprised a 15% weighting of the portfolio's equity fund allocation, was replaced by Columbia Select Large Cap Growth Fund as the large-cap growth offering with a 10% weighting of the equity fund allocation.

• Columbia Contrarian Core Fund, which provides exposure to the large-cap blend style, had its weighting increased from 10% to 15% of the equity fund allocation.

• Columbia U.S. Treasury Index Fund, which provides exposure to U.S. Treasury securities, had its weighting reduced from 30% to 20% of the fixed-income allocation.

• Columbia Income Opportunities Fund, which provides exposure to high-yield securities, had its weighting increased from 20% to 30% of the fixed-income allocation.

The changes were implemented to fine-tune the underlying investment style mix of the equity portion of the Fund and to address yield spreads in the fixed-income segment.

Results of the Funds Owned in Columbia Thermostat Fund as of December 31, 2011

Stock Funds	Weightings			4th
Fund	in category			quarter			1 year
Columbia Acorn International, Class I		20	%		1.99	%		-14.02	%
Columbia Dividend Income Fund, Class I		20	%		12.78	%		7.08	%
Columbia Acorn Fund, Class I		15	%		10.77	%		-4.57	%
Columbia Contrarian Core Fund, Class I		15	%		11.72	%		-0.84	%
Columbia Select Large Cap Growth Fund, Class I*		10	%		5.98	%		-2.97	%
Columbia Acorn Select, Class I		10	%		9.34	%		-16.25	%
Columbia Large Cap Enhanced Core Fund, Class I		10	%		12.06	%		4.75	%
*Weighted Average* *Equity Gain/Loss*		*100*	%		*9.37*	%		*-3.82*	%

*Replaced Columbia Marsico Growth Fund effective December 12, 2011. Weighted average equity returns through year-end reflect linked returns between the previous Fund holding and Columbia Select Large Cap Growth Fund.

Bond Funds	Weightings			4th
Fund	in category			quarter			1 year
Columbia Intermediate Bond Fund, Class I		50	%		1.60	%		6.78	%
Columbia U.S. Treasury Index Fund, Class I		20	%		0.83	%		9.46	%
Columbia Income Opportunities Fund, Class I		30	%		6.45	%		6.42	%
*Weighted Average* *Income Gain*		*100*	%		*2.41*	%		*7.67*	%

Columbia Thermostat Fund
Rebalancing in the Fourth Quarter

October 25, 2011				60% stocks, 40% bonds
November 25, 2011				70% stocks, 30% bonds
December 27, 2011				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 financial 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 advisor'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.

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, 2011

*Inception 9/25/02*	1 year			5 years			Life of fund
Returns before taxes		4.85	%		4.21	%		7.51	%
Returns after taxes on distributions		3.80			3.12			6.26
Returns after taxes on distributions and sale of fund shares		3.15			3.06			5.97
S&P 500 Index (pretax)*		2.11			-0.25			6.85
Barclays Capital U.S. Aggregate Bond Index (pretax)*		7.84			6.50			5.33
Lipper Flexible Portfolio Funds Index (pretax)		-1.16			2.02			7.10

All results shown assume reinvestment of distributions.

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

The Fund's Class Z annual operating expense ratio, as stated in the current prospectus, is 1.04%. Columbia Thermostat Fund has a contractual fee waiver and expense reimbursement with CWAM that expires April 30, 2012; expense ratios without and with the contractual waiver/reimbursement, including fees and expenses associated with the Fund's investment in other investment companies (underlying funds), are 1.16% and 1.04%, respectively. Absent the waiver or reimbursement, performance results would have been lower.

Columbia Thermostat Fund Asset Allocation

as a percentage of net assets, as of 12/31/11

Columbia Thermostat Fund Portfolio Weightings

as a percentage of assets in each investment category, as of 12/31/11

Stock Mutual Funds

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

*Replaced Columbia Marsico Growth Fund effective December 12, 2011.

Bond Mutual Funds

Columbia Intermediate Bond Fund, Class I	50	%
Columbia U.S. Treasury Index Fund, Class I	20	%
Columbia Income Opportunities Fund, Class I	30	%

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

September 25, 2002 through December 31, 2011

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: $189.6 million

Columbia Acorn Emerging Markets Fund

In a Nutshell



Fritz Kaegi				Stephen Kusmierczak

Lead Portfolio Manager				Lead Portfolio Manager



P. Zachary Egan				Louis J. Mendes

Co-Portfolio Manager				Co-Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Far Eastone Telecom	2.5	%
Ace Indonesia	2.5	%
Nagacorp	1.8	%
Madalena Ventures	1.6	%
Mongolian Mining	1.1	%

As of December 31, 2011, Columbia Acorn Emerging Markets Fund was up 4.98% for the fourth quarter and down 7.20% for the period since its August 19, 2011 launch. The Fund outperformed its primary benchmark, the S&P Emerging Markets Between $500M and $5B Index, by 4.02% for the quarter and by 6.26% for the period since inception.

Madalena Ventures, an oil and gas exploration company, rose 95% during the quarter thanks to others' notable successes in drilling large oil- and gas-bearing shale reservoirs adjoining Madalena's acreage in Argentina. Far Eastone Telecom, the third largest mobile operator in Taiwan, was up 26% for the quarter, as smartphone sales accelerated and the larger user base rapidly increased data usage. Several of the Fund's holdings exposed to Southeast Asia also did well in the fourth quarter, including Nagacorp, up 21%, and Ace Indonesia, up 25%. Nagacorp, a casino/entertainment complex operator based in Hong Kong, has done well due to significant increased patronage and business volume at its flagship Nagaworld casino in Phnom Penh, Cambodia. Ace Indonesia's 2011 sales were up 43% and same-store sales were up nearly 20% for the home improvement retailer.

Two poor performers were the Market Vectors Indian Small Cap Index (down 23%) and EGShares Indian Small Cap (down 21%), both exchange traded funds (ETFs). Negative sentiment about Indian growth prospects and the regulatory environment, as well as rupee depreciation, drove the underperformance. The Fund held ETFs while waiting for Indian regulatory approval to own local shares directly, in order to provide Indian exposure. The Fund received the approval in December and sold the ETFs and added five new Indian positions.

Hong Kong-listed Mongolian Mining, a producer of coking coal, was down 15% as of the year end. Investors worried about the sustainability of steel input prices and Chinese consumption. We don't disagree, but believe that Mongolian Mining's low-cost position and volume growth potential give it a valuable franchise even during a period of low coal prices.

As mentioned in our third quarter shareholder report, the Fund favors companies with defensive business models and healthier balance sheets, as it aims to outperform in falling markets and to keep up in strong bull markets. So far, so good. Cash has added 1.5% to outperformance since inception. We generally aim to keep the cash position between 5% and 10%. Daily cash inflows can occasionally cause the Fund's cash position to exceed this range.

We have found what we believe are good companies with strong dividend yields. The Fund's stocks generated a healthy dividend yield of 2.4% (before fees, at year end), while the Fund's benchmark yielded 3.1% (the Russell 2500 index yielded only 1.5%). As of year-end, about 28% of the Fund was invested in stocks with an expected dividend yield of greater than 4%. Yield makes for a visible and concrete valuation marker during market downdrafts, hopefully leading to outperformance. A healthy dividend can attract buying interest from hard-nosed local investors in emerging markets when foreigners head for the exits. Dividends also give us cash to deploy when stock prices are low.

We believe that being able to grow while paying out significant dividends is the ultimate acid test of a good business. We'll be looking for more businesses like these to add to the Fund in 2012.

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

Columbia Acorn Emerging
Markets Fund (CEFZX)

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 Total Returns (Class Z)

through December 31, 2011

*Inception 8/19/11*	Life of fund*
Returns before taxes		-7.20	%
Returns after taxes on distributions		-7.19
Returns after taxes on distributions and sale of fund shares		-4.67
S&P Emerging Markets Between $500M and $5B Index (pretax)**		-13.46

All results shown assume reinvestment of distributions.

*Reflects performance from Fund inception on 8/19/11 through 12/31/11.

**The Fund's primary benchmark. For purposes of the Fund's principal investment strategies, CWAM generally determines which countries are emerging market countries by reference to the countries included in the S&P Emerging Markets Broad Market Index.

The Fund's Class Z annual operating expense ratio, as stated in the current prospectus, is 1.58%. Columbia Acorn Emerging Markets Fund has a contractual fee waiver and expense reimbursement agreement with CWAM that generally limits the Fund's ordinary expenses to 1.60% of the Fund's average daily net assets, and which expires April 30, 2013; expense ratios without and with the contractual waiver/reimbursement are 1.58%.

Columbia Acorn Emerging Markets Fund Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn Emerging Markets Fund
Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Archipelago Resources (Indonesia) Gold Mining Projects in Indonesia, Vietnam & the Philippines	2.6	%
2.	Far Eastone Telecom (Taiwan) Taiwan's Third Largest Mobile Operator	2.5	%
3.	Ace Indonesia (Indonesia) Home Improvement Retailer	2.5	%
4.	Adcock Ingram Holdings (South Africa) Manufacturer of Pharmaceuticals & Medical Supplies	2.3	%
5.	Alliance Grain Traders (Canada) Global Leader in Pulse Processing & Distribution	2.3	%
6.	Coronation Fund Managers (South Africa) South African Fund Manager	2.1	%
7.	Grupo Aeroportuario del Sureste - ADR (Mexico) Mexican Airport Operator	2.1	%
8.	Rand Merchant Insurance (South Africa) Directly Sold Property & Casualty Insurance; Holdings in Other Insurers	2.0	%
9.	MRV Engenharia (Brazil) Brazilan Property Developer	2.0	%
10.	Tower Bersama Infrastructure (Indonesia) Communications Towers	2.0	%

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 Emerging Markets Fund (Class Z)

August 19, 2011 through December 31, 2011

This graph compares the results of $10,000 invested in Columbia Acorn Emerging Markets Fund at inception on August 19, 2011 to the S&P Emerging Markets 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 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:
$3.2 million

Columbia Acorn European Fund

In a Nutshell



Andreas Waldburg-Wolfegg				Stephen Kusmierczak

Lead Portfolio Manager				Co-Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Core Laboratories	2.9	%
Chemring	2.1	%
Atea	2.0	%
Dürr	1.4	%
Rotork	1.2	%
Mersen	1.1	%
Intralot	0.7	%

Columbia Acorn European Fund was up 1.19% in the fourth quarter of 2011, outperforming its primary benchmark, the S&P Europe Between $500M and $5B Index, by 78 basis points. Since its launch on August 19, 2011, through December 31, 2011, the Fund declined 4.78% versus its benchmark's drop of 7.17%. We believe this outperformance is explained by the Fund's more conservative positioning and focus on companies with durable business models, solid dividends and less-levered balance sheets.

Despite persistent concerns about the European debt crisis, some companies continued to experience robust growth due to more favorable geographic or business exposures. Dürr, a German automotive plant engineer, climbed 37% in the fourth quarter on strong order wins in China. Norwegian IT hardware and services reseller Atea was up 29% for the quarter after it announced ambitious new growth targets and raised its dividend 250%. Unlike most of our investments in the portfolio, Atea's exposure is Europe only and, more specifically, the Nordic region. Two holdings that continued to benefit from large global investments in energy were Core Laboratories and Rotork, up 27% and 25%, respectively, during the fourth quarter. Dutch Core Laboratories helps oil and gas exploration companies better identify energy reservoirs, while UK-listed Rotork provides actuators and valves for energy distribution.

The Fund's largest detractors fell across several industries and geographies. French vacation property operator Pierre & Vacances dropped 28% in the quarter after the government announced plans to curtail subsidies on vacation homes. We opted to sell the Fund's position in this stock. Mersen, a French maker of equipment used in a wide array of industrial and engineering applications, fell 26% as investor concern over softening industrial order books worldwide took its toll on the shares' valuation. Intralot, a Greek-based operator of online gaming and lotteries, fell 24%. Although Greece represents only 5% of Intralot's operating earnings, the stock has traded down sharply along with poor Greek sentiment. Chemring, a UK defense manufacturer, fell 24% on fears of reduced government spending on defense.

Relative to its benchmark, the Fund maintained a considerable 1,400 basis point underweight position in the United Kingdom and Ireland, and was overweight in France, Germany and the Netherlands as of year end. This UK underweight was a headwind for the Fund, as the British pound appreciated 4.1% against the euro during the period. The Fund's geographic exposures are a product of our bottom-up investment process, not macroeconomic calls on currencies or geographies. We don't hedge currencies in the Fund, believing that we can provide no added value in predicting exchange rates. However, we closely evaluate the impact that currencies have on our companies' production costs and cashflow, and their competitive situation versus competitors operating in other currencies.

Importantly, we believe the domicile of a company or its listing country does not necessarily reflect its true economic exposure. Indeed most of the companies in the Fund have at least pan-European exposures and, in many cases, global footprints. We are not sure how the European crisis will eventually play out, but it is important to note that Europe is composed of a highly diverse group of countries. Some countries, like Germany, the Scandinavian countries and Poland, have been growing strongly the last couple of years. While concerns about the future of Europe and the Eurozone will likely persist for many more months, many of the Fund's export-based industrial and luxury goods companies are enjoying the advantages of the resulting euro depreciation. We remain vigilant in evaluating the Fund's companies' prospects in this tumultuous period.

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

Columbia Acorn
European Fund (CAEZX)

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 Total Returns (Class Z)

through December 31, 2011

*Inception 8/19/11*	Life of fund*
Returns before taxes		-4.78	%
Returns after taxes on distributions		-4.99
Returns after taxes on distributions and sale of fund shares		-3.03
S&P Europe Between $500M and $5B Index (pretax)**		-7.17

All results shown assume reinvestment of distributions.

*Reflects performance from Fund inception on 8/19/11 through 12/31/11.

**The Fund's primary benchmark.

The Fund's Class Z annual operating expense ratio, as stated in the current prospectus, is 1.50%. Columbia Acorn European Fund has a contractual fee waiver and expense reimbursement agreement with CWAM that expires April 30, 2013; expense ratios without and with the contractual waiver/reimbursement are 1.51% and 1.50%, respectively. Absent the waiver or reimbursement, performance results would have been lower.

Columbia Acorn European Fund Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn European Fund
Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Gemalto (France) Digital Security & Solutions	3.2	%
2.	Wirecard (Germany) Online Payment Processing & Risk Management	2.9	%
3.	Core Laboratories (Netherlands) Oil & Gas Reservoir Consulting	2.9	%
4.	Geberit (Switzerland) Plumbing Supplies	2.9	%
5.	Marel (Iceland) Largest Manufacturer of Poultry & Fish Processing Equipment	2.7	%
6.	Intertek Group (United Kingdom) Testing, Inspection & Certification Services	2.6	%
7.	Eurofins Scientific (France) Food, Pharmaceuticals & Materials Screening & Testing	2.6	%
8.	1000 mercis (France) Interactive Advertising and Marketing	2.4	%
9.	Aalberts Industries (Netherlands) Flow Control & Heat Treatment	2.4	%
10.	Hexagon (Sweden) Design, Measurement & Visualization Software & Equipment	2.3	%

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 European Fund (Class Z)

August 19, 2011 through December 31, 2011

This graph compares the results of $10,000 invested in Columbia Acorn European Fund at inception on August 19, 2011 to the S&P Europe 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 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:
$1.7 million

Columbia Acorn Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Information
AboveNet		1,200,000		1,400,000
Akamai		0		700,500
Ariba		1,200,000		2,850,000
Atmel		9,065,000		12,300,000
Boingo Wireless		1,400,000		1,500,000
Concur Technologies		1,480,000		1,830,000
Entegris		4,000,000		5,000,000
Equinix		435,000		585,000
Hittite Microwave		0		400,000
iGATE		3,307,204		3,400,000
Informatica		4,700,000		4,850,000
Ixia		2,030,000		2,330,000
Monolithic Power Systems		800,000		1,165,000
NetEase.com - ADR (China)		0		365,000
ON Semiconductor		6,202,000		6,842,000
Quality Systems		1,100,000		2,333,500
Sanmina-SCI		2,800,000		3,800,000
SBA Communications		3,150,000		3,700,000
Solera Holdings		0		55,000
TIBCO		2,000,000		2,139,800
Ultratech		0		415,000
Velti		0		2,500,000
Verisk Analytics		1,400,000		1,900,000
Industrial Goods & Services
Acorn Energy		1,336,001		1,500,000
Drew Industries		1,260,000		1,500,000
Fortune Brands Home & Security		0		1,300,000
Generac		1,667,021		1,775,704
Kennametal		3,200,000		3,725,000
LKQ		900,000		1,635,000
Middleby		0		123,344
Moog		2,050,000		2,775,000
Consumer Goods & Services
Expedia		0		1,450,000
Fossil		0		115,000
Hertz		3,000,000		3,750,000
Interface		1,000,000		1,750,000
Knoll		4,000,000		4,200,000
Move		0		1,062,500
PVH		1,410,000		1,660,000
Shutterfly		2,300,000		3,070,000
United Stationers		0		493,771
Vail Resorts		1,470,000		1,680,000
Finance
Alliance Data Systems		350,000		400,000
Allied World Holdings		0		500,000
Associated Banc-Corp		4,487,800		6,287,800

	Number of Shares
	09/30/11		12/31/11
Enstar Group		150,000		216,766
Hudson Valley		772,632		811,295
Kemper		0		762,252
Selective Insurance Group		1,420,000		2,050,000
Tower Group		1,225,000		1,675,000
TrustCo Bank		779,305		1,940,318
Wright Express		100,000		180,000
Energy & Minerals
Athabasca Oil Sands		0		2,160,000
Celtic Exploration (Canada)		631,000		1,140,000
Crew Energy (Canada)		847,000		1,399,000
Hornbeck Offshore		500,000		1,000,000
Kirkland Lake Gold (Canada)		0		920,000
Kodiak Oil and Gas		0		2,200,000
Oasis Petroleum		228,200		840,000
PetroMagdalena Energy (Colombia)		6,866,628		7,582,928
SM Energy		715,000		900,000
Health Care
Adcock Ingram Holdings (South Africa)		2,859,820		3,388,000
Auxilium Pharmaceuticals		2,400,000		3,033,715
HealthSouth		1,725,000		2,075,000
Hill-Rom Holdings		625,100		1,975,000
Horizon Pharma		870,000		1,095,000
InterMune		2,226,000		2,950,000
Micromet		5,500,000		6,702,347
NPS Pharmaceuticals		4,500,000		6,000,000
Seattle Genetics		4,200,000		6,153,000
Sirona Dental Systems		1,800,000		2,075,000
Other Industries
Associated Estates Realty		3,000,000		3,700,000
DuPont Fabros Technology		2,200,000		3,350,000
Kite Realty Group		3,050,000		3,500,000

See accompanying notes to financial statements.

	Number of Shares
	09/30/11		12/31/11
Sales
Information
Amphenol		3,565,000		3,495,000
Blackbaud		2,250,000		1,680,198
Carbonite		362,577		295,591
Crown Castle International		5,700,000		4,600,000
Discovery Series C		3,000,000		2,050,000
Dolby Laboratories		605,000		0
Hamamatsu Photonics (Japan)		400,000		0
Kenexa		2,025,000		1,700,000
Mail.ru - GDR (Russia)		464,305		423,040
Microsemi		2,345,000		2,160,000
Navigant Consulting		3,000,000		2,800,000
NetSuite		1,450,000		1,150,000
PAETEC Holding		9,000,000		0
Plexus		1,210,000		1,100,000
Polycom		4,130,000		1,165,000
Supertex		644,280		535,000
Tangoe		313,100		0
TheStreet.com		656,585		55,624
Industrial Goods & Services
Arcadis (Netherlands)		626,524		100,000
Mersen (France)		495,086		420,000
Mine Safety Appliances		926,962		566,497
Mueller Water Products		649,000		0
Neopost (France)		265,907		212,972
Silgan Holdings		400,000		200,000
WW Grainger		605,000		270,000
Consumer Goods & Services
Avis Budget Group		4,000,000		3,800,000
Career Education		2,800,000		0
CTS Eventim (Germany)		320,000		265,000
Deckers Outdoor		1,120,000		1,045,000
Expedia		3,100,000		0
Guess?		1,455,000		530,000
Hansen Natural		1,780,000		1,170,000
Lifestyle International (Hong Kong)		14,000,000		13,500,000
lululemon athletica		7,490,000		5,740,000
Move		4,250,000		0
Olam International (Singapore)		32,896,000		32,000,000
Penn National Gaming		1,100,000		850,000
Pool		2,100,000		2,015,000
Thor Industries		2,180,000		1,100,000
True Religion Apparel		1,747,000		1,507,000
Universal Technical Institute		1,400,000		650,000
Finance
Aaron's		2,300,000		1,834,695
CNO Financial Group		11,900,000		8,900,000

	Number of Shares
	09/30/11		12/31/11
Hanover Insurance Group		1,320,000		1,120,000
HCC Insurance Holdings		1,200,000		1,100,000
MB Financial		2,860,000		2,360,000
SVB Financial Group		910,000		810,000
Symetra Financial		694,343		0
TCF Financial		3,000,000		2,200,000
Valley National Bancorp		5,700,000		5,450,000
ViewPoint Financial		700,000		470,000
Energy & Minerals
Atwood Oceanics		2,399,000		2,114,000
Bristow		375,000		0
FMC Technologies		6,200,000		6,036,100
Fugro (Netherlands)		2,641,054		1,988,054
Houston American Energy		1,143,800		900,000
Northern Oil & Gas		850,000		638,000
Orko Silver (Canada)		5,000,000		0
Pacific Rubiales Energy (Colombia)		4,810,550		4,300,000
Silver Standard Resources		900,000		0
Silver Wheaton (Canada)		1,950,000		1,600,000
Southwestern Energy		1,389,000		75,071
STR Holdings		500,000		0
Tuscany International Drilling (Colombia)		8,870,000		4,435,000
Ultra Petroleum		383,000		0
Venoco		575,000		0
Vopak (Netherlands)		600,000		300,000
Health Care
Akorn		4,788,400		4,432,716
Alexion Pharmaceuticals		4,200,000		3,208,000
Community Health Systems		1,625,000		625,000
Edwards Lifesciences		340,000		0
Health Management Associates		3,800,000		1,875,000
Neogen		325,200		0
Pacific Biosciences of California		1,650,000		0
United Therapeutics		142,825		0
Other Industries
BioMed Realty Trust		4,575,000		3,000,000
Federal Realty Investment Trust		840,000		750,000
Heartland Express		2,730,000		2,400,000
JB Hunt Transport Services		1,275,000		1,155,000
Red Eléctrica de España (Spain)		333,000		200,000
Washington REIT		700,000		0

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 97.3%
Information 27.1%
		> Business Software 7.4%
	4,850,000	Informatica (a)	$	179,110
		Enterprise Data Integration Software
	2,550,000	Ansys (a)		146,064
		Simulation Software for Engineers and Designers
	2,700,000	Micros Systems (a)		125,766
		Information Systems for Hotels, Restaurants and Retailers
	1,830,000	Concur Technologies (a)		92,946
		Web Enabled Cost & Expense Management Software
	2,333,500	Quality Systems		86,316
		IT Systems for Medical Groups & Ambulatory Care Centers
	2,850,000	Ariba (a)		80,028
		Cost Management Software
	5,164,999	Hexagon (Sweden)		77,227
		Design, Measurement & Visualization Software & Equipment
	2,350,000	Constant Contact (a)(b)(c)		54,543
		E-mail & Other Marketing Campaign Mgmt Systems Delivered Over the Web
	1,700,000	Tyler Technologies (a)(b)(c)		51,187
		Financial, Tax, Court, & Document Mgmt Systems for Local Governments
	2,139,800	TIBCO (a)		51,163
		Datacenter Software
	1,150,000	NetSuite (a)		46,633
		End to End IT Systems Solution Delivered Over the Web
	1,680,198	Blackbaud		46,541
		Software & Services for Non-Profits
	1,700,000	Kenexa (a)(b)		45,390
		Recruiting and Workforce Management Solutions
	850,000	Red Hat (a)		35,097
		Maintenance & Support for Opensource OS & Middleware
	920,000	Jack Henry & Associates		30,921
		Systems Financial Institutions
	900,000	SPS Commerce (a)(b)		23,355
		Supply Chain Management Software Delivered via the Web
	2,500,000	Velti (a)		17,000
		Mobile Marketing Software Platform
	690,000	Advent Software (a)		16,808
		Asset Management & Trading Systems
	1,000,000	InContact (a)		4,430
		Call Center Systems Delivered Via the Web & Telco Services
	550,000	Intralinks (a)		3,432
		Collaboration Software
	55,000	Solera Holdings		2,450
		Software for Automotive Insurance Claims Processing
				1,216,407

Number of Shares			Value (000)
		> Instrumentation 2.6%
	1,600,000	Mettler Toledo (a)(b)	$	236,336
		Laboratory Equipment
	2,780,000	IPG Photonics (a)(b)		94,159
		Fiber Lasers
	2,035,000	Trimble Navigation (a)		88,319
		GPS-based Instruments
				418,814
		> Computer Hardware & Related Equipment 2.4%
	3,495,000	Amphenol		158,638
		Electronic Connectors
	4,550,000	II-VI (a)(b)		83,538
		Laser Optics and Specialty Materials
	1,605,000	Zebra Technologies (a)		57,427
		Bar Code Printers
	1,200,000	Netgear (a)		40,284
		Networking Products for Small Business & Home
	800,000	Nice Systems - ADR (Israel) (a)		27,560
		Audio & Video Recording Solutions
	605,000	Stratasys (a)		18,398
		Rapid Prototyping Systems
	230,000	Gemalto (France)		11,187
		Digital Security Solutions
				397,032
		> Mobile Communications 2.3%
	4,600,000	Crown Castle International (a)		206,080
		Communications Towers
	3,700,000	SBA Communications (a)		158,952
		Communications Towers
	600,000	MetroPCS Communications (a)		5,208
		Discount Cellular Telephone Services
	1,500,000	Globalstar (a)(c)		810
		Satellite Mobile Voice & Data Carrier
				371,050
		> Semiconductors & Related Equipment 2.2%
	12,300,000	Atmel (a)		99,630
		Microcontrollers, Radio Frequency, and Memory Semiconductors
	6,842,000	ON Semiconductor (a)		52,820
		Mixed-signal & Power Management Semiconductors
	5,000,000	Entegris (a)		43,625
		Semiconductor Materials Management Products
	2,160,000	Microsemi (a)		36,180
		Analog/Mixed-signal Semiconductors
	500,000	Littelfuse		21,490
		Little Fuses
	1,900,000	IXYS (a)(b)		20,577
		Power Semiconductors
	400,000	Hittite Microwave (a)		19,752
		Radio Frequency, Microwave & Millimeterwave Semiconductors

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Semiconductors & Related Equipment—continued
	1,165,000	Monolithic Power Systems (a)	$	17,556
		High Performance Analog & Mixed-signal Integrated Circuits (ICs)
	1,765,000	Pericom Semiconductor (a)(b)		13,432
		Interface Integrated Circuits (ICs) & Frequency Control Products
	2,290,000	TriQuint Semiconductor (a)		11,152
		Radio Frequency Semiconductors
	415,000	Ultratech (a)		10,197
		Semiconductor Equipment
	535,000	Supertex (a)		10,101
		Analog/Mixed Signal Semiconductors
				356,512
		> Telephone and Data Services 2.1%
	9,500,000	tw telecom (a)(b)		184,110
		Fiber Optic Telephone/Data Services
	1,400,000	AboveNet (a)(b)		91,014
		Metropolitan Fiber Communications Services
	2,520,000	Cogent Communications (a)(b)		42,563
		Internet Data Pipelines
	2,000,000	General Communications (a)		19,580
		Commercial Comm & Consumer CATV, Web & Phone in Alaska
	1,500,000	Boingo Wireless (a)(c)		12,900
		Wholesale and Retail WiFi Networks
				350,167
		> Computer Services 1.2%
	3,400,000	iGATE (a)(b)(c)		53,482
		IT & Business Process Outsourcing Services
	680,000	Syntel		31,804
		Offshore IT Services
	2,125,000	Virtusa (a)(b)		30,770
		Offshore IT Outsourcing
	1,145,000	ExlService Holdings (a)		25,614
		Business Process Outsourcing
	1,575,000	Genpact (a)		23,546
		Business Process Outsourcing
	4,500,000	Hackett Group (a)(b)		16,830
		IT Integration & Best Practice Research
	1,076,353	WNS - ADR (India) (a)		9,676
		Offshore BPO (Business Process Outsourcing) Services
				191,722
		> Gaming Equipment & Services 1.1%
	3,725,000	Bally Technologies (a)(b)		147,361
		Slot Machines & Software
	1,530,000	WMS Industries (a)		31,396
		Slot Machine Provider
				178,757
		> Telecommunications Equipment 1.0%
	685,000	F5 Networks (a)		72,692
		Internet Traffic Management Equipment
	1,905,000	Finisar (a)		31,899
		Optical Sub-systems and Components
	2,330,000	Ixia (a)		24,488
		Telecom Network Test Equipment

Number of Shares			Value (000)
	1,165,000	Polycom (a)	$	18,990
		Video Conferencing Equipment
	1,925,000	Infinera (a)		12,089
		Optical Networking Equipment
				160,158
		> Business Information & Marketing Services 0.9%
	1,900,000	Verisk Analytics (a)		76,247
		Risk & Decision Analytics
	900,000	FTI Consulting (a)		38,178
		Financial Consulting Firm
	2,800,000	Navigant Consulting (a)(b)		31,948
		Financial Consulting Firm
	505,000	RPX (a)		6,388
		Patent Aggregation and Defensive Patent Consulting
				152,761
		> CATV 0.9%
	2,050,000	Discovery, Series C (a)		77,285
		CATV programming
	1,250,000	Liberty Global, Series A (a)		51,287
		Cable TV Franchises Outside the USA
	15,770	Jupiter Telecommunications (Japan)		15,963
		Largest Cable Service Provider in Japan
				144,535
		> Financial Processors 0.9%
	2,429,000	Global Payments		115,086
		Credit Card Processor
	5,000,000	Singapore Exchange (Singapore)		23,633
		Singapore Equity & Derivatives Market Operator
				138,719
		> Internet Related 0.9%
	585,000	Equinix (a)		59,319
		Network Neutral Data Centers
	1,450,000	TripAdvisor (a)		36,554
		Online Travel Research
	700,500	Akamai (a)		22,612
		Content Delivery Network (CDN) for Better Delivery of Online Content
	365,000	NetEase.com - ADR (China) (a)		16,370
		Chinese Online Gaming Services
	423,040	Mail.ru - GDR (Russia) (a)(d)		10,999
		Internet Social Networking & Games for Russian Speakers
	55,624	TheStreet.com		94
		Financial Information Websites
				145,948
		> Electronics Distribution 0.6%
	3,125,000	Avnet (a)		97,156
		Electronic Components Distribution
				97,156
		> Contract Manufacturing 0.4%
	3,800,000	Sanmina-SCI (a)		35,378
		Electronic Manufacturing Services
	1,100,000	Plexus (a)		30,118
		Electronic Manufacturing Services
				65,496

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Entertainment Programming 0.1%
	1,250,000	IMAX (Canada) (a)	$	22,912
		IMAX Movies, Theatre Equipment and Theatre Joint Ventures
				22,912
		> Radio 0.1%
	164,991	Saga Communications (a)		6,168
		Radio Stations in Small & Mid-sized Cities
	1,527,700	Salem Communications (a)(b)		3,926
		Radio Stations for Religious Programming
				10,094
		> TV Broadcasting —%
	2,500,000	Entravision Communications		3,900
		Spanish Language TV & Radio Stations
	1,750,000	Gray Television (a)		2,835
		Mid Market Affiliated TV Stations
				6,735
		> Consumer Software —%
	295,591	Carbonite (a)(c)		3,281
		Online File Storage
				3,281
		> Advertising —%
	1,500,000	VisionChina Media - ADR (China) (a)		1,860
		Advertising on Digital Screens in China's Mass Transit System
				1,860
Information: Total				4,430,116
Industrial Goods & Services 19.0%
		> Machinery 11.0%
	4,200,000	Donaldson (b)		285,936
		Industrial Air Filtration
	6,750,000	Ametek		284,175
		Aerospace/Industrial Instruments
	3,725,000	Kennametal		136,037
		Consumable Cutting Tools
	3,000,000	Nordson		123,540
		Dispensing Systems for Adhesives & Coatings
	2,775,000	Moog (a)(b)		121,906
		Motion Control Products for Aerospace, Defense & Industrial Markets
	3,535,000	Pentair		117,680
		Pumps & Water Treatment
	2,325,000	Clarcor		116,227
		Mobile & Industrial Filters
	1,800,000	Pall		102,870
		Filtration & Fluids Clarification
	2,250,000	HEICO (b)		88,537
		FAA Approved Aircraft Replacement Parts
	2,200,000	ESCO Technologies (b)		63,316
		Automatic Electric Meter Readers
	2,675,000	Oshkosh Corporation (a)		57,192
		Specialty Truck Manufacturer
	1,150,000	WABCO Holdings (a)		49,910
		Truck & Bus Component Supplier
	1,775,704	Generac (a)		49,773
		Standby Power Generators

Number of Shares			Value (000)
	805,000	Toro	$	48,831
		Turf Maintenance Equipment
	600,000	Wabtec		41,970
		Freight & Transit Component Supplier
	1,300,000	Kaydon		39,650
		Specialized Friction & Motion Control Products
	566,497	Mine Safety Appliances		18,762
		Safety Equipment
	212,972	Neopost (France)		14,350
		Postage Meter Machines
	123,344	Middleby (a)		11,599
		Manufacturer of Cooking Equipment
	10,000,000	Marel (Iceland) (a)		10,228
		Largest Manufacturer of Poultry & Fish Processing Equipment
	100,000	Valmont Industries		9,079
		Center Pivot Irrigation Systems & Utility Poles
	1,250,000	Spartan Motors		6,013
		Specialty Truck & Chassis Manufacturer
	3,450,000	Jain Irrigation Systems (India)		5,611
	172,500	Jain Irrigation Systems - DVR (India) (a)		115
		Agricultural Micro-irrigation Systems & Food Processing
				1,803,307
		> Industrial Materials & Specialty Chemicals 2.1%
	1,750,000	Albemarle		90,143
		Refinery Catalysts and Other Specialty Chemicals
	760,000	FMC Corporation		65,390
		Niche Specialty Chemicals
	1,525,000	Novozymes (Denmark)		47,078
		Industrial Enzymes
	1,500,000	Drew Industries (a)(b)		36,795
		RV & Manufactured Home Components
	673,000	Sociedad Quimica y Minera de Chile - ADR (Chile) (c)		36,241
		Producer of Specialty Fertilizers, Lithium & Iodine
	900,000	Albany International		20,808
		Paper Machine Clothing and Advanced Textiles
	2,218,700	Kansai Paint (Japan)		19,761
		Paint Producer in Japan, India, China and Southeast Asia
	420,000	Mersen (France)		12,693
		Advanced Industrial Materials
	200,000	Silgan Holdings		7,728
		Metal & Plastic Packaging
				336,637
		> Other Industrial Services 1.9%
	3,200,000	Expeditors International of Washington		131,072
		International Freight Forwarder
	1,635,000	LKQ (a)		49,181
		Alternative Auto Parts Distribution
	1,767,165	Imtech (Netherlands) (c)		45,777
		Electromechanical & ICT Installation & Maintenance

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Other Industrial Services—continued
	1,300,000	Forward Air	$	41,665
		Freight Transportation Between Airports
	1,600,000	Mobile Mini (a)		27,920
		Portable Storage Units Leasing
	750,000	UTI Worldwide		9,968
		Freight Forwarding & Logistics
	1,500,000	Acorn Energy (b)		9,060
		Frac Well Exploration/Monitoring Device, Sonar Security,Electric Grid Monitoring
	100,000	Arcadis (Netherlands)		1,566
		Engineering Consultants
				316,209
		> Construction 0.9%
	1,725,000	Chicago Bridge & Iron		65,205
		Engineering & Construction for LNG & Petrochemicals
	66,000	NVR (a)		45,276
		DC Homebuilder
	1,300,000	Fortune Brands Home & Security (a)		22,139
		Home Building Supplies & Small Locks
	1,800,000	Mills Estruturas e Servicos de Engenharia (Brazil)		17,081
		Civil Engineering & Construction
				149,701
		> Waste Management 0.7%
	2,400,000	Waste Connections		79,536
		Solid Waste Management
	560,000	Clean Harbors (a)		35,689
		Hazardous Waste Services & Disposal
				115,225
		> Electrical Components 0.7%
	1,440,000	Acuity Brands		76,320
		Commercial Lighting Fixtures
	1,500,000	Ushio (Japan)		21,559
		Industrial Light Sources
	351,000	Saft Batteries (France)		9,926
		Niche Battery Manufacturer
				107,805
		> Outsourcing Services 0.6%
	2,800,000	Quanta Services (a)		60,312
		Electrical & Telecom Construction Services
	1,210,000	Insperity		30,673
		Professional Employer Organization
	600,000	GP Strategies (a)		8,088
		Training Programs
				99,073
		> Industrial Distribution 0.6%
	270,000	WW Grainger		50,541
		Industrial Distribution
	2,600,000	Interline Brands (a)(b)		40,482
		Industrial Distribution
				91,023
		> Steel 0.3%
	4,000,000	GrafTech International (a)		54,600
		Industrial Graphite Materials Producer
				54,600

Number of Shares			Value (000)
		> Conglomerates 0.2%
	2,263,654	Aalberts Industries (Netherlands)	$	38,028
		Flow Control & Heat Treatment
				38,028
Industrial Goods & Services: Total				3,111,608
Consumer Goods & Services 15.7%
		> Retail 4.2%
	5,740,000	lululemon athletica (a)(b)		267,829
		Premium Active Apparel Retailer
	3,510,000	Abercrombie & Fitch		171,429
		Teen Apparel Retailer
	5,600,000	Pier 1 Imports (a)(b)		78,008
		Home Furnishing Retailer
	3,070,000	Shutterfly (a)(b)		69,873
		Internet Photo-centric Retailer
	5,225,000	Saks (a)(c)		50,944
		Luxury Department Store Retailer
	525,000	DSW		23,210
		Branded Footwear Retailer
	971,500	Teavana (a)(c)		18,245
		Specialty Tea Retailer
	115,000	Fossil (a)		9,126
		Watch Designer & Retailer
	1,371,366	Gaiam (a)(b)		4,443
		Healthy Living Catalogs & E-Commerce
	66,000	The Fresh Market (a)		2,633
		Specialty Food Retailer
				695,740
		> Apparel 3.4%
	2,100,000	Coach		128,184
		Designer & Retailer of Branded Leather Accessories
	1,660,000	PVH		117,013
		Apparel Wholesaler and Retailer
	2,190,000	Warnaco Group (a)(b)		109,587
		Global Branded Apparel Manufacturer
	1,045,000	Deckers Outdoor (a)		78,971
		Fashion Footwear Wholesaler
	1,507,000	True Religion Apparel (a)(b)		52,112
		Premium Denim
	1,000,000	Hanesbrands (a)		21,860
		Apparel Wholesaler
	600,000	Steven Madden (a)		20,700
		Wholesaler/Retailer of Fashion Footwear
	530,000	Guess?		15,805
		Branded Apparel + Accessories + Licensor
	580,000	Crocs (a)		8,567
		Branded Footwear Wholesaler & Retailer
				552,799
		> Travel 2.4%
	3,850,000	Gaylord Entertainment (a)(b)		92,939
		Convention Hotels
	1,680,000	Vail Resorts		71,165
		Ski Resort Operator & Developer
	3,750,000	Hertz (a)		43,950
		Largest U.S. Rental Car Operator

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Travel—continued
	1,450,000	Expedia	$	42,079
		Online Travel Services Company
	3,800,000	Avis Budget Group (a)		40,736
		Second Largest Car Rental Company
	970,000	Choice Hotels		36,909
		Franchisor Of Budget Hotel Brands
	1,400,000	HomeAway (a)(c)		32,550
		Vacation Rental Online Marketplace
	2,000,000	Localiza Rent A Car (Brazil)		27,449
		Car Rental
				387,777
		> Food & Beverage 1.2%
	1,170,000	Hansen Natural (a)		107,804
		Alternative Beverages
	32,000,000	Olam International (Singapore)		52,453
		Agriculture Supply Chain Manager
	1,050,000	Diamond Foods		33,884
		Snack Foods and Culinary Ingredients
	240,000	Snyder's - Lance		5,400
		Snack Foods
	1,750,000	GLG Life Tech (Canada) (a)(b)		1,575
		Produce an All-Natural Sweetener Extracted from the Stevia Plant
				201,116
		> Other Consumer Services 0.8%
	2,190,000	Lifetime Fitness (a)(b)		102,382
		Sport & Fitness Club Operator
	13,500,000	Lifestyle International (Hong Kong)		29,715
		Mid- to High-end Department Store Operator in Hong Kong & China
	1,062,500	Move (a)		6,715
		Real Estate Internet Websites
	1,325,000	IFM Investments (Century 21 China RE) - ADR (China) (a)		424
		Provide Real Estate Services in China
				139,236
		> Furniture & Textiles 0.8%
	4,200,000	Knoll (b)		62,370
		Office Furniture
	2,250,000	Herman Miller		41,512
		Office Furniture
	1,750,000	Interface		20,195
		Modular & Broadloom Carpet
				124,077
		> Casinos & Gaming 0.7%
	3,950,000	Pinnacle Entertainment (a)(b)		40,132
		Regional Casino Operator
	850,000	Penn National Gaming (a)		32,359
		Regional Casino Operator
	3,000,000	Melco Crown Entertainment - ADR (Hong Kong) (a)(c)		28,860
		Macau Casino Operator
	12,000,000	MGM China Holdings (Hong Kong) (a)		15,611
		Macau Casino Operator
				116,962

Number of Shares			Value (000)
		> Other Durable Goods 0.5%
	1,650,000	Jarden	$	49,302
		Branded Household Products
	460,000	Cavco Industries (a)(b)		18,428
		Manufactured Homes
	400,000	Tesla Motors (a)(c)		11,424
		Design, Manufacture and Sell High Performance Electric Vehicles
				79,154
		> Consumer Goods Distribution 0.5%
	2,015,000	Pool		60,652
		Distributor of Swimming Pool Supplies & Equipment
	493,771	United Stationers		16,077
		Wholesale Distributor of Business Products
				76,729
		> Restaurants 0.3%
	2,000,000	AFC Enterprises (a)(b)		29,400
		Popeye's Restaurants
	450,000	Cheesecake Factory (a)		13,208
		Casual Dining Restaurants
	675,000	Bravo Brio Restaurant Group (a)		11,576
		Upscale Casual Italian Restaurants
				54,184
		> Nondurables 0.3%
	1,600,000	Helen of Troy (a)(b)		49,120
		Hair Dryers & Curling Irons
				49,120
		> Educational Services 0.3%
	800,000	New Oriental Education & Technology - ADR (China) (a)		19,240
		China's Largest Private Education Service Provider
	300,000	ITT Educational Services (a)(c)		17,067
		Post-secondary Degree Services
	650,000	Universal Technical Institute (a)		8,307
		Vocational Training
	2,000,000	Voyager Learning, Contingent Value Rights (a)(e)(f)		180
		Education Services for the K-12 Market
				44,794
		> Leisure Products 0.3%
	1,100,000	Thor Industries		30,173
		RV & Bus Manufacturer
	975,000	Skullcandy (a)(c)		12,207
		Lifestyle Branded Headphones
				42,380
		> Other Entertainment —%
	265,000	CTS Eventim (Germany)		7,957
		Event Ticket Sales
				7,957
Consumer Goods & Services: Total				2,572,025
Finance 10.4%
		> Banks 4.1%
	2,738,000	BOK Financial		150,398
		Tulsa Based S.W. Bank

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Banks—continued
	2,337,313	Hancock Holding	$	74,724
		Gulf Coast Bank
	6,287,800	Associated Banc-Corp		70,235
		Midwest Bank
	5,450,000	Valley National Bancorp (c)		67,416
		New Jersey/New York Bank
	1,275,000	City National		56,329
		Bank & Asset Manager
	4,300,000	CVB Financial (c)		43,129
		Inland Empire Business Bank
	2,360,000	MB Financial		40,356
		Chicago Bank
	810,000	SVB Financial Group (a)		38,629
		Bank to Venture Capitalists
	2,200,000	TCF Financial		22,704
		Great Lakes Bank
	4,299,507	First Busey		21,498
		Illinois Bank
	1,121,188	Sandy Spring Bancorp		19,677
		Baltimore, D.C. Bank
	1,350,000	TriCo Bancshares (b)		19,197
		California Central Valley Bank
	811,295	Hudson Valley		17,216
		Metro New York City Bank
	1,940,318	TrustCo Bank		10,885
		New York State Bank
	706,559	Eagle Bancorp (a)		10,273
		Metro D.C. Bank
	246,505	Pacific Continental Bank		2,182
		Pacific Northwest Bank
	158,389	Green Bankshares (a)		200
		Tennessee Bank
				665,048
		> Insurance 2.7%
	2,820,000	Leucadia National		64,127
		Insurance Holding Company
	8,900,000	CNO Financial Group (a)		56,159
		Life, Long-term Care & Medical Supplement Insurance
	1,200,000	Delphi Financial Group		53,160
		Workers Comp & Group Employee Benefit Products & Services
	1,120,000	Hanover Insurance Group		39,144
		Personal & Commercial Lines Insurance
	2,050,000	Selective Insurance Group		36,347
		Commercial & Personal Lines Insurance
	1,675,000	Tower Group		33,785
		Commercial & Personal Lines Insurance
	832,000	Willis Group (Ireland)		32,282
		Insurance Broker
	500,000	Allied World Holdings		31,465
		Commercial Lines Insurance/Reinsurance
	1,100,000	HCC Insurance Holdings		30,250
		Specialty Insurance
	762,252	Kemper		22,265
		Multi-line Insurance
	216,766	Enstar Group (a)		21,286
		Insurance/Reinsurance & Related Services

Number of Shares			Value (000)
	900,000	Brown & Brown	$	20,367
		Insurance Broker
	300,000	Assured Guaranty		3,942
		Global Muni Bond Insurance
				444,579
		> Finance Companies 1.9%
	1,505,202	World Acceptance (a)(b)		110,632
		Personal Loans
	2,150,000	McGrath Rentcorp (b)		62,328
		Temporary Space & IT Rentals
	1,834,695	Aaron's		48,950
		Rent to Own
	3,400,000	H&E Equipment Services (a)(b)		45,628
		Heavy Equipment Leasing
	1,123,400	CAI International (a)(b)		17,368
		International Container Leasing
	1,091,000	Marlin Business Services (b)		13,856
		Small Equipment Leasing
	78,500	Textainer Group Holdings		2,286
		Top International Container Leasor
				301,048
		> Brokerage & Money Management 1.2%
	6,198,000	SEI Investments		107,535
		Mutual Fund Administration & Investment Management
	3,700,000	Eaton Vance		87,468
		Specialty Mutual Funds
	1,000,000	Artio Global Investors (c)		4,880
		International Asset Manager
				199,883
		> Credit Cards 0.3%
	400,000	Alliance Data Systems (a)		41,536
		Diversified Credit Card Provider
	180,000	Wright Express (a)		9,770
		Pay Card Processor
				51,306
		> Savings & Loans 0.2%
	400,000	Financial Engines (a)		8,932
		Asset Management for 401k Plans
	1,010,000	Provident New York Bancorp		6,706
		New York State Thrift
	470,000	ViewPoint Financial		6,115
		Texas Thrift
	452,146	Kaiser Federal		5,797
		Los Angeles Savings & Loan
	65,991	Berkshire Hills Bancorp		1,464
		Northeast Thrift
				29,014
Finance: Total				1,690,878
Energy & Minerals 9.5%
		> Oil Services 4.2%
	6,036,100	FMC Technologies (a)		315,265
		Oil & Gas Wellhead Manufacturer
	1,988,054	Fugro (Netherlands)		115,517
		Sub-sea Oilfield Services

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Oil Services—continued
	2,114,000	Atwood Oceanics (a)	$	84,116
		Offshore Drilling Contractor
	743,000	Oil States International (a)		56,743
		Diversified North American Oil Service Provider
	1,670,000	ShawCor (Canada)		47,342
		Oil & Gas Pipeline Products
	1,000,000	Hornbeck Offshore (a)		31,020
		Supply Vessel Operator in U.S. Gulf of Mexico
	1,056,600	Black Diamond Group (Canada)		19,146
		Provides Accommodations/Equipment for Oil Sands Development
	2,890,900	Horizon North Logistics (Canada)		13,224
		Provides Diversified Oil Service Offering in Northern Canada
	4,435,000	Tuscany International Drilling (Colombia) (a)		2,612
		South America Based Drilling Rig Contractor
				684,985
		> Oil & Gas Producers 3.6%
	4,300,000	Pacific Rubiales Energy (Colombia) (c)		79,056
		Oil Production & Exploration in Colombia
	900,000	SM Energy		65,790
		Oil and Gas Producer
	2,400,000	Tullow Oil (United Kingdom)		52,255
		Oil and Gas Producer
	695,000	Range Resources		43,048
		Oil and Gas Producer
	974,000	Rosetta Resources (a)		42,369
		Oil and Gas Producer Exploring in South Texas and Montana
	2,700,000	Denbury Resources (a)		40,770
		Oil Producer Using Co2 Injection
	650,000	Baytex (Canada) (c)		36,349
		Oil & Gas Producer in Canada
	2,160,000	Athabasca Oil Sands (a)		26,482
		Oil Sands SAGD & Alberta Deep Basin Development
	1,140,000	Celtic Exploration (Canada) (a)		25,592
		Canadian Oil and Gas Producer
	840,000	Oasis Petroleum (a)		24,436
		Oil Producer in North Dakota
	2,200,000	Kodiak Oil and Gas (a)		20,900
		Bakken Oil & Gas Producer
	250,000	Cabot Oil and Gas		18,975
		Large Natural Gas Producer in Appalachia and Gulf Coast
	550,000	Swift Energy (a)		16,346
		Oil and Gas Exploration and Production
	1,399,000	Crew Energy (Canada) (a)		15,449
		Canadian Oil and Gas Producer
	638,000	Northern Oil & Gas (a)(c)		15,299
		Small E&P Company in North Dakota Bakken
	900,000	Houston American Energy (a)(c)		10,971
		Oil and Gas Exploration/Production in Colombia
	27,000,000	ShaMaran Petroleum (Iraq) (a)		9,409
		Oil Exploration in Kurdistan

Number of Shares			Value (000)
	7,582,928	PetroMagdalena Energy (Colombia) (a)(b)(c)	$	9,081
		Oil & Gas Exploration / Production in Colombia
	26,000,000	Petrodorado (Colombia) (a)(b)		5,232
	24,000,000	Petrodorado - Warrants (Colombia) (a)(e)(f)		895
		Oil & Gas Exploration/Production in Colombia, Peru & Paraguay
	37,500,000	Petromanas (Canada) (a)(b)		5,706
	18,750,000	Petromanas - Warrants (Canada) (a)(e)		136
		Exploring for Oil in Albania
	5,917,100	Canacol (Colombia) (a)		4,472
		Oil Producer in South America
	30,275,000	Petroamerica (Colombia) (a)(b)		3,120
		Oil Exploration & Production in Colombia
	8,400,000	Canadian Overseas Petroleum (United Kingdom) (a)(e)		2,788
	4,200,000	Canadian Overseas Petroleum - Warrants (United Kingdom) (a)(e)(f)		332
		Oil & Gas Exploration/Production in the North Sea
	75,071	Southwestern Energy (a)		2,398
		Oil and Gas Producer
	1,198,100	Pan Orient (Canada) (a)		2,293
		Growth Oriented, Return Focused Asian Explorer
	41,100,000	Quetzal Energy (Colombia) (a)(b)(e)		1,549
	8,900,000	Quetzal Energy (Colombia) (a)(b)		350
		Explores for Oil & Gas in Latin America
				581,848
		> Mining 1.4%
	545,000	Core Laboratories (Netherlands)		62,102
		Oil & Gas Reservoir Consulting
	1,600,000	Silver Wheaton (Canada)		46,336
		Silver Mining Royalty Company
	15,000,000	Zhaojin Mining Industry (China)		23,792
		Gold Mining and Refining in China
	1,150,000	Ivanhoe Mines (Mongolia) (a)		20,421
		Copper Mine Project in Mongolia
	2,800,000	Alexco Resource (a)		19,068
		Mining, Exploration & Environmental Services
	4,432,000	Northam Platinum (South Africa)		16,471
		Platinum Mining in South Africa
	7,500,000	Duluth Metals (Canada) (a)(b)		15,387
		Copper & Nickel Miner
	920,000	Kirkland Lake Gold (Canada) (a)		13,925
		Gold Mining
	12,000,000	Mongolian Mining (Mongolia) (a)		8,997
		Coking Coal Mining in Mongolia
	800,000	Augusta Resource (a)(c)		2,480
		U.S. Copper/Molybdenum Mine
	4,000,000	Wolverine Minerals (Canada) (a)(b)(e)		716
	2,000,000	Wolverine Minerals - Warrants (Canada) (a)(e)(f)		5
		Gold Miner

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Mining—continued
	500,000	Duluth Exploration - Special Warrants (Canada) (a)(e)(f)	$	44
		Copper & Nickel Miner
				229,744
		> Alternative Energy 0.1%
	2,800,000	GT Solar International (a)		20,272
		Largest Manufacturer of Furnaces & Reactors to Produce & Cast Polysilicon
	1,210,300	Synthesis Energy Systems (China) (a)		1,876
		Owner / Operator of Gasification Plants
				22,148
		> Oil Refining, Marketing & Distribution 0.1%
	300,000	Vopak (Netherlands)		15,851
		World's Largest Operator of Petroleum and Chemical Storage Terminals
				15,851
		> Agricultural Commodities 0.1%
	1,250,000	Union Agriculture Group (Argentina) (a)(e)(f)		12,463
		Farmland Operator in Uruguay
				12,463
Energy & Minerals: Total				1,547,039
Health Care 9.4%
		> Biotechnology & Drug Delivery 3.5%
	4,315,000	BioMarin Pharmaceutical (a)		148,350
		Biotech Focused on Orphan Diseases
	6,153,000	Seattle Genetics (a)(b)(c)		102,847
		Antibody-based Therapies for Cancer
	3,033,715	Auxilium Pharmaceuticals (a)(b)		60,462
		Biotech Focused on Niche Disease Areas
	1,170,000	Onyx Pharmaceuticals (a)		51,421
		Commercial-stage Biotech Focused on Cancer
	6,702,347	Micromet (a)(b)		48,190
		Next-generation Antibody Technology
	6,000,000	NPS Pharmaceuticals (a)(b)		39,540
		Orphan Drugs & Healthy Royalties
	2,950,000	InterMune (a)		37,170
		Drugs for Pulmonary Fibrosis & Hepatitis C
	3,430,000	Isis Pharmaceuticals (a)		24,730
		Biotech Pioneer in Anti-sense Drugs
	4,550,000	Chelsea Therapeutics International (a)(b)		23,342
		Biotech Focused on Rare Diseases
	3,455,000	Raptor Pharmaceutical (a)(b)(c)		21,628
		Orphan Drug Company
	1,740,000	Anthera Pharmaceuticals (a)		10,684
		Biotech Focused on Cardiovascular, Cancer & Immunology
	359,944	MicroDose Therapeutx (a)(e)(f)		270
		Drug Inhaler Development
				568,634
		> Medical Equipment & Devices 3.0%
	3,208,000	Alexion Pharmaceuticals (a)		229,372
		Biotech Focused on Orphan Diseases
	2,075,000	Sirona Dental Systems (a)		91,383
		Manufacturer of Dental Equipment

Number of Shares			Value (000)
	1,975,000	Hill-Rom Holdings	$	66,538
		Hospital Beds/Patient Handling
	860,000	Gen-Probe (a)		50,843
		Molecular In-vitro Diagnostics
	550,000	Haemonetics (a)		33,671
		Blood & Plasma Collection Equipment
	570,000	Orthofix International (a)		20,081
		Bone Fixation & Stimulation Devices
				491,888
		> Medical Supplies 1.3%
	3,200,000	Cepheid (a)		110,112
		Molecular Diagnostics
	2,126,000	Patterson Companies		62,760
		Dental/Vet/Med Distributor
	650,000	Henry Schein (a)		41,879
		Largest Distributor of Healthcare Products
				214,751
		> Health Care Services 1.1%
	665,000	Mednax (a)		47,887
		Physician Mgmt for Pediatric and Anesthesia Practices
	2,075,000	HealthSouth (a)		36,665
		Inpatient Rehabalitation Facilities
	850,000	HMS Holdings (a)		27,183
		Cost Containment Services
	4,900,000	eResearch Technology (a)(b)		22,981
		Clinical Research Services
	1,875,000	Health Management Associates (a)		13,819
		Non-urban Hospitals
	700,000	Allscripts Healthcare Solutions (a)		13,258
		IT for Physician Offices and Hospitals
	625,000	Community Health Systems (a)		10,906
		Non-Urban Hospitals
				172,699
		> Pharmaceuticals 0.5%
	4,432,716	Akorn (a)		49,292
		Develops, Manufactures & Sells Specialty Generic Drugs
	3,388,000	Adcock Ingram Holdings (South Africa)		25,916
		Manufacturer of Pharmaceuticals and Medical Supplies
	1,095,000	Horizon Pharma (a)(b)(c)		4,380
		Specialty Pharma Company
	2,040,000	Alimera Sciences (a)(b)(c)		2,550
		Ophthalmology-focused Pharmaceutical Company
				82,138
Health Care: Total				1,530,110
Other Industries 6.2%
		> Real Estate 3.8%
	3,350,000	DuPont Fabros Technology (b)(c)		81,137
		Technology-focused Office Buildings
	750,000	Federal Realty Investment Trust		68,063
		Shopping Centers
	3,700,000	Associated Estates Realty (b)		59,015
		Multi-family Properties
	3,000,000	BioMed Realty Trust		54,240
		Life Science-focused Office Buildings

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Real Estate—continued
	720,000	Digital Realty Trust (c)	$	48,002
		Technology-focused Office Buildings
	1,850,000	Extra Space Storage		44,826
		Self Storage Facilities
	1,120,000	Kilroy Realty		42,638
		West Coast Office and Industrial Properties
	975,000	Post Properties		42,627
		Multifamily Properties
	3,000,000	Education Realty Trust		30,690
		Student Housing
	43,000,000	Mapletree Logistics Trust (Singapore)		27,988
		Industrial Property Landlord
	530,000	Macerich		26,818
		Regional Shopping Malls
	15,000,000	Ascendas REIT (Singapore)		21,180
		Singapore Industrial Property Landlord
	3,750,000	DCT Industrial Trust		19,200
		Industrial Properties
	3,500,000	Kite Realty Group (b)		15,785
		Community Shopping Centers
	1,000,000	St. Joe (a)(c)		14,660
		Florida Panhandle Landowner
	1,500,000	Summit Hotel Properties (b)		14,160
		Owner of Select Service Hotels
	2,800	Orix JREIT (Japan)		11,515
		Diversified REIT
	37,407	Security Capital Euro Realty (Luxembourg) (a)(e)(f)(g)		—
		Self Storage Properties
				622,544
		> Transportation 1.4%
	2,800,000	Rush Enterprises, Class A (a)(b)		58,576
	550,000	Rush Enterprises, Class B (a)(b)		9,443
		Truck Sales and Service
	1,260,000	World Fuel Services		52,895
		Global Fuel Broker
	1,155,000	JB Hunt Transport Services		52,056
		Truck & Intermodal Carrier
	2,400,000	Heartland Express		34,296
		Regional Trucker
	300,000	Genesee & Wyoming (a)		18,174
		Short-line Operator
				225,440
		> Regulated Utilities 1.0%
	2,000,000	Northeast Utilities		72,140
		Regulated Electric Utility
	1,800,000	Wisconsin Energy		62,928
		Wisconsin Utility
	500,000	Allete		20,990
		Regulated Electric Utility- Minnesota
	200,000	Red Eléctrica de España (Spain)		8,559
		Spanish Power Transmission
				164,617
Other Industries: Total				1,012,601
Total Equities: 97.3% (Cost: $10,899,548)				15,894,377

Number of Shares			Value (000)
Securities Lending Collateral 2.3%
	382,045,475	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (h)	$	382,045
Total Securities Lending Collateral: (Cost: $382,045)				382,045
Total Investments: 99.6% (Cost: $11,281,593)(i)(j)				16,276,422
Obligation to Return Collateral for Securities Loaned: (2.3)%				(382,045	)
Cash and Other Assets Less Liabilities: 2.7%				442,198
Total Net Assets: 100.0%			$	16,336,575

ADR - American Depositary Receipts

DVR - Differential Voting Right Equity Shares

GDR - Global Depositary Receipts

See accompanying notes to financial statements.

> 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, 2011, are as follows:

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
AboveNet		1,200,000		200,000		-		1,400,000	$	91,014	$	-
Acorn Energy		-		1,500,000		-		1,500,000		9,060		53
AFC Enterprises		2,000,000		-		-		2,000,000		29,400		-
Akorn*		2,659,068		2,340,932		567,284		4,432,716		49,292		-
Allos Therapeutics*		7,035,000		-		7,035,000		-		-		-
Alimera Sciences		361,450		1,678,550		-		2,040,000		2,550		-
Anthera Pharmaceuticals*		1,450,000		290,000		-		1,740,000		10,684		-
Array Biopharma*		3,500,000		-		3,500,000		-		-		-
Art Technology Group*		9,000,000		-		9,000,000		-		-		-
Associated Estates Realty		2,200,000		1,500,000		-		3,700,000		59,015		1,717
Auxilium Pharmaceuticals		1,200,000		1,833,715		-		3,033,715		60,462		-
Bally Technologies		3,725,000		-		-		3,725,000		147,361		-
Blackbaud*		2,250,000		-		569,802		1,680,198		46,541		810
CAI International		1,650,000		-		526,600		1,123,400		17,368		-
Cavco Industries		180,000		280,000		-		460,000		18,428		-
Cepheid*		2,415,000		785,000		-		3,200,000		110,112		-
Chelsea Therapeutics International		3,449,900		1,100,100		-		4,550,000		23,342		-
Clarcor*		2,565,000		-		240,000		2,325,000		116,227		1,356
Cogent Communications		2,800,000		-		280,000		2,520,000		42,563		-
Constant Contact		1,400,000		950,000		-		2,350,000		54,543		-
Diamond Foods*		1,300,000		-		250,000		1,050,000		33,884		217
Donaldson		4,200,000		-		-		4,200,000		285,936		1,806
Drew Industries		1,260,000		240,000		-		1,500,000		36,795		-
Duluth Metals		3,154,000		4,346,000		-		7,500,000		15,387
DuPont Fabros Technology		1,935,579		1,414,421		-		3,350,000		81,137		684
Education Realty Trust*		3,000,000		-		-		3,000,000		30,690		510
eResearch Technology		4,250,000		650,000		-		4,900,000		22,981		-
ESCO Technologies		2,200,000		-		-		2,200,000		63,316		704
Gaiam		1,371,366		-		-		1,371,366		4,443		-
Gaylord Entertainment		3,850,000		-		-		3,850,000		92,939		-
GLG Life Tech		1,200,000		550,000		-		1,750,000		1,575		-
H&E Equipment Services		3,000,000		400,000		-		3,400,000		45,628		-
Hackett Group		4,500,000		-		-		4,500,000		16,830		-
HEICO+		1,700,000		550,000		-		2,250,000		88,537		237
Helen of Troy		1,600,000		-		-		1,600,000		49,120		-
Horizon Pharma		-		1,095,000		-		1,095,000		4,380
iGATE		2,913,065		500,000		13,065		3,400,000		53,482		-
II-VI+		2,225,000		2,325,000		-		4,550,000		83,538		-
Informatica*		5,200,000		150,000		500,000		4,850,000		179,110		-
Interline Brands		2,600,000		-		-		2,600,000		40,482		-
IPG Photonics		2,710,000		70,000		-		2,780,000		94,159		-
IXYS		1,900,000		-		-		1,900,000		20,577		-
Kenexa		2,025,000		-		325,000		1,700,000		45,390		-
Kite Realty Group		3,050,000		450,000		-		3,500,000		15,785		732
Knoll		4,000,000		200,000		-		4,200,000		62,370		1,060
Lifetime Fitness		2,190,000		-		-		2,190,000		102,382		-
lululemon athletica+		4,035,000		3,950,000		2,245,000		5,740,000		267,829		-
Marlin Business Services		1,091,000		-		-		1,091,000		13,856		65
MB Financial*		2,860,000		-		500,000		2,360,000		40,356		86
McGrath Rentcorp		2,350,000		-		200,000		2,150,000		62,328		2,105
Mettler Toledo		1,600,000		-		-		1,600,000		236,336
Micromet		5,500,000		1,202,347		-		6,702,347		48,190		-
Moog		1,820,000		955,000		-		2,775,000		121,906		-
Nabi Biopharmaceuticals*		1,383,454		1,916,546		3,300,000		-		-		-
Nanosphere*		1,480,056		-		1,480,056		-		-		-
Navigant Consulting		3,100,000		-		300,000		2,800,000		31,948		-
NPS Pharmaceuticals		3,200,000		2,800,000		-		6,000,000		39,540		-
Orko Silver*		10,000,000		-		10,000,000		-		-		-

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

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

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
Orthofix International*		1,150,000		-		580,000		570,000	$	20,081	$	-
PAETEC Holding		9,600,000		-		9,600,000		-		-		-
Pericom Semiconductor		1,765,000		-		-		1,765,000		13,432		-
Petroamerica		30,275,000		-		-		30,275,000		3,120		-
Petrodorado		24,000,000		2,000,000		-		26,000,000		5,232		-
Petrolifera Petroleum*		13,950,000		-		13,950,000		-		-		-
PetroMagdalena Energy+		-		7,582,928		-		7,582,928		9,081
Petromanas		37,500,000		-		-		37,500,000		5,706		-
Pier 1 Imports	5,600,000				-		-		5,600,000		78,008
Pinnacle Entertainment		3,400,000		550,000		-		3,950,000		40,132		-
Quetzal Energy		-		50,000,000		-		50,000,000		1,899		-
Raptor Pharmaceutical		-		3,455,000		-		3,455,000		21,628		-
Rush Enterprises		3,350,000		-		-		3,350,000		68,019		-
Salem Communications		1,541,000		-		13,300		1,527,700		3,926		-
Seattle Genetics		4,180,918		2,472,082		500,000		6,153,000		102,847
Shutterfly		1,700,000		1,370,000		-		3,070,000		69,873		-
Spanish Broadcasting System*+		2,400,000		240,000		2,640,000		-		-		-
SPS Commerce		856,429		43,571		-		900,000		23,355		-
Summit Hotel Properties		-		1,500,000		-		1,500,000		14,160		399
Supertex*		1,035,000		-		500,000		535,000		10,101		-
Talbots*		4,150,000		-		4,150,000		-		-		-
THQ*		3,567,000		-		3,567,000		-		-		-
TriCo Bancshares		1,350,000		-		-		1,350,000		19,197		365
True Religion Apparel		2,047,000		-		540,000		1,507,000		52,112		-
Tuscany International Drilling*		10,719,200		-		6,284,200		4,435,000		2,612		-
tw telecom		9,500,000		-		-		9,500,000		184,110		-
Tyler Technologies		2,000,000		-		300,000		1,700,000		51,187		-
Universal Technical Institute*		1,700,000		-		1,050,000		650,000		8,307		-
Virtusa		2,000,000		125,000		-		2,125,000		30,770		-
Warnaco Group		2,190,000		-		-		2,190,000		109,587		-
Wolverine Minerals		-		4,000,000		-		4,000,000		716		-
World Acceptance		1,505,202		-		-		1,505,202		110,632		-
Total of Affiliated Transactions		339,825,687		109,561,192		84,506,307		364,880,572	$	4,380,934	$	12,906

* At December 31, 2011, the Fund owned less than five percent of the company's outstanding voting shares.

+ Includes the effects of a stock split.

The aggregate cost and value of these companies at December 31, 2011, were $2,644,726 and $3,722,937, respectively. Investments in affiliated companies represented 22.79% of the Fund's total net assets at December 31, 2011.

(c) All or a portion of this security was on loan at December 31, 2011. The total market value of securities on loan at December 31, 2011 was $371,484.

(d) 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, 2011 this security had an aggregate value of $10,999, which represented 0.07% of total net assets.

(e) Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities, are valued at fair value determined in good faith under consistently applied procedures established by the Board of Trustees. At December 31, 2011, the market value of these securities amounted to $19,378 which represented 0.12% of total net assets.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Union Agriculture Group	12/8/10-12/16/11		1,250,000	$	15,000	$	12,463
Canadian Overseas Petroleum	11/24/10		8,400,000		3,591		2,788
Quetzal Energy	1/14/11		41,100,000		5,193		1,549
Petrodorado - Warrants	11/20/09		24,000,000		2,965		895
Wolverine Minerals	6/3/11		4,000,000		2,005		716
Canadian Overseas Petroleum - Warrants	11/24/10		4,200,000		526		332
MicroDose Therapeutx	11/24/00		359,944		2,005		270
Voyager Learning, Contingent Value Rights	12/24/09		2,000,000		-		180
Petromanas - Warrants	5/20/10		18,750,000		1,086		136
Duluth Exploration - Special Warrants	8/19/11		500,000		-		44
Wolverine Minerals - Warrants	6/3/11		2,000,000		243		5
Security Capital Euro Realty	8/20/98-7/20/99		37,407		205		-
				$	32,819	$	19,378

See accompanying notes to financial statements.

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

(f) Illiquid security.

(g) Security has no value.

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

(i) At December 31, 2011 for federal income tax purposes, the cost of investments was $11,332,536 and net unrealized appreciation was $4,943,887 consisting of gross unrealized appreciation of $5,820,886 and gross unrealized depreciation of $(876,999).

(j) On December 31, 2011, the market value of foreign securities represented 9.17% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percentage of Net Assets
Canada	$	266,137		1.63
Netherlands		278,841		1.71
Singapore		125,254		0.77
Colombia		106,367		0.65
Hong Kong		74,186		0.45
Sweden		77,227		0.47
Japan		68,798		0.42
China		63,562		0.39
United Kingdom		55,375		0.34
France		48,156		0.29
Denmark		47,078		0.29
Brazil		44,530		0.27
South Africa		42,387		0.26
Chile		36,241		0.22
	Value		Percentage of Net Assets
Ireland	$	32,282		0.20
Mongolia		29,418		0.18
Israel		27,560		0.17
India		15,402		0.09
Argentina		12,463		0.08
Russia		10,999		0.07
Iceland		10,228		0.06
Iraq		9,409		0.06
Spain		8,559		0.05
Germany		7,957		0.05
Luxembourg		-		-
Total Foreign Portfolio	$	1,498,416		9.17

Fair Value Measurements

Various inputs are used in determining the value of the 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 methodology 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 Fund 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 Valuation Committee of the Fund's Board of Trustees that rely on significant observable inputs are also included in Level 2. Typical Level 3 securities include any security fair valued by the Fund's Valuation Committee that relies on significant unobservable inputs.

The following table summarizes the inputs used, as of December 31, 2011, 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	$	4,291,107	$	139,009	$	-	$	4,430,116
Industrial Goods & Services		2,884,916		226,692		-		3,111,608
Consumer Goods & Services		2,466,109		105,736		180		2,572,025
Finance		1,690,878		-		-		1,690,878
Energy & Minerals		1,295,228		239,304		12,507		1,547,039
Health Care		1,503,924		25,916		270		1,530,110
Other Industries		943,359		69,242		-		1,012,601
Total Equities		15,075,521		805,899		12,957		15,894,377
Total Securities Lending Collateral		382,045		-		-		382,045
Total Investments	$	15,457,566	$	805,899	$	12,957	$	16,276,422

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

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

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, in accordance with the policy adopted by the Board of Trustees, 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 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. Warrants which do not trade are valued as a percentage of the actively trading common stock using a model based on Black Scholes.

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 the 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.

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
$	110,688	$	16,715	$	16,715	$	110,688

Financial assets were transferred from Level 2 to Level 1 as they resumed trading during the period and as resale restrictions no longer apply.

Foreign exchange-traded financial assets were transferred from Level 1 to Level 2 due to application of a systematic fair valuation model.

The following table reconciles asset balances for the year ending December 31, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)			Change in Unrealized Appreciation (Depreciation)			Purchases		Sales			Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Equities
Consumer Goods & Services	$	262	$	-		$	(82	)	$	-	$	-	��	$	-	$	-	$	180
Energy & Minerals		15,000		-			(2,594	)		101		-			-		-		12,507
Health Care		103		(7,780	)		7,947			-		-			-		-		270
	$	15,365	$	(7,780	)	$	5,271		$	101	$	-		$	-	$	-	$	12,957

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, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $(2,500). 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.

Columbia Acorn International

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Asia
> Japan
Asahi Diamond Industrial		1,851,900		1,885,600
Disco		0		306,000
FP Corporation		0		254,000
Ibiden		883,144		1,143,144
Japan Airport Terminal		2,052,572		2,137,272
Kuraray		2,129,100		2,981,100
NGK Insulators		0		2,400,000
Park24		736,600		2,263,000
> Taiwan
Advantech		3,458,700		6,603,000
Chroma Ate		7,025,500		9,857,400
CTCI Corp		9,315,800		13,957,000
Far Eastone Telecom		33,118,800		36,606,000
Lung Yen		510,800		2,468,300
PC Home		0		2,268,000
Simplo Technology		3,678,530		5,614,530
St. Shine Optical		2,240,000		2,450,000
Taiwan Mobile		0		6,647,000
Tripod Technologies		5,613,270		10,147,270
> China
Digital China		11,165,300		12,446,800
NetEase.com - ADR		401,000		644,000
New Oriental Education & Technology - ADR		965,387		1,100,000
> Hong Kong
AAC Technologies		0		8,475,000
L'Occitane International		15,000,000		15,625,000
> India
Shriram Transport Finance		767,100		1,550,000
Titan Industries		0		791,352
United Breweries		1,203,445		1,500,251
> Korea
Handsome		0		61,600
> Indonesia
Jasa Marga		0		6,937,300
Tower Bersama Infrastructure		0		13,942,000
> Thailand
Home Product Center		104,039,000		120,000,000
> Philippines
Manila Water Company		14,299,600		19,454,700
SM Prime Holdings		63,272,200		69,967,000
> Cambodia
Nagacorp		40,438,400		42,522,600

	Number of Shares
	09/30/11		12/31/11
Europe
> United Kingdom
Greggs		0		467,193
> Germany
Bertrandt		0		165,400
Wirecard		2,286,441		2,500,000
> Switzerland
Dufry Group		286,300		324,000
> Italy
Geox		4,973,000		5,300,000
Pirelli		0		1,756,000
> Belgium
EVS Broadcast Equipment		332,977		438,880
Other Countries
> United States
Hornbeck Offshore		0		555,500
Textainer Group Holdings		838,297		965,297
> Canada
Alliance Grain Traders		754,800		868,000
Athabasca Oil Sands		0		731,000
Celtic Exploration		505,000		721,000
Crew Energy		678,000		1,043,000
Latin America
> Brazil
Multiplus		1,179,000		1,200,000
Odontoprev		0		1,500,000

See accompanying notes to financial statements.

Columbia Acorn International

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

	Number of Shares
	09/30/11		12/31/11
Sales
Asia
> Japan
Asics		2,116,900		0
Hamamatsu Photonics		765,554		479,854
Kakaku.com		530,500		0
Kamigumi		634,794		0
Kansai Paint		8,187,600		7,044,100
Nippon Sheet Glass		6,107,300		0
Start Today		938,400		527,001
> Taiwan
China Steel Chemical		2,748,000		0
Formosa International Hotels		1,580,717		468,917
President Chain Store		7,017,009		7,000,000
Sinyi Realty		1,211,280		0
Taiwan Hon Chuan		11,315,800		10,357,000
> Singapore
Ascendas REIT		23,489,149		21,600,000
CDL Hospitality Trust		21,890,000		18,000,000
Mapletree Industrial Trust		42,675,997		39,000,000
Mapletree Logistics Trust		53,383,000		50,000,000
> China
Jiangsu Expressway		23,596,000		0
Noah Holdings - ADR		800,000		493,398
Wasion Group		8,479,200		0
> Hong Kong
Hutchison Port Holdings Trust		32,000,000		0
> India
Infrastructure Development Finance		3,807,700		0
> Korea
MegaStudy		129,332		63,916
NHN		160,150		101,150
Europe
> United Kingdom
Cobham		5,804,000		0
FlyBe		1,499,183		0
Intertek Group		1,853,000		1,480,000
JLT Group		3,644,400		3,000,000
Kesa Electricals		9,009,000		2,533,060
Workspace Group		8,028,385		8,000,000
> Netherlands
Fugro		844,967		687,967
USG People		454,772		0
Vopak		1,189,424		317,424

	Number of Shares
	09/30/11		12/31/11
> France
Eurofins Scientific		554,800		532,368
Mersen		556,874		460,000
Neopost		631,797		555,324
Pierre & Vacances		322,605		0
Teleperformance		1,158,000		0
> Switzerland
Bank Sarasin & Cie		773,707		696,331
Kuehne & Nagel		350,445		296,145
> Ireland
Aryzta		395,008		0
Paddy Power		350,000		289,400
United Drug		9,700,000		9,074,112
> Finland
Poyry		409,248		0
Other Countries
> United States
Alexion Pharmaceuticals		887,431		627,431
Atwood Oceanics		1,373,080		952,080
Bristow		421,732		0
FMC Technologies		707,213		606,253
> Canada
Black Diamond Group		1,189,576		1,049,576
Eacom Timber		13,000,000		0
Petromanas		12,500,000		0
ShawCor		1,790,397		1,212,597
> Australia
SAI Global		5,806,600		0
Latin America
> Brazil
Mills Estruturas e Servicos de Engenharia		3,184,900		2,303,200
MRV Engenharia		3,634,800		3,500,000
> Guatemala
Tahoe Resources		963,600		932,600

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 96.8%
Asia 43.3%
		> Japan 18.3%
	7,044,100	Kansai Paint	$	62,739
		Paint Producer in Japan, India, China and Southeast Asia
	22,694,000	Seven Bank		44,410
		ATM Processing Services
	2,981,100	Kuraray		42,307
		Special Resin, Fine Chemical, Fibers & Textures
	1,995,438	Aeon Delight		40,226
		Facility Maintenance & Management
	1,697,200	Hoshizaki Electric		39,817
		Commercial Kitchen Equipment
	1,139,000	Gree		39,155
		Mobile Social Networking Game Developer/Platform
	23,790	Wacom (a)(b)		36,080
		Computer Graphic Illustration Devices
	677,892	Ain Pharmaciez		32,621
		Dispensing Pharmacy/Drugstore Operator
	7,780	Orix JREIT		31,996
		Diversified REIT
	16,005	Advance Residence Investment		30,877
		Residential REIT
	2,263,000	Park24		29,932
		Parking Lot Operator
	2,400,000	NGK Insulators		28,415
		Ceramic Products for Auto, Power & Electronics
	2,137,272	Japan Airport Terminal		27,813
		Airport Terminal Operator at Haneda
	295,762	Nakanishi		27,295
		Dental Tools & Machinery
	937,651	Kintetsu World Express		27,235
		Airfreight Logistics
	25,769,649	Shinsei Bank		26,645
		Commercial Bank
	25,979	Jupiter Telecommunications		26,296
		Largest Cable Service Provider in Japan
	855,604	Tsumura		25,223
		Traditional Chinese/Japanese Herbal Rx Drugs (Kampo)
	1,055,562	Glory		22,706
		Currency Handling Systems & Related Equipment
	1,885,600	Asahi Diamond Industrial		22,690
		Consumable Diamond Tools
	1,143,144	Ibiden		22,506
		Electronic Parts & Ceramics
	2,600,000	Shimadzu		21,926
		Analytical Instrument, Medical & Industrial Equipment
	1,277,429	Daiseki		20,756
		Waste Disposal and Recycling
	1,405,739	Ushio		20,204
		Industrial Light Sources
	469,500	Pigeon		19,136
		Baby Care Products

Number of Shares			Value (000)
	2,874	Fukuoka REIT	$	18,883
		Diversified REIT in Fukuoka
	732,108	Icom		18,722
		Two Way Radio Communication Equipment
	880,474	Aeon Mall		18,679
		Suburban Shopping Mall Developer, Owner & Operator
	5,540	Mori Hills REIT Investment		18,092
		Tokyo Centric Diversified REIT
	636,250	Miura		17,921
		Industrial Boiler Manufacturer
	6,140	Kenedix Realty Investment		17,802
		Tokyo Mid Size Office REIT
	772,000	Misumi Group		17,667
		Industrial Components Distributor
	1,346,963	Torishima Pump Manufacturing (b)		17,239
		Industrial Pump for Power Generation and Water Supply Systems
	1,940,200	Sintokogio		17,014
		Automated Casting Machines, Surface Treatment System and Consumables
	479,854	Hamamatsu Photonics		16,730
		Optical Sensors for Medical and Industrial Applications
	254,000	FP Corporation		16,456
		Disposable Food Trays & Containers
	306,000	Disco		15,933
		Semiconductor Dicing & Grinding Equipment
	527,001	Start Today		12,364
		Online Japanese Apparel Retailer
	24,000	Doshisha		692
		Wholesaler
				993,200
		> Taiwan 6.1%
	36,606,000	Far Eastone Telecom		68,764
		Taiwan's 3rd Largest Mobile Operator
	7,000,000	President Chain Store		38,121
		Taiwan's Number One Convenience Chain Store Operator
	5,614,530	Simplo Technology		32,675
		Battery Packs for Notebook & Tablet PCs
	2,450,000	St. Shine Optical		25,841
		World's Leading Disposable Contact Lens OEM
	10,147,270	Tripod Technologies		24,441
		Printed Circuit Boards
	6,647,000	Taiwan Mobile		20,709
		Taiwan's 2nd Largest Mobile Operator
	9,857,400	Chroma Ate		19,317
		Automatic Test Systems, Testing & Measurement Instruments
	10,357,000	Taiwan Hon Chuan		19,071
		Beverage Packaging (bottles, caps, labels) Manufacturer
	13,957,000	CTCI Corp		19,020
		International Engineering Firm
	6,603,000	Advantech		18,258
		Industrial PC & Components
	5,910,000	Radiant Opto-Electronics		16,861
		Back Light Modules for LCDs

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		> Taiwan—continued
	2,268,000	PC Home	$	13,930
		Taiwanese Internet Retail Company
	2,468,300	Lung Yen		7,215
		Funeral Services and Columbaria
	468,917	Formosa International Hotels		6,067
		Hotel, Food & Beverage Operation & Hospitality Management Services
				330,290
		> Singapore 4.2%
	33,000,000	Olam International		54,093
		Agriculture Supply Chain Manager
	50,000,000	Mapletree Logistics Trust		32,544
		Industrial Property Landlord
	39,000,000	Mapletree Industrial Trust		32,315
		Singapore Industrial Property Landlord
	21,600,000	Ascendas REIT		30,500
		Singapore Industrial Property Landlord
	18,000,000	CDL Hospitality Trust		21,448
		Hotel Owner/Operator
	32,300,000	Mapletree Commercial Trust		21,171
		Retail and Office Property Landlord
	3,500,000	Singapore Exchange		16,543
		Singapore Equity & Derivatives Market Operator
	15,000,000	Goodpack Limited		16,013
		International Bulk Container Leasing
				224,627
		> China 4.1%
	34,745,554	Zhaojin Mining Industry		55,111
		Gold Mining and Refining in China
	644,000	NetEase.com - ADR (c)		28,883
		Chinese Online Gaming Services
	1,100,000	New Oriental Education & Technology - ADR (c)		26,455
		China's Largest Private Education Service Provider
	19,410,400	Want Want		19,334
		Chinese Branded Consumer Food Company
	12,446,800	Digital China		19,236
		IT Distribution & Systems Integration Services
	5,000,000	ENN Energy		16,008
		China's Largest Private Gas Operator
	12,047,000	China Yurun Food (b)		15,746
		Meat Processor in China
	28,757,700	AMVIG Holdings		15,239
		Chinese Tobacco Packaging Material Supplier
	220,000,000	RexLot Holdings		14,401
		Lottery Equipment Supplier in China
	263,700	51job - ADR (c)		11,060
		Integrated Human Resource Service
	493,398	Noah Holdings - ADR (b)(c)		3,034
		Wealth Management Product Distributor in China
				224,507

Number of Shares			Value (000)
		> Hong Kong 3.7%
	7,000,000	Melco Crown Entertainment - ADR (b)(c)	$	67,340
		Macau Casino Operator
	17,000,000	Lifestyle International		37,419
		Mid- to High-end Department Store Operator in Hong Kong & China
	15,625,000	L'Occitane International		31,334
		Skin Care and Cosmetics Producer
	37,703,800	Sasa International		20,782
		Cosmetics Retailer
	8,475,000	AAC Technologies		18,961
		Miniature Acoustic Components
	12,500,000	MGM China Holdings (c)		16,261
		Macau Casino Operator
	7,419,000	Melco International (c)		5,475
		Macau Casino Operator
				197,572
		> India 2.1%
	11,163,303	Jain Irrigation Systems		18,157
	558,165	Jain Irrigation Systems - DVR (c)		370
		Agricultural Micro-irrigation Systems & Food Processing
	8,052,053	Mundra Port & Special Economic Zone		18,174
		Indian West Coast Shipping Port
	341,652	Asian Paints		16,677
		India's Largest Paint Company
	16,621,332	Manappuram Finance		14,393
		Short-term Lending Collateralized by Household Gold
	1,550,000	Shriram Transport Finance		12,262
		Truck Financing in India
	1,500,251	United Breweries		10,840
		India's Largest Brewer
	32,642,905	REI Agro		10,130
		Basmati Rice Processing
	10,249,300	S. Kumars Nationwide		4,555
		Textiles, Clothing & Retail
	1,650,000	SKIL Ports and Logistics (c)		4,074
		Indian Container Port Project
	791,352	Titan Industries		2,545
		Jewelry, Watches & Eyeglasses
				112,177
		> Korea 1.2%
	1,242,590	Woongjin Coway (c)		39,568
		South Korean Household Appliance Rental Service Provider
	101,150	NHN (c)		18,538
		Korean Online Search Services
	63,916	MegaStudy (c)		6,110
		Education Service Provider
	61,600	Handsome (c)		1,590
		Korea's Leading High-end Apparel Company
				65,806
		> Mongolia 1.1%
	1,049,943	Ivanhoe Mines (c)		18,644
	914,678	Ivanhoe Mines (c)(d)		16,208
		Copper Mine Project in Mongolia

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Mongolia—continued
	35,923,500	Mongolian Mining (c)	$	26,933
		Coking Coal Mining in Mongolia
				61,785
		> Indonesia 0.8%
	29,063,787	Archipelago Resources (a)(c)		31,200
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
	8,913,600	Ace Indonesia		4,027
		Home Improvement Retailer
	13,942,000	Tower Bersama Infrastructure		3,650
		Communications Towers
	6,937,300	Jasa Marga		3,210
		Largest Toll Road Operator in Indonesia
				42,087
		> Thailand 0.8%
	120,000,000	Home Product Center		41,787
		Home Improvement Retailer
				41,787
		> Philippines 0.7%
	69,967,000	SM Prime Holdings		21,230
		Shopping Mall Operator
	7,931,700	Int'l Container Terminal		9,599
		Container Handling Terminals & Port Management
	19,454,700	Manila Water Company		8,615
		Water Utility Company in the Philippines
				39,444
		> Cambodia 0.2%
	42,522,600	Nagacorp		10,705
		Casino/Entertainment Complex in Cambodia
				10,705
Asia: Total				2,343,987
Europe 32.9%
		> United Kingdom 6.2%
	1,480,000	Intertek Group		46,773
		Testing, Inspection & Certification Services
	5,700,000	Chemring		35,400
		Defense Manufacturer of Countermeasures & Energetics
	3,000,000	JLT Group (b)		32,124
		International Business Insurance Broker
	8,000,000	Workspace Group (a)		28,047
		United Kingdom Real Estate
	3,305,000	Serco		24,329
		Facilities Management
	730,000	Rotork		21,880
		Valve Actuators for Oil & Water Pipelines
	446,300	Next		18,970
		Clothes and Home Retailer in the United Kingdom
	4,150,000	GlobeOp Financial Services		18,368
		Hedge Fund Administrator
	1,761,742	Smith and Nephew		17,114
		Medical Equipment & Supplies

Number of Shares			Value (000)
	2,950,000	Abcam	$	16,722
		Online Sales of Antibodies
	740,581	Tullow Oil		16,125
		Oil and Gas Producer
	2,497,000	Domino's Pizza United Kingdom & Ireland		15,608
		Pizza Delivery in United Kingdom, Ireland and Germany
	2,636,932	Premier Oil (c)		14,865
		Oil and Gas Producer in Europe, Pakistan and Asia
	1,773,408	Shaftesbury		12,867
		London Prime Retail REIT
	4,163,948	PureCircle (c)		6,143
		Natural Sweeteners
	1,692,525	Sterling Resources (c)		2,775
	1,147,475	Sterling Resources (c)(e)(f)		1,843
		Oil & Gas Exploration - Europe
	467,193	Greggs		3,671
		Bakery
	2,533,060	Kesa Electricals		2,648
		Europe's Leading Electricals Retailers
				336,272
		> Netherlands 5.0%
	1,955,311	Imtech (b)		50,651
		Electromechanical & ICT Installation & Maintenance
	2,479,123	Aalberts Industries		41,648
		Flow Control & Heat Treatment
	687,967	Fugro		39,975
		Sub-sea Oilfield Services
	1,371,573	Koninklijke TenCate (a)		37,740
		Advanced Textiles & Industrial Fabrics
	1,591,702	UNIT4 (a)		37,699
		Business Software Development
	228,095	Core Laboratories		25,991
		Oil & Gas Reservoir Consulting
	1,252,514	Arcadis		19,615
		Engineering Consultants
	317,424	Vopak		16,772
		World's Largest Operator of Petroleum and Chemical Storage Terminals
				270,091
		> Germany 4.0%
	2,500,000	Wirecard		40,187
		Online Payment Processing & Risk Management
	148,295	Rational		32,283
		Commercial Ovens
	1,600,000	Rhoen-Klinikum		30,482
		Health Care Services
	679,600	Rheinmetall		30,112
		Defense & Automotive
	636,800	Dürr		28,022
		Automotive Plant Engineering & Associated Capital Equipment
	819,889	CTS Eventim		24,619
		Event Ticket Sales

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		> Germany—continued
	555,700	Elringklinger	$	13,795
		Automobile Components
	165,400	Bertrandt		10,855
		Outsourced Engineering
	338,886	Deutsche Beteiligungs		6,833
		Private Equity Investment Management
				217,188
		> France 4.0%
	1,193,000	Gemalto		58,025
		Digital Security Solutions
	532,368	Eurofins Scientific		38,812
		Food, Pharmaceuticals & Materials Screening & Testing
	555,324	Neopost (b)		37,417
		Postage Meter Machines
	971,800	Saft Batteries		27,482
		Niche Battery Manufacturer
	353,648	Rubis		18,491
		Tank Storage & Liquefied Petroleum Gas Distribution
	232,400	Norbert Dentressangle		16,242
		Leading European Logistics & Transport Group
	460,000	Mersen		13,902
		Advanced Industrial Materials
	1,831,204	Hi-Media (b)(c)		5,238
		Online Advertiser in Europe
				215,609
		> Switzerland 3.7%
	265,000	Partners Group		46,240
		Private Markets Asset Management
	225,650	Geberit (c)		43,482
		Plumbing Supplies
	296,145	Kuehne & Nagel		33,262
		Freight Forwarding/Logistics
	324,000	Dufry Group (c)		29,820
		Operates Airport Duty Free and Duty Paid Shops
	15,500	Sika		29,208
		Chemicals for Construction & Industrial Applications
	696,331	Bank Sarasin & Cie		20,350
		Private Banking
				202,362
		> Sweden 2.2%
	4,056,007	Hexagon		60,645
		Design, Measurement & Visualization Software & Equipment
	4,150,024	Sweco (a)		34,674
		Engineering Consultants
	658,700	Unibet		15,170
		European Online Gaming Operator
	905,452	East Capital Explorer		7,072
		Sweden-based Russia/Central Eastern Europe Investment Fund
				117,561

Number of Shares			Value (000)
		> Italy 1.6%
	2,621,149	Ansaldo STS	$	24,859
		Railway Systems Integrator
	13,547,300	CIR (b)		21,605
		Italian Holding Company
	5,300,000	Geox (b)		14,816
		Apparel and Shoe Maker
	1,756,000	Pirelli		14,720
		Global Tire Supplier
	166,200	Tod's (b)		13,501
		Leather Shoes & Bags
				89,501
		> Denmark 1.4%
	1,648,800	Novozymes		50,900
		Industrial Enzymes
	168,042	SimCorp		25,660
		Software for Investment Managers
				76,560
		> Ireland 0.8%
	9,074,112	United Drug		24,076
		Irish Pharmaceutical Wholesaler & Outsourcer
	289,400	Paddy Power		16,673
		Irish Betting Services
				40,749
		> Iceland 0.7%
	35,982,499	Marel (c)		36,804
		Largest Manufacturer of Poultry & Fish Processing Equipment
				36,804
		> Russia 0.7%
	2,109,700	Petropavlovsk		20,149
		Gold and Iron Ore Mining in Russia
	629,642	Mail.ru - GDR (c)(f)		16,371
		Internet Social Networking & Games for Russian Speakers
				36,520
		> Norway 0.4%
	2,403,664	Atea		24,114
		Leading Nordic IT Hardware/Software Re-seller & Installation Company
				24,114
		> Belgium 0.4%
	438,880	EVS Broadcast Equipment		22,431
		Digital Live Mobile Production Software and Systems
				22,431
		> Czech Republic 0.4%
	130,682	Komercni Banka		22,027
		Leading Czech Republic Universal Bank
				22,027
		> Portugal 0.4%
	7,770,405	Redes Energéticas Nacionais		21,220
		Portuguese Power Transmission & Gas Transportation
				21,220

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Spain 0.4%
	494,320	Red Eléctrica de España	$	21,154
		Spanish Power Transmission
				21,154
		> Finland 0.3%
	1,039,429	Stockmann (b)		16,116
		Department Store & Fashion Retailer in Scandinavia & Russia
				16,116
		> Kazakhstan 0.2%
	1,770,000	Halyk Savings Bank of Kazakhstan - GDR (c)		8,602
		Largest Retail Bank & Insurer in Kazakhstan
				8,602
		> Greece 0.1%
	6,954,400	Intralot		6,057
		Lottery & Gaming Systems & Services
				6,057
Europe: Total				1,780,938
Other Countries 15.8%
		> United States 4.8%
	627,431	Alexion Pharmaceuticals (c)		44,861
		Biotech Focused on Orphan Diseases
	1,229,871	BioMarin Pharmaceutical (c)		42,283
		Biotech Focused on Orphan Diseases
	987,228	World Fuel Services		41,444
		Global Fuel Broker
	952,080	Atwood Oceanics (c)		37,883
		Offshore Drilling Contractor
	606,253	FMC Technologies (c)		31,665
		Oil & Gas Wellhead Manufacturer
	965,297	Textainer Group Holdings		28,109
		Top International Container Leasor
	270,000	Oil States International (c)		20,620
		Diversified North American Oil Service Provider
	555,500	Hornbeck Offshore (c)		17,232
		Supply Vessel Operator in U.S. Gulf of Mexico
				264,097
		> Canada 4.7%
	1,403,772	CCL Industries		43,143
		Leading Global Label Manufacturer
	615,857	Baytex (b)		34,440
		Oil & Gas Producer in Canada
	1,212,597	ShawCor		34,375
		Oil & Gas Pipeline Products
	582,942	AG Growth		21,446
		Leading Manufacturer of Augers and Grain Handling Equipment
	653,200	Onex Capital (b)		21,274
		Private Equity
	1,049,576	Black Diamond Group		19,019
		Provides Accommodations/Equipment for Oil Sands Development

Number of Shares			Value (000)
	868,000	Alliance Grain Traders	$	17,697
		Global Leader in Pulse Processing and Distribution
	721,000	Celtic Exploration (c)		16,186
		Canadian Oil and Gas Producer
	1,043,000	Crew Energy (c)		11,518
		Canadian Oil and Gas Producer
	2,411,514	Horizon North Logistics		11,031
		Provides Diversified Oil Service Offering in Northern Canada
	731,000	Athabasca Oil Sands (c)		8,962
		Oil Sands SAGD & Alberta Deep Basin Development
	2,919,000	DeeThree Exploration (a)(c)(e)		5,756
	1,142,377	DeeThree Exploration (a)(c)		2,299
		Canadian Oil & Gas Producer
	6,217,500	Southern Arc Minerals (a)(c)(e)		3,984
		Gold and Copper Exploration in Indonesia
	1,607,306	Pan Orient (c)		3,077
		Growth Oriented, Return Focused Asian Explorer
	6,250,000	Petromanas - Warrants (c)(e)		45
		Exploring for Oil in Albania
				254,252
		> South Africa 4.3%
	1,170,188	Naspers		51,198
		Media in Africa, China, Russia & Other Emerging Markets
	4,992,200	Adcock Ingram Holdings		38,187
		Manufacturer of Pharmaceuticals and Medical Supplies
	3,722,083	Mr. Price		36,794
		South African Retailer of Apparel, Household & Sporting Goods
	19,098,300	Rand Merchant Insurance		31,702
		Directly Sold Property and Casualty Insurance; Holdings in Other Insurers
	10,271,492	Coronation Fund Managers		28,884
		South African Fund Manager
	6,943,940	Northam Platinum		25,806
		Platinum Mining in South Africa
	1,025,504	Massmart Holdings		21,470
		General Merchandise, Food, and Home Improvement Stores; Wal-Mart Subsidiary
				234,041
		> Australia 1.2%
	2,653,389	UGL		32,245
		Engineering & Facilities Management
	498,560	Cochlear		31,664
		Cochlear Implants
				63,909
		> Israel 0.6%
	3,085,527	Israel Chemicals		31,980
		Producer of Potash, Phosphates, Bromine & Specialty Chemicals
				31,980

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		> Senegal 0.2%
	45,237	Sonatel	$	10,711
		Leading Telecoms Operator in Western Africa
				10,711
Other Countries: Total				858,990
Latin America 4.8%
		> Brazil 3.0%
	4,000,000	Localiza Rent A Car		54,899
		Car Rental
	6,344,043	Suzano		22,924
		Brazilian Pulp & Paper Producer
	2,303,200	Mills Estruturas e Servicos de Engenharia		21,856
		Civil Engineering & Construction
	1,500,000	Odontoprev		21,391
		Dental Insurance
	1,200,000	Multiplus		20,748
		Loyalty Program Operator in Brazil
	3,500,000	MRV Engenharia		20,078
		Brazilan Low-income Property Developer
				161,896
		> Mexico 0.6%
	624,168	Grupo Aeroportuario del Sureste - ADR		34,916
		Mexican Airport Operator
				34,916
		> Chile 0.4%
	362,996	Sociedad Quimica y Minera de Chile - ADR (b)		19,547
		Producer of Specialty Fertilizers, Lithium & Iodine
				19,547
		> Argentina 0.3%
	1,250,000	Union Agriculture Group (c)(e)(g)		12,462
		Farmland Operator in Uruguay
	5,940,000	Madalena Ventures (c)(e)		5,200
		Oil & Gas Exploration in Argentina
				17,662
		> Guatemala 0.3%
	932,600	Tahoe Resources (c)		16,185
		Silver Project in Guatemala
				16,185
		> Colombia 0.2%
	8,353,169	Canacol (c)		6,314
		Oil Producer in South America
	22,525,000	Gulf United (c)(e)		4,757
		Prospecting for Oil Alongside Large Producers in Colombia
				11,071
Latin America: Total				261,277
Total Equities: 96.8% (Cost: $4,603,524)				5,245,192

Number of Shares			Value (000)
Securities Lending Collateral 1.8%
	99,418,399	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (h)	$	99,418
Total Securities Lending Collateral: (Cost: $99,418)				99,418
Total Investments: 98.6% (Cost: $4,702,942)(i)(j)				5,344,610
Obligation to Return Collateral for Securities Loaned: (1.8)%				(99,418	)
Cash and Other Assets Less Liabilities: 3.2%				171,761
Total Net Assets: 100.0%			$	5,416,953

ADR - American Depositary Receipts

DVR - Differential Voting Right Equity Shares

GDR - Global Depository Receipts

See accompanying notes to financial statements.

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

(a) 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, 2011, are as follows:

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
Archipelago Resources		24,346,593		4,717,194		-		29,063,787	$	31,200	$	-
DeeThree Exploration+		2,392,877		1,668,500		-		4,061,377		8,055		-
Gulf United Energy*		-		22,525,000		-		22,525,000		4,757		-
Koninklijke TenCate		1,240,557		131,016		-		1,371,573		37,740		-
Southern Arc Minerals		-		6,217,500		-		6,217,500		3,984		-
Sweco		3,887,000		263,024		-		4,150,024		34,674		1,616
UNIT 4		1,476,800		114,902		-		1,591,702		37,699		450
United Drug*		12,110,000		737,752		3,773,640		9,074,112		24,076		1,371
Wacom		20,900		4,480		1,590		23,790		36,080		721
Workspace Group+		60,304,000		640,600		52,944,600		8,000,000		28,047		719
Total of Affiliated Transactions		105,778,727		37,019,968		56,719,830		86,078,865	$	246,312	$	4,877

+ Includes the effects of a corporate action.

* At December 31, 2011, the Fund owned less than five percent of the company's outstanding voting shares.

The aggregate cost and value of these companies at December 31, 2011, were $178,167 and $217,479, respectively. Investments in affiliated companies represented 4.01% of the Fund's total net assets at December 31, 2011.

(b) All or a portion of this security was on loan at December 31, 2011. The total market value of securities on loan at December 31, 2011 was $96,653.

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

(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, 2011, the market value of these securities amounted to $34,047, which represented 0.63% of total net assets.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Union Agriculture Group	12/8/10-12/16/11		1,250,000	$	15,000	$	12,462
DeeThree Exploration	9/7/10-3/8/11		2,919,000		10,228		5,756
Madalena Ventures	10/21/10		5,940,000		3,764		5,200
Gulf United	2/11/11		22,525,000		6,758		4,757
Southern Arc Minerals	2/16/11		6,217,500		10,087		3,984
Sterling Resources	12/2/10		1,147,475		3,425		1,843
Petromanas - Warrants	5/20/10		6,250,000		362		45
				$	49,624	$	34,047

(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, 2011, these securities had an aggregate value of $18,214, which represented 0.34% of total net assets.

(g) Illiquid security.

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

(i) On December 31, 2011, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Japanese Yen	$	993,200		18.3
Euro		894,125		16.5
U.S. Dollar		639,143		11.8
British Pound		387,079		7.1
Taiwan Dollar		330,290		6.1
Hong Kong Dollar		322,944		6.0
Canadian Dollar		305,212		5.6
Other currencies less than 5% of total net asets		1,472,617		27.2
Total Foreign Portfolio	$	5,344,610		98.6

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, continued

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

(j) At December 31, 2011, for federal income tax purposes, the cost of investments was $4,791,236 and net unrealized appreciation was $553,374 consisting of gross unrealized appreciation of $1,122,342 and gross unrealized depreciation of $(568,968).

At December 31, 2011, 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		36,208	$	36,500	1/13/12	$	492
CAD	USD		30,663		30,000	1/13/12		92
USD	EUR		47,693		65,685	1/13/12		3,955
				$	132,185		$	4,539

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

AUD - Australian Dollar

CAD - Canadian Dollar

EUR - Euro

USD - United States Dollar

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	171,624	$	2,172,363	$	-	$	2,343,987
Europe		28,766		1,752,172		-		1,780,938
Other Countries		508,564		350,426		-		858,990
Latin America		238,858		9,957		12,462		261,277
Total Equities		947,812		4,284,918		12,462		5,245,192
Total Securities Lending Collateral		99,418		-		-		99,418
Total Investments	$	1,047,230	$	4,284,918	$	12,462	$	5,344,610
Unrealized Appreciation on Forward Foreign Currency Exchange Contracts		-		4,539		-		4,539
Total	$	1,047,230	$	4,289,457	$	12,462	$	5,349,149

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, in accordance with the policy adopted by the Board of Trustees, 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.

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

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
$	208,336	$	30,015	$	30,015	$	208,336

Financial assets were transferred from Level 2 to Level 1 as they resumed trading during the period and as resale restrictions no longer apply.

Foreign exchange-traded financial assets were transferred from Level 1 to level 2 due to application of a systematic fair valuation model.

The following table reconciles asset balances for the year ending December 31, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)			Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Equities
Asia	$	79	$	(38,558	)	$	38,479		$	-	$	-	$	-	$	-	$	-
Latin America		15,000		-			(2,538	)		-		-		-		-		12,462
	$	15,079	$	(38,558	)	$	35,941		$	-	$	-	$	-	$	-	$	12,462

The change in unrealized depreciation attributed to securities owned at December 31, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $(2,538).

See accompanying notes to financial statements.

Columbia Acorn International

Portfolio Diversification

At December 31, 2011, 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	$	448,556		8.3
Industrial Materials & Specialty Chemicals		369,560		6.8
Machinery		363,876		6.7
Electrical Components		111,501		2.1
Conglomerates		85,758		1.6
Construction		84,357		1.6
Outsourcing Services		35,184		0.6
Industrial Distribution		16,014		0.3
		1,514,806		28.0
> Consumer Goods & Services
Retail		294,558		5.4
Casinos & Gaming		152,083		2.8
Food & Beverage		140,706		2.6
Nondurables		107,114		2.0
Other Consumer Services		95,261		1.8
Travel		54,899		1.0
Apparel		37,078		0.7
Educational Services		32,565		0.6
Other Entertainment		30,686		0.5
Restaurants		15,608		0.3
Other Durable Goods		14,720		0.3
Consumer Goods Distribution		692		0.0	*
		975,970		18.0
> Information
Computer Hardware & Related Equipment		227,732		4.2
Business Software		124,004		2.3
Internet Related		114,990		2.1
Mobile Communications		111,845		2.1
Instrumentation		57,973		1.1
Financial Processors		56,730		1.0
Gaming Equipment & Services		39,155		0.7
CATV		26,296		0.5
Computer Services		24,114		0.4
Electronics Distribution		19,236		0.4
Semiconductors & Related Equipment		15,933		0.3
Telephone and Data Services		10,711		0.2
Advertising		5,238		0.1
		833,957		15.4
> Energy & Minerals
Mining		240,212		4.4
Oil Services		211,799		3.9
Oil & Gas Producers		134,161		2.5
Agricultural Commodities		53,083		1.0
Oil Refining, Marketing & Distribution		35,263		0.6
		674,518		12.4

	Value (000)			Percentage of Net Assets
> Other Industries
Real Estate	$	337,850			6.2
Transportation		123,625			2.3
Regulated Utilities		66,996			1.2
		528,471			9.7
> Finance
Brokerage & Money Management		127,747			2.3
Banks		101,684			1.9
Insurance		85,217			1.6
Finance Companies		79,073			1.5
		393,721			7.3
> Health Care
Medical Equipment & Devices		120,934			2.2
Pharmaceuticals		87,486			1.6
Medical Supplies		42,563			0.8
Biotechnology & Drug Delivery		42,284			0.8
Health Care Services		30,482			0.6
		323,749			6.0
Total Equities:		5,245,192			96.8
Securities Lending Collateral:		99,418			1.8
Total Investments:		5,344,610			98.6
Obligation to Return Collateral for Securities Loaned:		(99,418	)		(1.8	)
Cash and Other Assets Less Liabilities:		171,761			3.2
Net Assets:	$	5,416,953			100.0

* Rounds to less than 0.1%.

See accompanying notes to financial statements.

Columbia Acorn USA

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Information
Boingo Wireless		0		400,000
Hittite Microwave		0		50,000
II-VI		1,238,000		1,317,000
Monolithic Power Systems		346,000		426,000
NetSuite		184,000		281,000
Syntel		0		97,000
Velti		0		400,000
Industrial Goods & Services
Fortune Brands Home & Security		0		200,000
Middleby Corp		0		18,627
Moog		280,000		355,000
Toro		136,800		166,219
Finance
Allied World Holdings		0		55,000
Associated Banc-Corp		623,000		923,000
City National		70,000		144,000
Eaton Vance		209,500		340,500
H&E Equipment Services		201,000		397,172
TrustCo Bank		595,300		764,100
Health Care
Akorn		796,500		812,100
Auxilium Pharmaceuticals		375,000		400,300
Hill-Rom Holdings		84,007		268,000
Micromet		810,000		843,689
NPS Pharmaceuticals		840,000		1,055,000
Seattle Genetics		495,000		682,000
Energy & Minerals
Oasis Petroleum		22,800		107,800
Petroleum Development Corporation		0		57,184

	Number of Shares
	09/30/11		12/31/11
Sales
Information
IPG Photonics		678,000		525,000
Polycom		460,000		330,000
Quality Systems		52,000		0
tw telecom		1,617,000		1,457,000
Consumer Goods & Services
Diamond Foods		197,000		72,000
lululemon athletica		780,000		730,000
Penn National Gaming		69,000		0
Thor Industries		162,000		0
Finance
Aaron's		412,500		231,320
Financial Engines		173,000		0
MF Global		675,000		0
Health Care
Alexion Pharmaceuticals		370,000		275,000
Neogen		49,000		0
Onyx Pharmaceuticals		178,000		160,000
Energy & Minerals
Atwood Oceanics		803,000		725,000
Bristow		86,000		0
FMC Technologies		1,000,000		844,600
Houston American Energy		368,200		300,000
Northern Oil & Gas		230,000		115,000
Quicksilver Resources		1,135,000		773,400

See accompanying notes to financial statements.

Columbia Acorn USA

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 99.7%
Information 31.1%
		> Business Software 9.7%
	910,000	Informatica (a)	$	33,606
		Enterprise Data Integration Software
	698,000	Micros Systems (a)		32,513
		Information Systems for Hotels, Restaurants and Retailers
	375,000	Ansys (a)		21,480
		Simulation Software for Engineers and Designers
	243,000	Concur Technologies (a)		12,342
		Web Enabled Cost & Expense Management Software
	408,000	Ariba (a)		11,457
		Cost Management Software
	281,000	NetSuite (a)		11,394
		End to End IT Systems Solution Delivered Over the Web
	322,000	SPS Commerce (a)		8,356
		Supply Chain Management Software Delivered via the Web
	300,000	Blackbaud		8,310
		Software & Services for Non-Profits
	198,000	Advent Software (a)		4,823
		Asset Management & Trading Systems
	198,000	Constant Contact (a)(b)		4,596
		E-mail & Other Marketing Campaign Mgmt Systems Delivered Over the Web
	400,000	Velti (a)		2,720
		Mobile Marketing Software Platform
				151,597
		> Computer Hardware & Related Equipment 3.7%
	1,317,000	II-VI (a)		24,180
		Laser Optics and Specialty Materials
	292,000	Zebra Technologies (a)		10,448
		Bar Code Printers
	252,000	Nice Systems - ADR (Israel) (a)		8,681
		Audio & Video Recording Solutions
	159,000	Amphenol		7,217
		Electronic Connectors
	196,000	Netgear (a)		6,580
		Networking Products for Small Business & Home
				57,106
		> Semiconductors & Related Equipment 3.4%
	1,958,000	Atmel (a)		15,860
		Microcontrollers, Radio Frequency, and Memory Semiconductors
	690,000	Microsemi (a)		11,557
		Analog/Mixed-signal Semiconductors
	1,061,750	ON Semiconductor (a)		8,197
		Mixed-signal & Power Management Semiconductors
	426,000	Monolithic Power Systems (a)		6,420
		High Performance Analog & Mixed-signal Integrated Circuits (ICs)
	1,075,000	TriQuint Semiconductor (a)		5,235
		Radio Frequency Semiconductors

Number of Shares			Value (000)
	390,000	Pericom Semiconductor (a)	$	2,968
		Interface Integrated Circuits (ICs) & Frequency Control Products
	50,000	Hittite Microwave (a)		2,469
		Radio Frequency, Microwave & Millimeterwave Semiconductors
				52,706
		> Instrumentation 3.3%
	180,000	Mettler Toledo (a)		26,588
		Laboratory Equipment
	525,000	IPG Photonics (a)		17,782
		Fiber Lasers
	168,000	Trimble Navigation (a)		7,291
		GPS-based Instruments
				51,661
		> Telephone and Data Services 2.8%
	1,457,000	tw telecom (a)		28,236
		Fiber Optic Telephone/Data Services
	192,800	AboveNet (a)		12,534
		Metropolitan Fiber Communications Services
	400,000	Boingo Wireless (a)		3,440
		Wholesale and Retail WiFi Networks
				44,210
		> Telecommunications Equipment 2.1%
	732,000	Finisar (a)		12,257
		Optical Sub-systems and Components
	903,000	Ixia (a)		9,490
		Telecom Network Test Equipment
	330,000	Polycom (a)		5,379
		Video Conferencing Equipment
	752,000	Infinera (a)		4,723
		Optical Networking Equipment
				31,849
		> Gaming Equipment & Services 2.0%
	660,000	Bally Technologies (a)		26,110
		Slot Machines & Software
	235,000	WMS Industries (a)		4,822
		Slot Machine Provider
				30,932
		> Mobile Communications 1.5%
	560,000	SBA Communications (a)		24,058
		Communications Towers
				24,058
		> Computer Services 1.5%
	556,000	ExlService Holdings (a)		12,438
		Business Process Outsourcing
	97,000	Syntel		4,537
		Offshore IT Services
	905,500	Hackett Group (a)		3,386
		IT Integration & Best Practice Research
	640,000	RCM Technologies (a)(c)		3,315
		Technology & Engineering Services
				23,676

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Financial Processors 0.5%
	170,000	Global Payments	$	8,055
		Credit Card Processor
				8,055
		> Contract Manufacturing 0.4%
	236,000	Plexus (a)		6,462
		Electronic Manufacturing Services
				6,462
		> TV Broadcasting 0.1%
	875,000	Entravision Communications		1,365
		Spanish Language TV & Radio Stations
				1,365
		> Radio 0.1%
	460,100	Salem Communications (a)		1,182
		Radio Stations for Religious Programming
				1,182
		> Internet Related —%
	20,000	TheStreet.com		34
		Financial Information Websites
				34
Information: Total				484,893
Industrial Goods & Services 17.5%
		> Machinery 13.0%
	941,250	Ametek		39,627
		Aerospace/Industrial Instruments
	747,200	Nordson		30,770
		Dispensing Systems for Adhesives & Coatings
	445,000	Donaldson		30,296
		Industrial Air Filtration
	835,000	ESCO Technologies		24,031
		Automatic Electric Meter Readers
	504,665	HEICO		19,858
		FAA Approved Aircraft Replacement Parts
	585,000	Pentair		19,475
		Pumps & Water Treatment
	355,000	Moog (a)		15,595
		Motion Control Products for Aerospace, Defense & Industrial Markets
	166,219	Toro		10,083
		Turf Maintenance Equipment
	226,000	Kennametal		8,253
		Consumable Cutting Tools
	146,000	Oshkosh Corporation (a)		3,121
		Specialty Truck Manufacturer
	18,627	Middleby (a)		1,752
		Manufacturer of Cooking Equipment
				202,861
		> Industrial Materials & Specialty Chemicals 1.0%
	496,000	Drew Industries (a)		12,167
		RV & Manufactured Home Components
	170,000	Albany International		3,930
		Paper Machine Clothing and Advanced Textiles
				16,097

Number of Shares			Value (000)
		> Electrical Components 1.0%
	280,000	Acuity Brands	$	14,840
		Commercial Lighting Fixtures
				14,840
		> Other Industrial Services 0.7%
	600,000	Acorn Energy		3,624
		Frac Well Exploration/Monitoring Device, Sonar Security,Electric Grid Monitoring
	109,000	Forward Air		3,494
		Freight Transportation Between Airports
	240,000	TrueBlue (a)		3,331
		Temporary Manual Labor
				10,449
		> Waste Management 0.7%
	176,000	Waste Connections		5,833
		Solid Waste Management
	65,000	Clean Harbors (a)		4,142
		Hazardous Waste Services & Disposal
				9,975
		> Steel 0.6%
	686,000	GrafTech International (a)		9,364
		Industrial Graphite Materials Producer
				9,364
		> Industrial Distribution 0.3%
	315,000	Interline Brands (a)		4,905
		Industrial Distribution
				4,905
		> Construction 0.2%
	200,000	Fortune Brands Home & Security (a)		3,406
		Home Building Supplies & Small Locks
				3,406
Industrial Goods & Services: Total				271,897
Consumer Goods & Services 14.8%
		> Retail 5.5%
	730,000	lululemon athletica (a)		34,062
		Premium Active Apparel Retailer
	468,500	Abercrombie & Fitch		22,881
		Teen Apparel Retailer
	805,000	Pier 1 Imports (a)		11,214
		Home Furnishing Retailer
	790,000	Saks (a)(b)		7,702
		Luxury Department Store Retailer
	289,000	Shutterfly (a)		6,578
		Internet Photo-centric Retailer
	161,500	Teavana (a)(b)		3,033
		Specialty Tea Retailer
	9,000	The Fresh Market (a)		359
		Specialty Food Retailer
				85,829
		> Travel 3.1%
	849,700	Gaylord Entertainment (a)		20,512
		Convention Hotels
	1,175,950	Avis Budget Group (a)		12,606
		Second Largest Car Rental Company

See accompanying notes to financial statements.

Columbia Acorn USA

Statement of Investments, continued

Number of Shares			Value (000)
		> Travel—continued
	750,000	Hertz (a)	$	8,790
		Largest U.S. Rental Car Operator
	140,000	HomeAway (a)(b)		3,255
		Vacation Rental Online Marketplace
	64,000	Vail Resorts		2,711
		Ski Resort Operator & Developer
				47,874
		> Apparel 1.5%
	222,000	Warnaco Group (a)		11,109
		Global Branded Apparel Manufacturer
	81,000	Deckers Outdoor (a)		6,121
		Fashion Footwear Wholesaler
	163,000	True Religion Apparel (a)		5,637
		Premium Denim
				22,867
		> Furniture & Textiles 1.4%
	880,000	Knoll		13,068
		Office Furniture
	540,000	Interface		6,231
		Modular & Broadloom Carpet
	148,000	Herman Miller		2,731
		Office Furniture
				22,030
		> Consumer Goods Distribution 0.9%
	472,000	Pool		14,207
		Distributor of Swimming Pool Supplies & Equipment
				14,207
		> Other Consumer Services 0.8%
	259,000	Lifetime Fitness (a)		12,108
		Sport & Fitness Club Operator
				12,108
		> Other Durable Goods 0.8%
	206,000	Cavco Industries (a)		8,252
		Manufactured Homes
	126,000	Jarden		3,765
		Branded Household Products
				12,017
		> Casinos & Gaming 0.5%
	775,000	Pinnacle Entertainment (a)		7,874
		Regional Casino Operator
				7,874
		> Food & Beverage 0.1%
	72,000	Diamond Foods		2,324
		Snack Foods and Culinary Ingredients
				2,324
		> Educational Services 0.1%
	37,350	ITT Educational Services (a)(b)		2,125
		Post-secondary Degree Services
				2,125

Number of Shares			Value (000)
		> Leisure Products 0.1%
	140,000	Skullcandy (a)(b)	$	1,753
		Lifestyle Branded Headphones
				1,753
Consumer Goods & Services: Total				231,008
Finance 11.9%
		> Banks 6.2%
	431,597	Lakeland Financial		11,165
		Indiana Bank
	923,000	Associated Banc-Corp		10,310
		Midwest Bank
	278,678	Hancock Holding		8,909
		Gulf Coast Bank
	675,000	Valley National Bancorp (b)		8,350
		New Jersey/New York Bank
	480,000	MB Financial		8,208
		Chicago Bank
	170,000	SVB Financial Group (a)		8,107
		Bank to Venture Capitalists
	1,478,200	First Busey		7,391
		Illinois Bank
	144,000	City National		6,362
		Bank & Asset Manager
	594,000	TCF Financial		6,130
		Great Lakes Bank
	513,755	Pacific Continental Bank		4,547
		Pacific Northwest Bank
	764,100	TrustCo Bank		4,287
		New York State Bank
	269,600	Eagle Bancorp (a)		3,920
		Metro D.C. Bank
	178,826	Sandy Spring Bancorp		3,138
		Baltimore, D.C. Bank
	210,000	CVB Financial (b)		2,106
		Inland Empire Business Bank
	90,000	TriCo Bancshares		1,280
		California Central Valley Bank
	851,247	Guaranty Bancorp (a)		1,251
		Colorado Bank
	26,935	Hudson Valley		572
		Metro New York City Bank
				96,033
		> Finance Companies 3.8%
	345,000	World Acceptance (a)		25,357
		Personal Loans
	345,000	Textainer Group Holdings		10,046
		Top International Container Leasor
	231,320	Aaron's		6,172
		Rent to Own
	210,000	McGrath Rentcorp		6,088
		Temporary Space & IT Rentals
	397,172	H&E Equipment Services (a)		5,330
		Heavy Equipment Leasing

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Finance Companies—continued
	330,000	CAI International (a)	$	5,102
		International Container Leasing
	100,000	Marlin Business Services		1,270
		Small Equipment Leasing
				59,365
		> Savings & Loans 0.9%
	602,487	ViewPoint Financial		7,838
		Texas Thrift
	194,000	Berkshire Hills Bancorp		4,305
		Northeast Thrift
	173,073	Kaiser Federal		2,219
		Los Angeles Savings & Loan
				14,362
		> Brokerage & Money Management 0.5%
	340,500	Eaton Vance		8,050
		Specialty Mutual Funds
				8,050
		> Insurance 0.5%
	39,000	Enstar Group (a)		3,830
		Insurance/Reinsurance & Related Services
	55,000	Allied World Holdings		3,461
		Commercial Lines Insurance/Reinsurance
				7,291
Finance: Total				185,101
Health Care 9.9%
		> Biotechnology & Drug Delivery 4.6%
	520,000	BioMarin Pharmaceutical (a)		17,878
		Biotech Focused on Orphan Diseases
	682,000	Seattle Genetics (a)(b)		11,400
		Antibody-based Therapies for Cancer
	400,300	Auxilium Pharmaceuticals (a)		7,978
		Biotech Focused on Niche Disease Areas
	160,000	Onyx Pharmaceuticals (a)		7,032
		Commercial-stage Biotech Focused on Cancer
	1,055,000	NPS Pharmaceuticals (a)		6,952
		Orphan Drugs & Healthy Royalties
	843,689	Micromet (a)(b)		6,066
		Next-generation Antibody Technology
	643,000	Isis Pharmaceuticals (a)		4,636
		Biotech Pioneer in Anti-sense Drugs
	790,000	Chelsea Therapeutics International (a)		4,053
		Biotech Focused on Rare Diseases
	313,000	InterMune (a)		3,944
		Drugs for Pulmonary Fibrosis & Hepatitis C
	265,000	Anthera Pharmaceuticals (a)		1,627
		Biotech Focused on Cardiovascular, Cancer & Immunology
	18,181	Metabolex (a)(d)(e)		27
		Diabetes Drug Development
				71,593
		> Medical Equipment & Devices 3.0%
	275,000	Alexion Pharmaceuticals (a)		19,662
		Biotech Focused on Orphan Diseases
	224,000	Sirona Dental Systems (a)		9,865
		Manufacturer of Dental Equipment

Number of Shares			Value (000)
	268,000	Hill-Rom Holdings	$	9,029
		Hospital Beds/Patient Handling
	126,000	Gen-Probe (a)		7,449
		Molecular In-vitro Diagnostics
				46,005
		> Medical Supplies 1.0%
	439,600	Cepheid (a)		15,127
		Molecular Diagnostics
				15,127
		> Health Care Services 0.7%
	738,900	Health Management Associates (a)		5,446
		Non-urban Hospitals
	205,000	HealthSouth (a)		3,622
		Inpatient Rehabalitation Facilities
	151,000	Community Health Systems (a)		2,635
		Non-Urban Hospitals
				11,703
		> Pharmaceuticals 0.6%
	812,100	Akorn (a)		9,031
		Develops, Manufactures & Sells Specialty Generic Drugs
	150,000	Horizon Pharma (a)(b)		600
		Specialty Pharma Company
	133,180	Alimera Sciences (a)(b)		166
		Ophthalmology-focused Pharmaceutical Company
				9,797
Health Care: Total				154,225
Energy & Minerals 8.0%
		> Oil Services 4.7%
	844,600	FMC Technologies (a)		44,113
		Oil & Gas Wellhead Manufacturer
	725,000	Atwood Oceanics (a)		28,848
		Offshore Drilling Contractor
				72,961
		> Oil & Gas Producers 2.4%
	133,000	SM Energy		9,722
		Oil and Gas Producer
	143,000	Rosetta Resources (a)		6,220
		Oil and Gas Producer Exploring in South Texas and Montana
	773,400	Quicksilver Resources (a)		5,189
		Natural Gas and Coal Steam Gas Producer
	168,000	Swift Energy (a)		4,993
		Oil and Gas Exploration and Production
	300,000	Houston American Energy (a)(b)		3,657
		Oil and Gas Exploration/Production in Colombia
	107,800	Oasis Petroleum (a)		3,136
		Oil Producer in North Dakota
	115,000	Northern Oil & Gas (a)(b)		2,758
		Small E&P Company in North Dakota Bakken
	57,184	Petroleum Development Corporation (a)		2,008
		Oil & Gas Producer in U.S.
				37,683
		> Mining 0.9%
	85,000	Core Laboratories (Netherlands)		9,686
		Oil & Gas Reservoir Consulting

See accompanying notes to financial statements.

Columbia Acorn USA

Statement of Investments, continued

Number of Shares			Value (000)
		> Mining—continued
	600,000	Alexco Resource (a)	$	4,086
		Mining, Exploration & Environmental Services
	180,000	Augusta Resource (a)		558
		U.S. Copper/Molybdenum Mine
				14,330
Energy & Minerals: Total				124,974
Other Industries 6.5%
		> Real Estate 5.1%
	915,000	Extra Space Storage		22,170
		Self Storage Facilities
	739,200	BioMed Realty Trust		13,365
		Life Science-focused Office Buildings
	600,000	Associated Estates Realty		9,570
		Multi-family Properties
	870,000	Education Realty Trust		8,900
		Student Housing
	1,380,000	Kite Realty Group		6,224
		Community Shopping Centers
	159,000	Kilroy Realty		6,053
		West Coast Office and Industrial Properties
	958,000	DCT Industrial Trust		4,905
		Industrial Properties
	191,000	DuPont Fabros Technology (b)		4,626
		Technology-focused Office Buildings
	100,000	Post Properties		4,372
		Multifamily Properties
				80,185
		> Transportation 1.4%
	256,000	World Fuel Services		10,747
		Global Fuel Broker
	410,091	Rush Enterprises, Class A (a)		8,579
	115,000	Rush Enterprises, Class B (a)		1,975
		Truck Sales and Service
				21,301
Other Industries: Total				101,486
Total Equities: 99.7% (Cost: $1,151,332)				1,553,584

Number of Shares			Value (000)
Securities Lending Collateral 2.2%
	34,671,363	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (f)	$	34,671
Total Securities Lending Collateral: (Cost: $34,671)				34,671
Total Investments: 101.9% (Cost: $1,186,003)(g)(h)				1,588,255
Obligation to Return Collateral for Securities Loaned: (2.2)%				(34,671	)
Cash and Other Assets Less Liabilities: 0.3%				4,861
Total Net Assets: 100.0%			$	1,558,445

ADR - American Depositary Receipts

> 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, 2011. The total market value of securities on loan at December 31, 2011 was $33,589.

(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, 2011, are as follows:

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
RCM Technologies		710,000		-		70,000		640,000	$	3,315	$	-
Total of Affiliated Transactions		710,000		-		70,000		640,000	$	3,315	$	-

See accompanying notes to financial statements.

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

The aggregate cost and value of this company at December 31, 2011, was $3,624 and $3,315, respectively. Investments in affiliated companies represented 0.21% of the Fund's total net assets at December 31, 2011.

(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, 2011, the market value of this security amounted to $27, which represented less than 0.001% 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	$	27
				$	2,000	$	27

(e) Illiquid security.

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

(g) On December 31, 2011, the market value of foreign securities represented 1.18% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percent
Netherlands	$	9,686		0.62
Israel		8,681		0.56
Total Foreign Portfolio	$	18,367		1.18

(h) At December 31, 2011, for federal income tax purposes, the cost of investments was $1,186,610 and net unrealized appreciation was $401,645 consisting of gross unrealized appreciation of $512,236 and gross unrealized depreciation of $(110,591).

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	484,893	$	-	$	-	$	484,893
Industrial Goods & Services		271,897		-		-		271,897
Consumer Goods & Services		231,008		-		-		231,008
Finance		185,101		-		-		185,101
Health Care		154,198		-		27		154,225
Energy & Minerals		124,974		-		-		124,974
Other Industries		101,486		-		-		101,486
Total Equities		1,553,557		-		27		1,553,584
Total Securities Lending Collateral		34,671		-		-		34,671
Total Investments	$	1,588,228	$	-	$	27	$	1,588,255

See accompanying notes to financial statements.

Columbia Acorn USA

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, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)			Change in Unrealized Appreciation (Depreciation)		Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Equities
Health Care	$	20	$	(1,556	)	$	1,563	$	-	$	-	$	-	$	-	$	27
	$	20	$	(1,556	)	$	1,563	$	-	$	-	$	-	$	-	$	27

The change in unrealized appreciation attributed to securities owned at December 31, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $9.

See accompanying notes to financial statements.

Columbia Acorn International Select

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Asia
> Singapore
Mapletree Industrial Trust		19,420,000		20,395,000
> Taiwan
CTCI Corp		0		2,789,400
Taiwan Mobile		0		1,179,000
> Indonesia
Archipelago Resources		6,886,399		8,808,000
Europe
> Netherlands
Imtech		235,519		277,519
Other Countries
> South Africa
Rand Merchant Insurance		7,209,798		7,415,000

	Number of Shares
	09/30/11		12/31/11
Sales
Asia
> Taiwan
Far Eastone Telecom		11,208,400		11,103,000
> China
Jiangsu Expressway		4,170,000		0
Zhaojin Mining Industry		6,276,000		4,146,000
> Korea
NHN		52,000		48,500
Europe
> United Kingdom
Chemring		1,480,000		810,000
Cobham		616,000		0
Intertek Group		312,000		210,000
JLT Group		1,014,600		665,000
Serco		850,000		659,000
Workspace Group		1,304,000		897,000
> Germany
Rheinmetall		115,500		109,500
Rhoen-Klinikum		270,000		175,000
> Netherlands
Aalberts Industries		242,103		0
AkzoNobel		166,000		0
Fugro		115,821		0
> Switzerland
Kuehne & Nagel		49,000		28,000
> Ireland
United Drug		1,930,000		1,329,400
> France
Neopost		32,657		0
Other Countries
> South Africa
Naspers		88,700		80,700
Latin America
> Colombia
Pacific Rubiales Energy		260,000		0

See accompanying notes to financial statements.

Columbia Acorn International Select

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 94.8%
Asia 50.6%
		> Japan 17.9%
	2,100,000	Kansai Paint	$	18,704
		Paint Producer in Japan, India, China and Southeast Asia
	6,753,000	Seven Bank		13,215
		ATM Processing Services
	8,970	Jupiter Telecommunications		9,080
		Largest Cable Service Provider in Japan
	528,000	Asahi Diamond Industrial		6,353
		Consumable Diamond Tools
	181,000	Gree		6,222
		Mobile Social Networking Game Developer/ Platform
	105,000	Ain Pharmaciez		5,053
		Dispensing Pharmacy/Drugstore Operator
				58,627
		> Singapore 13.1%
	13,130,000	Ascendas REIT		18,540
		Singapore Industrial Property Landlord
	20,395,000	Mapletree Industrial Trust		16,899
		Singapore Industrial Property Landlord
	11,142,000	Mapletree Logistics Trust		7,252
		Industrial Property Landlord
				42,691
		> Taiwan 8.7%
	11,103,000	Far Eastone Telecom		20,857
		Taiwan's 3rd Largest Mobile Operator
	2,789,400	CTCI Corp		3,801
		International Engineering Firm
	1,179,000	Taiwan Mobile		3,673
		Taiwan's 2nd Largest Mobile Operator
				28,331
		> China 4.2%
	4,146,000	Zhaojin Mining Industry		6,576
		Gold Mining and Refining in China
	84,000	NetEase.com - ADR (a)		3,767
		Chinese Online Gaming Services
	3,361,000	Want Want		3,348
		Chinese Branded Consumer Food Company
				13,691
		> Korea 3.8%
	48,500	NHN (a)		8,889
		Korean Online Search Services
	111,000	Woongjin Coway (a)		3,535
		South Korean Household Appliance Rental Service Provider
				12,424
		> Indonesia 2.9%
	8,808,000	Archipelago Resources (a)		9,456
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
				9,456
Asia: Total				165,220

Number of Shares			Value (000)
Europe 28.5%
		> United Kingdom 9.2%
	665,000	JLT Group (b)	$	7,121
		International Business Insurance Broker
	210,000	Intertek Group		6,637
		Testing, Inspection & Certification Services
	810,000	Chemring		5,030
		Defense Manufacturer of Countermeasures & Energetics
	659,000	Serco		4,851
		Facilities Management
	897,000	Workspace Group		3,145
		United Kingdom Real Estate
	432,000	Shaftesbury		3,134
		London Prime Retail REIT
				29,918
		> Germany 5.6%
	630,000	Wirecard		10,127
		Online Payment Processing & Risk Management
	109,500	Rheinmetall		4,852
		Defense & Automotive
	175,000	Rhoen-Klinikum		3,334
		Health Care Services
				18,313
		> Netherlands 3.3%
	277,519	Imtech (b)		7,189
		Electromechanical & ICT Installation & Maintenance
	32,000	Core Laboratories		3,646
		Oil & Gas Reservoir Consulting
				10,835
		> Sweden 3.0%
	658,666	Hexagon		9,848
		Design, Measurement & Visualization Software & Equipment
				9,848
		> Switzerland 2.2%
	24,000	Partners Group		4,188
		Private Markets Asset Management
	28,000	Kuehne & Nagel		3,145
		Freight Forwarding/Logistics
				7,333
		> Iceland 1.5%
	4,800,000	Marel (a)		4,910
		Largest Manufacturer of Poultry & Fish Processing Equipment
				4,910
		> Denmark 1.4%
	145,000	Novozymes		4,476
		Industrial Enzymes
				4,476
		> Belgium 1.2%
	74,000	EVS Broadcast Equipment		3,782
		Digital Live Mobile Production Software and Systems
				3,782

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Ireland 1.1%
	1,329,400	United Drug	$	3,527
		Irish Pharmaceutical Wholesaler & Outsourcer
				3,527
Europe: Total				92,942
Other Countries 14.9%
		> South Africa 7.7%
	7,415,000	Rand Merchant Insurance		12,308
		Directly Sold Property and Casualty Insurance; Holdings in Other Insurers
	1,220,200	Adcock Ingram Holdings		9,334
		Manufacturer of Pharmaceuticals and Medical Supplies
	80,700	Naspers		3,531
		Media in Africa, China, Russia & Other Emerging Markets
				25,173
		> Canada 3.4%
	210,400	CCL Industries		6,466
		Leading Global Label Manufacturer
	125,000	AG Growth		4,599
		Leading Manufacturer of Augers and Grain Handling Equipment
				11,065
		> United States 2.3%
	52,000	SM Energy		3,800
		Oil and Gas Producer
	94,000	Atwood Oceanics (a)		3,740
		Offshore Drilling Contractor
				7,540
		> Israel 1.5%
	460,000	Israel Chemicals		4,768
		Producer of Potash, Phosphates, Bromine & Specialty Chemicals
				4,768
Other Countries: Total				48,546
Latin America 0.8%
		> Argentina 0.6%
	183,333	Union Agriculture Group (a)(c)(d)		1,828
		Farmland Operator in Uruguay
				1,828
		> Colombia 0.2%
	18,800,000	Quetzal Energy (a)(c)		709
		Explores for Oil & Gas in Latin America
				709
Latin America: Total				2,537
Total Equities: 94.8% (Cost: $277,416)				309,245

Number of Shares			Value (000)
Securities Lending Collateral 1.2%
	3,949,607	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (e)	$	3,950
Total Securities Lending Collateral: (Cost: $3,950)				3,950
Total Investments: 96.0% (Cost: $281,366)(f)(g)				313,195
Obligation to Return Collateral for Securities Loaned: (1.2)%				(3,950	)
Cash and Other Assets Less Liabilities: 5.2%				17,138
Total Net Assets: 100.0%			$	326,383

See accompanying notes to financial statements.

Columbia Acorn International 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, 2011. The total market value of securities on loan at December 31, 2011 was $3,850.

(c) 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, 2011, the market value of these securities amounted to $2,537, which represented 0.78% of total net assets.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost (000)		Value (000)
Union Agriculture Group	12/8/10-12/16/11		183,333	$	2,200	$	1,828
Quetzal Energy	1/14/11		18,800,000		2,376		709
				$	4,576	$	2,537

(d) Illiquid security.

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

(f) On December 31, 2011, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Japanese Yen	$	58,627		18.0
Singapore Dollar		42,691		13.1
Pound Sterling		39,374		12.1
Euro		32,811		10.0
Taiwan Dollar		28,331		8.7
South African Rand		25,173		7.7
U.S. Dollar		20,732		6.3
Other currencies less than 5% of total net assets		65,456		20.1
	$	313,195		96.0

(g) At December 31, 2011, for federal income tax purposes, the cost of investments was $284,950 and net unrealized appreciation was $28,246 consisting of gross unrealized appreciation of $48,359 and gross unrealized depreciation of $(20,113).

At December 31, 2011, 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
Depreciation

USD

ZAR

169,376

$20,000

1/13/12

$(948)

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

USD = United States Dollar

ZAR = South African Rand

Fair Value Measurements

• 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)

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

See accompanying notes to financial statements.

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	3,767	$	161,453		$	-	$	165,220
Europe		3,646		89,296			-		92,942
Other Countries		18,605		29,941			-		48,546
Latin America		-		709			1,828		2,537
Total Equities		26,018		281,399			1,828		309,245
Total Securities Lending Collateral		3,950		-			-		3,950
Total Investments	$	29,968	$	281,399		$	1,828	$	313,195
Unrealized Depreciation on Forward Foreign Currency Exchange Contracts		-		(948	)		-		(948	)
Total	$	29,968	$	280,451		$	1,828	$	312,247

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, in accordance with the policy adopted by the Board of Trustees, 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.

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, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Latin America
Argentina	$	2,200	$	-	$	(372	)	$	-	$	-	$	-	$	-	$	1,828
	$	2,200	$	-	$	(372	)	$	-	$	-	$	-	$	-	$	1,828

The change in unrealized depreciation attributed to securities owned at December 31, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $(372).

See accompanying notes to financial statements.

Columbia Acorn International Select

Portfolio Diversification

At December 31, 2011, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value (000)		Percentage of Net Assets
> Information
Mobile Communications	$	24,530		7.5
Internet Related		16,187		5.0
Financial Processors		10,127		3.1
Business Software		9,848		3.0
CATV		9,080		2.8
Gaming Equipment & Services		6,222		1.9
Computer Hardware & Related Equipment		3,782		1.2
		79,776		24.5
> Industrial Goods & Services
Industrial Materials & Specialty Chemicals		27,948		8.6
Machinery		20,714		6.4
Other Industrial Services		16,971		5.2
Electrical Components		5,030		1.5
Outsourcing Services		4,851		1.5
Construction		3,801		1.1
		79,315		24.3
> Other Industries
Real Estate		48,970		15.0
> Finance
Insurance		19,429		6.0
Banks		13,215		4.0
Brokerage & Money Management		4,188		1.3
		36,832		11.3
> Energy & Minerals
Mining		19,678		6.0
Oil & Gas Producers		4,509		1.4
Oil Services		3,740		1.1
Agricultural Commodities		1,828		0.6
		29,755		9.1

	Value (000)			Percentage of Net Assets
> Consumer Goods & Services
Nondurables	$	6,466			2.0
Retail		5,053			1.5
Other Consumer Services		3,535			1.1
Food & Beverage		3,348			1.0
		18,402			5.6
> Health Care
Pharmaceuticals		12,861			4.0
Health Care Services		3,334			1.0
		16,195			5.0
Total Equities:		309,245			94.8
Securities Lending Collateral:		3,950			1.2
Total Investments:		313,195			96.0
Obligation to Return Collateral for Securities Loaned		(3,950	)		(1.2	)
Cash and Other Assets Less Liabilities:		17,138			5.2
Net Assets:	$	326,383			100.0

See accompanying notes to financial statements.

Columbia Acorn Select

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Consumer Goods & Services
IFM Investments (Century 21 China RE) - ADR (China)		2,946,537		3,430,000
Information
Atmel		0		825,000
Globalstar		12,000,000		13,184,322
SBA Communications		730,000		1,100,000
VisionChina Media - ADR (China)		2,573,400		7,000,000
Finance
City National		0		630,000
Energy & Minerals
Continental Resources		0		65,000
Health Care
NPS Pharmaceuticals		2,200,000		2,600,000

	Number of Shares
	09/30/11		12/31/11
Sales
Consumer Goods & Services
Abercrombie & Fitch		950,000		830,000
Coach		875,000		650,000
Hertz		7,525,000		6,625,000
ITT Educational Services		315,000		300,000
lululemon athletica		565,000		417,900
Safeway		2,625,000		2,000,000
Skullcandy		266,300		0
Tiffany & Co.		240,000		200,000
Industrial Goods & Services
Ametek		1,660,000		1,550,000
Donaldson		735,000		700,000
Expeditors International of Washington		685,000		620,000
Kennametal		1,085,000		1,035,000
Pall		790,000		740,000
Quanta Services		1,500,000		1,470,000
Waste Management		650,000		500,000
Information
Amphenol		700,000		670,000
Crown Castle International		1,360,000		825,000
Finisar		324,000		0
Sanmina-SCI		6,275,000		6,100,000
WNS - ADR (India)		4,276,336		4,254,230
Finance
CNO Financial Group		11,650,000		9,100,000
Discover Financial Services		3,800,000		3,225,000
MF Global		4,900,000		0
SEI Investments		1,050,000		1,000,000
Energy & Minerals
Canacol (Colombia)		33,500,000		31,372,300
Eacom Timber (Canada)		38,000,000		36,000,000
Houston American Energy		1,309,500		1,060,000
Kirkland Lake Gold (Canada)		950,000		900,000
Pacific Rubiales Energy (Colombia)		2,255,000		2,150,000
Petrodorado (Colombia)		34,856,000		34,700,000
Other Industries
BioMed Realty Trust		1,800,000		1,720,000
JB Hunt Transport Services		1,140,000		115,000
Health Care
Horizon Pharma		195,000		0

See accompanying notes to financial statements.

Columbia Acorn Select

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 99.7%
Consumer Goods & Services 23.1%
		> Retail 9.0%
	2,000,000	Safeway	$	42,080
		Supermarkets
	830,000	Abercrombie & Fitch		40,537
		Teen Apparel Retailer
	417,900	lululemon athletica (a)(b)		19,500
		Premium Active Apparel Retailer
	200,000	Tiffany & Co.		13,252
		Luxury Good Retailer
				115,369
		> Travel 8.0%
	6,625,000	Hertz (a)		77,645
		Largest U.S. Rental Car Operator
	1,060,000	Gaylord Entertainment (a)		25,588
		Convention Hotels
				103,233
		> Apparel 3.1%
	650,000	Coach		39,676
		Designer & Retailer of Branded Leather Accessories
				39,676
		> Casinos & Gaming 1.5%
	300,000,000	RexLot Holdings (China)		19,637
		Lottery Equipment Supplier in China
				19,637
		> Educational Services 1.3%
	300,000	ITT Educational Services (a)(b)		17,067
		Post-secondary Degree Services
				17,067
		> Food & Beverage 0.1%
	1,850,000	GLG Life Tech (Canada) (a)(b)(c)		1,665
		Produce an All-Natural Sweetener Extracted from the Stevia Plant
				1,665
		> Other Consumer Services 0.1%
	3,430,000	IFM Investments (Century 21 China RE) - ADR (China) (a)(c)		1,098
		Provide Real Estate Services in China
				1,098
Consumer Goods & Services: Total				297,745
Industrial Goods & Services 23.0%
		> Machinery 15.4%
	1,550,000	Ametek		65,255
		Aerospace/Industrial Instruments
	700,000	Donaldson		47,656
		Industrial Air Filtration
	740,000	Pall		42,291
		Filtration & Fluids Clarification
	1,035,000	Kennametal		37,798
		Consumable Cutting Tools
	250,000	Oshkosh Corporation (a)		5,345
		Specialty Truck Manufacturer
				198,345

Number of Shares			Value (000)
		> Outsourcing Services 2.4%
	1,470,000	Quanta Services (a)	$	31,664
		Electrical & Telecom Construction Services
				31,664
		> Other Industrial Services 2.0%
	620,000	Expeditors International of Washington		25,395
		International Freight Forwarder
				25,395
		> Industrial Distribution 1.9%
	135,000	WW Grainger		25,271
		Industrial Distribution
				25,271
		> Waste Management 1.3%
	500,000	Waste Management		16,355
		U.S. Garbage Collection & Disposal
				16,355
Industrial Goods & Services: Total				297,030
Information 20.0%
		> Mobile Communications 7.1%
	1,100,000	SBA Communications (a)		47,256
		Communications Towers
	825,000	Crown Castle International (a)		36,960
		Communications Towers
	13,184,322	Globalstar (a)(b)		7,120
		Satellite Mobile Voice & Data Carrier
				91,336
		> Contract Manufacturing 4.4%
	6,100,000	Sanmina-SCI (a)(c)		56,791
		Electronic Manufacturing Services
				56,791
		> Computer Services 3.0%
	4,254,230	WNS - ADR (India) (a)(c)		38,246
		Offshore BPO (Business Process Outsourcing) Services
				38,246
		> Computer Hardware & Related Equipment 2.3%
	670,000	Amphenol		30,411
		Electronic Connectors
				30,411
		> Instrumentation 1.3%
	110,000	Mettler Toledo (a)		16,248
		Laboratory Equipment
				16,248
		> Business Software 0.7%
	182,000	Concur Technologies (a)		9,244
		Web Enabled Cost & Expense Management Software
				9,244
		> Advertising 0.7%
	7,000,000	VisionChina Media - ADR (China) (a)(c)		8,680
		Advertising on Digital Screens in China's Mass Transit System
				8,680

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Semiconductors & Related Equipment 0.5%
	825,000	Atmel (a)	$	6,682
		Microcontrollers, Radio Frequency, and Memory Semiconductors
				6,682
Information: Total				257,638
Finance 13.9%
		> Credit Cards 6.0%
	3,225,000	Discover Financial Services		77,400
		Credit Card Company
				77,400
		> Insurance 4.4%
	9,100,000	CNO Financial Group (a)		57,421
		Life, Long-term Care & Medical Supplement Insurance
				57,421
		> Banks 2.2%
	630,000	City National		27,833
		Bank & Asset Manager
				27,833
		> Brokerage & Money Management 1.3%
	1,000,000	SEI Investments		17,350
		Mutual Fund Administration & Investment Management
				17,350
Finance: Total				180,004
Energy & Minerals 12.8%
		> Oil & Gas Producers 8.4%
	2,150,000	Pacific Rubiales Energy (Colombia) (b)		39,528
		Oil Production & Exploration in Colombia
	31,372,300	Canacol (Colombia) (a)(c)		23,712
		Oil Producer in South America
	1,060,000	Houston American Energy (a)(b)		12,921
		Oil and Gas Exploration/Production in Colombia
	36,500,000	ShaMaran Petroleum (Iraq) (a)		12,719
		Oil Exploration in Kurdistan
	24,000,000	Canadian Overseas Petroleum (United Kingdom) (a)(c)(d)		7,965
	12,000,000	Canadian Overseas Petroleum - Warrants (United Kingdom) (a)(d)(e)		948
		Oil & Gas Exploration/Production in the North Sea
	34,700,000	Petrodorado (Colombia) (a)(c)		6,983
	17,144,000	Petrodorado - Warrants (Colombia) (a)(d)(e)		639
		Oil & Gas Exploration/Production in Colombia, Peru & Paraguay
	18,125,000	Petromanas (Canada) (a)		2,758
	6,562,500	Petromanas - Warrants (Canada) (a)(d)		48
		Exploring for Oil in Albania
				108,221
		> Agricultural Commodities 1.5%
	1,666,667	Union Agriculture Group (Argentina) (a)(d)(e)		16,617
		Farmland Operator in Uruguay

Number of Shares			Value (000)
	36,000,000	Eacom Timber (Canada) (a)(c)	$	2,473
		Canadian Lumber Producer
				19,090
		> Mining 1.4%
	900,000	Kirkland Lake Gold (Canada) (a)		13,623
		Gold Mining
	65,000	Continental Resources (a)		4,336
		Oil & Gas Producer in U.S.
				17,959
		> Alternative Energy 1.0%
	2,700,000	Canadian Solar (China) (a)(b)(c)		7,182
		Solar Cell & Module Manufacturer
	2,950,372	Synthesis Energy Systems (China) (a)(b)(c)		4,573
		Owner/Operator of Gasification Plants
	1,500,000	Real Goods Solar (a)(c)		2,145
		Residential Solar Energy Installer
				13,900
		> Oil Services 0.5%
	10,600,000	Tuscany International Drilling (Colombia) (a)		6,243
		South America Based Drilling Rig Contractor
				6,243
Energy & Minerals: Total				165,413
Other Industries 4.0%
		> Real Estate 2.4%
	1,720,000	BioMed Realty Trust		31,098
		Life Science-focused Office Buildings
				31,098
		> Regulated Utilities 1.2%
	450,000	Wisconsin Energy		15,732
		Wisconsin Utility
				15,732
		> Transportation 0.4%
	115,000	JB Hunt Transport Services		5,183
		Truck & Intermodal Carrier
				5,183
Other Industries: Total				52,013
Health Care 2.9%
		> Pharmaceuticals 1.6%
	1,802,464	Akorn (a)		20,043
		Develops, Manufactures & Sells Specialty Generic Drugs
				20,043
		> Biotechnology & Drug Delivery 1.3%
	2,600,000	NPS Pharmaceuticals (a)		17,134
		Orphan Drugs & Healthy Royalties
				17,134
Health Care: Total				37,177
Total Equities: 99.7% (Cost: $1,099,673)				1,287,020

See accompanying notes to financial statements.

Columbia Acorn Select

Statement of Investments, continued

Number of Shares			Value (000)
Securities Lending Collateral 2.6%
	33,620,749	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (f)	$	33,621
Total Securities Lending Collateral: (Cost: $33,621)				33,621
Total Investments: 102.3% (Cost: $1,133,294)(g)(h)				1,320,641
Obligation to Return Collateral for Securities Loaned: (2.6)%				(33,621	)
Cash and Other Assets Less Liabilities: 0.3%				3,601
Total Net Assets: 100.0%			$	1,290,621

ADR - American Depositary Receipts

> 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, 2011. The total market value of securities on loan at December 31, 2011 was $32,075.

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
Canacol Energy		36,240,000		-		4,867,700		31,372,300	$	23,712	$	-
Canadian Overseas Petroleum+		7,200,000		16,800,000		-		24,000,000		7,965		-
Canadian Solar		3,200,000		100,000		600,000		2,700,000		7,182		-
Eacom Timber		38,000,000		-		2,000,000		36,000,000		2,473		-
GLG Life Tech		1,000,000		850,000		-		1,850,000		1,665		-
Globalstar*		15,000,000		2,184,322		4,000,000		13,184,322		7,120		-
IFM Investments (Century 21 China RE) - ADR		2,300,000		1,131,400		1,400		3,430,000		1,098		-
Petrodorado		28,400,000		6,456,000		156,000		34,700,000		6,983		-
Real Goods Solar		1,500,000		100,000		100,000		1,500,000		2,145		-
Sanmina-SCI		7,100,000		-		1,000,000		6,100,000		56,791		-
ShaMaran Petroleum*		35,950,000		2,843,100		2,293,100		36,500,000		12,719		-
Synthesis Energy Systems		4,500,000		-		1,549,628		2,950,372		4,573		-
Tuscany International Drilling*		11,324,000		-		724,000		10,600,000		6,243
VisionChina Media - ADR		3,675,000		4,600,000		1,275,000		7,000,000		8,680		-
WNS - ADR		4,200,000		76,336		22,106		4,254,230		38,246		-
Total of Affiliated Transactions		199,589,000		35,141,158		18,588,934		216,141,224	$	187,595	$	-

+ Includes the effects of a corporate action.

* At December 31, 2011, the Fund owned less than five percent of the company's outstanding voting shares.

See accompanying notes to financial statements.

The aggregate cost and value of these companies at December 31, 2011, were $266,958 and $161,513, respectively. Investments in affiliated companies represented 12.51% of the Fund's total net assets at December 31, 2011.

(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, 2011, the market value of these securities amounted to $26,217, which represented 2.03% of total net assets.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Union Agriculture Group	12/8/10-12/16/11		1,666,667	$	20,000	$	16,617
Canadian Overseas Petroleum	11/24/10		24,000,000		10,260		7,965
Canadian Overseas Petroleum - Warrants	11/24/10		12,000,000		1,502		948
Petrodorado - Warrants	11/20/09		17,144,000		2,118		639
Petromanas - Warrants	5/20/10		6,562,500		380		48
				$	34,260	$	26,217

(e) Illiquid security.

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

(g) On December 31, 2011, the market value of foreign securities represented 16.14% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percent
Colombia	$	77,105		5.97
China		41,170		3.19
India		38,246		2.96
Canada		20,567		1.59
Argentina		16,617		1.29
Iraq		12,719		0.99
United Kingdom		8,913		0.69
Total Foreign Portfolio	$	215,337		16.68

(h) At December 31, 2011, for federal income tax purposes, the cost of investments was $1,154,397 and net unrealized appreciation was $166,244 consisting of gross unrealized appreciation of $383,850 and gross unrealized depreciation of $(217,606).

Fair Value Measurements

• 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)

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

See accompanying notes to financial statements.

Columbia Acorn Select

Statement of Investments, continued

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	278,108	$	19,637	$	-	$	297,745
Industrial Goods & Services		297,030		-		-		297,030
Information		257,638		-		-		257,638
Finance		180,004		-		-		180,004
Energy & Minerals		139,196		9,600		16,617		165,413
Other Industries		52,013		-		-		52,013
Health Care		37,177		-		-		37,177
Total Equities		1,241,166		29,237		16,617		1,287,020
Total Securities Lending Collateral		33,621		-		-		33,621
Total Investments	$	1,274,787	$	29,237	$	16,617	$	1,320,641

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
$	63,267	$	-	$	-	$	63,267

Financial assets were transferred from Level 2 to Level 1 as resale restrictions no longer apply.

The following table reconciles asset balances for the year ending December 31, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Equities
Energy & Minerals	$	20,000	$	-	$	(3,383	)	$	-	$	-	$	-	$	-	$	16,617
	$	20,000	$	-	$	(3,383	)	$	-	$	-	$	-	$	-	$	16,617

The change in unrealized depreciation attributed to securities owned at December 31, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $(3,383).

See accompanying notes to financial statements.

Columbia Thermostat Fund

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
		> Affiliated Stock Funds: 57.7%
	641,872	Columbia Acorn International Fund, Class I	$	22,035
	1,600,740	Columbia Dividend Income Fund, Class I		21,818
	594,621	Columbia Acorn Fund, Class I		16,394
	1,190,969	Columbia Contrarian Core Fund, Class I		16,388
	462,662	Columbia Acorn Select Fund, Class I		10,942
	906,270	Columbia Select Large Cap Growth Fund, Class I (a)		10,929
	882,190	Columbia Large Cap Enhanced Core Fund, Class I		10,904
Total Stock Funds (Cost: $97,291)				109,410

Number of Shares			Value (000)
		> Affiliated Bond Funds: 38.7%
	3,948,225	Columbia Intermediate Bond Fund, Class I	$	36,640
	2,359,650	Columbia Income Opportunities Fund, Class I		21,992
	1,243,623	Columbia U.S. Treasury Index Fund, Class I		14,662
Total Bond Funds (Cost: $71,486)				73,294
Total Investments: 96.4% (Cost: $168,777)(b)				182,704
Cash and Other Assets Less Liabilities: 3.6%				6,903
Total Net Assets: 100.0%			$	189,607

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

(a) Non-income producing security.

(b) At December 31, 2011, for federal income tax purposes, the cost of investments was $169,439 and net unrealized appreciation was $13,265 consisting of gross unrealized appreciation of $13,595 and gross unrealized depreciation of $(330).

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	109,410	$	-	$	-	$	109,410
Total Bond Funds		73,294		-		-		73,294
Total Investments	$	182,704	$	-	$	-	$	182,704

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

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Asia
> Taiwan
Advantech		4,800		12,000
CTCI Corp		13,900		33,200
Far Eastone Telecom		25,902		43,700
Lung Yen		1,200		11,000
PC Home		0		3,900
St. Shine Optical		4,000		5,800
> Hong Kong
AAC Technologies		0		13,000
> China
Digital China		33,251		34,651
> Indonesia
Archipelago Resources		62,959		76,959
Jasa Marga		0		67,000
Surya Citra Media		0		44,000
Tower Bersama Infrastructure		0		241,000
> India
Jain Irrigation Systems		0		20,800
Manappuram Finance		0		35,100
Mundra Port & Special Economic Zone		0		12,250
United Breweries		0		4,180
> Cambodia
Nagacorp		219,935		229,035
> Thailand
Home Product Center		117,555		134,348
Other Countries
> Canada
Crew Energy		0		3,000
> United States
Hornbeck Offshore		0		1,000
Europe
> Italy
Pirelli		0		3,000

	Number of Shares
	09/30/11		12/31/11
Sales
Asia
> Taiwan
Formosa International Hotels		2,449		949
> China
China Yurun Food		3,065		0
Jiangsu Expressway		3,649		0
Noah Holdings - ADR		2,444		0
> India
EGShares India Small Cap ETF		10,727		0
Market Vectors India Small Cap Index ETF		37,812		0
Wisdomtree India Earnings Index ETF		3,000		0
Other Countries
> United States
Bristow		645		0

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 88.7%
Asia 50.4%
		> Taiwan 14.7%
	43,700	Far Eastone Telecom	$	82
		Taiwan's 3rd Largest Mobile Operator
	5,800	St. Shine Optical		61
		World's Leading Disposable Contact Lens OEM
	26,990	Chroma Ate		53
		Automatic Test Systems, Testing & Measurement Instruments
	33,200	CTCI Corp		45
		International Engineering Firm
	7,730	Simplo Technology		45
		Battery Packs for Notebook & Tablet PCs
	12,000	Advantech		33
		Industrial PC & Components
	11,277	Radiant Opto-Electronics		32
		Back Light Modules for LCDs
	11,000	Lung Yen		32
		Funeral Services and Columbaria
	15,385	Taiwan Hon Chuan		29
		Beverage Packaging (bottles, caps, labels) Manufacturer
	5,000	President Chain Store		27
		Taiwan's Number One Convenience Chain Store Operator
	3,900	PC Home		24
		Taiwanese Internet Retail Company
	949	Formosa International Hotels		13
		Hotel, Food & Beverage Operation & Hospitality Management Services
				476
		> Hong Kong 5.1%
	4,137	Melco Crown Entertainment - ADR (a)		40
		Macau Casino Operator
	16,865	Lifestyle International		37
		Mid- to High-end Department Store Operator in Hong Kong & China
	65,652	Sasa International		36
		Cosmetics Retailer
	13,000	AAC Technologies		29
		Miniature Acoustic Components
	33,000	Melco International (a)		24
		Macau Casino Operator
				166
		> China 7.1%
	34,651	Digital China		53
		IT Distribution & Systems Integration Services
	85,275	AMVIG Holdings		45
		Chinese Tobacco Packaging Material Supplier
	1,000	NetEase.com - ADR (a)		45
		Chinese Online Gaming Services
	741	51job - ADR (a)		31
		Integrated Human Resource Service
	451,892	RexLot Holdings		30
		Lottery Equipment Supplier in China
	7,538	ENN Energy		24
		China's Largest Private Gas Operator
				228

Number of Shares			Value (000)
		> Indonesia 9.2%
	76,959	Archipelago Resources (a)	$	83
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
	178,989	Ace Indonesia		81
		Home Improvement Retailer
	241,000	Tower Bersama Infrastructure		63
		Communications Towers
	44,000	Surya Citra Media		38
		Free to Air TV in Indonesia
	67,000	Jasa Marga		31
		Largest Toll Road Operator in Indonesia
				296
		> India 4.0%
	20,800	Jain Irrigation Systems		34
		Agricultural Micro-Irrigation Systems & Food Processing
	35,100	Manappuram Finance		30
		Short-term Lending Collateralized by Household Gold
	4,180	United Breweries		30
		India's Largest Brewer
	12,250	Mundra Port & Special Economic Zone		28
		Indian West Coast Shipping Port
	2,200	Titan Industries		7
		Jewelry, Watches & Eyeglasses
				129
		> Philippines 3.9%
	189,156	SM Prime Holdings		58
		Shopping Mall Operator
	88,382	Manila Water Company		39
		Water Utility Company in the Philippines
	25,567	Int'l Container Terminal		31
		Container Handling Terminals & Port Management
				128
		> Cambodia 1.8%
	229,035	Nagacorp		58
		Casino/Entertainment Complex in Cambodia
				58
		> Thailand 1.5%
	134,348	Home Product Center		47
		Home Improvement Retailer
				47
		> Mongolia 1.1%
	48,909	Mongolian Mining (a)		37
		Coking Coal Mining in Mongolia
				37
		> Japan 1.1%
	3,860	Kansai Paint		34
		Paint Producer in Japan, India, China and Southeast Asia
				34
		> Singapore 0.9%
	27,403	Goodpack Limited		29
		International Bulk Container Leasing
				29
Asia: Total				1,628

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Statement of Investments, continued

Number of Shares			Value (000)
Other Countries 16.9%
		> South Africa 10.6%
	9,580	Adcock Ingram Holdings	$	73
		Manufacturer of Pharmaceuticals and Medical Supplies
	24,626	Coronation Fund Managers		69
		South African Fund Manager
	39,175	Rand Merchant Insurance		65
		Directly Sold Property and Casualty Insurance; Holdings in Other Insurers
	5,370	Mr. Price		53
		South African Retailer of Apparel, Household & Sporting Goods
	11,354	Northam Platinum		42
		Platinum Mining in South Africa
	1,945	Massmart Holdings		41
		General Merchandise, Food, and Home Improvement Stores; Wal-Mart Subsidiary
				343
		> Canada 3.3%
	3,565	Alliance Grain Traders		73
		Global Leader in Pulse Processing and Distribution
	3,000	Crew Energy (a)		33
		Canadian Oil and Gas Producer
				106
		> United States 3.0%
	1,200	Textainer Group Holdings		35
		Top International Container Leasor
	1,000	Hornbeck Offshore (a)		31
		Supply Vessel Operator in U.S. Gulf of Mexico
	752	Atwood Oceanics (a)		30
		Offshore Drilling Contractor
				96
Other Countries: Total				545
Europe 10.7%
		> Sweden 3.1%
	3,498	Hexagon		52
		Design, Measurement & Visualization Software & Equipment
	6,072	East Capital Explorer		48
		Sweden-based Russia/Central Eastern Europe Investment Fund
				100
		> Switzerland 1.9%
	675	Dufry Group (a)		62
		Operates Airport Duty Free and Duty Paid Shops
				62
		> Czech Republic 1.8%
	352	Komercni Banka		59
		Leading Czech Republic Universal Bank
				59
		> France 1.3%
	780	Rubis		41
		Tank Storage & Liquefied Petroleum Gas Distribution
				41

Number of Shares			Value (000)
		> Germany 1.1%
	824	Dürr	$	36
		Automotive Plant Engineering & Associated Capital Equipment
				36
		> Italy 0.8%
	3,000	Pirelli		25
		Global Tire Supplier
				25
		> Kazakhstan 0.6%
	4,332	Halyk Savings Bank of Kazakhstan - GDR (a)		21
		Largest Retail Bank & Insurer in Kazakhstan
				21
Europe: Total				344
Latin America 10.7%
		> Brazil 7.0%
	11,121	MRV Engenharia		64
		Brazilian Property Developer
	4,436	Localiza Rent A Car		61
		Car Rental
	4,617	Mills Estruturas e Servicos de Engenharia		44
		Civil Engineering & Construction
	1,884	Multiplus		32
		Loyalty Program Operator in Brazil
	7,431	Suzano		27
		Brazilian Pulp & Paper Producer
				228
		> Mexico 2.1%
	1,203	Grupo Aeroportuario del Sureste - ADR		67
		Mexican Airport Operator
				67
		> Argentina 1.6%
	56,433	Madalena Ventures (a)		51
		Oil and Gas Exploration in Argentina
				51
Latin America: Total				346
Total Equities: 88.7% (Cost: $2,997)				2,863
Total Investments: 88.7% (Cost: $2,997)(b)(c)				2,863
Cash and Other Assets Less Liabilities: 11.3%				366
Total Net Assets: 100.0%			$	3,229

ADR - American Depositary Receipts

GDR - Global Depositary Receipts

See accompanying notes to financial statements.

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

(a) Non-income producing security.

(b) At December 31, 2011, for federal income tax purposes, the cost of investments was $2,999 and net unrealized depreciation was $(136) consisting of gross unrealized appreciation of $110 and gross unrealized depreciation of $(246).

Currency	Value		Percentage of Net Assets
Taiwan Dollar	$	476		14.7
Hong Kong Dollar		374		11.6
South African Rand		344		10.7
U.S. Dollar		300		9.3
Brazilian Real		228		7.1
Indonesian Rupiah		213		6.6
Other currencies less than 5% of total net assets		928		28.7
	$	2,863		88.7

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	116	$	1,512	$	-	$	1,628
Other Countries		202		343		-		545
Europe		-		344		-		344
Latin America		346		-		-		346
Total Equities		664		2,199		-		2,863
Total Investments	$	664	$	2,199	$	-	$	2,863

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

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Portfolio Diversification

At December 31, 2011, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value (000)		Percentage of Net Assets
> Consumer Goods & Services
Retail	$	378		11.7
Casinos & Gaming		151		4.7
Other Consumer Services		101		3.1
Food & Beverage		63		1.9
Travel		61		1.9
Other Durable Goods		25		0.8
Other Entertainment		12		0.4
		791		24.5
> Information
Mobile Communications		145		4.5
Computer Hardware & Related Equipment		139		4.3
Electronics Distribution		54		1.7
Instrumentation		53		1.6
Business Software		52		1.6
Internet Related		45		1.4
TV Broadcasting		38		1.2
		526		16.3
> Energy & Minerals
Mining		161		5.0
Agricultural Commodities		99		3.0
Oil & Gas Producers		84		2.6
Oil Services		61		1.9
Oil Refining, Marketing & Distribution		41		1.3
		446		13.8
> Industrial Goods & Services
Industrial Materials & Specialty Chemicals		108		3.3
Construction		89		2.8
Machinery		70		2.2
Other Industrial Services		59		1.8
Industrial Distribution		29		0.9
		355		11.0
> Finance
Brokerage & Money Management		117		3.6
Banks		80		2.5
Finance Companies		65		2.0
Insurance		65		2.0
		327		10.1
> Other Industries
Real Estate		121		3.7
Transportation		99		3.1
Regulated Utilities		63		2.0
		283		8.8

	Value (000)		Percentage of Net Assets
> Health Care
Pharmaceuticals	$	74		2.3
Medical Supplies		61		1.9
		135		4.2
Total Equities:		2,863		88.7
Total Investments:		2,863		88.7
Cash and Other Assets Less Liabilities:		366		11.3
Net Assets:	$	3,229		100.0

See accompanying notes to financial statements.

Columbia Acorn European Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Europe
> United Kingdom
Shaftesbury		160		3,180
> Germany
Bertrandt		0		300
Stratec Biomedical Systems		0		420
> Sweden
Unibet		0		1,000
> Italy
Pirelli		0		2,000
> Iceland
Marel		400		43,750
> Norway
Atea		1,900		3,310
> Belgium
EVS Broadcast Equipment		300		630
> Czech Republic
Komercni Banka		0		140
> Poland
FX Energy		0		4,000
Other Countries
> Canada
Alliance Grain Traders		0		1,270
Asia
> Hong Kong
L'Occitane International		0		9,000

	Number of Shares
	09/30/11		12/31/11
Sales
Europe
> United Kingdom
Cobham		4,850		0
> France
1000 mercis		1,580		700
Neopost		590		352
Teleperformance		1,050		0
> Netherlands
Arcadis		1,910		1,280
Vopak		770		0
> Germany
Rhoen-Klinikum		800		0

See accompanying notes to financial statements.

Columbia Acorn European Fund

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 96.7%
Europe 94.1%
		> United Kingdom 18.5%
	1,400	Intertek Group	$	44
		Testing, Inspection & Certification Services
	5,800	Chemring		36
		Defense Manufacturer of Countermeasures & Energetics
	2,927	JLT Group		31
		International Business Insurance Broker
	15,220	Charles Taylor		30
		Insurance Services
	6,480	GlobeOp Financial Services		29
		Hedge Fund Administrator
	3,180	Shaftesbury		23
		London Prime Retail REIT
	3,610	Domino's Pizza United Kingdom & Ireland		23
		Pizza Delivery in United Kingdom, Ireland and Germany
	5,830	Workspace Group		20
		United Kingdom Real Estate
	660	Rotork		20
		Valve Actuators for Oil & Water Pipelines
	2,480	Serco		18
		Facilities Management
	3,190	Abcam		18
		Online Sales of Antibodies
	2,870	Premier Oil (a)		16
		Oil and Gas Producer in Europe, Pakistan and Asia
	339	Greggs		3
		Bakery
				311
		> France 15.4%
	1,100	Gemalto		54
		Digital Security Solutions
	600	Eurofins Scientific		44
		Food, Pharmaceuticals & Materials Screening & Testing
	700	1000 mercis		41
		Interactive Advertising and Marketing
	360	Norbert Dentressangle		25
		Leading European Logistics & Transport Group
	352	Neopost		24
		Postage Meter Machines
	790	Saft Batteries		22
		Niche Battery Manufacturer
	600	Mersen		18
		Advanced Industrial Materials
	310	Rubis		16
		Tank Storage & Liquefied Petroleum Gas Distribution
	5,030	Hi-Media (a)		14
		Online Advertiser in Europe
				258

Number of Shares			Value (000)
		> Netherlands 14.2%
	430	Core Laboratories	$	49
		Oil & Gas Reservoir Consulting
	2,420	Aalberts Industries		41
		Flow Control & Heat Treatment
	1,530	UNIT4		36
		Business Software Development
	1,360	Imtech		35
		Electromechanical & ICT Installation & Maintenance
	1,210	Koninklijke TenCate		33
		Advanced Textiles & Industrial Fabrics
	410	Fugro		24
		Sub-sea Oilfield Services
	1,280	Arcadis		20
		Engineering Consultants
				238
		> Germany 12.6%
	3,080	Wirecard		49
		Online Payment Processing & Risk Management
	170	Rational		37
		Commercial Ovens
	560	Rheinmetall		25
		Defense & Automotive
	520	Dürr		23
		Automotive Plant Engineering & Associated Capital Equipment
	690	CTS Eventim		21
		Event Ticket Sales
	810	Elringklinger		20
		Automobile Components
	300	Bertrandt		20
		Outsourced Engineering
	420	Stratec Biomedical Systems		17
		Diagnostic Instrumentation
				212
		> Switzerland 7.1%
	250	Geberit (a)		48
		Plumbing Supplies
	15	Sika		28
		Chemicals for Construction & Industrial Applications
	160	Partners Group		28
		Private Markets Asset Management
	170	Dufry Group (a)		16
		Operates Airport Duty Free and Duty Paid Shops
				120
		> Sweden 5.7%
	2,570	Hexagon		39
		Design, Measurement & Visualization Software & Equipment
	4,070	Sweco		34
		Engineering Consultants
	1,000	Unibet		23
		European Online Gaming Operator
				96

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Italy 4.5%
	15,060	CIR	$	24
		Italian Holding Company
	6,400	Geox		18
		Apparel and Shoe Maker
	2,000	Pirelli		17
		Global Tire Supplier
	200	Tod's		16
		Leather Shoes & Bags
				75
		> Iceland 2.7%
	43,750	Marel (a)		45
		Largest Manufacturer of Poultry & Fish Processing Equipment
				45
		> Ireland 2.6%
	9,630	United Drug		26
		Irish Pharmaceutical Wholesaler & Outsourcer
	300	Paddy Power		17
		Irish Betting Services
				43
		> Portugal 2.2%
	13,480	Redes Energéticas Nacionais		37
		Portuguese Power Transmission & Gas Transportation
				37
		> Norway 2.0%
	3,310	Atea		33
		Leading Nordic IT Hardware/Software Re-seller & Installation Company
				33
		> Belgium 1.9%
	630	EVS Broadcast Equipment		32
		Digital Live Mobile Production Software and Systems
				32
		> Russia 1.5%
	1,000	Mail.ru - GDR (a)(b)		26
		Internet Social Networking & Games for Russian Speakers
				26
		> Czech Republic 1.4%
	140	Komercni Banka		24
		Leading Czech Republic Universal Bank
				24
		> Poland 1.1%
	4,000	FX Energy (a)		19
		Oil & Gas Producer in Poland
				19

Number of Shares			Value (000)
		> Greece 0.7%
	12,800	Intralot	$	11
		Lottery & Gaming Systems & Services
				11
Europe: Total				1,580
Other Countries 1.5%
		> Canada 1.5%
	1,270	Alliance Grain Traders		26
		Global Leader in Pulse Processing and Distribution
				26
Other Countries: Total				26
Asia 1.1%
		> Hong Kong 1.1%
	9,000	L'Occitane International		18
		Skin Care and Cosmetics Producer
				18
Asia: Total				18
Total Equities: 96.7% (Cost: $1,710)				1,624
Total Investments: 96.7% (Cost: $1,710)(c)(d)				1,624
Cash and Other Assets Less Liabilities: 3.3%				55
Total Net Assets: 100.0%			$	1,679

GDR – Global Depositary Receipts

See accompanying notes to financial statements.

Columbia Acorn European Fund

Statement of Investments, continued

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

(a) Non-income producing security.

(b) 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, 2011 this security had an aggregate value of $26, which represented 1.55% of total net assets.

(c) At December 31, 2011 for federal income tax purposes, the cost of investments was $1,715 and net unrealized depreciation was $91 consisting of gross unrealized appreciation of $0 and gross unrealized depreciation of $(91).

(d) On December 31, 2011, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Euro	$	858		51.1
British Pound		311		18.5
Swiss Franc		120		7.1
Swedish Krona		95		5.7
U.S. Dollar		94		5.6
Other currencies less than 5% of total net assets		146		8.7
	$	1,624		96.7

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	68	$	1,512	$	-	$	1,580
Other Countries		26		-		-		26
Asia		-		18		-		18
Total Equities		94		1,530		-		1,624
Total Investments	$	94	$	1,530	$	-	$	1,624

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

See accompanying notes to financial statements.

Columbia Acorn European Fund

Portfolio Diversification

At December 31, 2011, 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	$	177		10.5
Machinery		173		10.3
Industrial Machinery & Specialty Chemicals		100		5.9
Conglomerates		65		3.9
Electrical Components		58		3.5
Construction		48		2.9
Outsourcing Services		38		2.3
		659		39.3
> Information
Computer Hardware & Related Equipment		86		5.1
Business Software		75		4.5
Financial Processors		50		3.0
Business Information & Marketing Services		41		2.4
Computer Services		33		2.0
Internet Related		26		1.6
Advertising		14		0.8
		325		19.4
> Energy & Minerals
Mining		49		2.9
Oil & Gas Producers		35		2.1
Agricultural Commodities		26		1.5
Oil Services		24		1.4
Oil Refining, Marketing & Distribution		16		1.0
		150		8.9
> Finance
Insurance		61		3.6
Brokerage & Money Management		57		3.4
Banks		23		1.4
		141		8.4
> Consumer Goods & Services
Casinos & Gaming		51		3.0
Nondurables		34		2.0
Restaurants		22		1.3
Other Entertainment		21		1.3
Apparel		18		1.1
Other Durable Goods		17		1.0
Retail		16		0.9
Food & Beverage		3		0.2
		182		10.8

	Value (000)		Percentage of Net Assets
> Other Industries
Real Estate	$	44		2.6
Regulated Utilities		37		2.2
Transportation		25		1.5
		106		6.3
> Health Care
Pharmaceuticals		26		1.5
Medical Equipment & Devices		17		1.0
Medical Supplies		18		1.1
		61		3.6
Total Equities:		1,624		96.7
Total Investments:		1,624		96.7
Cash and Other Assets Less Liabilities:		55		3.3
Net Assets:	$	1,679		100.0

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Assets and Liabilities

December 31, 2011	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select
(in thousands)
Assets:
Unaffiliated investments, at cost	$	8,636,867		$	4,524,775		$	1,182,379		$	281,366
Affiliated investments, at cost (See Note 4)		2,644,726			178,167			3,624			—
Unaffiliated investments, at value (including securities on loan: Columbia Acorn Fund $371,484; Columbia Acorn International $96,653; Columbia Acorn USA $33,589; Columbia Acorn International Select $3,850; Columbia Acorn Select $32,075; Columbia Thermostat Fund $—; Columbia Acorn Emerging Markets Fund $—; Columbia Acorn European Fund $—)	$	12,553,485		$	5,127,131		$	1,584,940		$	313,195
Affiliated investments, at value (See Note 4)		3,722,937			217,479			3,315			—
Cash		480,945			157,234			5,733			16,190
Foreign currency (cost: Columbia Acorn International Fund $404)		—			404			—			—
Unrealized appreciation on forward foreign currency exchange contracts		—			4,539			—			—
Receivable for:
Investments sold		24,089			6,815			4,630			137
Fund shares sold		15,075			16,077			948			2,221
Dividends		9,889			6,101			721			257
Securities lending income		306			162			17			3
Foreign tax reclaims		166			2,615			—			136
Expense reimbursement due from Advisor		—			1			—			—
Trustees' Deferred Compensation
Investments		2,188			596			177			—
Other assets		177			60			18			4
Total Assets		16,809,257			5,539,214			1,600,499			332,143
Liabilities:
Collateral on securities loaned		382,045			99,418			34,671			3,950
Unrealized depreciation on forward foreign currency exchange contracts		—			—			—			948
Payable to adviser		—			—			—			—
Payable for:
Investments purchased		29,812			2,183			3,978			—
Fund shares redeemed		55,228			14,781			2,855			659
Management fee		289			113			37			8
Administration fee		18			6			2			—	*
12b-1 Service and Distribution fees		44			9			2			1
Reports to shareholders		617			367			109			48
Deferred Trustees' fees		2,188			596			177			—
Transfer agent fees		1,220			337			119			16
Trustees' fees		81			48			8			37
Registration and blue sky fees		5			7			5			4
Custody fees		75			482			3			37
Professional fee		489			216			78			49
Chief compliance officer expenses		93			31			9			3
Deferred foreign capital gains tax payable		—			2,321			—			—
Other liabilities		478			1,346			1			—	*
Total Liabilities		472,682			122,261			42,054			5,760
Net Assets	$	16,336,575		$	5,416,953		$	1,558,445		$	326,383
Composition of Net Assets:
Paid-in capital	$	11,198,023		$	5,139,384		$	1,154,235		$	299,340
Undistributed (overdistributed) net investment income (Accumulated net investment loss)		(32,074	)		(60,514	)		(167	)		(5,294	)
Accumulated net realized gain (loss)		175,809			(305,724	)		2,125			1,468
Net unrealized appreciation (depreciation) on:
Unaffiliated investments		3,916,618			602,356			402,561			31,829
Affiliated investments		1,078,211			39,312			(309	)		—
Foreign capital gains tax		—			(2,321	)		—			—
Foreign currency translations		(12	)		(79	)		—			(12	)
Forward foreign currency exchange contracts		—			4,539			—			(948	)
Net Assets	$	16,336,575		$	5,416,953		$	1,558,445		$	326,383
Net asset value per share – Class A (a)	$	26.63		$	34.15		$	25.94		$	24.26
(Net assets/shares)	($3,246,833/121,918)			($918,112/26,887)			($167,038/6,441)			($56,350/2,323)
Maximum offering price per share – Class A (b)	$	28.25		$	36.23		$	27.52		$	25.74
(Net asset value per share/front-end sales charge)	($26.63/0.9425)			($34.15/0.9425)			($25.94/0.9425)			($24.26/0.9425)
Net asset value and offering price per share – Class B (a)	$	24.53		$	33.17		$	23.98		$	23.27
(Net assets/shares)	($67,153/2,738)			($24,510/739)			($2,253/94)			($1,774/76)
Net asset value and offering price per share – Class C (a)	$	24.18		$	33.03		$	23.72		$	23.17
(Net assets/shares)	($721,446/29,834)			($97,328/2,946)			($30,584/1,289)			($8,704/376)
Net asset value and offering price per share – Class I (d)	$	27.57		$	34.33		$	27.00		$	24.45
(Net assets/shares)	($16,397/595)			($50,335/1,466)			($2,635/98)			($	2/—	**)
Net asset value and offering price per share – Class R (c)	$	—		$	34.11		$	—		$	—
(Net assets/shares)	($	—/—	)	($2,130/62)			($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class R5 (c)	$	—		$	34.31		$	—		$	—
(Net assets/shares)	($	—/—	)	($2,038/59)			($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class Z (d)	$	27.56		$	34.31		$	26.98		$	24.46
(Net assets/shares)	($12,284,746/445,806)			($4,322,500/126,000)			($1,355,935/50,253)			($259,553/10,613)

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

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

(d) Redemption price per share is equal to net asset value.

* Rounds to less than $500.

** Rounds to less than 500 shares.

See accompanying notes to financial statements.

December 31, 2011	Columbia Acorn Select			Columbia Thermostat Fund			Columbia Acorn Emerging Markets Fund			Columbia Acorn European Fund
(in thousands)
Assets:
Unaffiliated investments, at cost	$	866,336		$	—		$	2,997		$	1,710
Affiliated investments, at cost (See Note 4)		266,958			168,777			—			—
Unaffiliated investments, at value (including securities on loan: Columbia Acorn Fund $371,484; Columbia Acorn International $96,653; Columbia Acorn USA $33,589; Columbia Acorn International Select $3,850; Columbia Acorn Select $32,075; Columbia Thermostat Fund $—; Columbia Acorn Emerging Markets Fund $—; Columbia Acorn European Fund $—)	$	1,159,128		$	—		$	2,863		$	1,624
Affiliated investments, at value (See Note 4)		161,513			182,704			—			—
Cash		13,666			1,306			376			88
Foreign currency (cost: Columbia Acorn International Fund $404)		—			—			—			—
Unrealized appreciation on forward foreign currency exchange contracts		—			—			—			—
Receivable for:
Investments sold		794			—			—			—
Fund shares sold		708			6,134			47			—
Dividends		1,409			224			3			2
Securities lending income		89			—			—			—
Foreign tax reclaims		20			—			—	*		—	*
Expense reimbursement due from Advisor		—			3			—	*		—	*
Trustees' Deferred Compensation
Investments		230			—			—			—
Other assets		19			1			57			55
Total Assets		1,337,576			190,372			3,346			1,769
Liabilities:
Collateral on securities loaned		33,621			—			—			—
Unrealized depreciation on forward foreign currency exchange contracts		—			—			—			—
Payable to adviser		—			—			27			34
Payable for:
Investments purchased		2,076			572			21			—
Fund shares redeemed		10,617			109			—			—
Management fee		30			1			—	*		—	*
Administration fee		1			—	*		—	*		—	*
12b-1 Service and Distribution fees		5			2			—	*		—	*
Reports to shareholders		137			27			10			10
Deferred Trustees' fees		230			—			—			—
Transfer agent fees		131			9			—	*		—	*
Trustees' fees		7			20			—	*		—	*
Registration and blue sky fees		6			2			7			7
Custody fees		2			—	*		21			8
Professional fee		81			22			30			30
Chief compliance officer expenses		11			1			—	*		—	*
Deferred foreign capital gains tax payable		—			—			1			—
Other liabilities		—	*		—	*		—	*		1
Total Liabilities		46,955			765			117			90
Net Assets	$	1,290,621		$	189,607		$	3,229		$	1,679
Composition of Net Assets:
Paid-in capital	$	1,100,909		$	196,559		$	3,419		$	1,776
Undistributed (overdistributed) net investment income (Accumulated net investment loss)		(324	)		471			(1	)		—	*
Accumulated net realized gain (loss)		2,689			(21,350	)		(54	)		(11	)
Net unrealized appreciation (depreciation) on:
Unaffiliated investments		292,792			—			(134	)		(86	)
Affiliated investments		(105,445	)		13,927			—			—
Foreign capital gains tax		—			—			(1	)		—
Foreign currency translations		—			—			—	*		—	*
Forward foreign currency exchange contracts		—			—			—			—
Net Assets	$	1,290,621		$	189,607		$	3,229		$	1,679
Net asset value per share – Class A (a)	$	22.95		$	12.82		$	9.26		$	9.43
(Net assets/shares)	($340,325/14,826)			($79,744/6,219)			($332/36)			($154/16)
Maximum offering price per share – Class A (b)	$	24.35		$	13.60		$	9.82		$	10.01
(Net asset value per share/front-end sales charge)	($22.95/0.9425)			($12.82/0.9425)			($9.26/0.9425)			($9.43/0.9425)
Net asset value and offering price per share – Class B (a)	$	21.40		$	12.91		$	—		$	—
(Net assets/shares)	($26,126/1,221)			($11,318/877)			($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class C (a)	$	21.20		$	12.91		$	9.24		$	9.44
(Net assets/shares)	($62,887/2,966)			($33,378/2,585)			($127/14)			($5/1)
Net asset value and offering price per share – Class I (d)	$	23.65		$	—		$	9.29		$	9.43
(Net assets/shares)	($10,944/463)			($	—/—	)	($5/1)			($5/1)
Net asset value and offering price per share – Class R (c)	$	—		$	—		$	—		$	—
(Net assets/shares)	($	—/—	)	($	—/—	)	($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class R5 (c)	$	—		$	—		$	—		$	—
(Net assets/shares)	($	—/—	)	($	—/—	)	($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class Z (d)	$	23.62		$	12.67		$	9.28		$	9.44
(Net assets/shares)	($850,339/36,003)			($65,167/5,142)			($2,765/298)			($1,515/161)

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Operations For the Year Ended December 31, 2011

(in thousands)	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select
Investment Income:
Dividend income	$	114,994		$	139,245		$	8,706		$	9,725
Dividend income from affiliates (See Note 4)		12,906			4,877			—			—
Dividends from affiliated investment company shares (See Note 4)		—			—			—			—
Interest income		169			43			5			6
Securities lending income, net		3,532			900			286			24
		131,601			145,065			8,997			9,755
Foreign taxes withheld		(2,619	)		(12,305	)		(14	)		(782	)
Total Investment Income		128,982			132,760			8,983			8,973
Expenses:
Management fee		114,050			46,342			14,918			3,885
Administration fee		6,839			2,343			666			159
12b-1 Service and Distribution fees:
Class A		9,005			2,276			496			169
Class B		1,342			200			48			19
Class C		8,052			1,067			337			108
Class R		—			4			—			—
Transfer agent fees:
Class A		3,254			1,579			192			102
Class B		365			87			15			7
Class C		850			178			33			21
Class R		—			1			—			—
Class R5		—			—	*		—			—
Class Z		5,385			2,570			752			114
Custody fees		971			3,106			46			179
Trustees' fees		991			346			96			19
Registration and blue sky fees		194			143			94			74
Reports to shareholders	��	1,922			1,252			383			142
Audit fees		87			78			42			44
Legal fees		1,214			413			118			28
Chief compliance officer expenses (See Note 4)		752			257			74			18
Other expenses		567			283			56			28
Total Expenses		155,840			62,525			18,366			5,116
Less custody fees paid indirectly		—	*		—	*		—	*		—	*
Less reimbursement of expenses by Investment Advisor		—			(159	)		—			—
Net Expenses		155,840			62,366			18,366			5,116
Net Investment Income/(Loss)		(26,858	)		70,394			(9,383	)		3,857
Net Realized and Unrealized Gain/(Loss) on Portfolio Positions:
Net realized gain/(loss) on:
Unaffiliated investments		756,701			222,525			41,208			45,575
Affiliated investments (See Note 4)		(10,817	)		(3,603	)		(512	)		—
Foreign currency transactions		13			(4,273	)		—			(885	)
Forward foreign currency exchange contracts		—			7,872			—			1,262
Distributions from affiliated investment company shares		—			—			—			—
Reimbursement from affiliate (See Note 4)		—			174			—			—
Net realized gain/(loss)		745,897			222,695			40,696			45,952
Net change in net unrealized appreciation/(depreciation) on:
Unaffiliated investments		(1,530,752	)		(1,220,866	)		(112,790	)		(88,029	)
Affiliated investments (See Note 4)		(43,544	)		22,439			876			—
Foreign currency translations		(42	)		(1,536	)		—			(24	)
Forward foreign currency exchange contracts		—			(6,748	)		—			(948	)
Foreign capital gains tax		—			(1,814	)		—			—
Net change in unrealized depreciation		(1,574,338	)		(1,208,525	)		(111,914	)		(89,001	)
Net realized and unrealized gain/(loss)		(828,441	)		(985,830	)		(71,218	)		(43,049	)
Net Increase/(Decrease) in Net Assets resulting from Operations	$	(855,299	)	$	(915,436	)	$	(80,601	)	$	(39,192	)

* Rounds to less than $500.

See accompanying notes to financial statements.

(in thousands)	Columbia Acorn Select			Columbia Thermostat Fund			Columbia Acorn Emerging Markets Fund			Columbia Acorn European Fund
Investment Income:
Dividend income	$	12,579		$	—		$	17		$	6
Dividend income from affiliates (See Note 4)		—			—			—			—
Dividends from affiliated investment company shares (See Note 4)		—			3,668			—			—
Interest income		28			—	*		—			—
Securities lending income, net		579			—			—			—
		13,186			3,668			17			6
Foreign taxes withheld		(149	)		—			(1	)		—	*
Total Investment Income		13,037			3,668			16			6
Expenses:
Management fee		15,322			141			13			7
Administration fee		720			54			—	*		—	*
12b-1 Service and Distribution fees:
Class A		1,180			136			—	*		—	*
Class B		375			160			—			—
Class C		821			236			—	*		—	*
Class R		—			—			—			—
Transfer agent fees:
Class A		520			71			—	*		—	*
Class B		108			38			—			—
Class C		108			33			—	*		—	*
Class R		—			—			—			—
Class R5		—			—			—			—
Class Z		672			21			—	*		—	*
Custody fees		161			1			21			9
Trustees' fees		112			4			—	*		—	*
Registration and blue sky fees		94			69			32			32
Reports to shareholders		372			88			11			11
Audit fees		42			21			30			30
Legal fees		136			9			—	*		—	*
Chief compliance officer expenses (See Note 4)		83			6			—	*		—	*
Other expenses		183			12			90			94
Total Expenses		21,009			1,100			197			183
Less custody fees paid indirectly		—	*		—	*		—			—
Less reimbursement of expenses by Investment Advisor		—			(216	)		(182	)		(174	)
Net Expenses		21,009			884			15			9
Net Investment Income/(Loss)		(7,972	)		2,784			1			(3	)
Net Realized and Unrealized Gain/(Loss) on Portfolio Positions:
Net realized gain/(loss) on:
Unaffiliated investments		209,865			—			(54	)		(8	)
Affiliated investments (See Note 4)		(66,391	)		7,583			—			—
Foreign currency transactions		(69	)		—			(3	)		14
Forward foreign currency exchange contracts		—			—			—			—
Distributions from affiliated investment company shares		—			1,295			—			—
Reimbursement from affiliate (See Note 4)		—			—			—			—
Net realized gain/(loss)		143,405			8,878			(57	)		6
Net change in net unrealized appreciation/(depreciation) on:
Unaffiliated investments		(347,747	)		—			(134	)		(86	)
Affiliated investments (See Note 4)		(112,603	)		(4,866	)		—			—
Foreign currency translations		(1	)		—			—	*		—	*
Forward foreign currency exchange contracts		—			—			—			—
Foreign capital gains tax		—			—			(1	)		—
Net change in unrealized depreciation		(460,351	)		(4,866	)		(135	)		(86	)
Net realized and unrealized gain/(loss)		(316,946	)		4,012			(192	)		(80	)
Net Increase/(Decrease) in Net Assets resulting from Operations	$	(324,918	)	$	6,796		$	(191	)	$	(83	)

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Changes in Net Assets

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA						Columbia Acorn International Select
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2011			2010 (a)			2011 (b)			2010 (a)			2011			2010 (a)			2011			2010 (a)
Operations:
Net investment income/(loss)	$	(26,858	)	$	(7,374	)	$	70,394		$	45,340		$	(9,383	)	$	(5,972	)	$	3,857		$	2,667
Net realized gain/(loss) on investments, foreign currency transactions, forward foreign currency exchange contracts and foreign capital gains tax		756,714			971,334			226,124			276,374			41,208			96,553			45,952			42,527
Net realized gain/(loss) on affiliated investments and distributions from affiliated investment companies and affiliated investment company shares		(10,817	)		139,546			(3,603	)		5,786			(512	)		(1,208	)		—			—
Reimbursement from affiliate (See Note 4)		—			—			174			—			—			—			—			—
Net change in net unrealized appreciation/(depreciation) on investments, foreign currency translations, forward foreign currency exchange contracts and foreign capital gains tax		(1,530,794	)		1,864,571			(1,230,965	)		752,452			(112,790	)		224,623			(89,001	)		38,193
Net change in net unrealized appreciation/(depreciation) on affiliated investment companies and affiliated investment company shares		(43,544	)		758,959			22,440			6,050			876			4,434			—			—
Net Increase/(Decrease) from Operations		(855,299	)		3,727,036			(915,436	)		1,086,002			(80,601	)		318,430			(39,192	)		83,387
Distributions to Shareholders From:
Net investment income – Class A		(2,049	)		(2,387	)		(21,972	)		(12,578	)		—			—			(1,392	)		(776	)
Net realized gain – Class A		(144,445	)		(100,919	)		—			—			(1,096	)		—			(901	)		—
Net investment income – Class B		—			—			(600	)		(290	)		—			—			(23	)		(25	)
Net realized gain – Class B		(4,964	)		(9,116	)		—			—			(21	)		—			(31	)		—
Net investment income – Class C		—			—			(2,369	)		(714	)		—			—			(70	)		(65	)
Net realized gain – Class C		(35,291	)		(25,102	)		—			—			(217	)		—			(150	)		—
Net investment income – Class I		(34	)		—	*		(676	)		(9	)		—			—			—	*		—
Net realized gain – Class I		(670	)		—	*		—			—			(16	)		—			—	*		—
Net investment income – Class Z		(36,823	)		(18,634	)		(131,455	)		(109,328	)		—			—			(9,039	)		(5,241	)
Net realized gain – Class Z		(521,915	)		(361,156	)		—			—			(8,481	)		—			(4,186	)		—
Total Distributions to Shareholders		(746,191	)		(517,314	)		(157,072	)		(122,919	)		(9,831	)		—			(15,792	)		(6,107	)
Share Transactions:
Subscriptions – Class A		881,347			843,928			302,659			317,458			41,839			55,029			18,154			18,214
Distributions reinvested – Class A		134,125			94,158			18,983			10,862			993			—			2,039			675
Net assets of shares issued in connection with Merger – Class A		—			—			204,930			—			—			—			—			—
Redemptions – Class A		(1,072,697	)		(866,166	)		(251,677	)		(221,501	)		(80,479	)		(59,786	)		(26,422	)		(23,778	)
Net Increase/(Decrease) – Class A		(57,225	)		71,920			274,895			106,819			(37,647	)		(4,757	)		(6,229	)		(4,889	)
Subscriptions – Class B		543			989			64			35			9			2			5			—	*
Distributions reinvested – Class B		4,234			7,325			494			260			18			—			46			22
Net assets of shares issued in connection with Merger – Class B		—			—			12,517			—			—			—			—			—
Redemptions – Class B		(215,636	)		(312,686	)		(13,183	)		(15,278	)		(6,779	)		(13,951	)		(1,017	)		(1,418	)
Net Increase/(Decrease) – Class B		(210,859	)		(304,372	)		(108	)		(14,983	)		(6,752	)		(13,949	)		(966	)		(1,396	)
Subscriptions – Class C		101,181			76,903			19,819			24,476			2,255			1,669			966			1,883
Distributions reinvested – Class C		27,313			19,273			1,845			590			193			—			188			55
Net assets of shares issued in connection with Merger – Class C		—			—			25,563			—			—			—			—			—
Redemptions – Class C		(154,450	)		(145,469	)		(42,187	)		(17,799	)		(5,937	)		(4,671	)		(2,975	)		(3,121	)
Net Increase/(Decrease) – Class C		(25,956	)		(49,293	)		5,040			7,267			(3,489	)		(3,002	)		(1,821	)		(1,183	)
Subscriptions – Class I		17,610			13,063			27,930			66,675			11,070			28,852			—			3
Distributions reinvested – Class I		704			—			676			9			16			—			—			—
Net assets of shares issued in connection with Merger – Class I		—			—			152,987			—			—			—			—			—
Redemptions – Class I		(13,595	)		(1,538	)		(184,760	)		(2,003	)		(38,709	)		(293	)		—			—
Net Increase/(Decrease) – Class I		4,719			11,525			(3,167	)		64,681			(27,623	)		28,559			—			3
Subscriptions – Class R		—			—			370			—			—			—			—			—
Net assets of shares issued in connection with Merger – Class R		—			—			2,027			—			—			—			—			—
Redemptions – Class R		—			—			(77	)		—			—			—			—			—
Net Increase – Class R		—			—			2,320			—			—			—			—			—

(a) Class I shares reflect activity for the period September 27, 2010 (commencement of operations) through December 31, 2010.

(b) Class R and Class R5 shares reflect activity for the period August 15, 2011 (commencement of operations) through December 31, 2011.

* Rounds to less than $500.

See accompanying notes to financial statements.

	Columbia Acorn Select						Columbia Thermostat Fund							Columbia Acorn Emerging Markets Fund					Columbia Acorn European Fund
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,							Year ended December 31,					Year ended December 31,
(in thousands)	2011			2010 (a)			2011			2010				2011 (c)			2010		2011 (c)			2010
Operations:
Net investment income/(loss)	$	(7,972	)	$	(11,783	)	$	2,784		$	1,806			$	1		$	—	$	(3	)	$	—
Net realized gain/(loss) on investments, foreign currency transactions, forward foreign currency exchange contracts and foreign capital gains tax		209,796			59,672			—			—				(57	)		—		6			—
Net realized gain/(loss) on affiliated investments and distributions from affiliated investment companies and affiliated investment company shares		(66,391	)		(38,281	)		8,878			(1,976	)			—			—		—			—
Reimbursement from affiliate (See Note 4)		—			—			—			—				—			—		—			—
Net change in net unrealized appreciation/(depreciation) on investments, foreign currency translations, forward foreign currency exchange contracts and foreign capital gains tax		(347,748	)		283,123			—			—				(135	)		—		(86	)		—
Net change in net unrealized appreciation/(depreciation) on affiliated investment companies and affiliated investment company shares		(112,603	)		123,090			(4,866	)		19,741				—			—		—			—
Net Increase/(Decrease) from Operations		(324,918	)		415,821			6,796			19,571				(191	)		—		(83	)		—
Distributions to Shareholders From:
Net investment income – Class A		(7,162	)		—			(1,706	)		(678	)	��		—			—		(1	)		—
Net realized gain – Class A		—			—			—			—				—			—		—	*		—
Net investment income – Class B		(500	)		—			(351	)		(239	)			—			—		—			—
Net realized gain – Class B		—			—			—			—				—			—		—			—
Net investment income – Class C		(672	)		—			(405	)		(124	)			—			—		—	*		—
Net realized gain – Class C		—			—			—			—				—			—		—	*		—
Net investment income – Class I		(141	)		—			—			—				—			—		—	*		—
Net realized gain – Class I		—			—			—			—				—			—		—	*		—
Net investment income – Class Z		(22,715	)		—			(1,460	)		(625	)			—			—		(11	)		—
Net realized gain – Class Z		—			—			—			—				—			—		(3	)		—
Total Distributions to Shareholders		(31,190	)		—			(3,922	)		(1,666	)			—			—		(15	)		—
Share Transactions:
Subscriptions – Class A		72,441			115,498			44,385			8,937				351			—		164			—
Distributions reinvested – Class A		6,307			—			1,391			609				—			—		1			—
Net assets of shares issued in connection with Merger – Class A		—			—			—			—				—			—		—			—
Redemptions – Class A		(203,499	)		(187,411	)		(11,539	)		(13,847	)			(13	)		—		—			—
Net Increase/(Decrease) – Class A		(124,751	)		(71,913	)		34,237			(4,301	)			338			—		165			—
Subscriptions – Class B		73			34			120			4				—			—		—			—
Distributions reinvested – Class B		391			—			261			218				—			—		—			—
Net assets of shares issued in connection with Merger – Class B		—			—			—			—				—			—		—			—
Redemptions – Class B		(37,412	)		(30,406	)		(18,369	)		(8,516	)			—			—		—			—
Net Increase/(Decrease) – Class B		(36,948	)		(30,372	)		(17,988	)		(8,294	)			—			—		—			—
Subscriptions – Class C		3,603			6,743			15,268			3,195				138			—		5			—
Distributions reinvested – Class C		494			—			313			109				—			—		—	*		—
Net assets of shares issued in connection with Merger – Class C		—			—			—			—				—			—		—			—
Redemptions – Class C		(23,948	)		(19,302	)		(4,725	)		(5,530	)			(10	)		—		—			—
Net Increase/(Decrease) – Class C		(19,851	)		(12,559	)		10,856			(2,226	)			128			—		5			—
Subscriptions – Class I		12,447			8,577			—			—				5			—		5			—
Distributions reinvested – Class I		141			—			—			—				—			—		—	*		—
Net assets of shares issued in connection with Merger – Class I		—			—			—			—				—			—		—			—
Redemptions – Class I		(8,782	)		(931	)		—			—				—			—		—			—
Net Increase/(Decrease) – Class I		3,806			7,646			—			—				5			—		5			—
Subscriptions – Class R		—			—			—			—				—			—		—			—
Net assets of shares issued in connection with Merger – Class R		—			—			—			—				—			—		—			—
Redemptions – Class R		—			—			—			—				—			—		—			—
Net Increase – Class R		—			—			—			—				—			—		—			—

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Changes in Net Assets, continued

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA						Columbia Acorn International Select
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2011			2010 (a)			2011 (b)			2010 (a)			2011			2010 (a)			2011			2010 (a)
Subscriptions – Class R5		—			—			3			—			—			—			—			—
Net assets of shares issued in connection with Merger – Class R5		—			—			2,232			—			—			—			—			—
Redemptions – Class R5		—			—			—	*		—			—			—			—			—
Net Increase – Class R5		—			—			2,235			—			—			—			—			—
Subscriptions – Class Z		2,172,346			2,077,687			965,616			1,216,447			349,841			260,284			45,936			67,172
Distributions reinvested – Class Z		471,639			324,149			91,324			76,344			7,534			—			5,069			1,451
Redemptions – Class Z		(2,515,311	)		(1,969,788	)		(973,865	)		(726,019	)		(331,533	)		(276,628	)		(113,289	)		(96,502	)
Net Increase/(Decrease) – Class Z		128,674			432,058			83,075			566,772			25,842			(16,344	)		(62,284	)		(27,879	)
Net Increase/(Decrease) from Share Transactions		(160,647	)		161,838			364,290			730,556			(49,669	)		(9,493	)		(71,300	)		(35,344	)
Redemption Fees		—			—			—			239			—			—			—			10
Increase from regulatory settlements		—			1			108			447			—			—			—			46
Increase from contribution from affiliate		—			—			—			—			—			—			—			—
Total Increase/(Decrease) in Net Assets		(1,762,137	)		3,371,561			(708,110	)		1,694,325			(140,101	)		308,937			(126,284	)		41,992
Net Assets:
Beginning of period		18,098,712			14,727,151			6,125,063			4,430,738			1,698,546			1,389,609			452,667			410,675
End of period	$	16,336,575		$	18,098,712		$	5,416,953		$	6,125,063		$	1,558,445		$	1,698,546		$	326,383		$	452,667
Undistributed (Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(32,074	)	$	(48,598	)	$	(60,514	)	$	5,502		$	(167	)	$	(238	)	$	(5,294	)	$	(1,132	)

(a) Class I shares reflect activity for the period September 27, 2010 (commencement of operations) through December 31, 2010.

(b) Class R and Class R5 shares reflect activity for the period August 15, 2011 (commencement of operations) through December 31, 2011.

* Rounds to less than $500.

See accompanying notes to financial statements.

	Columbia Acorn Select						Columbia Thermostat Fund						Columbia Acorn Emerging Markets Fund					Columbia Acorn European Fund
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,					Year ended December 31,
(in thousands)	2011			2010 (a)			2011			2010			2011 (c)			2010		2011 (c)			2010
Subscriptions – Class R5		—			—			—			—			—			—		—			—
Net assets of shares issued in connection with Merger – Class R5		—			—			—			—			—			—		—			—
Redemptions – Class R5		—			—			—			—			—			—		—			—
Net Increase – Class R5		—			—			—			—			—			—		—			—
Subscriptions – Class Z		177,362			358,116			42,102			7,895			2,949			—		1,589			—
Distributions reinvested – Class Z		17,488			—			1,165			560			—			—		13			—
Redemptions – Class Z		(653,289	)		(328,729	)		(14,914	)		(18,853	)		—	*		—		—	*		—
Net Increase/(Decrease) – Class Z		(458,439	)		29,387			28,353			(10,398	)		2,949			—		1,602			—
Net Increase/(Decrease) from Share Transactions		(636,183	)		(77,811	)		55,458			(25,219	)		3,420			—		1,777			—
Redemption Fees		—			—			—			—			—			—		—			—
Increase from regulatory settlements		—			—			—			—			—			—		—			—
Increase from contribution from affiliate		57			—			—			—			—			—		—			—
Total Increase/(Decrease) in Net Assets		(992,234	)		338,010			58,332			(7,314	)		3,229			—		1,679			—
Net Assets:
Beginning of period		2,282,855			1,944,845			131,275			138,589			—			—		—			—
End of period	$	1,290,621		$	2,282,855		$	189,607		$	131,275		$	3,229		$	—	$	1,679		$	—
Undistributed (Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(324	)	$	(17,217	)	$	471		$	1,479		$	(1	)	$	—	$	—	*	$	—

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Changes in Net Assets, continued

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA						Columbia Acorn International Select
Changes in Shares of Beneficial Interest:	Year ended December 31,						Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2011			2010 (a)			2011 (b)			2010 (a)			2011			2010 (a)			2011			2010 (a)
Subscriptions – Class A		30,309			32,735			7,713			8,744			1,507			2,334			666			746
Shares issued in reinvestment and capital gains – Class A		4,849			3,306			463			325			38			—			78			31
Shares issued in connection with merger – Class A		—			—			5,467			—			—			—			—			—
Less shares redeemed – Class A		(37,725	)		(34,053	)		(6,592	)		(6,188	)		(2,879	)		(2,521	)		(980	)		(982	)
Net Increase/(Decrease) – Class A		(2,567	)		1,988			7,051			2,881			(1,334	)		(187	)		(236	)		(205	)
Subscriptions – Class B		21			38			2			1			—	*		—	*		—	*		—	*
Shares issued in reinvestment and capital gains – Class B		164			276			12			9			1			—			2			1
Shares issued in connection with merger – Class B		—			—			343			—			—			—			—			—
Less shares redeemed – Class B		(8,046	)		(13,126	)		(353	)		(444	)		(267	)		(636	)		(39	)		(62	)
Net Increase/(Decrease) – Class B		(7,861	)		(12,812	)		4			(434	)		(266	)		(636	)		(37	)		(61	)
Subscriptions – Class C		3,779			3,197			519			700			90			76			36			83
Shares issued in reinvestment and capital gains – Class C		1,086			733			46			19			8			—			8			2
Shares issued in connection with merger – Class C		—			—			703			—			—			—			—			—
Less shares redeemed – Class C		(5,913	)		(6,190	)		(1,110	)		(519	)		(231	)		(214	)		(115	)		(138	)
Net Increase/(Decrease) – Class C		(1,048	)		(2,260	)		158			200			(133	)		(138	)		(71	)		(53	)
Subscriptions – Class I		639			436			764			1,677			371			1,025			—			—	*
Shares issued in reinvestment and capital gains – Class I		25			—			17			—	*		1			—			—			—
Shares issued in connection with merger – Class I		—			—			4,062			—			—			—			—			—
Less shares redeemed – Class I		(454	)		(51	)		(5,004	)		(50	)		(1,289	)		(10	)		—			—
Net Increase/(Decrease) – Class I		210			385			(161	)		1,627			(917	)		1,015			—			—	*
Subscriptions – Class R		—			—			10			—			—			—			—			—
Shares issued in connection with merger – Class R		—			—			54			—			—			—			—			—
Less shares redeemed – Class R		—			—			(2	)		—			—			—			—			—
Net Increase – Class R		—			—			62			—			—			—			—			—
Subscriptions – Class R5		—			—			—	*		—			—			—			—			—
Shares issued in connection with merger – Class R5		—			—			59			—			—			—			—			—
Net Increase – Class R5		—			—			59			—			—			—			—			—
Subscriptions – Class Z		72,817			78,950			24,482			33,971			12,164			10,643			1,655			2,699
Shares issued in reinvestment and capital gains – Class Z		16,442			11,048			2,222			2,239			274			—			192			66
Less shares redeemed – Class Z		(85,040	)		(74,926	)		(25,537	)		(20,195	)		(11,564	)		(11,173	)		(4,157	)		(3,845	)
Net Increase/(Decrease) – Class Z		4,219			15,072			1,167			16,015			874			(530	)		(2,310	)		(1,080	)
Net Increase/(Decrease) in Shares of Beneficial Interest		(7,047	)		2,373			8,340			20,289			(1,776	)		(476	)		(2,654	)		(1,399	)

(a) Class I shares reflect activity for the period September 27, 2010 (commencement of operations) through December 31, 2010.

(b) Class R and Class R5 shares reflect activity for the period August 15, 2011 (commencement of operations) through December 31, 2011.

* Rounds to less than 500 shares.

See accompanying notes to financial statements.

	Columbia Acorn Select						Columbia Thermostat Fund						Columbia Acorn Emerging Markets Fund					Columbia Acorn European Fund
Changes in Shares of Beneficial Interest:	Year ended December 31,						Year ended December 31,						Year ended December 31,					Year ended December 31,
(in thousands)	2011			2010 (a)			2011			2010			2011 (c)			2010		2011 (c)			2010
Subscriptions – Class A		2,804			4,815			3,467			765			37			—		16			—
Shares issued in reinvestment and capital gains – Class A		242			—			109			56			—			—		—	*		—
Shares issued in connection with merger – Class A		—			—			—			—			—			—		—			—
Less shares redeemed – Class A		(8,092	)		(7,851	)		(898	)		(1,223	)		(1	)		—		—			—
Net Increase/(Decrease) – Class A		(5,046	)		(3,036	)		2,678			(402	)		36			—		16			—
Subscriptions – Class B		3			2			10			—	*		—			—		—			—
Shares issued in reinvestment and capital gains – Class B		16			—			20			21			—			—		—			—
Shares issued in connection with merger – Class B		—			—			—			—			—			—		—			—
Less shares redeemed – Class B		(1,569	)		(1,342	)		(1,427	)		(744	)		—			—		—			—
Net Increase/(Decrease) – Class B		(1,550	)		(1,340	)		(1,397	)		(723	)		—			—		—			—
Subscriptions – Class C		145			299			1,196			275			15			—		1			—
Shares issued in reinvestment and capital gains – Class C		21			—			24			10			—			—		—	*		—
Shares issued in connection with merger – Class C		—			—			—			—			—			—		—			—
Less shares redeemed – Class C		(1,011	)		(870	)		(368	)		(485	)		(1	)		—		—			—
Net Increase/(Decrease) – Class C		(845	)		(571	)		852			(200	)		14			—		1			—
Subscriptions – Class I		520			305			—			—			1			—		1			—
Shares issued in reinvestment and capital gains – Class I		5			—			—			—			—			—		—	*		—
Shares issued in connection with merger – Class I		—			—			—			—			—			—		—			—
Less shares redeemed – Class I		(335	)		(32	)		—			—			—			—		—			—
Net Increase/(Decrease) – Class I		190			273			—			—			1			—		1			—
Subscriptions – Class R		—			—			—			—			—			—		—			—
Shares issued in connection with merger – Class R		—			—			—			—			—			—		—			—
Less shares redeemed – Class R		—			—			—			—			—			—		—			—
Net Increase – Class R		—			—			—			—			—			—		—			—
Subscriptions – Class R5		—			—			—			—			—			—		—			—
Shares issued in connection with merger – Class R5		—			—			—			—			—			—		—			—
Net Increase – Class R5		—			—			—			—			—			—		—			—
Subscriptions – Class Z		6,576			14,221			3,338			697			298			—		159			—
Shares issued in reinvestment and capital gains – Class Z		654			—			92			51			—			—		2			—
Less shares redeemed – Class Z		(25,141	)		(13,400	)		(1,192	)		(1,710	)		—	*		—		—	*		—
Net Increase/(Decrease) – Class Z		(17,911	)		821			2,238			(962	)		298			—		161			—
Net Increase/(Decrease) in Shares of Beneficial Interest		(25,162	)		(3,853	)		4,371			(2,287	)		349			—		179			—

See accompanying notes to financial statements.

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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	30.19		$	24.68		$	17.71		$	29.61		$	29.71
Income from Investment Operations
Net investment income (a)		(0.01	)		0.02			0.04			0.06			0.15	(b)
Net realized and unrealized gain/(loss)		(1.34	)		6.37			6.98			(11.29	)		2.17
Total from Investment Operations		(1.35	)		6.39			7.02			(11.23	)		2.32
Less Distributions to Shareholders
From net investment income		(0.09	)		(0.04	)		(0.05	)		(0.01	)		(0.12	)
From net realized gains		(1.19	)		(0.84	)		—			(0.66	)		(2.30	)
Total Distributions to Shareholders		(1.28	)		(0.88	)		(0.05	)		(0.67	)		(2.42	)
Increase from regulatory settlements		—			0.00	(c)		0.00	(c)		—			—
Net Asset Value, End of Period	$	27.56		$	30.19		$	24.68		$	17.71		$	29.61
Total Return (d)		(4.61	)%		26.00	%		39.65	%		(38.55	)%		7.69	%(e)(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		0.76	%		0.76	%		0.77	%		0.76	%		0.74	%
Net investment income (g)		(0.03	)%		0.09	%		0.18	%		0.26	%		0.46	%
Waiver/Reimbursement		—			—			—			—			0.00	%(h)
Portfolio turnover rate		18	%		28	%		27	%		21	%		20	%
Net assets at end of period (in millions)	$	12,285		$	13,330		$	10,527		$	7,446		$	13,038

(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.

(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 Advisor 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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	40.92		$	34.26		$	23.13		$	43.60		$	40.31
Income from Investment Operations
Net investment income (a)		0.48			0.35			0.34			0.60			0.43
Net realized and unrealized gain/(loss)		(6.07	)		7.23			11.31			(20.26	)		6.56
Reimbursement from affiliate		0.00	(b)		—			—			—			—
Total from Investment Operations		(5.59	)		7.58			11.65			(19.66	)		6.99
Less Distributions to Shareholders
From net investment income		(1.02	)		(0.92	)		(0.53	)		(0.21	)		(0.34	)
From net realized gains		—			—			—			(0.60	)		(3.36	)
Total Distributions to Shareholders		(1.02	)		(0.92	)		(0.53	)		(0.81	)		(3.70	)
Redemption Fees
Redemption fees added to paid in capital (a)		—			0.00	(b)		0.00	(b)		0.00	(b)		0.00	(b)
Increase from regulatory settlements		0.00	(b)		0.00	(b)		0.01			—			—
Net Asset Value, End of Period	$	34.31		$	40.92		$	34.26		$	23.13		$	43.60
Total Return (c)		(14.06	)%(d)		22.70	%		50.97	%		(45.89	)%		17.28	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		0.95	%		0.97	%		0.99	%		0.96	%		0.91	%
Net investment income (f)		1.24	%		0.99	%		1.23	%		1.72	%		0.96	%
Waiver/Reimbursement		—			—			—			—			0.00	%(g)
Portfolio turnover rate		32	%		25	%		31	%		38	%		28	%
Net assets at end of period (in millions)	$	4,323		$	5,108		$	3,728		$	2,372		$	4,918

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

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

(d) During the year ended December 31, 2011, Columbia Management reimbursed the Fund for a loss on a trading error. Had the Fund not received this reimbursement, total return would have been lower by less than 0.01%.

(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.

Columbia Acorn USA

Class Z Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	28.56		$	23.19		$	16.39		$	27.97		$	28.66
Income from Investment Operations
Net investment loss (a)		(0.14	)		(0.08	)		(0.07	)		(0.07	)		(0.01	)(b)
Net realized and unrealized gain/(loss)		(1.27	)		5.45			6.87			(10.55	)		1.03
Total from Investment Operations		(1.41	)		5.37			6.80			(10.62	)		1.02
Less Distributions to Shareholders
From net realized gains		(0.17	)		—			—			(0.96	)		(1.71	)
Total Distributions to Shareholders		(0.17	)		—			—			(0.96	)		(1.71	)
Increase from regulatory settlements		—			—			0.00	(c)		—			—
Net Asset Value, End of Period	$	26.98		$	28.56		$	23.19		$	16.39		$	27.97
Total Return (d)		(4.95	)%		23.16	%		41.49	%		(39.22	)%		3.46	%(e)(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.00	%		1.01	%		1.03	%		1.01	%		0.98	%
Net investment loss (g)		(0.48	)%		(0.34	)%		(0.36	)%		(0.32	)%		(0.03	)%
Waiver/Reimbursement		—			—			—			—			0.00	%(h)
Portfolio turnover rate		20	%		32	%		28	%		23	%		21	%
Net assets at end of period (in millions)	$	1,356		$	1,410		$	1,158		$	758		$	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.

(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.

(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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	28.33		$	23.64		$	18.19		$	32.02		$	27.97
Income from Investment Operations
Net investment income (a)		0.29			0.18			0.17			0.28			0.14	(b)
Net realized and unrealized gain/(loss)		(2.98	)		4.89			5.50			(13.53	)		5.96
Total from Investment Operations		(2.69	)		5.07			5.67			(13.25	)		6.10
Less Distributions to Shareholders
From net investment income		(0.79	)		(0.38	)		(0.24	)		(0.04	)		(0.28	)
From net realized gains		(0.39	)		—			—			(0.54	)		(1.77	)
Total Distributions to Shareholders		(1.18	)		(0.38	)		(0.24	)		(0.58	)		(2.05	)
Redemption Fees
Redemption fees added to paid in capital (a)		—			0.00	(c)		0.00	(c)		0.00	(c)		0.00	(c)
Increase from regulatory settlements		—			0.00	(c)		0.02			—			—
Net Asset Value, End of Period	$	24.46		$	28.33		$	23.64		$	18.19		$	32.02
Total Return (d)		(9.76	)%		21.89	%		31.52	%		(42.10	)%		21.86	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		1.14	%		1.16	%		1.20	%		1.21	%		1.18	%
Net investment income (f)		1.03	%		0.75	%		0.84	%		1.09	%		0.44	%
Waiver/Reimbursement		—			—			—			—			0.00	%(g)
Portfolio turnover rate		44	%		42	%		56	%		68	%		57	%
Net assets at end of period (in millions)	$	260		$	366		$	331		$	186		$	204

(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.

(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.

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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	28.73		$	23.38		$	14.07		$	28.41		$	26.59
Income from Investment Operations
Net investment loss (a)		(0.07	)		(0.10	)		(0.08	)		(0.12	)		(0.07	)
Net realized and unrealized gain/(loss)		(4.58	)		5.45			9.39			(13.53	)		2.53
Total from Investment Operations		(4.65	)		5.35			9.31			(13.65	)		2.46
Less Distributions to Shareholders
From net investment income		(0.46	)		—			—			—			—
From net realized gains		—			—			—			(0.69	)		(0.64	)
Total Distributions to Shareholders		(0.46	)		—			—			(0.69	)		(0.64	)
Reimbursement from affiliate		0.00	(b)		—			—			—			—
Net Asset Value, End of Period	$	23.62		$	28.73		$	23.38		$	14.07		$	28.41
Total Return (c)		(16.37	)%(d)		22.88	%		66.17	%		(49.18	)%(e)		9.20	%(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		0.97	%		0.97	%		0.99	%		0.95	%		0.91	%
Net investment loss (g)		(0.28	)%		(0.41	)%		(0.47	)%		(0.51	)%		(0.24	)%
Waiver/Reimbursement		—			—			—			—			0.00	%(h)
Portfolio turnover rate		21	%		28	%		19	%		28	%		14	%
Net assets at end of period (in millions)	$	850		$	1,549		$	1,241		$	780		$	1,571

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

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

(d) During the year ended December 31, 2001, the Fund received a reimbursement by an affiliate. Had the Fund not received this payment, the total return would have been lower by 0.01%.

(e) Total return includes a voluntary reimbursement by the Advisor 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.

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

(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 Thermostat Fund

Class Z Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	12.44		$	10.80		$	8.19		$	12.26		$	12.57
Income from Investment Operations
Net investment income (a)		0.31			0.21			0.13			0.24			0.52
Net realized and unrealized gain/(loss)		0.29			1.66			2.51			(3.96	)		0.53
Total from Investment Operations		0.60			1.87			2.64			(3.72	)		1.05
Less Distributions to Shareholders
From net investment income		(0.37	)		(0.23	)		(0.03	)		(0.28	)		(0.57	)
From net realized gains		—			—			—			(0.07	)		(0.79	)
Total Distributions to Shareholders		(0.37	)		(0.23	)		(0.03	)		(0.35	)		(1.36	)
Net Asset Value, End of Period	$	12.67		$	12.44		$	10.80		$	8.19		$	12.26
Total Return (b)(c)		4.85	%		17.58	%		32.29	%		(30.53	)%		8.49	%
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)		2.43	%		1.87	%		1.48	%		2.23	%		4.05	%
Waiver/Reimbursement		0.09	%		0.12	%		0.14	%		0.08	%		0.15	%
Portfolio turnover rate		130	%		118	%		17	%		130	%		128	%
Net assets at end of period (in millions)	$	65		$	36		$	42		$	35		$	36

(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) In addition to the fees and expenses which the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of the affiliated funds in which it invests. Such indirect expenses are not included in the reported expense ratios.

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

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Class Z Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	10.00
Income from Investment Operations
Net investment income (b)		0.01
Net realized and unrealized loss		(0.73	)
Total from Investment Operations		(0.72	)
Net Asset Value, End of Period	$	9.28
Total Return (c)(d)		(7.20	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.46	%
Net investment income (e)		0.15	%
Waiver/Reimbursement		18.06	%
Portfolio turnover rate (d)		9	%
Net assets at end of period (in millions)	$	3

(a) Class Z shares commenced operations on August 19, 2011. 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 initial sales charge or contingent deferred sales charge.

(d) Not annualized.

(e) Annualized.

Columbia Acorn European Fund

Class Z Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	10.00
Income from Investment Operations
Net investment loss (b)		(0.02	)
Net realized and unrealized loss		(0.46	)
Total from Investment Operations		(0.48	)
Less Distributions to Shareholders
From net investment income		(0.06	)
From net realized gains		(0.02	)
Total Distributions to Shareholders		(0.08	)
Net Asset Value, End of Period	$	9.44
Total Return (c)(d)		(4.78	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.37	%
Net investment loss (e)		(0.52	)%
Waiver/Reimbursement		28.89	%
Portfolio turnover rate (c)		17	%
Net assets at end of period (in millions)	$	2

(a) Class Z shares commenced operations on August 19, 2011. 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.

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

(e) Annualized.

See accompanying notes to financial statements.

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, Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund and Columbia Acorn European 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 Acorn Emerging Markets Fund and Columbia Acorn European Fund commenced operations on August 19, 2011.

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 affiliated stock and bond mutual funds (underlying 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. Columbia Acorn Fund, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select each currently offers Class A, Class B, Class C, Class I and Class Z shares. Columbia Acorn International currently offers Class A, Class B, Class C, Class I, Class R, Class R5 and Class Z shares. Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund each currently offers Class A, Class C, Class I and Class Z shares. Columbia Thermostat Fund currently offers Class A, Class B, Class C and Class Z shares. Effective February 29, 2008, the Funds no longer accept investments by new or existing investors in the Fund's Class B shares, except in connection with the reinvestment of any dividend and/or capital gain distributions in Class B shares of the Funds and exchanges by existing Class B shareholders of certain other funds within the Columbia Acorn Family of Funds.

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 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 18 months of purchase.

Class B shares are subject to 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 at net asset value. There are certain restrictions on who may purchase Class I shares.

Class R and Class R5 shares are offered at net asset value. There are certain restrictions on who may purchase Class R and Class R5 shares. Class R and Class R5 shares commenced operations on August 15, 2011.

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, Class I, Class R and Class R5 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 agent fees, 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 disclosure 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.

Short-term investments maturing in 60 days or less are valued at amortized cost, which approximates market value.

Forward foreign currency exchange contracts are marked-to-market based upon foreign currency exchange rates provided by a pricing service.

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. A security for which there is no reported sale on the valuation date is valued at the latest bid quotations.

>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.

>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.

>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 Fund 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.

>Derivative Instruments

Columbia Acorn International and Columbia Acorn International Select invest in certain derivative instruments as detailed below to meet its investment objectives. Derivatives are instruments whose values depend on, or are derived from, in whole or in part, the value of one or more other assets, such as securities, currencies, commodities or indices. Derivative instruments may be used to maintain cash reserves while maintaining exposure to certain other assets, to offset anticipated declines in values of investments, to facilitate trading, to reduce transaction costs and to pursue higher investment returns. The Funds may also use derivative instruments to mitigate certain investment risks, such as foreign currency exchange rate risk, interest rate risk and credit risk. Derivatives may involve various risks, including the potential inability of the counterparty to fulfill its obligation under the terms of the contract, the potential for an illiquid secondary market and the potential for market movements, which may expose the Funds to gains or losses in excess of the amount shown in the Statements of Assets and Liabilities.

>Forward Foreign Currency Exchange Contracts

Forward foreign currency exchange contracts are agreements between two parties to buy and sell a currency at a set price on a future date. Columbia Acorn International and Columbia Acorn International Select utilized forward foreign currency exchange contracts to shift investment exposure from one currency to another or to recover an underweight country exposure in its portfolio.

The values of forward foreign currency exchange contracts fluctuate with changes in foreign currency exchange rates. Each Fund will record a realized gain or loss when the forward foreign currency exchange contract is closed.

The use of forward foreign currency exchange contracts does not eliminate fluctuations in the prices of the Funds' portfolio securities. The risks of forward foreign currency

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

exchange contracts include movement in the values of the foreign currencies relative to the U.S. dollar (or other foreign currencies) and the possibility that counterparties will not complete their contractual obligations, which may be in excess of the amount reflected, if any, in the Statements of Assets and Liabilities.

>Effects of Derivative Transactions in the Financial Statements

The following tables are intended to provide additional information about the effect of derivatives on the financial statements of Columbia Acorn International and Columbia Acorn International Select including: the fair value of derivatives by risk category and the location of those fair values in the Statements of Assets and Liabilities; the impact of derivative transactions on the Funds' operations over the period including realized gains or losses and unrealized gains or losses. The derivative schedules following the Statements of Investments present additional information regarding derivative instruments outstanding at the end of the period, if any.

During the year ended December 31, 2011, Columbia Acorn International entered into 104 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, 2011.

Fair Value of Derivative Instruments

Asset

Liability

Statement of Assets
and Liabilities

Fair
Value

Statement of Assets
and Liabilities

Fair
Value

(in thousands)

Unrealized
appreciation
on forward foreign
currency exchange
contracts

$4,539

Unrealized
depreciation
on forward foreign
currency exchange
contracts

$—

The effect of derivative instruments on Columbia Acorn International's Statement of Operations for the year ended December 31, 2011 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	$	7,872	$	(6,748	)

During the year ended December 31, 2011, Columbia Acorn International Select entered into four forward foreign currency exchange contracts.

The following table is a summary of the value of Columbia Acorn International Select's derivative Instruments as of December 31, 2011.

Fair Value of Derivative Instruments

Asset

Liability

Statement of Assets
and Liabilities

Fair
Value

Statement of Assets
and Liabilities

Fair
Value

(in thousands)

Unrealized
appreciation
on forward foreign
currency exchange
contracts

—

Unrealized
depreciation
on forward foreign
currency exchange
contracts

948

The effect of derivative instruments on Columbia Acorn International Select's Statement of Operations for the year ended December 31, 2011 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	$	1,262	$	(948	)

>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.

>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 distribution and service fees and transfer agent 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.

>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. 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, 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 as of December 31, 2011 by each Fund is included in the Statements of Operations.

>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. 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.

>Recent Accounting Pronouncement

Fair Value Measurements and Disclosures

In May 2011, the Financial Accounting and Standards Board (FASB) issued ASU No. 2011-04 modifying Topic 820, Fair Value Measurements and Disclosures. At the same time, the International Accounting Standards Board (IASB) issued International Financial Reporting Standard 13, Fair Value Measurement. The objective of the FASB and IASB is

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

convergence of their guidance on fair value measurements and disclosures.

Specifically, ASU No. 2011-04 requires reporting entities to disclose i) the amounts of any transfers between Level 1 and Level 2, and the reasons for the transfers, ii) for Level 3 fair value measurements, a) quantitative information about significant unobservable inputs used, b) a description of the valuation processes used by the reporting entity and c) a narrative description of the sensitivity of the fair value measurement to changes in unobservable inputs if a change in those inputs might result in a significantly higher or lower fair value measurement. The effective date of ASU No. 2011-04 is for interim and annual periods beginning after December 15, 2011. At this time, management is evaluating the implications of this guidance and the impact it will have on the financial statement amounts and footnote disclosures, if any.

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, 2011, permanent book and tax basis differences resulting primarily from differing treatments for net operating losses, capital loss carryforwards, distribution reclassifications, non-deductible organizational costs, proceeds from litigation settlements, short-term capital gain distributions from investments in mutual funds, foreign currency transactions, passive foreign investment company (PFIC) holdings and former PFIC holdings 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	$	82,288		$	(31,818	)	$	(50,470	)
Columbia Acorn International		34,709			50,375			(85,084	)
Columbia Acorn USA		9,454			—			(9,454	)
Columbia Acorn International Select		2,505			(2,505	)		—
Columbia Acorn Select		56,056			(20,699	)		(35,357	)
Columbia Thermostat Fund		130			(130	)		—
Columbia Acorn Emerging Markets Fund		(2	)		3			(1	)
Columbia Acorn European Fund		15			(14	)		(1	)

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, 2011 and December 31, 2010 was as follows:

	December 31, 2011				December 31, 2010
Fund	Ordinary Income*		Long-term Capital Gains		Ordinary Income*		Long-term Capital Gains
(in thousands)
Columbia Acorn Fund	$	38,838	$	707,353	$	21,020	$	496,293
Columbia Acorn International		157,072		—		122,919		—
Columbia Acorn USA		—		9,831		—		—
Columbia Acorn International Select		10,288		5,504		6,107		—
Columbia Acorn Select		31,148		42		—		—
Columbia Thermostat Fund		3,922		—		1,666		—
Columbia Acorn Emerging Markets Fund		—		—		N/A		N/A
Columbia Acorn European Fund		15		—		N/A		N/A

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

As of December 31, 2011, the components of distributable earnings on a tax basis were as follows:

	Undistributed Ordinary Income		Undistributed Long-Term Capital Gains		Unrealized Appreciation (Depreciation)
(in thousands)
Columbia Acorn Fund	$	—	$	255,805	$	4,943,887
Columbia Acorn International		27,270		—		553,374
Columbia Acorn USA		—		5,790		401,645
Columbia Acorn International Select		—		4,603		28,246
Columbia Acorn Select		—		26,965		166,244
Columbia Thermostat Fund		490		—		13,265
Columbia Acorn Emerging Markets Fund		1		—		(136	)
Columbia Acorn European Fund		2		—		(91	)

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

The following capital loss carryforwards, determined as of December 31, 2011, may be available to reduce taxable

100

income arising from future net realized gains on investments, if any, to the extent permitted by the Internal Revenue Code:

	Year of Expiration
	2015		2016		2017		2018		Unlimited		Total
(in thousands)
Columbia Acorn International	$	15,640	$	82,683	$	189,008	$	—	$	—	$	287,331
Columbia Thermostat Fund		—		—		17,733		2,955		—		20,688
Columbia Acorn Emerging Markets Fund		—		—		—		—		11		11

On December 22, 2010, the Regulated Investment Company Modernization Act of 2010 (the Act) was enacted, which changed various technical rules governing the tax treatment of regulated investment companies. The changes are generally effective for taxable years beginning after the date of enactment. Under the Act, the Funds will be permitted to carry forward capital losses incurred in taxable years beginning after the date of enactment for an unlimited period. However, any losses incurred during those future taxable years will be required to be utilized prior to the losses incurred in pre-enactment taxable years, which carry an expiration date. As a result of this ordering rule, pre-enactment capital loss carryforwards may be more likely to expire unused.

Capital loss carryforwards that were utilized and expired for the Funds during the year ended December 31, 2011, were as follows:

	Utilized		Expired
(in thousands)
Columbia Acorn International	$	211,304	$	82,542
Columbia Acorn USA		28,408		—
Columbia Acorn International Select		36,610		—
Columbia Acorn Select		119,037		—
Columbia Thermostat Fund		9,197		—

Columbia Acorn International acquired capital loss carryforwards in connection with the merger with RiverSource Partners International Select Growth Fund and RiverSource Partners International Small Cap Fund of $121,174,098 and $73,618,287, respectively (Note 8). In addition to the acquired capital loss carryforwards, the Fund also acquired unrealized capital gains as a result of the merger. The yearly utilization of the acquired capital loss carryforwards may be limited by the Internal Revenue Code. Any capital loss carryforwards acquired as part of a merger that are permanently lost due to the provisions under the Internal Revenue Code are included as being expired.

Under current tax rules, Regulated Investment Companies can elect to treat certain late-year ordinary losses incurred and post-October capital losses (capital losses realized after October 31) as arising on the first day of the following taxable year. As of December 31, 2011, the Funds will elect to treat the following late-year ordinary losses and post-October capital losses as arising on January 1, 2012:

Fund	Late-year ordinary losses		Post-October capital losses
(in thousands)
Columbia Acorn Fund	$	9,350	$	50,163
Columbia Acorn International		—		12,775
Columbia Acorn USA		—		3,057
Columbia Acorn International Select		2,622		3,120
Columbia Acorn Select		107		3,172
Columbia Acorn Emerging Markets Fund		—		42
Columbia Acorn European Fund		2		7

Management of the Funds has concluded that there are no significant uncertain tax positions that would require recognition in the financial statements. However, management's conclusion 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). Generally, the Funds' federal tax returns for the prior three fiscal years remain subject to examination by the Internal Revenue Service.

4. Transactions with Affiliates

Columbia Wanger Asset Management (CWAM) is a wholly owned subsidiary of Columbia Management Investment Advisers, LLC (Columbia Management), which 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.

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	%

101

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

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	%

Columbia Acorn Emerging Markets Fund

Average Daily Net Assets	Annual Fee Rate
Up to $100 million		1.25	%
$100 million to $500 million		1.00	%
$500 million and over		0.80	%

Columbia Acorn European Fund

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	%

For the year ended December 31, 2011, the effective investment advisory fee rate were as follows:

Fund
Columbia Acorn Fund	0.64	%
Columbia Acorn International	0.76	%
Columbia Acorn USA	0.86	%
Columbia Acorn International Select	0.94	%
Columbia Acorn Select	0.82	%
Columbia Thermostat Fund	0.10	%
Columbia Acorn Emerging Markets Fund	1.25	%
Columbia Acorn European Fund	1.19	%

>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 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, 2012. There is no guarantee that this arrangement will continue thereafter.

CWAM has contractually agreed to waive fees and/or reimburse expenses of Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund through April 30, 2013, so that the ordinary operating expenses (exclusive of interest and fees on borrowings, and expenses associated with each Fund's investment in other investment companies, if any, do not exceed the following annual rates based on each Fund's average daily net assets:

Fund	Class Z
Columbia Acorn Emerging Markets Fund		1.60	%
Columbia Acorn European Fund		1.50	%

There is no guarantee that these arrangements will continue after April 30, 2013.

CWAM may recoup any fees waived and/or expenses reimbursed with respect to any share class of Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund for a one-year period following the date of such fee waiver and/or reimbursement if such recovery does not cause the Funds' ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Funds' investment in other investment companies, if any) to exceed the annual expense limitations above, or to exceed such annual expense limitations as may be in place at the time of the recoupment, whichever is less.

Effective August 15, 2011, CWAM and its affiliates have contractually agreed to waive a portion of total annual Fund

102

operating expenses incurred by Class A shares, Class B shares and Class C shares of Columbia Acorn International such that the Fund's total annual Fund operating expenses will be reduced by 0.04%, 0.03% and 0.02% for Class A, Class B and Class C shares of the Fund, respectively through August 14, 2013. There is no guarantee that this arrangement will continue thereafter.

Expenses reimbursed by CWAM and its affiliates for the year ended December 31, 2011, were as follows:

Fund	Expenses reimbursed
(in thousands)
Columbia Acorn International	$	159
Columbia Thermostat Fund	$	216
Columbia Acorn Emerging Markets Fund	$	217
Columbia Acorn European Fund	$	218

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, 2011, the effective administration fee rate was 0.04% of each Fund's average daily net assets. CWAM has delegated to Columbia Management responsibility to provide certain sub-administrative services to the Funds.

Columbia Management Investment Distributors, Inc. (CMID), an indirect wholly owned subsidiary of Ameriprise Financial, is the distributor of the Funds.

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%, 0.75% and 0.50%, annually, of the average daily net assets attributable to Class B, Class C and Class R shares, respectively. CMID receives no compensation with respect to Class R5 and Class Z shares.

Columbia Management Investment Services Corp. (CMIS), a wholly owned subsidiary of Ameriprise Financial, is the transfer agent of the Funds. For its services, each Fund pays CMIS a monthly fee at the annual rate of $17.00 per open account. CMIS also receives reimbursement from the Funds for certain out-of-pocket expenses. Class I shares do not pay transfer agent fees.

In connection with the acquisition that closed August 15, 2011, Columbia Acorn International assumed the assets and obligations of RiverSource Partners International Small Cap Fund and RiverSource Partners International Select Growth Fund (See Note 8), which together with certain other associated investment companies (together, the Guarantors), have severally, but not jointly, guaranteed the performance and observance of all the terms and conditions of a lease (including the payment of rent (the Guaranty)) entered into by Seligman Data Corp. (SDC), the former transfer agent of Seligman Global Smaller Companies Fund and Seligman International Growth Fund, which were acquired by RiverSource Partners International Small Cap Fund and RiverSource Partners International Select Growth Fund, respectively, in previous years. The lease and the Guaranty expire in January 2019. At December 31, 2011, Columbia Acorn International's total potential future obligation over the life of the Guaranty was $140,903. The liability remaining at December 31, 2011 for non-recurring charges associated with the lease amounted to $97,731 and is included within other accrued expenses in the Statements of Assets and Liabilities.

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 has 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. These 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 as specified by the trustee. Benefits under the deferred compensation plan are payable in accordance with the plan.

An affiliated person of a Fund may include any company in which a Fund owns five percent or more of its outstanding

103

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

voting shares. On December 31, 2011, 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 35, 36, 47, 56, 57, 68 and 69, respectively.

For the year ended December 31, 2011, the Funds engaged in purchase and sales 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	$	24,382	$	—
Columbia Acorn International		35,187		—
Columbia Acorn USA		578		—
Columbia Acorn International Select		213		—
Columbia Acorn Select		—		23,766
Columbia Acorn European Fund		53		10

During the year ended December 31, 2011, Columbia Management reimbursed Columbia Acorn International $174,055 for a loss on a trading error.

During the year ended December 31, 2011, Columbia Acorn Select Class Z shares received a payment of $56,666 from Columbia Management as a reimbursement for certain shareholder transactions processed at an incorrect price. The payment has been included in "Increase from contribution from affiliate" on the Statement of Changes in Net Assets.

5. Borrowing Arrangements

Effective July 22, 2011, the Trust participates in a $150 million credit facility with JPMorgan Chase Bank, N.A., 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 0.10% per annum of the unutilized line of credit is accrued and apportioned among the participating Funds based on their relative net assets. The commitment fee is included in "Other expenses" in the Statement of Operations. The Trust enters into this line of credit for one year durations.

Prior to July 22, 2011, the Trust participated in a $150 million credit facility with State Street Bank and Trust Company (State Street) under similar lending terms. The commitment fee under the State Street arrangement was 0.125% per annum of the unutilized line of credit.

No amounts were borrowed by the Fund under either facility during the year ended December 31, 2011.

6. Investment Transactions

The aggregate cost of purchases and proceeds from sales, other than short-term obligations, for the year ended December 31, 2011, were:

	Purchases		Proceeds from Sales
(in thousands)
Columbia Acorn Fund	$	3,205,101	$	4,069,128
Columbia Acorn International		2,350,871		1,899,789
Columbia Acorn USA		343,125		407,720
Columbia Acorn International Select		169,127		246,489
Columbia Acorn Select		386,396		951,396
Columbia Thermostat Fund		235,550		186,041
Columbia Acorn Emerging Markets Fund		3,285		234
Columbia Acorn European Fund		1,983		264

7. Regulatory Settlements with Third Parties

During the year ended December 31, 2011, Columbia Acorn International received payments of $107,617 resulting from certain regulatory settlements with third parties in which the Fund had participated. The payments have been included in "Increase from regulatory settlements" in the Statements of Changes in Net Assets.

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.

8. Fund Merger

On August 15, 2011, Columbia Acorn International acquired the assets and assumed the identified liabilities of RiverSource Partners International Select Growth Fund and RiverSource Partners International Small Cap Fund, both a series of RiverSource International Managers Series, Inc., which were sub-advised by CWAM. The reorganization was completed after shareholders approved the plan on May 11, 2011. The purpose

104

of the transaction was to combine funds managed by CWAM with comparable investment objectives and strategies.

The aggregate net assets of Columbia Acorn International immediately before the acquisitions were $5,887,634,436 and the combined net assets immediately after the acquisitions were $6,287,891,195.

The merger was accomplished by a tax-free exchange of 48,230,699 shares of RiverSource Partners International Select Growth valued at $311,482,971 (including $29,840,736 of unrealized appreciation) and 15,801,504 shares of RiverSource Partners International Small Cap Fund valued at $88,773,788 (including $6,322,097 of unrealized appreciation).

In exchange for RiverSource Partners International Select Growth and RiverSource Partners International Small Cap Fund shares, Columbia Acorn International issued the following number of shares:

	RiverSource Partners International Select Growth Fund		��	RiverSource Partners International Small Cap Fund
Class A		3,800,227			1,666,707
Class B		267,259			75,499
Class C		183,761			518,779
Class I		4,010,380			51,634
Class R		35,341			48,348
Class R5		5,711			23,983

For financial reporting purposes, net assets received and shares issued by Columbia Acorn International Fund were recorded at fair value; however, RiverSource Partners International Small Cap Fund and RiverSource Partners International Select Growth Fund's cost of investments was carried forward.

The financial statements reflect the operations of Columbia Acorn International for the period prior to the merger and the combined fund for the period subsequent to the merger. Because the combined investment portfolios have been managed as a single integrated portfolio since the merger was completed, it is not practicable to separate the amounts of revenue and earnings of RiverSource Partners International Small Cap Fund and RiverSource Partners International Select Growth that have been included in the combined Fund's Statement of Operations since the merger was completed.

Assuming the merger had been completed on January 1, 2011, Columbia Acorn International's pro-forma net investment income, net gain on investments, net change in unrealized depreciation and net increase in net assets from operations for the year ended December 31, 2011 would have been approximately $76.7 million, $260.0 million, $(1,274.8) million and $(938.1) million, respectively.

9. Shareholder Concentration

At December 31, 2011, one unaffiliated shareholder account owned 18.0% of the outstanding shares of Columbia Acorn International; three unaffiliated shareholder accounts owned 47.3% of the outstanding shares of Columbia Acorn USA; one unaffiliated shareholder account owned 45.2% of the outstanding shares of Columbia Acorn International Select; two unaffiliated shareholder accounts owned 26.2% of the outstanding shares of Columbia Acorn Select; one unaffiliated shareholder account owned 15.7% of the outstanding shares of Columbia Thermostat Fund. Affiliated shareholder accounts owned 28.9% of the outstanding shares of Columbia Acorn Emerging Markets Fund and 66.3% of the outstanding shares of Columbia Acorn European Fund. The Funds have no knowledge about whether any portion of those shares was owned beneficially. Subscription and redemption activity of these accounts may have a significant effect on the operations of the Funds.

10. Subsequent Events

Management has evaluated the events and transactions that have occurred through the date the financial statements were issued and noted no items requiring adjustment of the financial statements or additional disclosure.

11. Information Regarding Pending and Settled Legal Proceedings

105

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

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 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 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 response to the plaintiffs' opening appellate brief filed on March 18, 2011, the defendants filed a response brief on May 4, 2011 with the Eighth Circuit. The plaintiffs filed a reply brief on May 26, 2011 and oral arguments took place on November 17, 2011.

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 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 funds' Boards of 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 Securities and Exchange Commission 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.sec.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.

106

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, Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund, and Columbia Acorn European Fund (each a series of the Columbia Acorn Trust, hereinafter referred to as the "Funds") at December 31, 2011, the results of their operations, and the changes in their net assets and the financial highlights for the periods presented, 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, 2011 by correspondence with the custodian and brokers, provide a reasonable basis for our opinion.

PricewaterhouseCoopers LLP
Chicago, Illinois
February 17, 2012

107

Columbia Acorn Family of Funds

Federal Income Tax Information (in thousands) (Unaudited) — Class A, B, C, I, R, R5 and Z shares

Columbia Acorn Fund

The Fund hereby designates as a capital gain dividend with respect to the fiscal year ended December 31, 2011, $818,375, 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, 2011 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, 2011 may represent qualified dividend income.

Columbia Acorn International

Foreign taxes paid during the fiscal year ended December 31, 2011 of $10,332 are being passed through to shareholders. This represents $0.07 per share. Eligible shareholders may claim this amount as a foreign tax credit.

Gross income derived from sources within foreign countries was $143,798 ($0.91 per share) for the fiscal year ended December 31, 2011.

For non-corporate shareholders, 34.72% 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, 2011 may represent qualified dividend income.

Columbia Acorn USA

The Fund hereby designates as a capital gain dividend with respect to the fiscal year ended December 31, 2011, $16,402, or, if subsequently determined to be different, the net capital gain of such year.

Columbia Acorn International Select

The Fund hereby designates as a capital gain dividend with respect to the fiscal year ended December 31, 2011 $10,612, or, if subsequently determined to be different, the net capital gain of such year.

Foreign taxes paid during the fiscal year ended December 31, 2011, of $518 are being passed through to shareholders. This represents $0.04 per share. Eligible shareholders may claim this amount as a foreign tax credit.

Gross income derived from sources within foreign countries was $9,719 ($0.73 per share) for the fiscal year ended December 31, 2011.

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, 2011 may represent qualified dividend income.

Columbia Acorn Select

The Fund hereby designates as a capital gain dividend with respect to the fiscal year ended December 31, 2011, $28,357, or, if subsequently determined to be different, the net capital gain of such year.

30.25% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2011 qualified for the corporate dividends received deduction.

For non-corporate shareholders 32.41% 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, 2011 may represent qualified dividend income.

Columbia Thermostat Fund

53.13% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2011 qualified for the corporate dividends received deduction.

For non-corporate shareholders, 54.67% 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, 2011 may represent qualified dividend income.

Columbia Acorn Emerging Markets Fund

Foreign taxes paid during the fiscal year ended December 31, 2011, of $1 are being passed through to shareholders. This represents $0.001 per share. Eligible shareholders may claim this amount as a foreign tax credit.

Gross income derived from sources within foreign countries was $16 ($0.05 per share) for the fiscal year ended December 31, 2011.

Columbia Acorn European Fund

Foreign taxes paid during the fiscal year ended December 31, 2011, of $1 are being passed through to shareholders. This represents $0.003 per share. Eligible shareholders may claim this amount as a foreign tax credit.

Gross income derived from sources within foreign countries was $6 ($0.03 per share) for the fiscal year ended December 31, 2011.

For non-corporate shareholders 36.58% 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, 2011 may represent qualified dividend income.

108

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 eight series 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, 2011

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, 46,
Trustee and Chair

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.

Wanger Advisors Trust

Michelle L. Collins, 51,
Trustee

2008

President, Cambium LLC (financial and business advisory firm) since 2007; Advisory Board Member, Svoboda Capital Partners LLC (private equity firm) since 2007; Managing Director Svoboda Capital Partners LLC, 1998-2006.

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, 63,
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.

Wanger Advisors Trust

Margaret M. Eisen, 58,
Trustee

2002

Chief Investment Officer, EAM International LLC (corporate finance and asset management) since 2003; Managing Director, CFA Institute, 2005-2008.

Wanger Advisors Trust; Antigenics, Inc. (biotechnology and pharmaceuticals) until June 2009.

John C. Heaton, 52,
Trustee

2010

Joseph L. Gidwitz Professor of Finance, University of Chicago Booth School of Business; James H. Lorie Professor of Finance, University of Chicago Booth School of Business July 2000 – July 2006; financial consultant since 2004.

Wanger Advisors Trust

Steven N. Kaplan, 52,
Trustee and Vice Chair

1999

Neubauer Family Professor of Entrepreneurship and Finance, University of Chicago Booth School of Business; faculty member of the University of Chicago Booth School of Business since 1988.

Wanger Advisors Trust; Accretive Health, Inc. (healthcare management services provider); Morningstar, Inc. (provider of independent investment research).

Allan B. Muchin, 75,
Trustee⁽¹⁾

1998

Chairman Emeritus, Katten Muchin Rosenman LLP (law firm).

Wanger Advisors Trust

David J. Rudis, 58,
Trustee⁽²⁾

2010

National Checking and Debit Executive, and Illinois President, Bank of America, 2007-2009; President, Consumer Banking Group, LaSalle National Bank, 2004-2007.

Wanger Advisors Trust

David B. Small, 55,
Trustee

2010

Managing Director, Grosvenor Capital Management, L.P. (investment adviser) since 1994; Adjunct Associate Professor of Finance, University of Chicago Booth School of Business.

Wanger Advisors Trust

Trustees who are interested persons of Columbia Acorn Trust:

Charles P. McQuaid, 58,
Trustee and President⁽³⁾

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.

Wanger Advisors Trust

109

Name, Position(s)
with Columbia Acorn
Trust and Age at
December 31, 2011

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

Trustee Emeritus

Ralph Wanger, 77,
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 to CWAM or its predecessors, September 2003 – September 2005.

Wanger Advisors Trust

Officers of Columbia Acorn Trust:

Ben Andrews, 45,
Vice President

2004

Portfolio manager and analyst, CWAM or its predecessors, since 1998; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2004.

None

Robert A. Chalupnik, 45,
Vice President

2011

Portfolio manager and analyst, CWAM or its predecessors since 1998. Vice President Columbia Acorn Trust and Wanger Advisors Trust since May 2011.

None

Michael G. Clarke, 42,
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 Funds and affiliated funds since 2002.

None

Joseph F. DiMaria, 44,
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.

None

P. Zachary Egan, 43,
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.

None

Fritz Kaegi, 40,
Vice President

2011

Portfolio manager and analyst, CWAM or its predecessors since 2004. Vice President Columbia Acorn Trust and Wanger Advisors Trust since September 2011.

None

John Kunka, 41,
Assistant Treasurer

2006

Director of Accounting and Operations, CWAM since May 2006; Manager of Mutual Fund Operations, Calamos Advisors, Inc. (investment adviser), September 2005 – May 2006; prior thereto, Manager of Mutual Fund Administration, Van Kampen Investments.

None

Stephen Kusmierczak, 44,
Vice President

2011

Portfolio manager and analyst, CWAM or its predecessors since 2001. Vice President Columbia Acorn Trust and Wanger Advisors Trust since September 2011.

None

Joseph C. LaPalm, 42,
Vice President

2006

Chief Compliance Officer, CWAM since 2005; prior thereto, compliance officer, William Blair & Company (investment firm).

None

Bruce H. Lauer, 54,
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.

None

110

Name, Position(s)
with Columbia Acorn
Trust and Age at
December 31, 2011

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)

Louis J. Mendes III, 47,
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.

None

Robert A. Mohn, 50,
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.

None

Christopher J. Olson, 47,
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.

None

Scott R. Plummer, 52,
Assistant Secretary

2010

Chief Legal Officer and Assistant Secretary, Columbia Management Investment Advisers, LLC (or its predecessors) 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 predecessors) 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, legacy RiverSource Funds since December 2006; Senior Vice President, Assistant Secretary and Chief Legal Officer, Columbia Funds since May 2010.

None

Christopher O. Petersen, 42,
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 legacy RiverSource Funds since January 2007.

None

Robert P. Scales, 59,
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.

None

Andreas Waldburg-Wolfegg, 45,
Vice President

2011

Portfolio Manager and analyst of CWAM since 2002. Vice President Columbia Acorn Trust and Wanger Advisors Trust since September 2011

None

Linda Roth-Wiszowaty, 42,
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.

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. Muchin retired at the end of calendar year 2011.

(2) Prior to December 31, 2011, Mr. Rudis was considered 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. The Order expired with respect to Columbia Acorn Trust on December 31, 2011.

(3) 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.

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

111

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112

Columbia Acorn Family of Funds

Fourth Quarter Class Z Share Information (Unaudited)

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

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		0.76	%
12b-1 Fee		None
Other Expenses		0.18	%
Net Expense Ratio		0.94	%
Columbia Acorn USA	AUSAX
Management Fee		0.86	%
12b-1 Fee		None
Other Expenses		0.14	%
Net Expense Ratio		1.00	%
Columbia Acorn International Select	ACFFX
Management Fee		0.94	%
12b-1 Fee		None
Other Expenses		0.20	%
Net Expense Ratio		1.14	%
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	%*
Columbia Acorn Emerging Markets Fund	CEFZX
Management Fee		1.25	%
12b-1 Fee		None
Other Expenses		0.21	%
Net Expense Ratio		1.46	%
Columbia Acorn European Fund	CAEZX
Management Fee		1.19	%
12b-1 Fee		None
Other Expenses		0.18	%
Net Expense Ratio		1.37	%

Fees and expenses are for the year ended December 31, 2011. Some share classes of Columbia Acorn Select and Columbia Acorn International Select include the effect of the voluntary 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, 2012. There is no guarantee that this arrangement will continue thereafter.

The fees and expenses of Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund also include the effect of fee waivers/reimbursements. CWAM has contractually undertaken to waive fees and/or reimburse Columbia Acorn Emerging Markets Fund so that the Fund's ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund's investment in other investment companies, if any) do not exceed the annual rate of 1.60% of the Fund's average daily net assets attributable to Class Z shares, through April 30, 2013. There is no guarantee that this arrangement will continue thereafter. CWAM has contractually undertaken to waive fees and/or reimburse Columbia Acorn European Fund so that its ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund's investment in other investment companies, if any) do not exceed the annual rate of 1.50% of the Fund's average daily net assets attributable to Class Z shares, through April 30, 2013. There is no guarantee that this arrangement will continue thereafter.

* Does not include estimated fees and expenses of 0.65% incurred by the Fund from the underlying portfolio funds in which it invests.

113

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.
225 Franklin Street
Boston, Massachusetts 02110

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

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 www.columbiamanagement.com under "About Us." From there, click on "Disclosures."

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.

This document contains Global Industry Classification Standard data. The Global Industry Classification Standard ("GICS") was developed by and is the exclusive property and a service mark of MSCI Inc. ("MSCI") and Standard & Poor's Financial Services LLC ("S&P") and is licensed for use by Columbia Wanger Asset Management, LLC ("CWAM"). Neither MSCI, S&P, nor any other party involved in making or compiling the GICS or any GICS classifications makes any express or implied warranties or representations with respect to such standard or classification (or the results to be obtained by the use thereof), and all such parties hereby expressly disclaim all warranties of originality, accuracy, completeness, merchantability and fitness for a particular purpose with respect to any of such standard or classification. Without limiting any of the foregoing, in no event shall MSCI, S&P, any of their affiliates or any third party involved in making or compiling the GICS or any GICS classifications have any liability for any direct, indirect, special, punitive, consequential or any other damages (including lost profits) even if notified of the possibility of such damages.

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.

114

Columbia Management^®

Columbia Acorn Family of Funds
Class Z Shares

Annual Report, December 31, 2011

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.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1561 C (2/12) 132571

Q4 2011

Columbia Acorn Family of Funds

Class A, B, C, I, R and R5 Shares

Managed by Columbia Wanger Asset Management, LLC

Annual Report

December 31, 2011

n Columbia
Acorn® Fund

n Columbia
Acorn International®

n Columbia
Acorn USA®

n Columbia
Acorn International Select^SM

n Columbia
Acorn Select^SM

n Columbia
Thermostat Fund^SM

n Columbia
Acorn Emerging Markets Fund^SM

n Columbia
Acorn European Fund^SM

Not FDIC insured • No bank guarantee • May lose value

The views expressed in the "Chattering Squirrels" 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

Stewardship and Growth

Fellow Shareholders:

Stewardship requires that we maintain our independence. It also requires that we promote a culture at CWAM that places investment results ahead of all other considerations, that retains and motivates talented individuals, and that continues to employ the investment philosophy established by Ralph Wanger over 40 years ago. Our Board is composed entirely of Trustees who are independent of CWAM, with the exception of Chuck McQuaid, CWAM's Chief Investment Officer.¹ The CWAM team serves our shareholders under the ownership of Columbia Management Investment Advisors, LLC (Columbia Management), a subsidiary of Ameriprise Financial, Inc. The Board has taken the steps necessary to ensure CWAM's autonomy in managing the Acorn Funds, while securing the advantages of the larger Ameriprise organization. On February 15, 2012, the president of Columbia Management, to whom CWAM reported, resigned. Columbia Management has assured the Board that this departure will not impact CWAM's independence.

Thank you for your continued confidence in the Acorn Funds.

Laura M. Born
Independent Chair of the Board of Trustees
Columbia Acorn Trust

¹ Mr. David Rudis became a disinterested Trustee on January 1, 2012. Ralph Wanger, CWAM's founder, serves as non-voting Trustee Emeritus.

Columbia Acorn Family of Funds

Table of Contents

Year-End Distributions					1
Fund Net Asset Values					1
Share Class Performance					2
Fund Performance vs. Benchmark					3
Descriptions of Indexes					4
Squirrel Chatter: Vaccines, Medicine's Greatest Lifesaver					5
Understanding Your Expenses					9
Columbia Acorn Fund
In a Nutshell					12
At a Glance					13
Major Portfolio Changes					28
Statement of Investments					30
Columbia Acorn International
In a Nutshell					14
At a Glance					15
Major Portfolio Changes					43
Statement of Investments					45
Portfolio Diversification					54
Columbia Acorn USA
In a Nutshell					16
At a Glance					17
Major Portfolio Changes					55
Statement of Investments					56
Columbia Acorn International Select
In a Nutshell					18
At a Glance					19
Major Portfolio Changes					63
Statement of Investments					64
Portfolio Diversification					68
Columbia Acorn Select
In a Nutshell					20
At a Glance					21
Major Portfolio Changes					69
Statement of Investments					70
Columbia Thermostat Fund
In a Nutshell					22
At a Glance					23
Statement of Investments					75
Columbia Acorn Emerging Markets Fund
In a Nutshell					24
At a Glance					25
Major Portfolio Changes					76
Statement of Investments					77
Portfolio Diversification					80
Columbia Acorn European Fund
In a Nutshell					26
At a Glance					27
Major Portfolio Changes					81
Statement of Investments					82
Portfolio Diversification					85
Columbia Acorn Family of Funds
Statements of Assets and Liabilities					86
Statements of Operations					88
Statements of Changes in Net Assets					90
Financial Highlights					96
Notes to Financial Statements					112
Report of Independent Registered Public Accounting Firm					123
Federal Income Tax Information					124
Board of Trustees and Management of Columbia Acorn Funds					125
Columbia Acorn Family of Funds Information					128

Columbia Acorn Family of Funds

2011 Year-End Distributions

	Short-term Capital Gains		Long-term Capital Gains		Ordinary Income		Reinvestment Price
Columbia Acorn Fund Class A		None	$	0.88962		None	$	27.04
Columbia Acorn Fund Class B		None	$	0.88962		None	$	24.84
Columbia Acorn Fund Class C		None	$	0.88962		None	$	24.57
Columbia Acorn Fund Class I		None	$	0.88962		None	$	27.99
Columbia Acorn International Class A, B, C, I, R and R5		None		None		None		N/A
Columbia Acorn USA Class A		None	$	0.16883		None	$	26.39
Columbia Acorn USA Class B		None	$	0.16883		None	$	24.35
Columbia Acorn USA Class C		None	$	0.16883		None	$	24.14
Columbia Acorn USA Class I		None	$	0.16883		None	$	27.46
Columbia Acorn International Select Class A		None	$	0.39302	$	0.27134	$	24.91
Columbia Acorn International Select Class B		None	$	0.39302	$	0.09046	$	23.89
Columbia Acorn International Select Class C		None	$	0.39302	$	0.05151	$	23.80
Columbia Acorn International Select Class I		None	$	0.39302	$	0.40490	$	25.10
Columbia Acorn Select Class A, B, C and I		None		None		None		N/A
Columbia Thermostat Fund Class A		None		None	$	0.18136	$	12.75
Columbia Thermostat Fund Class B		None		None	$	0.11752	$	12.84
Columbia Thermostat Fund Class C		None		None	$	0.08560	$	12.84
Columbia Acorn Emerging Markets Class A, C and I		None		None		None		N/A
Columbia Acorn European Class A	$	0.01544		None	$	0.05931	$	9.67
Columbia Acorn European Class C	$	0.01544		None	$	0.03142	$	9.68
Columbia Acorn European Class I	$	0.01544		None	$	0.07568	$	9.67

Net Asset Value Per Share as of 12/31/11

	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn International Select		Columbia Acorn Select		Columbia Thermostat Fund		Columbia Acorn Emerging Markets Fund		Columbia Acorn European Fund
Class A	$	26.63	$	34.15	$	25.94	$	24.26	$	22.95	$	12.82	$	9.26	$	9.43
Class B	$	24.53	$	33.17	$	23.98	$	23.27	$	21.40	$	12.91		N/A		N/A
Class C	$	24.18	$	33.03	$	23.72	$	23.17	$	21.20	$	12.91	$	9.24	$	9.44
Class I	$	27.57	$	34.33	$	27.00	$	24.45	$	23.65		N/A	$	9.29	$	9.43
Class R		N/A	$	34.11		N/A		N/A		N/A		N/A		N/A		N/A
Class R5		N/A	$	34.31		N/A		N/A		N/A		N/A		N/A		N/A

Columbia Acorn Family of Funds

Share Class Performance Average Annual Total Returns through 12/31/11

	Class A						Class B*						Class C						Class I			Class R†			Class R5†
	Without Sales Charge			With Sales Charge			Without Sales Charge			With Sales Charge			Without Sales Charge			With Sales Charge			Without Sales Charge			Without Sales Charge**			Without Sales Charge**
Columbia Acorn Fund (10/16/00)
3 months**		10.64	%		4.27	%		10.76	%		5.76	%		10.47	%		9.47	%		10.77	%		N/A			N/A
1 year		-4.91	%		-10.36	%		-5.34	%		-9.86	%		-5.63	%		-6.53	%		-4.57	%		N/A			N/A
5 years		1.82	%		0.62	%		1.23	%		0.89	%		1.02	%		1.02	%		N/A			N/A			N/A
10 years		7.85	%		7.21	%		7.17	%		7.17	%		7.04	%		7.04	%		N/A			N/A			N/A
Life of Fund		8.17	%		7.60	%		7.49	%		7.49	%		7.37	%		7.37	%		8.35	%		N/A			N/A
Columbia Acorn International (10/16/00)
3 months**		1.91	%		-3.94	%		1.75	%		-3.25	%		1.69	%		0.69	%		1.99	%		1.82	%		2.02	%
1 year		-14.37	%		-19.29	%		-14.92	%		-19.07	%		-15.02	%		-15.85	%		-14.02	%		N/A			N/A
5 years		-0.16	%		-1.33	%		-0.78	%		-1.13	%		-0.93	%		-0.93	%		N/A			N/A			N/A
10 years		9.85	%		9.20	%		9.12	%		9.12	%		9.03	%		9.03	%		N/A			N/A			N/A
Life of Fund		5.93	%		5.37	%		5.24	%		5.24	%		5.16	%		5.16	%		-4.67	%		-14.96	%		-14.74	%
Columbia Acorn USA (10/16/00)
3 months**		11.90	%		5.48	%		11.94	%		6.94	%		11.67	%		10.67	%		11.98	%		N/A			N/A
1 year		-5.21	%		-10.66	%		-5.68	%		-10.36	%		-5.92	%		-6.86	%		-4.88	%		N/A			N/A
5 years		0.54	%		-0.65	%		-0.09	%		-0.45	%		-0.25	%		-0.25	%		N/A			N/A			N/A
10 years		5.93	%		5.30	%		5.25	%		5.25	%		5.14	%		5.14	%		N/A			N/A			N/A
Life of Fund		7.58	%		7.02	%		6.90	%		6.90	%		6.80	%		6.80	%		9.46	%		N/A			N/A
Columbia Acorn International Select (10/16/00)
3 months**		1.83	%		-4.02	%		1.72	%		-3.27	%		1.65	%		0.65	%		1.93	%		N/A			N/A
1 year		-10.11	%		-15.28	%		-10.64	%		-14.99	%		-10.81	%		-11.69	%		-9.68	%		N/A			N/A
5 years		0.05	%		-1.13	%		-0.59	%		-0.95	%		-0.75	%		-0.75	%		N/A			N/A			N/A
10 years		8.85	%		8.20	%		8.14	%		8.14	%		8.03	%		8.03	%		N/A			N/A			N/A
Life of Fund		4.29	%		3.74	%		3.60	%		3.60	%		3.51	%		3.51	%		-1.59	%		N/A			N/A
Columbia Acorn Select (10/16/00)
3 months**		9.23	%		2.96	%		9.13	%		4.13	%		9.05	%		8.05	%		9.34	%		N/A			N/A
1 year		-16.65	%		-21.43	%		-17.11	%		-21.22	%		-17.27	%		-18.09	%		-16.25	%		N/A			N/A
5 years		-1.36	%		-2.52	%		-1.99	%		-2.36	%		-2.15	%		-2.15	%		N/A			N/A			N/A
10 years		5.70	%		5.07	%		5.00	%		5.00	%		4.89	%		4.89	%		N/A			N/A			N/A
Life of Fund		6.34	%		5.78	%		5.64	%		5.64	%		5.54	%		5.54	%		-2.16	%		N/A			N/A
Columbia Thermostat Fund (3/3/03)††
3 months**		7.64	%		1.42	%		7.49	%		2.49	%		7.41	%		6.41	%		N/A			N/A			N/A
1 year		4.62	%		-1.41	%		4.19	%		-0.81	%		3.87	%		2.87	%		N/A			N/A			N/A
5 years		3.97	%		2.74	%		3.45	%		3.10	%		3.19	%		3.19	%		N/A			N/A			N/A
Life of Fund		7.50	%		6.78	%		6.90	%		6.90	%		6.71	%		6.71	%		N/A			N/A			N/A
Columbia Acorn Emerging Markets Fund (8/19/11)
3 months**		4.75	%		-1.28	%		N/A			N/A			4.64	%		3.64	%		5.09	%		N/A			N/A
Life of Fund**		-7.40	%		-12.72	%		N/A			N/A			-7.60	%		-8.52	%		-7.10	%		N/A			N/A
Columbia Acorn European Fund (8/19/11)
3 months**		0.99	%		-4.78	%		N/A			N/A			0.91	%		-0.09	%		1.16	%		N/A			N/A
Life of Fund**		-4.97	%		-10.43	%		N/A			N/A			-5.14	%		-6.09	%		-4.81	%		N/A			N/A

*The Funds generally no longer accept investments by new or existing investors in Class B shares, except in connection with the reinvestment of any dividend and/or capital gain distributions in Class B shares of the Funds and exchanges by existing Class B shareholders of certain other funds within the Columbia Family of Funds.

**Not annualized.

†Class R and Class R5 shares of Columbia Acorn International commenced operations on August 15, 2011, in connection with the completed merger of two series of RiverSource International Managers Series, Inc. into Columbia Acorn International.

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. 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. Current performance may be lower or higher than the performance data shown. Please visit columbiamanagement.com for daily and most recent month-end updates.

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%, 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.

Please see Page 3 of this report for each Fund's annual operating expense ratio. Annual operating expense ratios are as stated in each Fund's current prospectus and differences in expense ratios disclosed elsewhere in this report may result from including fee waivers and expense reimbursements as well as different time periods used in calculating the ratios. Please see Page 128 of this report for information on fee waiver and expense reimbursement arrangements in place for Columbia Acorn International, Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund.

††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.

Columbia Acorn Family of Funds

Fund Performance vs. Benchmarks Average Annual Total Returns through 12/31/11

Class A Shares, without sales charge	4th quarter*			1 year			5 years			10 years			Life of Fund
Columbia Acorn Fund (LACAX) (10/16/00)		10.64	%		-4.91	%		1.82	%		7.85	%		8.17	%
Russell 2500 Index		14.52	%		-2.51	%		1.24	%		6.57	%		6.27	%
S&P 500 Index**		11.82	%		2.11	%		-0.25	%		2.92	%		1.11	%
Lipper Mid-Cap Growth Funds Index		10.30	%		-5.30	%		2.89	%		4.48	%		0.45	%
Columbia Acorn International (LAIAX) (10/16/00)		1.91	%		-14.37	%		-0.16	%		9.85	%		5.93	%
S&P Global Ex-U.S. Between $500M and $5B Index		0.75	%		-16.94	%		-0.58	%		11.10	%		8.50	%
S&P Global Ex-U.S. SmallCap Index		1.15	%		-17.40	%		-2.14	%		10.33	%		7.56	%
Lipper International Small/Mid Growth Funds Index		2.88	%		-14.22	%		-1.73	%		8.98	%		4.62	%
Columbia Acorn USA (LAUAX) (10/16/00)		11.90	%		-5.21	%		0.54	%		5.93	%		7.58	%
Russell 2000 Index		15.47	%		-4.18	%		0.15	%		5.62	%		5.32	%
Russell 2500 Index		14.52	%		-2.51	%		1.24	%		6.57	%		6.27	%
Lipper Small-Cap Growth Funds Index		12.88	%		-3.40	%		1.14	%		3.65	%		1.23	%
Columbia Acorn Int'l Select (LAFAX) (10/16/00)		1.83	%		-10.11	%		0.05	%		8.85	%		4.29	%
S&P Developed Ex-U.S. Between $2B and $10B Index		0.99	%		-14.01	%		-3.06	%		8.41	%		6.17	%
MSCI EAFE Index		3.33	%		-12.14	%		-4.72	%		4.67	%		2.04	%
Lipper International Small/Mid Growth Funds Index		2.88	%		-14.22	%		-1.73	%		8.98	%		4.62	%
Columbia Acorn Select (LATFX) (10/16/00)		9.23	%		-16.65	%		-1.36	%		5.70	%		6.34	%
S&P MidCap 400 Index		12.98	%		-1.73	%		3.32	%		7.04	%		6.50	%
S&P 500 Index**		11.82	%		2.11	%		-0.25	%		2.92	%		1.11	%
Lipper Mid-Cap Growth Funds Index		10.30	%		-5.30	%		2.89	%		4.48	%		0.45	%
Columbia Thermostat Fund (CTFAX) (3/3/03)†		7.64	%		4.62	%		3.97	%		—			7.50	%
S&P 500 Index		11.82	%		2.11	%		-0.25	%		—			6.77	%
Barclays Capital U.S. Aggregate Bond Index		1.12	%		7.84	%		6.50	%		—			5.22	%
Lipper Flexible Portfolio Funds Index		6.28	%		-1.16	%		2.02	%		—			7.11	%
50/50 Blended Benchmark		6.47	%		5.28	%		3.54	%		—			6.32	%
Columbia Acorn Emerging Markets Fund (CAGAX) (8/19/11)		4.75	%		—			—			—			-7.40	%*
S&P Emerging Markets Between $500M and $5B Index		0.96	%		—			—			—			-13.46	%*
MSCI Emering Markets Small Cap Index		-0.66	%		—			—			—			-16.65	%*
Lipper Emerging Markets Index		5.09	%		—			—			—			-6.81	%*
Columbia Acorn European Fund (CAEAX) (8/19/11)		0.99	%		—			—			—			-4.97	%*
S&P Europe Between $500M and $5B Index		0.41	%		—			—			—			-7.17	%*
HSBC Smaller European Companies Index		-0.94	%		—			—			—			-9.54	%*
Lipper European Region Index		5.89	%		—			—			—			-1.24	%*

*Not annualized.

Performance results reflect any fee waivers or reimbursements of Fund expenses by the investment adviser and/or its affiliates. Please see Page 128 of this report for information on fee waiver and expense reimbursement arrangements in place for Columbia Acorn International, Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund. Absent these fee waivers/expense reimbursement arrangements, performance results would have been lower. Annual operating expense ratios are stated as of each Fund's current prospectus and differences in expense ratios disclosed elsewhere in this report may result from application of any fee waivers/expense reimbursements as well as different time periods used in calculating the ratios. Columbia Acorn Fund: Class A: 1.07%; Class B: 1.69%; Class C: 1.85%; Class I: 0.72%. Columbia Acorn International: Class A: 1.35%; Class B: 1.96%; Class C: 2.11%; Class I: 0.93%; Class R: 1.60%; Class R5: 0.98%. Columbia Acorn USA: Class A: 1.30%; Class B: 1.98%; Class C: 2.08%; Class I: 0.95%. Columbia Acorn International Select: Class A: 1.56%; Class B: 2.24%; Class C: 2.36%; Class I: 1.13%. Columbia Acorn Select: Class A: 1.28%; Class B: 1.93%; Class C: 2.08%; Class I: 0.92%. Columbia Thermostat Fund: Class A: 1.29%; Class B: 1.79%; Class C: 2.04%. Columbia Acorn Emerging Markets Fund Class A: 1.85%; Class C: 2.60%; Class I: 1.41%. Columbia Acorn European Fund Class A: 1.75%; Class C: 2.50%; Class I: 1.31%.

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.

Columbia Acorn Family of Funds

Descriptions of Indexes Included in this Report

• 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, 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.

Squirrel Chatter II: Vaccines, Medicine's Greatest Lifesaver

I recently read several books on the history of vaccines. As one of the authors put it, "Of all of the benefits of medical science, vaccination is at or near the summit."¹

Deadly Diseases

The First Vaccine

The Golden Age of Vaccines

Maurice Hilleman's Mission

Vaccine Scares

Two notable scares set back progress on vaccine usage.

In 1998, the British medical journal The Lancet published a paper alleging a link between the MMR vaccine

Perspectives on Risks

1971 and the number dropped to seven U.S. cases in 1983.³¹

Charles P. McQuaid

President and Chief Investment Officer
Columbia Wanger Asset Management, LLC

The information included on Pages 5-8 of this report is unaudited.

¹ Link, M.D., Kurt, The Vaccine Controversy, The History, Use, And Safety of Vaccinations, (Westport, Connecticut, Praeger Publishers 2005) p. 38.

²Mnookin, Seth, The Panic Virus, A True Story of Medicine, Science, and Fear, (New York, New York, Simon & Schuster 2011) p. 30.

³Offit, M.D., Paul A., Vaccinated, One Man's Quest to Defeat the World's Deadliest Diseases, (New York, New York, HarperCollins Publishers 2007) pg. 32.

⁴Link, M.D., Kurt, op. cit., p. 12.

⁵Allen, Arthur, Vaccine, The Controversial Story of Medicines Greatest Lifesaver, (New York, New York, W. W. Norton & Company 2007) p. 49-50.

⁶Ibid., p. 115, 303.

⁷Offit, M.D., Paul A., op. cit., p. 144.

⁸Allen, Arthur, op. cit., p. 65, 121.

⁹Offit, M.D., Paul A., op. cit., p. 37, 41-42.

¹⁰ Ibid., p. 2-3.

¹¹Allen, Arthur, op. cit., p. 119, 159.

¹²Ibid., p. 221.

¹³Link, M.D., Kurt, op. cit., p. 101.

¹⁴Offit, M.D., Paul A., op. cit., p. 115.

¹⁵Ibid., p. 130, 156.

¹⁶Allen, Arthur, op. cit., p. 251-256.

¹⁷Wakefield, Andrew J., et al., "Ileal-lymphoid-nodular Hyperplasia, Non-Specific Colitis, and Pervasive Developmental Disorders in Children," The Lancet 351, Issue 9103 (1998), p. 637-41.

¹⁸Mnookin, Seth, op. cit., p. 106-107, 114.

¹⁹Offit, M.D., Paul A., op. cit., p. 167.

²⁰Mnookin, Seth, op. cit., p. 163.

²¹Murch, Simon H., et al., "Retraction of an Interpretation," The Lancet 363, Issue 9411 (2004), p. 750.

²²Mnookin, Seth, op. cit., p. 167.

²³Link, M.D., Kurt, op. cit., p. 21.

²⁴Ibid., p. 57.

²⁵Mnookin, Seth, op. cit., p. 277.

²⁶Synett, Lawerence, "Whooping Cough Strikes Collar Counties," Chicago Tribune, December 6, 2011.

²⁷Mnookin, Seth, op. cit., p. 19.

²⁸Allen, Arthur, op. cit., p. 217.

²⁹Offit, M.D., Paul A., op. cit., p. 102.

³⁰Link, M.D., Kurt, op. cit., p. 82-84.

³¹Allen, Arthur, op. cit., p. 240.

³²Ibid., p. 352, 286.

³³Link, M.D., Kurt, op. cit., p. 163.

³⁴Offit, M.D., Paul A., op. cit., p. xiv.

Understanding Your Expenses

Analyzing Your Fund's Expenses

To illustrate these ongoing costs, we have provided examples and calculated the expenses paid by investors in Class A, B, C, I, R and R5 shares of the Funds during the period. The actual and hypothetical information in the tables is based on an initial investment of $1,000 at the beginning of the period indicated 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 the Funds' actual operating expenses and total return for the period. You may use the Actual information, together with the amount invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the results by the expenses paid during the period under the Actual column. The amount listed in the "Hypothetical" column assumes a 5% annual rate of return before expenses (which is not the Funds' actual return) and then applies the Funds' 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 period. See "Compare With Other Funds" below for details on how to use the hypothetical data.

Compare With Other Funds

July 1, 2011 – December 31, 2011

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during period ($)				Fund's annualized expense ratio (%)*
	Actual		Hypothetical		Actual		Hypothetical		Actual		Hypothetical		Actual
Columbia Acorn Fund
Class A		1,000.00		1,000.00		888.70		1,019.70		5.07		5.42		1.07
Class B		1,000.00		1,000.00		887.80		1,017.60		7.05		7.54		1.49
Class C		1,000.00		1,000.00		885.40		1,015.94		8.60		9.20		1.82
Class I		1,000.00		1,000.00		890.10		1,021.46		3.41		3.65		0.72

Understanding Your Expenses

continued

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during period ($)				Fund's annualized expense ratio (%)*
	Actual		Hypothetical		Actual		Hypothetical		Actual		Hypothetical		Actual
Columbia Acorn International
Class A		1,000.00		1,000.00		832.50		1,018.50		6.02		6.63		1.31
Class B		1,000.00		1,000.00		829.90		1,015.19		9.04		9.95		1.97
Class C		1,000.00		1,000.00		829.50		1,014.74		9.45		10.40		2.06
Class I		1,000.00		1,000.00		834.30		1,020.51		4.18		4.61		0.91
Class R		1,000.00		1,000.00		850.40		1,017.10		6.01		8.04		1.59
Class R5		1,000.00		1,000.00		852.60		1,020.51		3.44		4.61		0.91
Columbia Acorn USA
Class A		1,000.00		1,000.00		869.90		1,018.45		6.19		6.68		1.32
Class B		1,000.00		1,000.00		868.90		1,016.44		8.06		8.69		1.72
Class C		1,000.00		1,000.00		866.40		1,014.79		9.59		10.35		2.05
Class I		1,000.00		1,000.00		871.30		1,020.21		4.55		4.91		0.97
Columbia Acorn International Select
Class A		1,000.00		1,000.00		868.10		1,017.60		6.98		7.54		1.49
Class B		1,000.00		1,000.00		865.80		1,014.74		9.64		10.40		2.06
Class C		1,000.00		1,000.00		864.90		1,013.64		10.66		11.51		2.28
Class I		1,000.00		1,000.00		869.90		1,020.26		4.50		4.86		0.96
Columbia Acorn Select
Class A		1,000.00		1,000.00		834.50		1,018.55		5.98		6.58		1.30
Class B		1,000.00		1,000.00		832.70		1,016.09		8.22		9.05		1.79
Class C		1,000.00		1,000.00		831.70		1,014.84		9.37		10.30		2.04
Class I		1,000.00		1,000.00		837.20		1,020.46		4.24		4.66		0.92
Columbia Acorn Emerging Markets Fund
Class A		1,000.00		1,000.00		926.00		1,011.56		6.54		9.33		1.85
Class C		1,000.00		1,000.00		924.00		1,008.81		6.53		13.09		2.60
Class I		1,000.00		1,000.00		929.00		1,013.18		4.99		7.12		1.41
Columbia Acorn European Fund
Class A		1,000.00		1,000.00		950.30		1,011.93		6.27		8.83		1.75
Class C		1,000.00		1,000.00		948.60		1,009.18		8.94		12.59		2.50
Class I		1,000.00		1,000.00		951.90		1,013.55		4.69		6.61		1.31

Fund of Funds—Columbia Thermostat Fund

July 1, 2011 – December 31, 2011

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during period ($)				Fund's annualized expense ratio (%)		Effective expenses paid during the period				Fund's effective annualized expense ratio (%)
	Actual		Hypothetical		Actual		Hypothetical		Actual		Hypothetical		Actual		Actual		Hypothetical		Actual
Columbia Thermostat Fund
Class A		1,000.00		1,000.00		1,001.70		1,022.56		2.51		2.54		0.50		5.77		5.83		1.15
Class B		1,000.00		1,000.00		999.10		1,020.05		5.01		5.06		1.00		8.27		8.36		1.65
Class C		1,000.00		1,000.00		998.20		1,018.80		6.26		6.33		1.25		9.52		9.62		1.90

Had the investment adviser and/or certain of its affiliates not waived/reimbursed certain fees and expenses, account value at the end of the period would have been reduced.

Columbia Acorn Fund

In a Nutshell



Charles P. McQuaid				Robert A. Mohn

Lead Portfolio Manager				Co-Portfolio Manager

Fund Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

FMC Technologies	1.9	%
Donaldson	1.8	%
Ametek	1.7	%
lululemon athletica	1.6	%
Alexion Pharmaceuticals	1.4	%
tw telecom	1.1	%
Abercrombie & Fitch	1.0	%
SBA Communications	1.0	%
Fugro	0.7	%
Pall	0.6	%
Pacific Rubiales Energy	0.5	%
Shutterfly	0.4	%
Delphi Financial Group	0.3	%
True Religion Apparel	0.3	%
InterMune	0.2	%
Diamond Foods	0.2	%

Columbia Acorn Fund rose 10.64% (Class A shares, without sales charge) in the fourth quarter of 2011, but ended the year down 4.91%. The Fund underperformed its primary benchmark, the Russell 2500 Index, by 3.88% during the quarter and 2.40% for the year. Performance was hurt by the underperformance of the Fund's international stocks. During both periods, Columbia Acorn Fund slightly beat its peers, as measured by the Lipper Mid-Cap Growth Funds Index.

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

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, 2011

*Inception 10/16/00*		1 year			5 years			10 years
Returns before taxes	NAV POP		-4.91 -10.36	%		1.82 0.62	%		7.85 7.21	%
Returns after taxes on distributions	NAV POP		-5.51 -10.94			1.29 0.10			7.28 6.65
Returns after taxes on distributions and sale of fund shares	NAV POP		-2.35 -5.94			1.56 0.53			6.90 6.32
Russell 2500 Index*(pretax)			-2.51			1.24			6.57

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).

The Fund's Class A shares annual operating expense ratio, as stated in the current prospectus, is 1.07%.

Columbia Acorn Fund Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn Fund Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	FMC Technologies Oil & Gas Wellhead Manufacturer	1.9	%
2.	Donaldson Industrial Air Filtration	1.8	%
3.	Ametek Aerospace/Industrial Instruments	1.7	%
4.	lululemon athletica Premium Active Apparel Retailer	1.6	%
5.	Mettler Toledo Laboratory Equipment	1.4	%
6.	Alexion Pharmaceuticals Biotech Focused on Orphan Diseases	1.4	%
7.	Crown Castle International Communications Towers	1.3	%
8.	tw telecom Fiber Optic Telephone/Data Services	1.1	%
9.	Informatica Enterprise Data Integration Software	1.1	%
10.	Abercrombie & Fitch Teen Apparel Retailer	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, 2011

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: $16.3 billion

Columbia Acorn International

In a Nutshell



P. Zachary Egan				Louis J. Mendes III

Co-Portfolio Manager				Co-Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Novozymes	0.9	%
Gree	0.7	%
Rheinmetall	0.6	%
Start Today	0.2	%

Columbia Acorn International returned 1.91% (Class A shares, without sales charge) in the fourth quarter of 2011, 1.16% ahead of its primary benchmark, the S&P Global Ex-U.S. Between $500M and $5B Index. For 2011, the Fund fell 14.37%, which was 2.57% ahead of its benchmark. International small-cap stocks underperformed larger-cap stocks in a year marked by extreme volatility and high correlation among most risk assets. For comparison, the large-cap developed international market, as tracked by the MSCI EAFE Index, declined 12.14% during the year.

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

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, 2011

*Inception 10/16/00*		1 year			5 years			10 years
Returns before taxes	NAV POP		-14.37 -19.29	%		-0.16 -1.33	%		9.85 9.20	%
Returns after taxes on distributions	NAV POP		-14.93 -19.82			-0.62 -1.79			9.38 8.73
Returns after taxes on distributions and sale of fund shares	NAV POP		-9.08 -12.29			-0.10 -1.09			8.83 8.23
S&P Global Ex-US Between $500M and $5B Index* (pretax)			-16.94			-0.58			11.10

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.

The Fund's Class A shares annual operating expense ratio, as stated in the current prospectus, is 1.35%. Effective August 15, 2011, CWAM and its affiliates contractually agreed, through August 14, 2013, to waive a portion of total annual Fund operating expenses incurred by Class A shares of Columbia Acorn International such that total annual Fund operating expenses will be reduced by 0.04% for Class A shares of the Fund.

Columbia Acorn International Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn International Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Far Eastone Telecom (Taiwan) Taiwan's Third Largest Mobile Operator	1.3	%
2.	Melco Crown Entertainment - ADR (Hong Kong) Macau Casino Operator	1.2	%
3.	Kansai Paint (Japan) Paint Producer in Japan, India, China & Southeast Asia	1.2	%
4.	Hexagon (Sweden) Design, Measurement & Visualization Software & Equipment	1.1	%
5.	Gemalto (France) Digital Security Solutions	1.1	%
6.	Zhaojin Mining Industry (China) Gold Mining & Refining in China	1.0	%
7.	Localiza Rent A Car (Brazil) Car Rental	1.0	%
8.	Olam International (Singapore) Agriculture Supply Chain Manager	1.0	%
9.	Naspers (South Africa) Media in Africa, China, Russia & Other Emerging Markets	0.9	%
10.	Novozymes (Denmark) Industrial Enzymes	0.9	%

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, 2011

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: $5.4 billion

Columbia Acorn USA

In a Nutshell



Robert A. Mohn

Lead Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

FMC Technologies	2.8	%
Ametek	2.5	%
lululemon athletica	2.2	%
Donaldson	1.9	%
Bally Technologies	1.7	%
World Acceptance	1.6	%
Abercrombie & Fitch	1.5	%
Extra Space Storage	1.4	%
Gaylord Entertainment	1.3	%
Alexion Pharmaceuticals	1.3	%
IPG Photonics	1.1	%
Atmel	1.0	%
Acuity Brands	1.0	%
Finisar	0.8	%
Shutterfly	0.4	%
Quicksilver Resources	0.3	%
TriQuint Semiconductor	0.3	%
InterMune	0.3	%
Diamond Foods	0.1	%

Columbia Acorn USA ended the fourth quarter of 2011 up 11.90% (Class A shares, without sales charge), underperforming the 15.47% return of its primary benchmark, the Russell 2000 Index. For the annual period, Fund performance was more in line with the benchmark, though still below it, with the Fund down 5.21% vs. the Russell 2000's 4.18% decline. Relative Fund performance was strong through the end of October, but returns for the final two months of the year were hard hit by the poor performance of the Fund's consumer stocks.

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

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, 2011

*Inception 10/16/00*		1 year			5 years			10 years
Returns before taxes	NAV POP		-5.21 -10.66	%		0.54 -0.65	%		5.93 5.30	%
Returns after taxes on distributions	NAV POP		-5.30 -10.74			0.23 -0.95			5.64 5.02
Returns after taxes on distributions and sale of fund shares	NAV POP		-3.26 -6.81			0.46 -0.55			5.20 4.63
Russell 2000 Index*(pretax)			-4.18			0.15			5.62

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.

The Fund's Class A shares annual operating expense ratio, as stated in the current prospectus, is 1.30%.

Columbia Acorn USA Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn USA Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	FMC Technologies Oil & Gas Wellhead Manufacturer	2.8	%
2.	Ametek Aerospace/Industrial Instruments	2.5	%
3.	lululemon athletica Premium Active Apparel Retailer	2.2	%
4.	Informatica Enterprise Data Integration Software	2.2	%
5.	Micros Systems Information Systems for Hotels, Restaurants & Retailers	2.1	%
6.	Nordson Dispensing Systems for Adhesives & Coatings	2.0	%
7.	Donaldson Industrial Air Filtration	1.9	%
8.	Atwood Oceanics Offshore Drilling Contractor	1.8	%
9.	tw telecom Fiber Optic Telephone/Data Services	1.8	%
10.	Mettler Toledo Laboratory Equipment	1.7	%

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, 2011

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: $1.6 billion

Columbia Acorn International Select

In a Nutshell

Christopher J. Olson

Lead Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Far Eastone Telecom	6.4	%
Wirecard	3.1	%
Intertek Group	2.0	%
Asahi Diamond Industrial	1.9	%
Gree	1.9	%
Ain Pharmaciez	1.5	%
Chemring	1.5	%
Rheinmetall	1.5	%
Israel Chemicals	1.5	%

Columbia Acorn International Select ended the fourth quarter of 2011 up 1.83% (Class A shares, without sales charge), outperforming the 0.99% gain of its primary benchmark, the S&P Developed Ex-U.S. Between $2B and $10B Index. For the year, the Fund was down 10.11%, holding up better than the benchmark's 14.01% decline. Fears of a global recession and continuing financial crisis plagued international market performance throughout the year.

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

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, 2011

*Inception 10/16/00*		1 year			5 years			10 years
Returns before taxes	NAV POP		-10.11 -15.28	%		0.05 -1.13	%		8.85 8.20	%
Returns after taxes on distributions	NAV POP		-10.49 -15.64			-0.29 -1.47			8.69 8.04
Returns after taxes on distributions and sale of fund shares	NAV POP		-5.73 -9.14			0.14 -0.86			7.97 7.38
S&P Developed Ex-US Between $2B and $10B Index* (pretax)			-14.01			-3.06			8.41

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.

The Fund's Class A shares annual operating expense ratio, as stated in the current prospectus, is 1.56%.

Columbia Acorn International Select Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn International Select
Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Far Eastone Telecom (Taiwan) Taiwan's Third Largest Mobile Operator	6.4	%
2.	Kansai Paint (Japan) Paint Producer in Japan, India, China & Southeast Asia	5.7	%
3.	Ascendas REIT (Singapore) Singapore Industrial Property Landlord	5.7	%
4.	Mapletree Industrial Trust (Singapore) Singapore Industrial Property Landlrd	5.2	%
5.	Seven Bank (Japan) ATM Processing Services	4.0	%
6.	Rand Merchant Insurance (South Africa) Directly Sold Property & Casualty Insurance; Holdings in Other Insurers	3.8	%
7.	Wirecard (Germany) Online Payment Processing & Risk Management	3.1	%
8.	Hexagon (Sweden) Design, Measurement & Visualization Software & Equipment	3.0	%
9.	Archipelago Resources (Indonesia) Gold Mining Projects in Indonesia, Vietnam & the Philippines	2.9	%
10.	Adcock Ingram Holdings (South Africa) Manufacturer of Pharmaceuticals & Medical Supplies	2.9	%

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, 2011

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: $326.4 million

Columbia Acorn Select

In a Nutshell



Ben Andrews				Robert A. Chalupnik

Lead Portfolio Manager				Co-Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Hertz	6.0	%
CNO Financial Group	4.4	%
Sanmina-SCI	4.4	%
Pacific Rubiales Energy	3.1	%

Diversification Status Change

Columbia Acorn Select gained 9.23% (Class A shares, without sales charge) in the fourth quarter of 2011 but fell 16.65% for the year. The S&P MidCap 400 Index, the Fund's primary benchmark, was up 12.98% in the fourth quarter and off 1.73% for the annual period. The large-cap S&P 500 Index gained 11.82% in the quarter and was up 2.11% for the year.

The loss and the performance lag were disappointments to us as Fund managers. So, what happened? What changes have we made to improve this performance?

Thank you for your continued investment in Columbia Acorn Select.

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

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, 2011

*Inception 10/16/00*		1 year			5 years			10 years
Returns before taxes	NAV POP		-16.65 -21.43	%		-1.36 -2.52	%		5.70 5.07	%
Returns after taxes on distributions	NAV POP		-17.07 -21.83			-1.60 -2.76			5.44 4.82
Returns after taxes on distributions and sale of fund shares	NAV POP		-10.78 -13.89			-1.18 -2.16			4.97 4.40
S&P MidCap 400 Index* (pretax)			-1.73			3.32			7.04

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.

The Fund's Class A shares annual operating expense ratio, as stated in the current prospectus, is 1.28%.

Columbia Acorn Select Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn Select Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Hertz Largest U.S. Rental Car Operator	6.0	%
2.	Discover Financial Services Credit Card Company	6.0	%
3.	Ametek Aerospace/Industrial Instruments	5.1	%
4.	CNO Financial Group Life, Long-term Care & Medical Supplement Insurance	4.4	%
5.	Sanmina-SCI Electronic Manufacturing Services	4.4	%
6.	Donaldson Industrial Air Filtration	3.7	%
7.	SBA Communications Communications Towers	3.7	%
8.	Pall Filtration & Fluids Clarification	3.3	%
9.	Safeway Supermarkets	3.3	%
10.	Abercrombie & Fitch Teen Apparel Retailer	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 Select (Class A)

October 16, 2000 through December 31, 2011

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: $1.3 billion

Columbia Thermostat Fund

In a Nutshell

Charles P. McQuaid

Lead Portfolio Manager

Columbia Thermostat Fund ended the fourth quarter of 2011 up 7.64% (Class A shares, without sales charge) and had a 4.62% gain for the annual period. This compares to an 11.82% fourth quarter return for its primary equity benchmark, the S&P 500 Index, and a 2.11% gain in the equity benchmark for the full year. The Fund's primary debt benchmark, the Barclays Capital U.S. Aggregate Bond Index, had a 1.12% return in the fourth quarter and ended the year up 7.84%.

As a result of the periodic review of underlying funds called for by Columbia Thermostat Fund's prospectus, effective December 12, 2011, the following changes were made to Columbia Thermostat Fund:

• Columbia Contrarian Core Fund, which provides exposure to the large-cap blend style, had its weighting increased from 10% to 15% of the equity fund allocation.

• Columbia U.S. Treasury Index Fund, which provides exposure to U.S. Treasury securities, had its weighting reduced from 30% to 20% of the fixed-income allocation.

• Columbia Income Opportunities Fund, which provides exposure to high-yield securities, had its weighting increased from 20% to 30% of the fixed-income allocation.

The changes were implemented to fine-tune the underlying investment style mix of the equity portion of the Fund and to address yield spreads in the fixed-income segment.

Results of the Funds Owned in Columbia Thermostat Fund as of December 31, 2011

Stock Funds	Weightings			4th
Fund	in category			quarter			1 year
Columbia Acorn International, Class I		20	%		1.99	%		-14.02	%
Columbia Dividend Income Fund, Class I		20	%		12.78	%		7.08	%
Columbia Acorn Fund, Class I		15	%		10.77	%		-4.57	%
Columbia Contrarian Core Fund, Class I		15	%		11.72	%		-0.84	%
Columbia Select Large Cap Growth Fund, Class I*		10	%		5.98	%		-2.97	%
Columbia Acorn Select, Class I		10	%		9.34	%		-16.25	%
Columbia Large Cap Enhanced Core Fund, Class I		10	%		12.06	%		4.75	%
*Weighted Average* *Equity Gain/Loss*		*100*	%		*9.37*	%		*-3.82*	%

*Replaced Columbia Marsico Growth Fund effective December 12, 2011. Weighted average equity returns through year-end reflect linked returns between the previous fund holding and Columbia Select Large Cap Growth Fund.

Bond Funds	Weightings			4th
Fund	in category			quarter			1 year
Columbia Intermediate Bond Fund, Class I		50	%		1.60	%		6.78	%
Columbia U.S. Treasury Index Fund, Class I		20	%		0.83	%		9.46	%
Columbia Income Opportunities Fund, Class I		30	%		6.45	%		6.42	%
*Weighted Average* *Income Gain*		*100*	%		*2.41*	%		*7.67*	%

Columbia Thermostat Fund
Rebalancing in the Fourth Quarter

October 25, 2011				60% stocks, 40% bonds
November 25, 2011				70% stocks, 30% bonds
December 27, 2011				60% stocks, 40% bonds

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, 2011

*Inception 3/3/03*		1 year			5 years			Life of fund
Returns before taxes	NAV POP		4.62 -1.41	%		3.97 2.74	%		7.50 6.78	%
Returns after taxes on distributions	NAV POP		3.67 -2.31			2.99 1.77			6.30 5.59
Returns after taxes on distributions and sale of fund shares	NAV POP		3.00 -0.92			2.90 1.85			5.99 5.34
S&P 500 Index* (pretax)			2.11			-0.25			6.77
Barclays Capital U.S. Aggregate Bond Index* (pretax)			7.84			6.50			5.22
Lipper Flexible Portfolio Funds Index (pretax)			-1.16			2.02			7.11

All results shown assume reinvestment of distributions.

*The Fund's primary stock and bond benchmarks.

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.

The Fund's annual operating expense ratio, as stated in the current prospectus, reflects a contractual fee waiver and expense reimbursement with CWAM that expires April 30, 2012. Class A expense ratios without and with the contractual waiver/reimbursement, including fees and expenses associated with the Fund's investment in other investment companies, are 1.52% and 1.29%, respectively. Absent the waiver or reimbursement, performance results would have been lower.

Columbia Thermostat Fund Asset Allocation

as a percentage of net assets, as of 12/31/11

Columbia Thermostat Fund Portfolio Weightings

as a percentage of assets in each investment category, as of 12/31/11

Stock Mutual Funds

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

*Replaced Columbia Marsico Growth Fund effective December 12, 2011.

Bond Mutual Funds

Columbia Intermediate Bond Fund, Class I	50	%
Columbia U.S. Treasury Index Fund, Class I	20	%
Columbia Income Opportunities Fund, Class I	30	%

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

March 3, 2003 through December 31, 2011

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: $189.6 million

Columbia Acorn Emerging Markets Fund

In a Nutshell



Fritz Kaegi				Stephen Kusmierczak

Lead Portfolio Manager				Lead Portfolio Manager



P. Zachary Egan				Louis J. Mendes

Co-Portfolio Manager				Co-Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Far Eastone Telecom	2.5	%
Ace Indonesia	2.5	%
Nagacorp	1.8	%
Madalena Ventures	1.6	%
Mongolian Mining	1.1	%

As of December 31, 2011, Columbia Acorn Emerging Markets Fund was up 4.75% (Class A shares, without sales charge) for the fourth quarter and down 7.40% for the period since its August 19, 2011 launch. The Fund outperformed its primary benchmark, the S&P Emerging Markets Between $500M and $5B Index, by 3.79% for the quarter and by 6.06% for the period since inception.

We believe that being able to grow while paying out significant dividends is the ultimate acid test of a good business. We'll be looking for more businesses like these to add to the Fund in 2012.

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

Columbia Acorn Emerging
Markets Fund

At a Glance (Class A Shares - CAGAX)

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, 2011

*Inception 8/19/11*		Life of fund*
Returns before taxes	NAV POP		-7.40 -12.72	%
Returns after taxes on distributions	NAV POP		-7.39 -12.72
Returns after taxes on distributions and sale of fund shares	NAV POP		-4.80 -8.26
S&P Emerging Markets Between $500M and $5B Index (pretax)**			-13.46

All results shown assume reinvestment of distributions.

*Reflects performance from Fund inception on 8/19/11 through 12/31/11.

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.

The Fund's annual operating expense ratio, as stated in the current prospectus, reflects a contractual fee waiver and expense reimbursement agreement with CWAM that expires April 30, 2013; Class A share expense ratios without and with the contractual fee waiver/reimbursement are 1.96% and 1.85%, respectively.

Columbia Acorn Emerging Markets Fund Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn Emerging Markets Fund
Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Archipelago Resources (Indonesia) Gold Mining Projects in Indonesia, Vietnam & the Philippines	2.6	%
2.	Far Eastone Telecom (Taiwan) Taiwan's Third Largest Mobile Operator	2.5	%
3.	Ace Indonesia (Indonesia) Home Improvement Retailer	2.5	%
4.	Adcock Ingram Holdings (South Africa) Manufacturer of Pharmaceuticals & Medical Supplies	2.3	%
5.	Alliance Grain Traders (Canada) Global Leader in Pulse Processing & Distribution	2.3	%
6.	Coronation Fund Managers (South Africa) South African Fund Manager	2.1	%
7.	Grupo Aeroportuario del Sureste - ADR (Mexico) Mexican Airport Operator	2.1	%
8.	Rand Merchant Insurance (South Africa) Directly Sold Property & Casualty Insurance; Holdings in Other Insurers	2.0	%
9.	MRV Engenharia (Brazil) Brazilan Property Developer	2.0	%
10.	Tower Bersama Infrastructure (Indonesia) Communications Towers	2.0	%

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 Emerging Markets Fund (Class A)

August 19, 2011 through December 31, 2011

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 Emerging Markets 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 would pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund:
$3.2 million

Columbia Acorn European Fund

In a Nutshell



Andreas Waldburg-Wolfegg				Stephen Kusmierczak

Lead Portfolio Manager				Co-Portfolio Manager

Fund's Positions
in Mentioned Holdings

As a percentage of net assets, as of 12/31/11

Core Laboratories	2.9	%
Chemring	2.1	%
Atea	2.0	%
Dürr	1.4	%
Rotork	1.2	%
Mersen	1.1	%
Intralot	0.7	%

Columbia Acorn European Fund was up 0.99% (Class A shares, without sales charge) in the fourth quarter of 2011, outperforming its primary benchmark, the S&P Europe Between $500M and $5B Index, by 58 basis points. Since its launch on August 19, 2011, through December 31, 2011, the Fund declined 4.97% versus its benchmark's drop of 7.17%. We believe this outperformance is explained by the Fund's more conservative positioning and focus on companies with durable business models, solid dividends and less-levered balance sheets.

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

Columbia Acorn
European Fund

At a Glance (Class A Shares - CAEAX)

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, 2011

*Inception 8/19/11*		Life of fund*
Returns before taxes	NAV POP		-4.97 -10.43	%
Returns after taxes on distributions	NAV POP		-5.16 -10.61
Returns after taxes on distributions and sale of fund shares	NAV POP		-3.16 -6.72
S&P Europe Between $500M and $5B Index (pretax)**			-7.17

All results shown assume reinvestment of distributions.

*Reflects performance from Fund inception on 8/19/11 through 12/31/11.

**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.

Columbia Acorn European Fund Portfolio Diversification

as a percentage of net assets, as of 12/31/11

Columbia Acorn European Fund
Top 10 Holdings

as a percentage of net assets, as of 12/31/11

1.	Gemalto (France) Digital Security & Solutions	3.2	%
2.	Wirecard (Germany) Online Payment Processing & Risk Management	2.9	%
3.	Core Laboratories (Netherlands) Oil & Gas Reservoir Consulting	2.9	%
4.	Geberit (Switzerland) Plumbing Supplies	2.9	%
5.	Marel (Iceland) Largest Manufacturer of Poultry & Fish Processing Equipment	2.7	%
6.	Intertek Group (United Kingdom) Testing, Inspection & Certification Services	2.6	%
7.	Eurofins Scientific (France) Food, Pharmaceuticals & Materials Screening & Testing	2.6	%
8.	1000 mercis (France) Interactive Advertising and Marketing	2.4	%
9.	Aalberts Industries (Netherlands) Flow Control & Heat Treatment	2.4	%
10.	Hexagon (Sweden) Design, Measurement & Visualization Software & Equipment	2.3	%

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 European Fund (Class A)

August 19, 2011 through December 31, 2011

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 Europe 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 would pay on Fund distributions or on a sale of Fund shares.

Total Net Assets of the Fund:
$1.7 million

Columbia Acorn Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Information
AboveNet		1,200,000		1,400,000
Akamai		0		700,500
Ariba		1,200,000		2,850,000
Atmel		9,065,000		12,300,000
Boingo Wireless		1,400,000		1,500,000
Concur Technologies		1,480,000		1,830,000
Entegris		4,000,000		5,000,000
Equinix		435,000		585,000
Hittite Microwave		0		400,000
iGATE		3,307,204		3,400,000
Informatica		4,700,000		4,850,000
Ixia		2,030,000		2,330,000
Monolithic Power Systems		800,000		1,165,000
NetEase.com - ADR (China)		0		365,000
ON Semiconductor		6,202,000		6,842,000
Quality Systems		1,100,000		2,333,500
Sanmina-SCI		2,800,000		3,800,000
SBA Communications		3,150,000		3,700,000
Solera Holdings		0		55,000
TIBCO		2,000,000		2,139,800
Ultratech		0		415,000
Velti		0		2,500,000
Verisk Analytics		1,400,000		1,900,000
Industrial Goods & Services
Acorn Energy		1,336,001		1,500,000
Drew Industries		1,260,000		1,500,000
Fortune Brands Home & Security		0		1,300,000
Generac		1,667,021		1,775,704
Kennametal		3,200,000		3,725,000
LKQ		900,000		1,635,000
Middleby		0		123,344
Moog		2,050,000		2,775,000
Consumer Goods & Services
Expedia		0		1,450,000
Fossil		0		115,000
Hertz		3,000,000		3,750,000
Interface		1,000,000		1,750,000
Knoll		4,000,000		4,200,000
Move		0		1,062,500
PVH		1,410,000		1,660,000
Shutterfly		2,300,000		3,070,000
United Stationers		0		493,771
Vail Resorts		1,470,000		1,680,000
Finance
Alliance Data Systems		350,000		400,000
Allied World Holdings		0		500,000
Associated Banc-Corp		4,487,800		6,287,800

	Number of Shares
	09/30/11		12/31/11
Enstar Group		150,000		216,766
Hudson Valley		772,632		811,295
Kemper		0		762,252
Selective Insurance Group		1,420,000		2,050,000
Tower Group		1,225,000		1,675,000
TrustCo Bank		779,305		1,940,318
Wright Express		100,000		180,000
Energy & Minerals
Athabasca Oil Sands		0		2,160,000
Celtic Exploration (Canada)		631,000		1,140,000
Crew Energy (Canada)		847,000		1,399,000
Hornbeck Offshore		500,000		1,000,000
Kirkland Lake Gold (Canada)		0		920,000
Kodiak Oil and Gas		0		2,200,000
Oasis Petroleum		228,200		840,000
PetroMagdalena Energy (Colombia)		6,866,628		7,582,928
SM Energy		715,000		900,000
Health Care
Adcock Ingram Holdings (South Africa)		2,859,820		3,388,000
Auxilium Pharmaceuticals		2,400,000		3,033,715
HealthSouth		1,725,000		2,075,000
Hill-Rom Holdings		625,100		1,975,000
Horizon Pharma		870,000		1,095,000
InterMune		2,226,000		2,950,000
Micromet		5,500,000		6,702,347
NPS Pharmaceuticals		4,500,000		6,000,000
Seattle Genetics		4,200,000		6,153,000
Sirona Dental Systems		1,800,000		2,075,000
Other Industries
Associated Estates Realty		3,000,000		3,700,000
DuPont Fabros Technology		2,200,000		3,350,000
Kite Realty Group		3,050,000		3,500,000

See accompanying notes to financial statements.

	Number of Shares
	09/30/11		12/31/11
Sales
Information
Amphenol		3,565,000		3,495,000
Blackbaud		2,250,000		1,680,198
Carbonite		362,577		295,591
Crown Castle International		5,700,000		4,600,000
Discovery Series C		3,000,000		2,050,000
Dolby Laboratories		605,000		0
Hamamatsu Photonics (Japan)		400,000		0
Kenexa		2,025,000		1,700,000
Mail.ru - GDR (Russia)		464,305		423,040	��
Microsemi		2,345,000		2,160,000
Navigant Consulting		3,000,000		2,800,000
NetSuite		1,450,000		1,150,000
PAETEC Holding		9,000,000		0
Plexus		1,210,000		1,100,000
Polycom		4,130,000		1,165,000
Supertex		644,280		535,000
Tangoe		313,100		0
TheStreet.com		656,585		55,624
Industrial Goods & Services
Arcadis (Netherlands)		626,524		100,000
Mersen (France)		495,086		420,000
Mine Safety Appliances		926,962		566,497
Mueller Water Products		649,000		0
Neopost (France)		265,907		212,972
Silgan Holdings		400,000		200,000
WW Grainger		605,000		270,000
Consumer Goods & Services
Avis Budget Group		4,000,000		3,800,000
Career Education		2,800,000		0
CTS Eventim (Germany)		320,000		265,000
Deckers Outdoor		1,120,000		1,045,000
Expedia		3,100,000		0
Guess?		1,455,000		530,000
Hansen Natural		1,780,000		1,170,000
Lifestyle International (Hong Kong)		14,000,000		13,500,000
lululemon athletica		7,490,000		5,740,000
Move		4,250,000		0
Olam International (Singapore)		32,896,000		32,000,000
Penn National Gaming		1,100,000		850,000
Pool		2,100,000		2,015,000
Thor Industries		2,180,000		1,100,000
True Religion Apparel		1,747,000		1,507,000
Universal Technical Institute		1,400,000		650,000
Finance
Aaron's		2,300,000		1,834,695
CNO Financial Group		11,900,000		8,900,000

	Number of Shares
	09/30/11		12/31/11
Hanover Insurance Group		1,320,000		1,120,000
HCC Insurance Holdings		1,200,000		1,100,000
MB Financial		2,860,000		2,360,000
SVB Financial Group		910,000		810,000
Symetra Financial		694,343		0
TCF Financial		3,000,000		2,200,000
Valley National Bancorp		5,700,000		5,450,000
ViewPoint Financial		700,000		470,000
Energy & Minerals
Atwood Oceanics		2,399,000		2,114,000
Bristow		375,000		0
FMC Technologies		6,200,000		6,036,100
Fugro (Netherlands)		2,641,054		1,988,054
Houston American Energy		1,143,800		900,000
Northern Oil & Gas		850,000		638,000
Orko Silver (Canada)		5,000,000		0
Pacific Rubiales Energy (Colombia)		4,810,550		4,300,000
Silver Standard Resources		900,000		0
Silver Wheaton (Canada)		1,950,000		1,600,000
Southwestern Energy		1,389,000		75,071
STR Holdings		500,000		0
Tuscany International Drilling (Colombia)		8,870,000		4,435,000
Ultra Petroleum		383,000		0
Venoco		575,000		0
Vopak (Netherlands)		600,000		300,000
Health Care
Akorn		4,788,400		4,432,716
Alexion Pharmaceuticals		4,200,000		3,208,000
Community Health Systems		1,625,000		625,000
Edwards Lifesciences		340,000		0
Health Management Associates		3,800,000		1,875,000
Neogen		325,200		0
Pacific Biosciences of California		1,650,000		0
United Therapeutics		142,825		0
Other Industries
BioMed Realty Trust		4,575,000		3,000,000
Federal Realty Investment Trust		840,000		750,000
Heartland Express		2,730,000		2,400,000
JB Hunt Transport Services		1,275,000		1,155,000
Red Eléctrica de España (Spain)		333,000		200,000
Washington REIT		700,000		0

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 97.3%
Information 27.1%
		> Business Software 7.4%
	4,850,000	Informatica (a)	$	179,110
		Enterprise Data Integration Software
	2,550,000	Ansys (a)		146,064
		Simulation Software for Engineers and Designers
	2,700,000	Micros Systems (a)		125,766
		Information Systems for Hotels, Restaurants and Retailers
	1,830,000	Concur Technologies (a)		92,946
		Web Enabled Cost & Expense Management Software
	2,333,500	Quality Systems		86,316
		IT Systems for Medical Groups & Ambulatory Care Centers
	2,850,000	Ariba (a)		80,028
		Cost Management Software
	5,164,999	Hexagon (Sweden)		77,227
		Design, Measurement & Visualization Software & Equipment
	2,350,000	Constant Contact (a)(b)(c)		54,543
		E-mail & Other Marketing Campaign Mgmt Systems Delivered Over the Web
	1,700,000	Tyler Technologies (a)(b)(c)		51,187
		Financial, Tax, Court, & Document Mgmt Systems for Local Governments
	2,139,800	TIBCO (a)		51,163
		Datacenter Software
	1,150,000	NetSuite (a)		46,633
		End to End IT Systems Solution Delivered Over the Web
	1,680,198	Blackbaud		46,541
		Software & Services for Non-Profits
	1,700,000	Kenexa (a)(b)		45,390
		Recruiting and Workforce Management Solutions
	850,000	Red Hat (a)		35,097
		Maintenance & Support for Opensource OS & Middleware
	920,000	Jack Henry & Associates		30,921
		Systems Financial Institutions
	900,000	SPS Commerce (a)(b)		23,355
		Supply Chain Management Software Delivered via the Web
	2,500,000	Velti (a)		17,000
		Mobile Marketing Software Platform
	690,000	Advent Software (a)		16,808
		Asset Management & Trading Systems
	1,000,000	InContact (a)		4,430
		Call Center Systems Delivered Via the Web & Telco Services
	550,000	Intralinks (a)		3,432
		Collaboration Software
	55,000	Solera Holdings		2,450
		Software for Automotive Insurance Claims Processing
				1,216,407

Number of Shares			Value (000)
		> Instrumentation 2.6%
	1,600,000	Mettler Toledo (a)(b)	$	236,336
		Laboratory Equipment
	2,780,000	IPG Photonics (a)(b)		94,159
		Fiber Lasers
	2,035,000	Trimble Navigation (a)		88,319
		GPS-based Instruments
				418,814
		> Computer Hardware & Related Equipment 2.4%
	3,495,000	Amphenol		158,638
		Electronic Connectors
	4,550,000	II-VI (a)(b)		83,538
		Laser Optics and Specialty Materials
	1,605,000	Zebra Technologies (a)		57,427
		Bar Code Printers
	1,200,000	Netgear (a)		40,284
		Networking Products for Small Business & Home
	800,000	Nice Systems - ADR (Israel) (a)		27,560
		Audio & Video Recording Solutions
	605,000	Stratasys (a)		18,398
		Rapid Prototyping Systems
	230,000	Gemalto (France)		11,187
		Digital Security Solutions
				397,032
		> Mobile Communications 2.3%
	4,600,000	Crown Castle International (a)		206,080
		Communications Towers
	3,700,000	SBA Communications (a)		158,952
		Communications Towers
	600,000	MetroPCS Communications (a)		5,208
		Discount Cellular Telephone Services
	1,500,000	Globalstar (a)(c)		810
		Satellite Mobile Voice & Data Carrier
				371,050
		> Semiconductors & Related Equipment 2.2%
	12,300,000	Atmel (a)		99,630
		Microcontrollers, Radio Frequency, and Memory Semiconductors
	6,842,000	ON Semiconductor (a)		52,820
		Mixed-signal & Power Management Semiconductors
	5,000,000	Entegris (a)		43,625
		Semiconductor Materials Management Products
	2,160,000	Microsemi (a)		36,180
		Analog/Mixed-signal Semiconductors
	500,000	Littelfuse		21,490
		Little Fuses
	1,900,000	IXYS (a)(b)		20,577
		Power Semiconductors
	400,000	Hittite Microwave (a)		19,752
		Radio Frequency, Microwave & Millimeterwave Semiconductors

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Semiconductors & Related Equipment—continued
	1,165,000	Monolithic Power Systems (a)	$	17,556
		High Performance Analog & Mixed-signal Integrated Circuits (ICs)
	1,765,000	Pericom Semiconductor (a)(b)		13,432
		Interface Integrated Circuits (ICs) & Frequency Control Products
	2,290,000	TriQuint Semiconductor (a)		11,152
		Radio Frequency Semiconductors
	415,000	Ultratech (a)		10,197
		Semiconductor Equipment
	535,000	Supertex (a)		10,101
		Analog/Mixed Signal Semiconductors
				356,512
		> Telephone and Data Services 2.1%
	9,500,000	tw telecom (a)(b)		184,110
		Fiber Optic Telephone/Data Services
	1,400,000	AboveNet (a)(b)		91,014
		Metropolitan Fiber Communications Services
	2,520,000	Cogent Communications (a)(b)		42,563
		Internet Data Pipelines
	2,000,000	General Communications (a)		19,580
		Commercial Comm & Consumer CATV, Web & Phone in Alaska
	1,500,000	Boingo Wireless (a)(c)		12,900
		Wholesale and Retail WiFi Networks
				350,167
		> Computer Services 1.2%
	3,400,000	iGATE (a)(b)(c)		53,482
		IT & Business Process Outsourcing Services
	680,000	Syntel		31,804
		Offshore IT Services
	2,125,000	Virtusa (a)(b)		30,770
		Offshore IT Outsourcing
	1,145,000	ExlService Holdings (a)		25,614
		Business Process Outsourcing
	1,575,000	Genpact (a)		23,546
		Business Process Outsourcing
	4,500,000	Hackett Group (a)(b)		16,830
		IT Integration & Best Practice Research
	1,076,353	WNS - ADR (India) (a)		9,676
		Offshore BPO (Business Process Outsourcing) Services
				191,722
		> Gaming Equipment & Services 1.1%
	3,725,000	Bally Technologies (a)(b)		147,361
		Slot Machines & Software
	1,530,000	WMS Industries (a)		31,396
		Slot Machine Provider
				178,757
		> Telecommunications Equipment 1.0%
	685,000	F5 Networks (a)		72,692
		Internet Traffic Management Equipment
	1,905,000	Finisar (a)		31,899
		Optical Sub-systems and Components
	2,330,000	Ixia (a)		24,488
		Telecom Network Test Equipment

Number of Shares			Value (000)
	1,165,000	Polycom (a)	$	18,990
		Video Conferencing Equipment
	1,925,000	Infinera (a)		12,089
		Optical Networking Equipment
				160,158
		> Business Information & Marketing Services 0.9%
	1,900,000	Verisk Analytics (a)		76,247
		Risk & Decision Analytics
	900,000	FTI Consulting (a)		38,178
		Financial Consulting Firm
	2,800,000	Navigant Consulting (a)(b)		31,948
		Financial Consulting Firm
	505,000	RPX (a)		6,388
		Patent Aggregation and Defensive Patent Consulting
				152,761
		> CATV 0.9%
	2,050,000	Discovery, Series C (a)		77,285
		CATV programming
	1,250,000	Liberty Global, Series A (a)		51,287
		Cable TV Franchises Outside the USA
	15,770	Jupiter Telecommunications (Japan)		15,963
		Largest Cable Service Provider in Japan
				144,535
		> Financial Processors 0.9%
	2,429,000	Global Payments		115,086
		Credit Card Processor
	5,000,000	Singapore Exchange (Singapore)		23,633
		Singapore Equity & Derivatives Market Operator
				138,719
		> Internet Related 0.9%
	585,000	Equinix (a)		59,319
		Network Neutral Data Centers
	1,450,000	TripAdvisor (a)		36,554
		Online Travel Research
	700,500	Akamai (a)		22,612
		Content Delivery Network (CDN) for Better Delivery of Online Content
	365,000	NetEase.com - ADR (China) (a)		16,370
		Chinese Online Gaming Services
	423,040	Mail.ru - GDR (Russia) (a)(d)		10,999
		Internet Social Networking & Games for Russian Speakers
	55,624	TheStreet.com		94
		Financial Information Websites
				145,948
		> Electronics Distribution 0.6%
	3,125,000	Avnet (a)		97,156
		Electronic Components Distribution
				97,156
		> Contract Manufacturing 0.4%
	3,800,000	Sanmina-SCI (a)		35,378
		Electronic Manufacturing Services
	1,100,000	Plexus (a)		30,118
		Electronic Manufacturing Services
				65,496

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Entertainment Programming 0.1%
	1,250,000	IMAX (Canada) (a)	$	22,912
		IMAX Movies, Theatre Equipment and Theatre Joint Ventures
				22,912
		> Radio 0.1%
	164,991	Saga Communications (a)		6,168
		Radio Stations in Small & Mid-sized Cities
	1,527,700	Salem Communications (a)(b)		3,926
		Radio Stations for Religious Programming
				10,094
		> TV Broadcasting —%
	2,500,000	Entravision Communications		3,900
		Spanish Language TV & Radio Stations
	1,750,000	Gray Television (a)		2,835
		Mid Market Affiliated TV Stations
				6,735
		> Consumer Software —%
	295,591	Carbonite (a)(c)		3,281
		Online File Storage
				3,281
		> Advertising —%
	1,500,000	VisionChina Media - ADR (China) (a)		1,860
		Advertising on Digital Screens in China's Mass Transit System
				1,860
Information: Total				4,430,116
Industrial Goods & Services 19.0%
		> Machinery 11.0%
	4,200,000	Donaldson (b)		285,936
		Industrial Air Filtration
	6,750,000	Ametek		284,175
		Aerospace/Industrial Instruments
	3,725,000	Kennametal		136,037
		Consumable Cutting Tools
	3,000,000	Nordson		123,540
		Dispensing Systems for Adhesives & Coatings
	2,775,000	Moog (a)(b)		121,906
		Motion Control Products for Aerospace, Defense & Industrial Markets
	3,535,000	Pentair		117,680
		Pumps & Water Treatment
	2,325,000	Clarcor		116,227
		Mobile & Industrial Filters
	1,800,000	Pall		102,870
		Filtration & Fluids Clarification
	2,250,000	HEICO (b)		88,537
		FAA Approved Aircraft Replacement Parts
	2,200,000	ESCO Technologies (b)		63,316
		Automatic Electric Meter Readers
	2,675,000	Oshkosh Corporation (a)		57,192
		Specialty Truck Manufacturer
	1,150,000	WABCO Holdings (a)		49,910
		Truck & Bus Component Supplier
	1,775,704	Generac (a)		49,773
		Standby Power Generators

Number of Shares			Value (000)
	805,000	Toro	$	48,831
		Turf Maintenance Equipment
	600,000	Wabtec		41,970
		Freight & Transit Component Supplier
	1,300,000	Kaydon		39,650
		Specialized Friction & Motion Control Products
	566,497	Mine Safety Appliances		18,762
		Safety Equipment
	212,972	Neopost (France)		14,350
		Postage Meter Machines
	123,344	Middleby (a)		11,599
		Manufacturer of Cooking Equipment
	10,000,000	Marel (Iceland) (a)		10,228
		Largest Manufacturer of Poultry & Fish Processing Equipment
	100,000	Valmont Industries		9,079
		Center Pivot Irrigation Systems & Utility Poles
	1,250,000	Spartan Motors		6,013
		Specialty Truck & Chassis Manufacturer
	3,450,000	Jain Irrigation Systems (India)		5,611
	172,500	Jain Irrigation Systems - DVR (India) (a)		115
		Agricultural Micro-irrigation Systems & Food Processing
				1,803,307
		> Industrial Materials & Specialty Chemicals 2.1%
	1,750,000	Albemarle		90,143
		Refinery Catalysts and Other Specialty Chemicals
	760,000	FMC Corporation		65,390
		Niche Specialty Chemicals
	1,525,000	Novozymes (Denmark)		47,078
		Industrial Enzymes
	1,500,000	Drew Industries (a)(b)		36,795
		RV & Manufactured Home Components
	673,000	Sociedad Quimica y Minera de Chile - ADR (Chile) (c)		36,241
		Producer of Specialty Fertilizers, Lithium & Iodine
	900,000	Albany International		20,808
		Paper Machine Clothing and Advanced Textiles
	2,218,700	Kansai Paint (Japan)		19,761
		Paint Producer in Japan, India, China and Southeast Asia
	420,000	Mersen (France)		12,693
		Advanced Industrial Materials
	200,000	Silgan Holdings		7,728
		Metal & Plastic Packaging
				336,637
		> Other Industrial Services 1.9%
	3,200,000	Expeditors International of Washington		131,072
		International Freight Forwarder
	1,635,000	LKQ (a)		49,181
		Alternative Auto Parts Distribution
	1,767,165	Imtech (Netherlands) (c)		45,777
		Electromechanical & ICT Installation & Maintenance

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Other Industrial Services—continued
	1,300,000	Forward Air	$	41,665
		Freight Transportation Between Airports
	1,600,000	Mobile Mini (a)		27,920
		Portable Storage Units Leasing
	750,000	UTI Worldwide		9,968
		Freight Forwarding & Logistics
	1,500,000	Acorn Energy (b)		9,060
		Frac Well Exploration/Monitoring Device, Sonar Security,Electric Grid Monitoring
	100,000	Arcadis (Netherlands)		1,566
		Engineering Consultants
				316,209
		> Construction 0.9%
	1,725,000	Chicago Bridge & Iron		65,205
		Engineering & Construction for LNG & Petrochemicals
	66,000	NVR (a)		45,276
		DC Homebuilder
	1,300,000	Fortune Brands Home & Security (a)		22,139
		Home Building Supplies & Small Locks
	1,800,000	Mills Estruturas e Servicos de Engenharia (Brazil)		17,081
		Civil Engineering & Construction
				149,701
		> Waste Management 0.7%
	2,400,000	Waste Connections		79,536
		Solid Waste Management
	560,000	Clean Harbors (a)		35,689
		Hazardous Waste Services & Disposal
				115,225
		> Electrical Components 0.7%
	1,440,000	Acuity Brands		76,320
		Commercial Lighting Fixtures
	1,500,000	Ushio (Japan)		21,559
		Industrial Light Sources
	351,000	Saft Batteries (France)		9,926
		Niche Battery Manufacturer
				107,805
		> Outsourcing Services 0.6%
	2,800,000	Quanta Services (a)		60,312
		Electrical & Telecom Construction Services
	1,210,000	Insperity		30,673
		Professional Employer Organization
	600,000	GP Strategies (a)		8,088
		Training Programs
				99,073
		> Industrial Distribution 0.6%
	270,000	WW Grainger		50,541
		Industrial Distribution
	2,600,000	Interline Brands (a)(b)		40,482
		Industrial Distribution
				91,023
		> Steel 0.3%
	4,000,000	GrafTech International (a)		54,600
		Industrial Graphite Materials Producer
				54,600

Number of Shares			Value (000)
		> Conglomerates 0.2%
	2,263,654	Aalberts Industries (Netherlands)	$	38,028
		Flow Control & Heat Treatment
				38,028
Industrial Goods & Services: Total				3,111,608
Consumer Goods & Services 15.7%
		> Retail 4.2%
	5,740,000	lululemon athletica (a)(b)		267,829
		Premium Active Apparel Retailer
	3,510,000	Abercrombie & Fitch		171,429
		Teen Apparel Retailer
	5,600,000	Pier 1 Imports (a)(b)		78,008
		Home Furnishing Retailer
	3,070,000	Shutterfly (a)(b)		69,873
		Internet Photo-centric Retailer
	5,225,000	Saks (a)(c)		50,944
		Luxury Department Store Retailer
	525,000	DSW		23,210
		Branded Footwear Retailer
	971,500	Teavana (a)(c)		18,245
		Specialty Tea Retailer
	115,000	Fossil (a)		9,126
		Watch Designer & Retailer
	1,371,366	Gaiam (a)(b)		4,443
		Healthy Living Catalogs & E-Commerce
	66,000	The Fresh Market (a)		2,633
		Specialty Food Retailer
				695,740
		> Apparel 3.4%
	2,100,000	Coach		128,184
		Designer & Retailer of Branded Leather Accessories
	1,660,000	PVH		117,013
		Apparel Wholesaler and Retailer
	2,190,000	Warnaco Group (a)(b)		109,587
		Global Branded Apparel Manufacturer
	1,045,000	Deckers Outdoor (a)		78,971
		Fashion Footwear Wholesaler
	1,507,000	True Religion Apparel (a)(b)		52,112
		Premium Denim
	1,000,000	Hanesbrands (a)		21,860
		Apparel Wholesaler
	600,000	Steven Madden (a)		20,700
		Wholesaler/Retailer of Fashion Footwear
	530,000	Guess?		15,805
		Branded Apparel + Accessories + Licensor
	580,000	Crocs (a)		8,567
		Branded Footwear Wholesaler & Retailer
				552,799
		> Travel 2.4%
	3,850,000	Gaylord Entertainment (a)(b)		92,939
		Convention Hotels
	1,680,000	Vail Resorts		71,165
		Ski Resort Operator & Developer
	3,750,000	Hertz (a)		43,950
		Largest U.S. Rental Car Operator

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Travel—continued
	1,450,000	Expedia	$	42,079
		Online Travel Services Company
	3,800,000	Avis Budget Group (a)		40,736
		Second Largest Car Rental Company
	970,000	Choice Hotels		36,909
		Franchisor Of Budget Hotel Brands
	1,400,000	HomeAway (a)(c)		32,550
		Vacation Rental Online Marketplace
	2,000,000	Localiza Rent A Car (Brazil)		27,449
		Car Rental
				387,777
		> Food & Beverage 1.2%
	1,170,000	Hansen Natural (a)		107,804
		Alternative Beverages
	32,000,000	Olam International (Singapore)		52,453
		Agriculture Supply Chain Manager
	1,050,000	Diamond Foods		33,884
		Snack Foods and Culinary Ingredients
	240,000	Snyder's - Lance		5,400
		Snack Foods
	1,750,000	GLG Life Tech (Canada) (a)(b)		1,575
		Produce an All-Natural Sweetener Extracted from the Stevia Plant
				201,116
		> Other Consumer Services 0.8%
	2,190,000	Lifetime Fitness (a)(b)		102,382
		Sport & Fitness Club Operator
	13,500,000	Lifestyle International (Hong Kong)		29,715
		Mid- to High-end Department Store Operator in Hong Kong & China
	1,062,500	Move (a)		6,715
		Real Estate Internet Websites
	1,325,000	IFM Investments (Century 21 China RE) - ADR (China) (a)		424
		Provide Real Estate Services in China
				139,236
		> Furniture & Textiles 0.8%
	4,200,000	Knoll (b)		62,370
		Office Furniture
	2,250,000	Herman Miller		41,512
		Office Furniture
	1,750,000	Interface		20,195
		Modular & Broadloom Carpet
				124,077
		> Casinos & Gaming 0.7%
	3,950,000	Pinnacle Entertainment (a)(b)		40,132
		Regional Casino Operator
	850,000	Penn National Gaming (a)		32,359
		Regional Casino Operator
	3,000,000	Melco Crown Entertainment - ADR (Hong Kong) (a)(c)		28,860
		Macau Casino Operator
	12,000,000	MGM China Holdings (Hong Kong) (a)		15,611
		Macau Casino Operator
				116,962

Number of Shares			Value (000)
		> Other Durable Goods 0.5%
	1,650,000	Jarden	$	49,302
		Branded Household Products
	460,000	Cavco Industries (a)(b)		18,428
		Manufactured Homes
	400,000	Tesla Motors (a)(c)		11,424
		Design, Manufacture and Sell High Performance Electric Vehicles
				79,154
		> Consumer Goods Distribution 0.5%
	2,015,000	Pool		60,652
		Distributor of Swimming Pool Supplies & Equipment
	493,771	United Stationers		16,077
		Wholesale Distributor of Business Products
				76,729
		> Restaurants 0.3%
	2,000,000	AFC Enterprises (a)(b)		29,400
		Popeye's Restaurants
	450,000	Cheesecake Factory (a)		13,208
		Casual Dining Restaurants
	675,000	Bravo Brio Restaurant Group (a)		11,576
		Upscale Casual Italian Restaurants
				54,184
		> Nondurables 0.3%
	1,600,000	Helen of Troy (a)(b)		49,120
		Hair Dryers & Curling Irons
				49,120
		> Educational Services 0.3%
	800,000	New Oriental Education & Technology - ADR (China) (a)		19,240
		China's Largest Private Education Service Provider
	300,000	ITT Educational Services (a)(c)		17,067
		Post-secondary Degree Services
	650,000	Universal Technical Institute (a)		8,307
		Vocational Training
	2,000,000	Voyager Learning, Contingent Value Rights (a)(e)(f)		180
		Education Services for the K-12 Market
				44,794
		> Leisure Products 0.3%
	1,100,000	Thor Industries		30,173
		RV & Bus Manufacturer
	975,000	Skullcandy (a)(c)		12,207
		Lifestyle Branded Headphones
				42,380
		> Other Entertainment —%
	265,000	CTS Eventim (Germany)		7,957
		Event Ticket Sales
				7,957
Consumer Goods & Services: Total				2,572,025
Finance 10.4%
		> Banks 4.1%
	2,738,000	BOK Financial		150,398
		Tulsa Based S.W. Bank

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Banks—continued
	2,337,313	Hancock Holding	$	74,724
		Gulf Coast Bank
	6,287,800	Associated Banc-Corp		70,235
		Midwest Bank
	5,450,000	Valley National Bancorp (c)		67,416
		New Jersey/New York Bank
	1,275,000	City National		56,329
		Bank & Asset Manager
	4,300,000	CVB Financial (c)		43,129
		Inland Empire Business Bank
	2,360,000	MB Financial		40,356
		Chicago Bank
	810,000	SVB Financial Group (a)		38,629
		Bank to Venture Capitalists
	2,200,000	TCF Financial		22,704
		Great Lakes Bank
	4,299,507	First Busey		21,498
		Illinois Bank
	1,121,188	Sandy Spring Bancorp		19,677
		Baltimore, D.C. Bank
	1,350,000	TriCo Bancshares (b)		19,197
		California Central Valley Bank
	811,295	Hudson Valley		17,216
		Metro New York City Bank
	1,940,318	TrustCo Bank		10,885
		New York State Bank
	706,559	Eagle Bancorp (a)		10,273
		Metro D.C. Bank
	246,505	Pacific Continental Bank		2,182
		Pacific Northwest Bank
	158,389	Green Bankshares (a)		200
		Tennessee Bank
				665,048
		> Insurance 2.7%
	2,820,000	Leucadia National		64,127
		Insurance Holding Company
	8,900,000	CNO Financial Group (a)		56,159
		Life, Long-term Care & Medical Supplement Insurance
	1,200,000	Delphi Financial Group		53,160
		Workers Comp & Group Employee Benefit Products & Services
	1,120,000	Hanover Insurance Group		39,144
		Personal & Commercial Lines Insurance
	2,050,000	Selective Insurance Group		36,347
		Commercial & Personal Lines Insurance
	1,675,000	Tower Group		33,785
		Commercial & Personal Lines Insurance
	832,000	Willis Group (Ireland)		32,282
		Insurance Broker
	500,000	Allied World Holdings		31,465
		Commercial Lines Insurance/Reinsurance
	1,100,000	HCC Insurance Holdings		30,250
		Specialty Insurance
	762,252	Kemper		22,265
		Multi-line Insurance
	216,766	Enstar Group (a)		21,286
		Insurance/Reinsurance & Related Services

Number of Shares			Value (000)
	900,000	Brown & Brown	$	20,367
		Insurance Broker
	300,000	Assured Guaranty		3,942
		Global Muni Bond Insurance
				444,579
		> Finance Companies 1.9%
	1,505,202	World Acceptance (a)(b)		110,632
		Personal Loans
	2,150,000	McGrath Rentcorp (b)		62,328
		Temporary Space & IT Rentals
	1,834,695	Aaron's		48,950
		Rent to Own
	3,400,000	H&E Equipment Services (a)(b)		45,628
		Heavy Equipment Leasing
	1,123,400	CAI International (a)(b)		17,368
		International Container Leasing
	1,091,000	Marlin Business Services (b)		13,856
		Small Equipment Leasing
	78,500	Textainer Group Holdings		2,286
		Top International Container Leasor
				301,048
		> Brokerage & Money Management 1.2%
	6,198,000	SEI Investments		107,535
		Mutual Fund Administration & Investment Management
	3,700,000	Eaton Vance		87,468
		Specialty Mutual Funds
	1,000,000	Artio Global Investors (c)		4,880
		International Asset Manager
				199,883
		> Credit Cards 0.3%
	400,000	Alliance Data Systems (a)		41,536
		Diversified Credit Card Provider
	180,000	Wright Express (a)		9,770
		Pay Card Processor
				51,306
		> Savings & Loans 0.2%
	400,000	Financial Engines (a)		8,932
		Asset Management for 401k Plans
	1,010,000	Provident New York Bancorp		6,706
		New York State Thrift
	470,000	ViewPoint Financial		6,115
		Texas Thrift
	452,146	Kaiser Federal		5,797
		Los Angeles Savings & Loan
	65,991	Berkshire Hills Bancorp		1,464
		Northeast Thrift
				29,014
Finance: Total				1,690,878
Energy & Minerals 9.5%
		> Oil Services 4.2%
	6,036,100	FMC Technologies (a)		315,265
		Oil & Gas Wellhead Manufacturer
	1,988,054	Fugro (Netherlands)		115,517
		Sub-sea Oilfield Services

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Oil Services—continued
	2,114,000	Atwood Oceanics (a)	$	84,116
		Offshore Drilling Contractor
	743,000	Oil States International (a)		56,743
		Diversified North American Oil Service Provider
	1,670,000	ShawCor (Canada)		47,342
		Oil & Gas Pipeline Products
	1,000,000	Hornbeck Offshore (a)		31,020
		Supply Vessel Operator in U.S. Gulf of Mexico
	1,056,600	Black Diamond Group (Canada)		19,146
		Provides Accommodations/Equipment for Oil Sands Development
	2,890,900	Horizon North Logistics (Canada)		13,224
		Provides Diversified Oil Service Offering in Northern Canada
	4,435,000	Tuscany International Drilling (Colombia) (a)		2,612
		South America Based Drilling Rig Contractor
				684,985
		> Oil & Gas Producers 3.6%
	4,300,000	Pacific Rubiales Energy (Colombia) (c)		79,056
		Oil Production & Exploration in Colombia
	900,000	SM Energy		65,790
		Oil and Gas Producer
	2,400,000	Tullow Oil (United Kingdom)		52,255
		Oil and Gas Producer
	695,000	Range Resources		43,048
		Oil and Gas Producer
	974,000	Rosetta Resources (a)		42,369
		Oil and Gas Producer Exploring in South Texas and Montana
	2,700,000	Denbury Resources (a)		40,770
		Oil Producer Using Co2 Injection
	650,000	Baytex (Canada) (c)		36,349
		Oil & Gas Producer in Canada
	2,160,000	Athabasca Oil Sands (a)		26,482
		Oil Sands SAGD & Alberta Deep Basin Development
	1,140,000	Celtic Exploration (Canada) (a)		25,592
		Canadian Oil and Gas Producer
	840,000	Oasis Petroleum (a)		24,436
		Oil Producer in North Dakota
	2,200,000	Kodiak Oil and Gas (a)		20,900
		Bakken Oil & Gas Producer
	250,000	Cabot Oil and Gas		18,975
		Large Natural Gas Producer in Appalachia and Gulf Coast
	550,000	Swift Energy (a)		16,346
		Oil and Gas Exploration and Production
	1,399,000	Crew Energy (Canada) (a)		15,449
		Canadian Oil and Gas Producer
	638,000	Northern Oil & Gas (a)(c)		15,299
		Small E&P Company in North Dakota Bakken
	900,000	Houston American Energy (a)(c)		10,971
		Oil and Gas Exploration/Production in Colombia
	27,000,000	ShaMaran Petroleum (Iraq) (a)		9,409
		Oil Exploration in Kurdistan

Number of Shares			Value (000)
	7,582,928	PetroMagdalena Energy (Colombia) (a)(b)(c)	$	9,081
		Oil & Gas Exploration / Production in Colombia
	26,000,000	Petrodorado (Colombia) (a)(b)		5,232
	24,000,000	Petrodorado - Warrants (Colombia) (a)(e)(f)		895
		Oil & Gas Exploration/Production in Colombia, Peru & Paraguay
	37,500,000	Petromanas (Canada) (a)(b)		5,706
	18,750,000	Petromanas - Warrants (Canada) (a)(e)		136
		Exploring for Oil in Albania
	5,917,100	Canacol (Colombia) (a)		4,472
		Oil Producer in South America
	30,275,000	Petroamerica (Colombia) (a)(b)		3,120
		Oil Exploration & Production in Colombia
	8,400,000	Canadian Overseas Petroleum (United Kingdom) (a)(e)		2,788
	4,200,000	Canadian Overseas Petroleum - Warrants (United Kingdom) (a)(e)(f)		332
		Oil & Gas Exploration/Production in the North Sea
	75,071	Southwestern Energy (a)		2,398
		Oil and Gas Producer
	1,198,100	Pan Orient (Canada) (a)		2,293
		Growth Oriented, Return Focused Asian Explorer
	41,100,000	Quetzal Energy (Colombia) (a)(b)(e)		1,549
	8,900,000	Quetzal Energy (Colombia) (a)(b)		350
		Explores for Oil & Gas in Latin America
				581,848
		> Mining 1.4%
	545,000	Core Laboratories (Netherlands)		62,102
		Oil & Gas Reservoir Consulting
	1,600,000	Silver Wheaton (Canada)		46,336
		Silver Mining Royalty Company
	15,000,000	Zhaojin Mining Industry (China)		23,792
		Gold Mining and Refining in China
	1,150,000	Ivanhoe Mines (Mongolia) (a)		20,421
		Copper Mine Project in Mongolia
	2,800,000	Alexco Resource (a)		19,068
		Mining, Exploration & Environmental Services
	4,432,000	Northam Platinum (South Africa)		16,471
		Platinum Mining in South Africa
	7,500,000	Duluth Metals (Canada) (a)(b)		15,387
		Copper & Nickel Miner
	920,000	Kirkland Lake Gold (Canada) (a)		13,925
		Gold Mining
	12,000,000	Mongolian Mining (Mongolia) (a)		8,997
		Coking Coal Mining in Mongolia
	800,000	Augusta Resource (a)(c)		2,480
		U.S. Copper/Molybdenum Mine
	4,000,000	Wolverine Minerals (Canada) (a)(b)(e)		716
	2,000,000	Wolverine Minerals - Warrants (Canada) (a)(e)(f)		5
		Gold Miner

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Mining—continued
	500,000	Duluth Exploration - Special Warrants (Canada) (a)(e)(f)	$	44
		Copper & Nickel Miner
				229,744
		> Alternative Energy 0.1%
	2,800,000	GT Solar International (a)		20,272
		Largest Manufacturer of Furnaces & Reactors to Produce & Cast Polysilicon
	1,210,300	Synthesis Energy Systems (China) (a)		1,876
		Owner / Operator of Gasification Plants
				22,148
		> Oil Refining, Marketing & Distribution 0.1%
	300,000	Vopak (Netherlands)		15,851
		World's Largest Operator of Petroleum and Chemical Storage Terminals
				15,851
		> Agricultural Commodities 0.1%
	1,250,000	Union Agriculture Group (Argentina) (a)(e)(f)		12,463
		Farmland Operator in Uruguay
				12,463
Energy & Minerals: Total				1,547,039
Health Care 9.4%
		> Biotechnology & Drug Delivery 3.5%
	4,315,000	BioMarin Pharmaceutical (a)		148,350
		Biotech Focused on Orphan Diseases
	6,153,000	Seattle Genetics (a)(b)(c)		102,847
		Antibody-based Therapies for Cancer
	3,033,715	Auxilium Pharmaceuticals (a)(b)		60,462
		Biotech Focused on Niche Disease Areas
	1,170,000	Onyx Pharmaceuticals (a)		51,421
		Commercial-stage Biotech Focused on Cancer
	6,702,347	Micromet (a)(b)		48,190
		Next-generation Antibody Technology
	6,000,000	NPS Pharmaceuticals (a)(b)		39,540
		Orphan Drugs & Healthy Royalties
	2,950,000	InterMune (a)		37,170
		Drugs for Pulmonary Fibrosis & Hepatitis C
	3,430,000	Isis Pharmaceuticals (a)		24,730
		Biotech Pioneer in Anti-sense Drugs
	4,550,000	Chelsea Therapeutics International (a)(b)		23,342
		Biotech Focused on Rare Diseases
	3,455,000	Raptor Pharmaceutical (a)(b)(c)		21,628
		Orphan Drug Company
	1,740,000	Anthera Pharmaceuticals (a)		10,684
		Biotech Focused on Cardiovascular, Cancer & Immunology
	359,944	MicroDose Therapeutx (a)(e)(f)		270
		Drug Inhaler Development
				568,634
		> Medical Equipment & Devices 3.0%
	3,208,000	Alexion Pharmaceuticals (a)		229,372
		Biotech Focused on Orphan Diseases
	2,075,000	Sirona Dental Systems (a)		91,383
		Manufacturer of Dental Equipment

Number of Shares			Value (000)
	1,975,000	Hill-Rom Holdings	$	66,538
		Hospital Beds/Patient Handling
	860,000	Gen-Probe (a)		50,843
		Molecular In-vitro Diagnostics
	550,000	Haemonetics (a)		33,671
		Blood & Plasma Collection Equipment
	570,000	Orthofix International (a)		20,081
		Bone Fixation & Stimulation Devices
				491,888
		> Medical Supplies 1.3%
	3,200,000	Cepheid (a)		110,112
		Molecular Diagnostics
	2,126,000	Patterson Companies		62,760
		Dental/Vet/Med Distributor
	650,000	Henry Schein (a)		41,879
		Largest Distributor of Healthcare Products
				214,751
		> Health Care Services 1.1%
	665,000	Mednax (a)		47,887
		Physician Mgmt for Pediatric and Anesthesia Practices
	2,075,000	HealthSouth (a)		36,665
		Inpatient Rehabalitation Facilities
	850,000	HMS Holdings (a)		27,183
		Cost Containment Services
	4,900,000	eResearch Technology (a)(b)		22,981
		Clinical Research Services
	1,875,000	Health Management Associates (a)		13,819
		Non-urban Hospitals
	700,000	Allscripts Healthcare Solutions (a)		13,258
		IT for Physician Offices and Hospitals
	625,000	Community Health Systems (a)		10,906
		Non-Urban Hospitals
				172,699
		> Pharmaceuticals 0.5%
	4,432,716	Akorn (a)		49,292
		Develops, Manufactures & Sells Specialty Generic Drugs
	3,388,000	Adcock Ingram Holdings (South Africa)		25,916
		Manufacturer of Pharmaceuticals and Medical Supplies
	1,095,000	Horizon Pharma (a)(b)(c)		4,380
		Specialty Pharma Company
	2,040,000	Alimera Sciences (a)(b)(c)		2,550
		Ophthalmology-focused Pharmaceutical Company
				82,138
Health Care: Total				1,530,110
Other Industries 6.2%
		> Real Estate 3.8%
	3,350,000	DuPont Fabros Technology (b)(c)		81,137
		Technology-focused Office Buildings
	750,000	Federal Realty Investment Trust		68,063
		Shopping Centers
	3,700,000	Associated Estates Realty (b)		59,015
		Multi-family Properties
	3,000,000	BioMed Realty Trust		54,240
		Life Science-focused Office Buildings

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

Number of Shares			Value (000)
		> Real Estate—continued
	720,000	Digital Realty Trust (c)	$	48,002
		Technology-focused Office Buildings
	1,850,000	Extra Space Storage		44,826
		Self Storage Facilities
	1,120,000	Kilroy Realty		42,638
		West Coast Office and Industrial Properties
	975,000	Post Properties		42,627
		Multifamily Properties
	3,000,000	Education Realty Trust		30,690
		Student Housing
	43,000,000	Mapletree Logistics Trust (Singapore)		27,988
		Industrial Property Landlord
	530,000	Macerich		26,818
		Regional Shopping Malls
	15,000,000	Ascendas REIT (Singapore)		21,180
		Singapore Industrial Property Landlord
	3,750,000	DCT Industrial Trust		19,200
		Industrial Properties
	3,500,000	Kite Realty Group (b)		15,785
		Community Shopping Centers
	1,000,000	St. Joe (a)(c)		14,660
		Florida Panhandle Landowner
	1,500,000	Summit Hotel Properties (b)		14,160
		Owner of Select Service Hotels
	2,800	Orix JREIT (Japan)		11,515
		Diversified REIT
	37,407	Security Capital Euro Realty (Luxembourg) (a)(e)(f)(g)		—
		Self Storage Properties
				622,544
		> Transportation 1.4%
	2,800,000	Rush Enterprises, Class A (a)(b)		58,576
	550,000	Rush Enterprises, Class B (a)(b)		9,443
		Truck Sales and Service
	1,260,000	World Fuel Services		52,895
		Global Fuel Broker
	1,155,000	JB Hunt Transport Services		52,056
		Truck & Intermodal Carrier
	2,400,000	Heartland Express		34,296
		Regional Trucker
	300,000	Genesee & Wyoming (a)		18,174
		Short-line Operator
				225,440
		> Regulated Utilities 1.0%
	2,000,000	Northeast Utilities		72,140
		Regulated Electric Utility
	1,800,000	Wisconsin Energy		62,928
		Wisconsin Utility
	500,000	Allete		20,990
		Regulated Electric Utility- Minnesota
	200,000	Red Eléctrica de España (Spain)		8,559
		Spanish Power Transmission
				164,617
Other Industries: Total				1,012,601
Total Equities: 97.3% (Cost: $10,899,548)				15,894,377

Number of Shares			Value (000)
Securities Lending Collateral 2.3%
	382,045,475	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (h)	$	382,045
Total Securities Lending Collateral:		(Cost: $382,045)		382,045
Total Investments: 99.6% (Cost: $11,281,593)(i)(j)				16,276,422
Obligation to Return Collateral for Securities Loaned: (2.3)%				(382,045	)
Cash and Other Assets Less Liabilities: 2.7%				442,198
Total Net Assets: 100.0%			$	16,336,575

ADR - American Depositary Receipts

DVR - Differential Voting Right Equity Shares

GDR - Global Depositary Receipts

See accompanying notes to financial statements.

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

(a) Non-income producing security.

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
AboveNet		1,200,000		200,000		-		1,400,000	$	91,014	$	-
Acorn Energy		-		1,500,000		-		1,500,000		9,060		53
AFC Enterprises		2,000,000		-		-		2,000,000		29,400		-
Akorn*		2,659,068		2,340,932		567,284		4,432,716		49,292		-
Allos Therapeutics*		7,035,000		-		7,035,000		-		-		-
Alimera Sciences		361,450		1,678,550		-		2,040,000		2,550		-
Anthera Pharmaceuticals*		1,450,000		290,000		-		1,740,000		10,684		-
Array Biopharma*		3,500,000		-		3,500,000		-		-		-
Art Technology Group*		9,000,000		-		9,000,000		-		-		-
Associated Estates Realty		2,200,000		1,500,000		-		3,700,000		59,015		1,717
Auxilium Pharmaceuticals		1,200,000		1,833,715		-		3,033,715		60,462		-
Bally Technologies		3,725,000		-		-		3,725,000		147,361		-
Blackbaud*		2,250,000		-		569,802		1,680,198		46,541		810
CAI International		1,650,000		-		526,600		1,123,400		17,368		-
Cavco Industries		180,000		280,000		-		460,000		18,428		-
Cepheid*		2,415,000		785,000		-		3,200,000		110,112		-
Chelsea Therapeutics International		3,449,900		1,100,100		-		4,550,000		23,342		-
Clarcor*		2,565,000		-		240,000		2,325,000		116,227		1,356
Cogent Communications		2,800,000		-		280,000		2,520,000		42,563		-
Constant Contact		1,400,000		950,000		-		2,350,000		54,543		-
Diamond Foods*		1,300,000		-		250,000		1,050,000		33,884		217
Donaldson		4,200,000		-		-		4,200,000		285,936		1,806
Drew Industries		1,260,000		240,000		-		1,500,000		36,795		-
Duluth Metals		3,154,000		4,346,000		-		7,500,000		15,387
DuPont Fabros Technology		1,935,579		1,414,421		-		3,350,000		81,137		684
Education Realty Trust*		3,000,000		-		-		3,000,000		30,690		510
eResearch Technology		4,250,000		650,000		-		4,900,000		22,981		-
ESCO Technologies		2,200,000		-		-		2,200,000		63,316		704
Gaiam		1,371,366		-		-		1,371,366		4,443		-
Gaylord Entertainment		3,850,000		-		-		3,850,000		92,939		-
GLG Life Tech		1,200,000		550,000		-		1,750,000		1,575		-
H&E Equipment Services		3,000,000		400,000		-		3,400,000		45,628		-
Hackett Group		4,500,000		-		-		4,500,000		16,830		-
HEICO+		1,700,000		550,000		-		2,250,000		88,537		237
Helen of Troy		1,600,000		-		-		1,600,000		49,120		-
Horizon Pharma		-		1,095,000		-		1,095,000		4,380
iGATE		2,913,065		500,000		13,065		3,400,000		53,482		-
II-VI+		2,225,000		2,325,000		-		4,550,000		83,538		-
Informatica*		5,200,000		150,000		500,000		4,850,000		179,110		-
Interline Brands		2,600,000		-		-		2,600,000		40,482		-
IPG Photonics		2,710,000		70,000		-		2,780,000		94,159		-
IXYS		1,900,000		-		-		1,900,000		20,577		-
Kenexa		2,025,000		-		325,000		1,700,000		45,390		-
Kite Realty Group		3,050,000		450,000		-		3,500,000		15,785		732
Knoll		4,000,000		200,000		-		4,200,000		62,370		1,060
Lifetime Fitness		2,190,000		-		-		2,190,000		102,382		-
lululemon athletica+		4,035,000		3,950,000		2,245,000		5,740,000		267,829		-
Marlin Business Services		1,091,000		-		-		1,091,000		13,856		65
MB Financial*		2,860,000		-		500,000		2,360,000		40,356		86
McGrath Rentcorp		2,350,000		-		200,000		2,150,000		62,328		2,105
Mettler Toledo		1,600,000		-		-		1,600,000		236,336
Micromet		5,500,000		1,202,347		-		6,702,347		48,190		-
Moog		1,820,000		955,000		-		2,775,000		121,906		-
Nabi Biopharmaceuticals*		1,383,454		1,916,546		3,300,000		-		-		-
Nanosphere*		1,480,056		-		1,480,056		-		-		-
Navigant Consulting		3,100,000		-		300,000		2,800,000		31,948		-
NPS Pharmaceuticals		3,200,000		2,800,000		-		6,000,000		39,540		-
Orko Silver*		10,000,000		-		10,000,000		-		-		-

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

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

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
Orthofix International*		1,150,000		-		580,000		570,000	$	20,081	$	-
PAETEC Holding		9,600,000		-		9,600,000		-		-		-
Pericom Semiconductor		1,765,000		-		-		1,765,000		13,432		-
Petroamerica		30,275,000		-		-		30,275,000		3,120		-
Petrodorado		24,000,000		2,000,000		-		26,000,000		5,232		-
Petrolifera Petroleum*		13,950,000		-		13,950,000		-		-		-
PetroMagdalena Energy+		-		7,582,928		-		7,582,928		9,081
Petromanas		37,500,000		-		-		37,500,000		5,706		-
Pier 1 Imports		5,600,000		-		-		5,600,000		78,008
Pinnacle Entertainment		3,400,000		550,000		-		3,950,000		40,132		-
Quetzal Energy		-		50,000,000		-		50,000,000		1,899		-
Raptor Pharmaceutical		-		3,455,000		-		3,455,000		21,628		-
Rush Enterprises		3,350,000		-		-		3,350,000		68,019		-
Salem Communications		1,541,000		-		13,300		1,527,700		3,926		-
Seattle Genetics		4,180,918		2,472,082		500,000		6,153,000		102,847
Shutterfly		1,700,000		1,370,000		-		3,070,000		69,873		-
Spanish Broadcasting System*+		2,400,000		240,000		2,640,000		-		-		-
SPS Commerce		856,429		43,571		-		900,000		23,355		-
Summit Hotel Properties		-		1,500,000		-		1,500,000		14,160		399
Supertex*		1,035,000		-		500,000		535,000		10,101		-
Talbots*		4,150,000		-		4,150,000		-		-		-
THQ*		3,567,000		-		3,567,000		-		-		-
TriCo Bancshares		1,350,000		-		-		1,350,000		19,197		365
True Religion Apparel		2,047,000		-		540,000		1,507,000		52,112		-
Tuscany International Drilling*		10,719,200		-		6,284,200		4,435,000		2,612		-
tw telecom		9,500,000		-		-		9,500,000		184,110		-
Tyler Technologies		2,000,000		-		300,000		1,700,000		51,187		-
Universal Technical Institute*		1,700,000		-		1,050,000		650,000		8,307		-
Virtusa		2,000,000		125,000		-		2,125,000		30,770		-
Warnaco Group		2,190,000		-		-		2,190,000		109,587		-
Wolverine Minerals		-		4,000,000		-		4,000,000		716		-
World Acceptance		1,505,202		-		-		1,505,202		110,632		-
Total of Affiliated Transactions		339,825,687		109,561,192		84,506,307		364,880,572	$	4,380,934	$	12,906

* At December 31, 2011, the Fund owned less than five percent of the company's outstanding voting shares.

+ Includes the effects of a stock split.

(c) All or a portion of this security was on loan at December 31, 2011. The total market value of securities on loan at December 31, 2011 was $371,484.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Union Agriculture Group	12/8/10-12/16/11		1,250,000	$	15,000	$	12,463
Canadian Overseas Petroleum	11/24/10		8,400,000		3,591		2,788
Quetzal Energy	1/14/11		41,100,000		5,193		1,549
Petrodorado - Warrants	11/20/09		24,000,000		2,965		895
Wolverine Minerals	6/3/11		4,000,000		2,005		716
Canadian Overseas Petroleum - Warrants	11/24/10		4,200,000		526		332
MicroDose Therapeutx	11/24/00		359,944		2,005		270
Voyager Learning, Contingent Value Rights	12/24/09		2,000,000		-		180
Petromanas - Warrants	5/20/10		18,750,000		1,086		136
Duluth Exploration - Special Warrants	8/19/11		500,000		-		44
Wolverine Minerals - Warrants	6/3/11		2,000,000		243		5
Security Capital Euro Realty	8/20/98-7/20/99		37,407		205		-
				$	32,819	$	19,378

See accompanying notes to financial statements.

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

(f) Illiquid security.

(g) Security has no value.

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

(j) On December 31, 2011, the market value of foreign securities represented 9.17% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percentage of Net Assets
Canada	$	266,137		1.63
Netherlands		278,841		1.71
Singapore		125,254		0.77
Colombia		106,367		0.65
Hong Kong		74,186		0.45
Sweden		77,227		0.47
Japan		68,798		0.42
China		63,562		0.39
United Kingdom		55,375		0.34
France		48,156		0.29
Denmark		47,078		0.29
Brazil		44,530		0.27
South Africa		42,387		0.26
Chile		36,241		0.22
	Value		Percentage of Net Assets
Ireland	$	32,282		0.20
Mongolia		29,418		0.18
Israel		27,560		0.17
India		15,402		0.09
Argentina		12,463		0.08
Russia		10,999		0.07
Iceland		10,228		0.06
Iraq		9,409		0.06
Spain		8,559		0.05
Germany		7,957		0.05
Luxembourg		-		-
Total Foreign Portfolio	$	1,498,416		9.17

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	4,291,107	$	139,009	$	-	$	4,430,116
Industrial Goods & Services		2,884,916		226,692		-		3,111,608
Consumer Goods & Services		2,466,109		105,736		180		2,572,025
Finance		1,690,878		-		-		1,690,878
Energy & Minerals		1,295,228		239,304		12,507		1,547,039
Health Care		1,503,924		25,916		270		1,530,110
Other Industries		943,359		69,242		-		1,012,601
Total Equities		15,075,521		805,899		12,957		15,894,377
Total Securities Lending Collateral		382,045		-		-		382,045
Total Investments	$	15,457,566	$	805,899	$	12,957	$	16,276,422

See accompanying notes to financial statements.

Columbia Acorn Fund

Statement of Investments, continued

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

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
$	110,688	$	16,715	$	16,715	$	110,688

Financial assets were transferred from Level 2 to Level 1 as they resumed trading during the period and as resale restrictions no longer apply.

Foreign exchange-traded financial assets were transferred from Level 1 to Level 2 due to application of a systematic fair valuation model.

The following table reconciles asset balances for the year ending December 31, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)			Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Equities
Consumer Goods & Services	$	262	$	-		$	(82	)	$	-	$	-	$	-	$	-	$	180
Energy & Minerals		15,000		-			(2,594	)		101		-		-		-		12,507
Health Care		103		(7,780	)		7,947			-		-		-		-		270
	$	15,365	$	(7,780	)	$	5,271		$	101	$	-	$	-	$	-	$	12,957

See accompanying notes to financial statements.

Columbia Acorn International

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Asia
> Japan
Asahi Diamond Industrial		1,851,900		1,885,600
Disco		0		306,000
FP Corporation		0		254,000
Ibiden		883,144		1,143,144
Japan Airport Terminal		2,052,572		2,137,272
Kuraray		2,129,100		2,981,100
NGK Insulators		0		2,400,000
Park24		736,600		2,263,000
> Taiwan
Advantech		3,458,700		6,603,000
Chroma Ate		7,025,500		9,857,400
CTCI Corp		9,315,800		13,957,000
Far Eastone Telecom		33,118,800		36,606,000
Lung Yen		510,800		2,468,300
PC Home		0		2,268,000
Simplo Technology		3,678,530		5,614,530
St. Shine Optical		2,240,000		2,450,000
Taiwan Mobile		0		6,647,000
Tripod Technologies		5,613,270		10,147,270
> China
Digital China		11,165,300		12,446,800
NetEase.com - ADR		401,000		644,000
New Oriental Education & Technology - ADR		965,387		1,100,000
> Hong Kong
AAC Technologies		0		8,475,000
L'Occitane International		15,000,000		15,625,000
> India
Shriram Transport Finance		767,100		1,550,000
Titan Industries		0		791,352
United Breweries		1,203,445		1,500,251
> Korea
Handsome		0		61,600
> Indonesia
Jasa Marga		0		6,937,300
Tower Bersama Infrastructure		0		13,942,000
> Thailand
Home Product Center		104,039,000		120,000,000
> Philippines
Manila Water Company		14,299,600		19,454,700
SM Prime Holdings		63,272,200		69,967,000
> Cambodia
Nagacorp		40,438,400		42,522,600

	Number of Shares
	09/30/11		12/31/11
Europe
> United Kingdom
Greggs		0		467,193
> Germany
Bertrandt		0		165,400
Wirecard		2,286,441		2,500,000
> Switzerland
Dufry Group		286,300		324,000
> Italy
Geox		4,973,000		5,300,000
Pirelli		0		1,756,000
> Belgium
EVS Broadcast Equipment		332,977		438,880
Other Countries
> United States
Hornbeck Offshore		0		555,500
Textainer Group Holdings		838,297		965,297
> Canada
Alliance Grain Traders		754,800		868,000
Athabasca Oil Sands		0		731,000
Celtic Exploration		505,000		721,000
Crew Energy		678,000		1,043,000
Latin America
> Brazil
Multiplus		1,179,000		1,200,000
Odontoprev		0		1,500,000

See accompanying notes to financial statements.

Columbia Acorn International

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

	Number of Shares
	09/30/11		12/31/11
Sales
Asia
> Japan
Asics		2,116,900		0
Hamamatsu Photonics		765,554		479,854
Kakaku.com		530,500		0
Kamigumi		634,794		0
Kansai Paint		8,187,600		7,044,100
Nippon Sheet Glass		6,107,300		0
Start Today		938,400		527,001
> Taiwan
China Steel Chemical		2,748,000		0
Formosa International Hotels		1,580,717		468,917
President Chain Store		7,017,009		7,000,000
Sinyi Realty		1,211,280		0
Taiwan Hon Chuan		11,315,800		10,357,000
> Singapore
Ascendas REIT		23,489,149		21,600,000
CDL Hospitality Trust		21,890,000		18,000,000
Mapletree Industrial Trust		42,675,997		39,000,000
Mapletree Logistics Trust		53,383,000		50,000,000
> China
Jiangsu Expressway		23,596,000		0
Noah Holdings - ADR		800,000		493,398
Wasion Group		8,479,200		0
> Hong Kong
Hutchison Port Holdings Trust		32,000,000		0
> India
Infrastructure Development Finance		3,807,700		0
> Korea
MegaStudy		129,332		63,916
NHN		160,150		101,150
Europe
> United Kingdom
Cobham		5,804,000		0
FlyBe		1,499,183		0
Intertek Group		1,853,000		1,480,000
JLT Group		3,644,400		3,000,000
Kesa Electricals		9,009,000		2,533,060
Workspace Group		8,028,385		8,000,000
> Netherlands
Fugro		844,967		687,967
USG People		454,772		0
Vopak		1,189,424		317,424

	Number of Shares
	09/30/11		12/31/11
> France
Eurofins Scientific		554,800		532,368
Mersen		556,874		460,000
Neopost		631,797		555,324
Pierre & Vacances		322,605		0
Teleperformance		1,158,000		0
> Switzerland
Bank Sarasin & Cie		773,707		696,331
Kuehne & Nagel		350,445		296,145
> Ireland
Aryzta		395,008		0
Paddy Power		350,000		289,400
United Drug		9,700,000		9,074,112
> Finland
Poyry		409,248		0
Other Countries
> United States
Alexion Pharmaceuticals		887,431		627,431
Atwood Oceanics		1,373,080		952,080
Bristow		421,732		0
FMC Technologies		707,213		606,253
> Canada
Black Diamond Group		1,189,576		1,049,576
Eacom Timber		13,000,000		0
Petromanas		12,500,000		0
ShawCor		1,790,397		1,212,597
> Australia
SAI Global		5,806,600		0
Latin America
> Brazil
Mills Estruturas e Servicos de Engenharia		3,184,900		2,303,200
MRV Engenharia		3,634,800		3,500,000
> Guatemala
Tahoe Resources		963,600		932,600

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 96.8%
Asia 43.3%
		> Japan 18.3%
	7,044,100	Kansai Paint	$	62,739
		Paint Producer in Japan, India, China and Southeast Asia
	22,694,000	Seven Bank		44,410
		ATM Processing Services
	2,981,100	Kuraray		42,307
		Special Resin, Fine Chemical, Fibers & Textures
	1,995,438	Aeon Delight		40,226
		Facility Maintenance & Management
	1,697,200	Hoshizaki Electric		39,817
		Commercial Kitchen Equipment
	1,139,000	Gree		39,155
		Mobile Social Networking Game Developer/Platform
	23,790	Wacom (a)(b)		36,080
		Computer Graphic Illustration Devices
	677,892	Ain Pharmaciez		32,621
		Dispensing Pharmacy/Drugstore Operator
	7,780	Orix JREIT		31,996
		Diversified REIT
	16,005	Advance Residence Investment		30,877
		Residential REIT
	2,263,000	Park24		29,932
		Parking Lot Operator
	2,400,000	NGK Insulators		28,415
		Ceramic Products for Auto, Power & Electronics
	2,137,272	Japan Airport Terminal		27,813
		Airport Terminal Operator at Haneda
	295,762	Nakanishi		27,295
		Dental Tools & Machinery
	937,651	Kintetsu World Express		27,235
		Airfreight Logistics
	25,769,649	Shinsei Bank		26,645
		Commercial Bank
	25,979	Jupiter Telecommunications		26,296
		Largest Cable Service Provider in Japan
	855,604	Tsumura		25,223
		Traditional Chinese/Japanese Herbal Rx Drugs (Kampo)
	1,055,562	Glory		22,706
		Currency Handling Systems & Related Equipment
	1,885,600	Asahi Diamond Industrial		22,690
		Consumable Diamond Tools
	1,143,144	Ibiden		22,506
		Electronic Parts & Ceramics
	2,600,000	Shimadzu		21,926
		Analytical Instrument, Medical & Industrial Equipment
	1,277,429	Daiseki		20,756
		Waste Disposal and Recycling
	1,405,739	Ushio		20,204
		Industrial Light Sources
	469,500	Pigeon		19,136
		Baby Care Products

Number of Shares			Value (000)
	2,874	Fukuoka REIT	$	18,883
		Diversified REIT in Fukuoka
	732,108	Icom		18,722
		Two Way Radio Communication Equipment
	880,474	Aeon Mall		18,679
		Suburban Shopping Mall Developer, Owner & Operator
	5,540	Mori Hills REIT Investment		18,092
		Tokyo Centric Diversified REIT
	636,250	Miura		17,921
		Industrial Boiler Manufacturer
	6,140	Kenedix Realty Investment		17,802
		Tokyo Mid Size Office REIT
	772,000	Misumi Group		17,667
		Industrial Components Distributor
	1,346,963	Torishima Pump Manufacturing (b)		17,239
		Industrial Pump for Power Generation and Water Supply Systems
	1,940,200	Sintokogio		17,014
		Automated Casting Machines, Surface Treatment System and Consumables
	479,854	Hamamatsu Photonics		16,730
		Optical Sensors for Medical and Industrial Applications
	254,000	FP Corporation		16,456
		Disposable Food Trays & Containers
	306,000	Disco		15,933
		Semiconductor Dicing & Grinding Equipment
	527,001	Start Today		12,364
		Online Japanese Apparel Retailer
	24,000	Doshisha		692
		Wholesaler
				993,200
		> Taiwan 6.1%
	36,606,000	Far Eastone Telecom		68,764
		Taiwan's 3rd Largest Mobile Operator
	7,000,000	President Chain Store		38,121
		Taiwan's Number One Convenience Chain Store Operator
	5,614,530	Simplo Technology		32,675
		Battery Packs for Notebook & Tablet PCs
	2,450,000	St. Shine Optical		25,841
		World's Leading Disposable Contact Lens OEM
	10,147,270	Tripod Technologies		24,441
		Printed Circuit Boards
	6,647,000	Taiwan Mobile		20,709
		Taiwan's 2nd Largest Mobile Operator
	9,857,400	Chroma Ate		19,317
		Automatic Test Systems, Testing & Measurement Instruments
	10,357,000	Taiwan Hon Chuan		19,071
		Beverage Packaging (bottles, caps, labels) Manufacturer
	13,957,000	CTCI Corp		19,020
		International Engineering Firm
	6,603,000	Advantech		18,258
		Industrial PC & Components
	5,910,000	Radiant Opto-Electronics		16,861
		Back Light Modules for LCDs

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		> Taiwan—continued
	2,268,000	PC Home	$	13,930
		Taiwanese Internet Retail Company
	2,468,300	Lung Yen		7,215
		Funeral Services and Columbaria
	468,917	Formosa International Hotels		6,067
		Hotel, Food & Beverage Operation & Hospitality Management Services
				330,290
		> Singapore 4.2%
	33,000,000	Olam International		54,093
		Agriculture Supply Chain Manager
	50,000,000	Mapletree Logistics Trust		32,544
		Industrial Property Landlord
	39,000,000	Mapletree Industrial Trust		32,315
		Singapore Industrial Property Landlord
	21,600,000	Ascendas REIT		30,500
		Singapore Industrial Property Landlord
	18,000,000	CDL Hospitality Trust		21,448
		Hotel Owner/Operator
	32,300,000	Mapletree Commercial Trust		21,171
		Retail and Office Property Landlord
	3,500,000	Singapore Exchange		16,543
		Singapore Equity & Derivatives Market Operator
	15,000,000	Goodpack Limited		16,013
		International Bulk Container Leasing
				224,627
		> China 4.1%
	34,745,554	Zhaojin Mining Industry		55,111
		Gold Mining and Refining in China
	644,000	NetEase.com - ADR (c)		28,883
		Chinese Online Gaming Services
	1,100,000	New Oriental Education & Technology - ADR (c)		26,455
		China's Largest Private Education Service Provider
	19,410,400	Want Want		19,334
		Chinese Branded Consumer Food Company
	12,446,800	Digital China		19,236
		IT Distribution & Systems Integration Services
	5,000,000	ENN Energy		16,008
		China's Largest Private Gas Operator
	12,047,000	China Yurun Food (b)		15,746
		Meat Processor in China
	28,757,700	AMVIG Holdings		15,239
		Chinese Tobacco Packaging Material Supplier
	220,000,000	RexLot Holdings		14,401
		Lottery Equipment Supplier in China
	263,700	51job - ADR (c)		11,060
		Integrated Human Resource Service
	493,398	Noah Holdings - ADR (b)(c)		3,034
		Wealth Management Product Distributor in China
				224,507

Number of Shares			Value (000)
		> Hong Kong 3.7%
	7,000,000	Melco Crown Entertainment - ADR (b)(c)	$	67,340
		Macau Casino Operator
	17,000,000	Lifestyle International		37,419
		Mid- to High-end Department Store Operator in Hong Kong & China
	15,625,000	L'Occitane International		31,334
		Skin Care and Cosmetics Producer
	37,703,800	Sasa International		20,782
		Cosmetics Retailer
	8,475,000	AAC Technologies		18,961
		Miniature Acoustic Components
	12,500,000	MGM China Holdings (c)		16,261
		Macau Casino Operator
	7,419,000	Melco International (c)		5,475
		Macau Casino Operator
				197,572
		> India 2.1%
	11,163,303	Jain Irrigation Systems		18,157
	558,165	Jain Irrigation Systems - DVR (c)		370
		Agricultural Micro-irrigation Systems & Food Processing
	8,052,053	Mundra Port & Special Economic Zone		18,174
		Indian West Coast Shipping Port
	341,652	Asian Paints		16,677
		India's Largest Paint Company
	16,621,332	Manappuram Finance		14,393
		Short-term Lending Collateralized by Household Gold
	1,550,000	Shriram Transport Finance		12,262
		Truck Financing in India
	1,500,251	United Breweries		10,840
		India's Largest Brewer
	32,642,905	REI Agro		10,130
		Basmati Rice Processing
	10,249,300	S. Kumars Nationwide		4,555
		Textiles, Clothing & Retail
	1,650,000	SKIL Ports and Logistics (c)		4,074
		Indian Container Port Project
	791,352	Titan Industries		2,545
		Jewelry, Watches & Eyeglasses
				112,177
		> Korea 1.2%
	1,242,590	Woongjin Coway (c)		39,568
		South Korean Household Appliance Rental Service Provider
	101,150	NHN (c)		18,538
		Korean Online Search Services
	63,916	MegaStudy (c)		6,110
		Education Service Provider
	61,600	Handsome (c)		1,590
		Korea's Leading High-end Apparel Company
				65,806
		> Mongolia 1.1%
	1,049,943	Ivanhoe Mines (c)		18,644
	914,678	Ivanhoe Mines (c)(d)		16,208
		Copper Mine Project in Mongolia

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Mongolia—continued
	35,923,500	Mongolian Mining (c)	$	26,933
		Coking Coal Mining in Mongolia
				61,785
		> Indonesia 0.8%
	29,063,787	Archipelago Resources (a)(c)		31,200
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
	8,913,600	Ace Indonesia		4,027
		Home Improvement Retailer
	13,942,000	Tower Bersama Infrastructure		3,650
		Communications Towers
	6,937,300	Jasa Marga		3,210
		Largest Toll Road Operator in Indonesia
				42,087
		> Thailand 0.8%
	120,000,000	Home Product Center		41,787
		Home Improvement Retailer
				41,787
		> Philippines 0.7%
	69,967,000	SM Prime Holdings		21,230
		Shopping Mall Operator
	7,931,700	Int'l Container Terminal		9,599
		Container Handling Terminals & Port Management
	19,454,700	Manila Water Company		8,615
		Water Utility Company in the Philippines
				39,444
		> Cambodia 0.2%
	42,522,600	Nagacorp		10,705
		Casino/Entertainment Complex in Cambodia
				10,705
Asia: Total				2,343,987
Europe 32.9%
		> United Kingdom 6.2%
	1,480,000	Intertek Group		46,773
		Testing, Inspection & Certification Services
	5,700,000	Chemring		35,400
		Defense Manufacturer of Countermeasures & Energetics
	3,000,000	JLT Group (b)		32,124
		International Business Insurance Broker
	8,000,000	Workspace Group (a)		28,047
		United Kingdom Real Estate
	3,305,000	Serco		24,329
		Facilities Management
	730,000	Rotork		21,880
		Valve Actuators for Oil & Water Pipelines
	446,300	Next		18,970
		Clothes and Home Retailer in the United Kingdom
	4,150,000	GlobeOp Financial Services		18,368
		Hedge Fund Administrator
	1,761,742	Smith and Nephew		17,114
		Medical Equipment & Supplies

Number of Shares			Value (000)
	2,950,000	Abcam	$	16,722
		Online Sales of Antibodies
	740,581	Tullow Oil		16,125
		Oil and Gas Producer
	2,497,000	Domino's Pizza United Kingdom & Ireland		15,608
		Pizza Delivery in United Kingdom, Ireland and Germany
	2,636,932	Premier Oil (c)		14,865
		Oil and Gas Producer in Europe, Pakistan and Asia
	1,773,408	Shaftesbury		12,867
		London Prime Retail REIT
	4,163,948	PureCircle (c)		6,143
		Natural Sweeteners
	1,692,525	Sterling Resources (c)		2,775
	1,147,475	Sterling Resources (c)(e)(f)		1,843
		Oil & Gas Exploration - Europe
	467,193	Greggs		3,671
		Bakery
	2,533,060	Kesa Electricals		2,648
		Europe's Leading Electricals Retailers
				336,272
		> Netherlands 5.0%
	1,955,311	Imtech (b)		50,651
		Electromechanical & ICT Installation & Maintenance
	2,479,123	Aalberts Industries		41,648
		Flow Control & Heat Treatment
	687,967	Fugro		39,975
		Sub-sea Oilfield Services
	1,371,573	Koninklijke TenCate (a)		37,740
		Advanced Textiles & Industrial Fabrics
	1,591,702	UNIT4 (a)		37,699
		Business Software Development
	228,095	Core Laboratories		25,991
		Oil & Gas Reservoir Consulting
	1,252,514	Arcadis		19,615
		Engineering Consultants
	317,424	Vopak		16,772
		World's Largest Operator of Petroleum and Chemical Storage Terminals
				270,091
		> Germany 4.0%
	2,500,000	Wirecard		40,187
		Online Payment Processing & Risk Management
	148,295	Rational		32,283
		Commercial Ovens
	1,600,000	Rhoen-Klinikum		30,482
		Health Care Services
	679,600	Rheinmetall		30,112
		Defense & Automotive
	636,800	Dürr		28,022
		Automotive Plant Engineering & Associated Capital Equipment
	819,889	CTS Eventim		24,619
		Event Ticket Sales

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		> Germany—continued
	555,700	Elringklinger	$	13,795
		Automobile Components
	165,400	Bertrandt		10,855
		Outsourced Engineering
	338,886	Deutsche Beteiligungs		6,833
		Private Equity Investment Management
				217,188
		> France 4.0%
	1,193,000	Gemalto		58,025
		Digital Security Solutions
	532,368	Eurofins Scientific		38,812
		Food, Pharmaceuticals & Materials Screening & Testing
	555,324	Neopost (b)		37,417
		Postage Meter Machines
	971,800	Saft Batteries		27,482
		Niche Battery Manufacturer
	353,648	Rubis		18,491
		Tank Storage & Liquefied Petroleum Gas Distribution
	232,400	Norbert Dentressangle		16,242
		Leading European Logistics & Transport Group
	460,000	Mersen		13,902
		Advanced Industrial Materials
	1,831,204	Hi-Media (b)(c)		5,238
		Online Advertiser in Europe
				215,609
		> Switzerland 3.7%
	265,000	Partners Group		46,240
		Private Markets Asset Management
	225,650	Geberit (c)		43,482
		Plumbing Supplies
	296,145	Kuehne & Nagel		33,262
		Freight Forwarding/Logistics
	324,000	Dufry Group (c)		29,820
		Operates Airport Duty Free and Duty Paid Shops
	15,500	Sika		29,208
		Chemicals for Construction & Industrial Applications
	696,331	Bank Sarasin & Cie		20,350
		Private Banking
				202,362
		> Sweden 2.2%
	4,056,007	Hexagon		60,645
		Design, Measurement & Visualization Software & Equipment
	4,150,024	Sweco (a)		34,674
		Engineering Consultants
	658,700	Unibet		15,170
		European Online Gaming Operator
	905,452	East Capital Explorer		7,072
		Sweden-based Russia/Central Eastern Europe Investment Fund
				117,561

Number of Shares			Value (000)
		> Italy 1.6%
	2,621,149	Ansaldo STS	$	24,859
		Railway Systems Integrator
	13,547,300	CIR (b)		21,605
		Italian Holding Company
	5,300,000	Geox (b)		14,816
		Apparel and Shoe Maker
	1,756,000	Pirelli		14,720
		Global Tire Supplier
	166,200	Tod's (b)		13,501
		Leather Shoes & Bags
				89,501
		> Denmark 1.4%
	1,648,800	Novozymes		50,900
		Industrial Enzymes
	168,042	SimCorp		25,660
		Software for Investment Managers
				76,560
		> Ireland 0.8%
	9,074,112	United Drug		24,076
		Irish Pharmaceutical Wholesaler & Outsourcer
	289,400	Paddy Power		16,673
		Irish Betting Services
				40,749
		> Iceland 0.7%
	35,982,499	Marel (c)		36,804
		Largest Manufacturer of Poultry & Fish Processing Equipment
				36,804
		> Russia 0.7%
	2,109,700	Petropavlovsk		20,149
		Gold and Iron Ore Mining in Russia
	629,642	Mail.ru - GDR (c)(f)		16,371
		Internet Social Networking & Games for Russian Speakers
				36,520
		> Norway 0.4%
	2,403,664	Atea		24,114
		Leading Nordic IT Hardware/Software Re-seller & Installation Company
				24,114
		> Belgium 0.4%
	438,880	EVS Broadcast Equipment		22,431
		Digital Live Mobile Production Software and Systems
				22,431
		> Czech Republic 0.4%
	130,682	Komercni Banka		22,027
		Leading Czech Republic Universal Bank
				22,027
		> Portugal 0.4%
	7,770,405	Redes Energéticas Nacionais		21,220
		Portuguese Power Transmission & Gas Transportation
				21,220

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Spain 0.4%
	494,320	Red Eléctrica de España	$	21,154
		Spanish Power Transmission
				21,154
		> Finland 0.3%
	1,039,429	Stockmann (b)		16,116
		Department Store & Fashion Retailer in Scandinavia & Russia
				16,116
		> Kazakhstan 0.2%
	1,770,000	Halyk Savings Bank of Kazakhstan - GDR (c)		8,602
		Largest Retail Bank & Insurer in Kazakhstan
				8,602
		> Greece 0.1%
	6,954,400	Intralot		6,057
		Lottery & Gaming Systems & Services
				6,057
Europe: Total				1,780,938
Other Countries 15.8%
		> United States 4.8%
	627,431	Alexion Pharmaceuticals (c)		44,861
		Biotech Focused on Orphan Diseases
	1,229,871	BioMarin Pharmaceutical (c)		42,283
		Biotech Focused on Orphan Diseases
	987,228	World Fuel Services		41,444
		Global Fuel Broker
	952,080	Atwood Oceanics (c)		37,883
		Offshore Drilling Contractor
	606,253	FMC Technologies (c)		31,665
		Oil & Gas Wellhead Manufacturer
	965,297	Textainer Group Holdings		28,109
		Top International Container Leasor
	270,000	Oil States International (c)		20,620
		Diversified North American Oil Service Provider
	555,500	Hornbeck Offshore (c)		17,232
		Supply Vessel Operator in U.S. Gulf of Mexico
				264,097
		> Canada 4.7%
	1,403,772	CCL Industries		43,143
		Leading Global Label Manufacturer
	615,857	Baytex (b)		34,440
		Oil & Gas Producer in Canada
	1,212,597	ShawCor		34,375
		Oil & Gas Pipeline Products
	582,942	AG Growth		21,446
		Leading Manufacturer of Augers and Grain Handling Equipment
	653,200	Onex Capital (b)		21,274
		Private Equity
	1,049,576	Black Diamond Group		19,019
		Provides Accommodations/Equipment for Oil Sands Development

Number of Shares			Value (000)
	868,000	Alliance Grain Traders	$	17,697
		Global Leader in Pulse Processing and Distribution
	721,000	Celtic Exploration (c)		16,186
		Canadian Oil and Gas Producer
	1,043,000	Crew Energy (c)		11,518
		Canadian Oil and Gas Producer
	2,411,514	Horizon North Logistics		11,031
		Provides Diversified Oil Service Offering in Northern Canada
	731,000	Athabasca Oil Sands (c)		8,962
		Oil Sands SAGD & Alberta Deep Basin Development
	2,919,000	DeeThree Exploration (a)(c)(e)		5,756
	1,142,377	DeeThree Exploration (a)(c)		2,299
		Canadian Oil & Gas Producer
	6,217,500	Southern Arc Minerals (a)(c)(e)		3,984
		Gold and Copper Exploration in Indonesia
	1,607,306	Pan Orient (c)		3,077
		Growth Oriented, Return Focused Asian Explorer
	6,250,000	Petromanas - Warrants (c)(e)		45
		Exploring for Oil in Albania
				254,252
		> South Africa 4.3%
	1,170,188	Naspers		51,198
		Media in Africa, China, Russia & Other Emerging Markets
	4,992,200	Adcock Ingram Holdings		38,187
		Manufacturer of Pharmaceuticals and Medical Supplies
	3,722,083	Mr. Price		36,794
		South African Retailer of Apparel, Household & Sporting Goods
	19,098,300	Rand Merchant Insurance		31,702
		Directly Sold Property and Casualty Insurance; Holdings in Other Insurers
	10,271,492	Coronation Fund Managers		28,884
		South African Fund Manager
	6,943,940	Northam Platinum		25,806
		Platinum Mining in South Africa
	1,025,504	Massmart Holdings		21,470
		General Merchandise, Food, and Home Improvement Stores; Wal-Mart Subsidiary
				234,041
		> Australia 1.2%
	2,653,389	UGL		32,245
		Engineering & Facilities Management
	498,560	Cochlear		31,664
		Cochlear Implants
				63,909
		> Israel 0.6%
	3,085,527	Israel Chemicals		31,980
		Producer of Potash, Phosphates, Bromine & Specialty Chemicals
				31,980

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, continued

Number of Shares			Value (000)
		> Senegal 0.2%
	45,237	Sonatel	$	10,711
		Leading Telecoms Operator in Western Africa
				10,711
Other Countries: Total				858,990
Latin America 4.8%
		> Brazil 3.0%
	4,000,000	Localiza Rent A Car		54,899
		Car Rental
	6,344,043	Suzano		22,924
		Brazilian Pulp & Paper Producer
	2,303,200	Mills Estruturas e Servicos de Engenharia		21,856
		Civil Engineering & Construction
	1,500,000	Odontoprev		21,391
		Dental Insurance
	1,200,000	Multiplus		20,748
		Loyalty Program Operator in Brazil
	3,500,000	MRV Engenharia		20,078
		Brazilan Low-income Property Developer
				161,896
		> Mexico 0.6%
	624,168	Grupo Aeroportuario del Sureste - ADR		34,916
		Mexican Airport Operator
				34,916
		> Chile 0.4%
	362,996	Sociedad Quimica y Minera de Chile - ADR (b)		19,547
		Producer of Specialty Fertilizers, Lithium & Iodine
				19,547
		> Argentina 0.3%
	1,250,000	Union Agriculture Group (c)(e)(g)		12,462
		Farmland Operator in Uruguay
	5,940,000	Madalena Ventures (c)(e)		5,200
		Oil & Gas Exploration in Argentina
				17,662
		> Guatemala 0.3%
	932,600	Tahoe Resources (c)		16,185
		Silver Project in Guatemala
				16,185
		> Colombia 0.2%
	8,353,169	Canacol (c)		6,314
		Oil Producer in South America
	22,525,000	Gulf United (c)(e)		4,757
		Prospecting for Oil Alongside Large Producers in Colombia
				11,071
Latin America: Total				261,277
Total Equities: 96.8% (Cost: $4,603,524)				5,245,192

Number of Shares			Value (000)
Securities Lending Collateral 1.8%
	99,418,399	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (h)	$	99,418
Total Securities Lending Collateral: (Cost: $99,418)				99,418
Total Investments: 98.6% (Cost: $4,702,942)(i)(j)				5,344,610
Obligation to Return Collateral for Securities Loaned: (1.8)%				(99,418	)
Cash and Other Assets Less Liabilities: 3.2%				171,761
Total Net Assets: 100.0%			$	5,416,953

ADR - American Depositary Receipts

DVR - Differential Voting Right Equity Shares

GDR - Global Depository Receipts

See accompanying notes to financial statements.

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

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
Archipelago Resources		24,346,593		4,717,194		-		29,063,787	$	31,200	$	-
DeeThree Exploration+		2,392,877		1,668,500		-		4,061,377		8,055		-
Gulf United Energy*		-		22,525,000		-		22,525,000		4,757		-
Koninklijke TenCate		1,240,557		131,016		-		1,371,573		37,740		-
Southern Arc Minerals		-		6,217,500		-		6,217,500		3,984		-
Sweco		3,887,000		263,024		-		4,150,024		34,674		1,616
UNIT4		1,476,800		114,902		-		1,591,702		37,699		450
United Drug*		12,110,000		737,752		3,773,640		9,074,112		24,076		1,371
Wacom		20,900		4,480		1,590		23,790		36,080		721
Workspace Group+		60,304,000		640,600		52,944,600		8,000,000		28,047		719
Total of Affiliated Transactions		105,778,727		37,019,968		56,719,830		86,078,865	$	246,312	$	4,877

+ Includes the effects of a corporate action.

* At December 31, 2011, the Fund owned less than five percent of the company's outstanding voting shares.

(b) All or a portion of this security was on loan at December 31, 2011. The total market value of securities on loan at December 31, 2011 was $96,653.

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

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Union Agriculture Group	12/8/10-12/16/11		1,250,000	$	15,000	$	12,462
DeeThree Exploration	9/7/10-3/8/11		2,919,000		10,228		5,756
Madalena Ventures	10/21/10		5,940,000		3,764		5,200
Gulf United	2/11/11		22,525,000		6,758		4,757
Southern Arc Minerals	2/16/11		6,217,500		10,087		3,984
Sterling Resources	12/2/10		1,147,475		3,425		1,843
Petromanas - Warrants	5/20/10		6,250,000		362		45
				$	49,624	$	34,047

(g) Illiquid security.

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

(i) On December 31, 2011, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Japanese Yen	$	993,200		18.3
Euro		894,125		16.5
U.S. Dollar		639,143		11.8
British Pound		387,079		7.1
Taiwan Dollar		330,290		6.1
Hong Kong Dollar		322,944		6.0
Canadian Dollar		305,212		5.6
Other currencies less than 5% of total net asets		1,472,617		27.2
Total Foreign Portfolio	$	5,344,610		98.6

See accompanying notes to financial statements.

Columbia Acorn International

Statement of Investments, continued

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

At December 31, 2011, 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		36,208	$	36,500	1/13/12	$	492
CAD	USD		30,663		30,000	1/13/12		92
USD	EUR		47,693		65,685	1/13/12		3,955
				$	132,185		$	4,539

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

AUD - Australian Dollar

CAD - Canadian Dollar

EUR - Euro

USD - United States Dollar

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	171,624	$	2,172,363	$	-	$	2,343,987
Europe		28,766		1,752,172		-		1,780,938
Other Countries		508,564		350,426		-		858,990
Latin America		238,858		9,957		12,462		261,277
Total Equities		947,812		4,284,918		12,462		5,245,192
Total Securities Lending Collateral		99,418		-		-		99,418
Total Investments	$	1,047,230	$	4,284,918	$	12,462	$	5,344,610
Unrealized Appreciation on Forward Foreign Currency Exchange Contracts		-		4,539		-		4,539
Total	$	1,047,230	$	4,289,457	$	12,462	$	5,349,149

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, in accordance with the policy adopted by the Board of Trustees, 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.

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

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
$	208,336	$	30,015	$	30,015	$	208,336

Financial assets were transferred from Level 2 to Level 1 as they resumed trading during the period and as resale restrictions no longer apply.

Foreign exchange-traded financial assets were transferred from Level 1 to level 2 due to application of a systematic fair valuation model.

The following table reconciles asset balances for the year ending December 31, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)			Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Equities
Asia	$	79	$	(38,558	)	$	38,479		$	-	$	-	$	-	$	-	$	-
Latin America		15,000		-			(2,538	)		-		-		-		-		12,462
	$	15,079	$	(38,558	)	$	35,941		$	-	$	-	$	-	$	-	$	12,462

The change in unrealized depreciation attributed to securities owned at December 31, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $(2,538).

See accompanying notes to financial statements.

Columbia Acorn International

Portfolio Diversification

At December 31, 2011, 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	$	448,556		8.3
Industrial Materials & Specialty Chemicals		369,560		6.8
Machinery		363,876		6.7
Electrical Components		111,501		2.1
Conglomerates		85,758		1.6
Construction		84,357		1.6
Outsourcing Services		35,184		0.6
Industrial Distribution		16,014		0.3
		1,514,806		28.0
> Consumer Goods & Services
Retail		294,558		5.4
Casinos & Gaming		152,083		2.8
Food & Beverage		140,706		2.6
Nondurables		107,114		2.0
Other Consumer Services		95,261		1.8
Travel		54,899		1.0
Apparel		37,078		0.7
Educational Services		32,565		0.6
Other Entertainment		30,686		0.5
Restaurants		15,608		0.3
Other Durable Goods		14,720		0.3
Consumer Goods Distribution		692		0.0	*
		975,970		18.0
> Information
Computer Hardware & Related Equipment		227,732		4.2
Business Software		124,004		2.3
Internet Related		114,990		2.1
Mobile Communications		111,845		2.1
Instrumentation		57,973		1.1
Financial Processors		56,730		1.0
Gaming Equipment & Services		39,155		0.7
CATV		26,296		0.5
Computer Services		24,114		0.4
Electronics Distribution		19,236		0.4
Semiconductors & Related Equipment		15,933		0.3
Telephone and Data Services		10,711		0.2
Advertising		5,238		0.1
		833,957		15.4
> Energy & Minerals
Mining		240,212		4.4
Oil Services		211,799		3.9
Oil & Gas Producers		134,161		2.5
Agricultural Commodities		53,083		1.0
Oil Refining, Marketing & Distribution		35,263		0.6
		674,518		12.4

	Value (000)			Percentage of Net Assets
> Other Industries
Real Estate	$	337,850			6.2
Transportation		123,625			2.3
Regulated Utilities		66,996			1.2
		528,471			9.7
> Finance
Brokerage & Money Management		127,747			2.3
Banks		101,684			1.9
Insurance		85,217			1.6
Finance Companies		79,073			1.5
		393,721			7.3
> Health Care
Medical Equipment & Devices		120,934			2.2
Pharmaceuticals		87,486			1.6
Medical Supplies		42,563			0.8
Biotechnology & Drug Delivery		42,284			0.8
Health Care Services		30,482			0.6
		323,749			6.0
Total Equities:		5,245,192			96.8
Securities Lending Collateral:		99,418			1.8
Total Investments:		5,344,610			98.6
Obligation to Return Collateral for Securities Loaned:		(99,418	)		(1.8	)
Cash and Other Assets Less Liabilities:		171,761			3.2
Net Assets:	$	5,416,953			100.0

* Rounds to less than 0.1%.

See accompanying notes to financial statements.

Columbia Acorn USA

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Information
Boingo Wireless		0		400,000
Hittite Microwave		0		50,000
II-VI		1,238,000		1,317,000
Monolithic Power Systems		346,000		426,000
NetSuite		184,000		281,000
Syntel		0		97,000
Velti		0		400,000
Industrial Goods & Services
Fortune Brands Home & Security		0		200,000
Middleby Corp		0		18,627
Moog		280,000		355,000
Toro		136,800		166,219
Finance
Allied World Holdings		0		55,000
Associated Banc-Corp		623,000		923,000
City National		70,000		144,000
Eaton Vance		209,500		340,500
H&E Equipment Services		201,000		397,172
TrustCo Bank		595,300		764,100
Health Care
Akorn		796,500		812,100
Auxilium Pharmaceuticals		375,000		400,300
Hill-Rom Holdings		84,007		268,000
Micromet		810,000		843,689
NPS Pharmaceuticals		840,000		1,055,000
Seattle Genetics		495,000		682,000
Energy & Minerals
Oasis Petroleum		22,800		107,800
Petroleum Development Corporation		0		57,184

	Number of Shares
	09/30/11		12/31/11
Sales
Information
IPG Photonics		678,000		525,000
Polycom		460,000		330,000
Quality Systems		52,000		0
tw telecom		1,617,000		1,457,000
Consumer Goods & Services
Diamond Foods		197,000		72,000
lululemon athletica		780,000		730,000
Penn National Gaming		69,000		0
Thor Industries		162,000		0
Finance
Aaron's		412,500		231,320
Financial Engines		173,000		0
MF Global		675,000		0
Health Care
Alexion Pharmaceuticals		370,000		275,000
Neogen		49,000		0
Onyx Pharmaceuticals		178,000		160,000
Energy & Minerals
Atwood Oceanics		803,000		725,000
Bristow		86,000		0
FMC Technologies		1,000,000		844,600
Houston American Energy		368,200		300,000
Northern Oil & Gas		230,000		115,000
Quicksilver Resources		1,135,000		773,400

See accompanying notes to financial statements.

Columbia Acorn USA

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 99.7%
Information 31.1%
		> Business Software 9.7%
	910,000	Informatica (a)	$	33,606
		Enterprise Data Integration Software
	698,000	Micros Systems (a)		32,513
		Information Systems for Hotels, Restaurants and Retailers
	375,000	Ansys (a)		21,480
		Simulation Software for Engineers and Designers
	243,000	Concur Technologies (a)		12,342
		Web Enabled Cost & Expense Management Software
	408,000	Ariba (a)		11,457
		Cost Management Software
	281,000	NetSuite (a)		11,394
		End to End IT Systems Solution Delivered Over the Web
	322,000	SPS Commerce (a)		8,356
		Supply Chain Management Software Delivered via the Web
	300,000	Blackbaud		8,310
		Software & Services for Non-Profits
	198,000	Advent Software (a)		4,823
		Asset Management & Trading Systems
	198,000	Constant Contact (a)(b)		4,596
		E-mail & Other Marketing Campaign Mgmt Systems Delivered Over the Web
	400,000	Velti (a)		2,720
		Mobile Marketing Software Platform
				151,597
		> Computer Hardware & Related Equipment 3.7%
	1,317,000	II-VI (a)		24,180
		Laser Optics and Specialty Materials
	292,000	Zebra Technologies (a)		10,448
		Bar Code Printers
	252,000	Nice Systems - ADR (Israel) (a)		8,681
		Audio & Video Recording Solutions
	159,000	Amphenol		7,217
		Electronic Connectors
	196,000	Netgear (a)		6,580
		Networking Products for Small Business & Home
				57,106
		> Semiconductors & Related Equipment 3.4%
	1,958,000	Atmel (a)		15,860
		Microcontrollers, Radio Frequency, and Memory Semiconductors
	690,000	Microsemi (a)		11,557
		Analog/Mixed-signal Semiconductors
	1,061,750	ON Semiconductor (a)		8,197
		Mixed-signal & Power Management Semiconductors
	426,000	Monolithic Power Systems (a)		6,420
		High Performance Analog & Mixed-signal Integrated Circuits (ICs)
	1,075,000	TriQuint Semiconductor (a)		5,235
		Radio Frequency Semiconductors

Number of Shares			Value (000)
	390,000	Pericom Semiconductor (a)	$	2,968
		Interface Integrated Circuits (ICs) & Frequency Control Products
	50,000	Hittite Microwave (a)		2,469
		Radio Frequency, Microwave & Millimeterwave Semiconductors
				52,706
		> Instrumentation 3.3%
	180,000	Mettler Toledo (a)		26,588
		Laboratory Equipment
	525,000	IPG Photonics (a)		17,782
		Fiber Lasers
	168,000	Trimble Navigation (a)		7,291
		GPS-based Instruments
				51,661
		> Telephone and Data Services 2.8%
	1,457,000	tw telecom (a)		28,236
		Fiber Optic Telephone/Data Services
	192,800	AboveNet (a)		12,534
		Metropolitan Fiber Communications Services
	400,000	Boingo Wireless (a)		3,440
		Wholesale and Retail WiFi Networks
				44,210
		> Telecommunications Equipment 2.1%
	732,000	Finisar (a)		12,257
		Optical Sub-systems and Components
	903,000	Ixia (a)		9,490
		Telecom Network Test Equipment
	330,000	Polycom (a)		5,379
		Video Conferencing Equipment
	752,000	Infinera (a)		4,723
		Optical Networking Equipment
				31,849
		> Gaming Equipment & Services 2.0%
	660,000	Bally Technologies (a)		26,110
		Slot Machines & Software
	235,000	WMS Industries (a)		4,822
		Slot Machine Provider
				30,932
		> Mobile Communications 1.5%
	560,000	SBA Communications (a)		24,058
		Communications Towers
				24,058
		> Computer Services 1.5%
	556,000	ExlService Holdings (a)		12,438
		Business Process Outsourcing
	97,000	Syntel		4,537
		Offshore IT Services
	905,500	Hackett Group (a)		3,386
		IT Integration & Best Practice Research
	640,000	RCM Technologies (a)(c)		3,315
		Technology & Engineering Services
				23,676

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Financial Processors 0.5%
	170,000	Global Payments	$	8,055
		Credit Card Processor
				8,055
		> Contract Manufacturing 0.4%
	236,000	Plexus (a)		6,462
		Electronic Manufacturing Services
				6,462
		> TV Broadcasting 0.1%
	875,000	Entravision Communications		1,365
		Spanish Language TV & Radio Stations
				1,365
		> Radio 0.1%
	460,100	Salem Communications (a)		1,182
		Radio Stations for Religious Programming
				1,182
		> Internet Related —%
	20,000	TheStreet.com		34
		Financial Information Websites
				34
Information: Total				484,893
Industrial Goods & Services 17.5%
		> Machinery 13.0%
	941,250	Ametek		39,627
		Aerospace/Industrial Instruments
	747,200	Nordson		30,770
		Dispensing Systems for Adhesives & Coatings
	445,000	Donaldson		30,296
		Industrial Air Filtration
	835,000	ESCO Technologies		24,031
		Automatic Electric Meter Readers
	504,665	HEICO		19,858
		FAA Approved Aircraft Replacement Parts
	585,000	Pentair		19,475
		Pumps & Water Treatment
	355,000	Moog (a)		15,595
		Motion Control Products for Aerospace, Defense & Industrial Markets
	166,219	Toro		10,083
		Turf Maintenance Equipment
	226,000	Kennametal		8,253
		Consumable Cutting Tools
	146,000	Oshkosh Corporation (a)		3,121
		Specialty Truck Manufacturer
	18,627	Middleby (a)		1,752
		Manufacturer of Cooking Equipment
				202,861
		> Industrial Materials & Specialty Chemicals 1.0%
	496,000	Drew Industries (a)		12,167
		RV & Manufactured Home Components
	170,000	Albany International		3,930
		Paper Machine Clothing and Advanced Textiles
				16,097

Number of Shares			Value (000)
		> Electrical Components 1.0%
	280,000	Acuity Brands	$	14,840
		Commercial Lighting Fixtures
				14,840
		> Other Industrial Services 0.7%
	600,000	Acorn Energy		3,624
		Frac Well Exploration/Monitoring Device, Sonar Security,Electric Grid Monitoring
	109,000	Forward Air		3,494
		Freight Transportation Between Airports
	240,000	TrueBlue (a)		3,331
		Temporary Manual Labor
				10,449
		> Waste Management 0.7%
	176,000	Waste Connections		5,833
		Solid Waste Management
	65,000	Clean Harbors (a)		4,142
		Hazardous Waste Services & Disposal
				9,975
		> Steel 0.6%
	686,000	GrafTech International (a)		9,364
		Industrial Graphite Materials Producer
				9,364
		> Industrial Distribution 0.3%
	315,000	Interline Brands (a)		4,905
		Industrial Distribution
				4,905
		> Construction 0.2%
	200,000	Fortune Brands Home & Security (a)		3,406
		Home Building Supplies & Small Locks
				3,406
Industrial Goods & Services: Total				271,897
Consumer Goods & Services 14.8%
		> Retail 5.5%
	730,000	lululemon athletica (a)		34,062
		Premium Active Apparel Retailer
	468,500	Abercrombie & Fitch		22,881
		Teen Apparel Retailer
	805,000	Pier 1 Imports (a)		11,214
		Home Furnishing Retailer
	790,000	Saks (a)(b)		7,702
		Luxury Department Store Retailer
	289,000	Shutterfly (a)		6,578
		Internet Photo-centric Retailer
	161,500	Teavana (a)(b)		3,033
		Specialty Tea Retailer
	9,000	The Fresh Market (a)		359
		Specialty Food Retailer
				85,829
		> Travel 3.1%
	849,700	Gaylord Entertainment (a)		20,512
		Convention Hotels
	1,175,950	Avis Budget Group (a)		12,606
		Second Largest Car Rental Company

See accompanying notes to financial statements.

Columbia Acorn USA

Statement of Investments, continued

Number of Shares			Value (000)
		> Travel—continued
	750,000	Hertz (a)	$	8,790
		Largest U.S. Rental Car Operator
	140,000	HomeAway (a)(b)		3,255
		Vacation Rental Online Marketplace
	64,000	Vail Resorts		2,711
		Ski Resort Operator & Developer
				47,874
		> Apparel 1.5%
	222,000	Warnaco Group (a)		11,109
		Global Branded Apparel Manufacturer
	81,000	Deckers Outdoor (a)		6,121
		Fashion Footwear Wholesaler
	163,000	True Religion Apparel (a)		5,637
		Premium Denim
				22,867
		> Furniture & Textiles 1.4%
	880,000	Knoll		13,068
		Office Furniture
	540,000	Interface		6,231
		Modular & Broadloom Carpet
	148,000	Herman Miller		2,731
		Office Furniture
				22,030
		> Consumer Goods Distribution 0.9%
	472,000	Pool		14,207
		Distributor of Swimming Pool Supplies & Equipment
				14,207
		> Other Consumer Services 0.8%
	259,000	Lifetime Fitness (a)		12,108
		Sport & Fitness Club Operator
				12,108
		> Other Durable Goods 0.8%
	206,000	Cavco Industries (a)		8,252
		Manufactured Homes
	126,000	Jarden		3,765
		Branded Household Products
				12,017
		> Casinos & Gaming 0.5%
	775,000	Pinnacle Entertainment (a)		7,874
		Regional Casino Operator
				7,874
		> Food & Beverage 0.1%
	72,000	Diamond Foods		2,324
		Snack Foods and Culinary Ingredients
				2,324
		> Educational Services 0.1%
	37,350	ITT Educational Services (a)(b)		2,125
		Post-secondary Degree Services
				2,125

Number of Shares			Value (000)
		> Leisure Products 0.1%
	140,000	Skullcandy (a)(b)	$	1,753
		Lifestyle Branded Headphones
				1,753
Consumer Goods & Services: Total				231,008
Finance 11.9%
		> Banks 6.2%
	431,597	Lakeland Financial		11,165
		Indiana Bank
	923,000	Associated Banc-Corp		10,310
		Midwest Bank
	278,678	Hancock Holding		8,909
		Gulf Coast Bank
	675,000	Valley National Bancorp (b)		8,350
		New Jersey/New York Bank
	480,000	MB Financial		8,208
		Chicago Bank
	170,000	SVB Financial Group (a)		8,107
		Bank to Venture Capitalists
	1,478,200	First Busey		7,391
		Illinois Bank
	144,000	City National		6,362
		Bank & Asset Manager
	594,000	TCF Financial		6,130
		Great Lakes Bank
	513,755	Pacific Continental Bank		4,547
		Pacific Northwest Bank
	764,100	TrustCo Bank		4,287
		New York State Bank
	269,600	Eagle Bancorp (a)		3,920
		Metro D.C. Bank
	178,826	Sandy Spring Bancorp		3,138
		Baltimore, D.C. Bank
	210,000	CVB Financial (b)		2,106
		Inland Empire Business Bank
	90,000	TriCo Bancshares		1,280
		California Central Valley Bank
	851,247	Guaranty Bancorp (a)		1,251
		Colorado Bank
	26,935	Hudson Valley		572
		Metro New York City Bank
				96,033
		> Finance Companies 3.8%
	345,000	World Acceptance (a)		25,357
		Personal Loans
	345,000	Textainer Group Holdings		10,046
		Top International Container Leasor
	231,320	Aaron's		6,172
		Rent to Own
	210,000	McGrath Rentcorp		6,088
		Temporary Space & IT Rentals
	397,172	H&E Equipment Services (a)		5,330
		Heavy Equipment Leasing

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Finance Companies—continued
	330,000	CAI International (a)	$	5,102
		International Container Leasing
	100,000	Marlin Business Services		1,270
		Small Equipment Leasing
				59,365
		> Savings & Loans 0.9%
	602,487	ViewPoint Financial		7,838
		Texas Thrift
	194,000	Berkshire Hills Bancorp		4,305
		Northeast Thrift
	173,073	Kaiser Federal		2,219
		Los Angeles Savings & Loan
				14,362
		> Brokerage & Money Management 0.5%
	340,500	Eaton Vance		8,050
		Specialty Mutual Funds
				8,050
		> Insurance 0.5%
	39,000	Enstar Group (a)		3,830
		Insurance/Reinsurance & Related Services
	55,000	Allied World Holdings		3,461
		Commercial Lines Insurance/Reinsurance
				7,291
Finance: Total				185,101
Health Care 9.9%
		> Biotechnology & Drug Delivery 4.6%
	520,000	BioMarin Pharmaceutical (a)		17,878
		Biotech Focused on Orphan Diseases
	682,000	Seattle Genetics (a)(b)		11,400
		Antibody-based Therapies for Cancer
	400,300	Auxilium Pharmaceuticals (a)		7,978
		Biotech Focused on Niche Disease Areas
	160,000	Onyx Pharmaceuticals (a)		7,032
		Commercial-stage Biotech Focused on Cancer
	1,055,000	NPS Pharmaceuticals (a)		6,952
		Orphan Drugs & Healthy Royalties
	843,689	Micromet (a)(b)		6,066
		Next-generation Antibody Technology
	643,000	Isis Pharmaceuticals (a)		4,636
		Biotech Pioneer in Anti-sense Drugs
	790,000	Chelsea Therapeutics International (a)		4,053
		Biotech Focused on Rare Diseases
	313,000	InterMune (a)		3,944
		Drugs for Pulmonary Fibrosis & Hepatitis C
	265,000	Anthera Pharmaceuticals (a)		1,627
		Biotech Focused on Cardiovascular, Cancer & Immunology
	18,181	Metabolex (a)(d)(e)		27
		Diabetes Drug Development
				71,593
		> Medical Equipment & Devices 3.0%
	275,000	Alexion Pharmaceuticals (a)		19,662
		Biotech Focused on Orphan Diseases
	224,000	Sirona Dental Systems (a)		9,865
		Manufacturer of Dental Equipment

Number of Shares			Value (000)
	268,000	Hill-Rom Holdings	$	9,029
		Hospital Beds/Patient Handling
	126,000	Gen-Probe (a)		7,449
		Molecular In-vitro Diagnostics
				46,005
		> Medical Supplies 1.0%
	439,600	Cepheid (a)		15,127
		Molecular Diagnostics
				15,127
		> Health Care Services 0.7%
	738,900	Health Management Associates (a)		5,446
		Non-urban Hospitals
	205,000	HealthSouth (a)		3,622
		Inpatient Rehabalitation Facilities
	151,000	Community Health Systems (a)		2,635
		Non-Urban Hospitals
				11,703
		> Pharmaceuticals 0.6%
	812,100	Akorn (a)		9,031
		Develops, Manufactures & Sells Specialty Generic Drugs
	150,000	Horizon Pharma (a)(b)		600
		Specialty Pharma Company
	133,180	Alimera Sciences (a)(b)		166
		Ophthalmology-focused Pharmaceutical Company
				9,797
Health Care: Total				154,225
Energy & Minerals 8.0%
		> Oil Services 4.7%
	844,600	FMC Technologies (a)		44,113
		Oil & Gas Wellhead Manufacturer
	725,000	Atwood Oceanics (a)		28,848
		Offshore Drilling Contractor
				72,961
		> Oil & Gas Producers 2.4%
	133,000	SM Energy		9,722
		Oil and Gas Producer
	143,000	Rosetta Resources (a)		6,220
		Oil and Gas Producer Exploring in South Texas and Montana
	773,400	Quicksilver Resources (a)		5,189
		Natural Gas and Coal Steam Gas Producer
	168,000	Swift Energy (a)		4,993
		Oil and Gas Exploration and Production
	300,000	Houston American Energy (a)(b)		3,657
		Oil and Gas Exploration/Production in Colombia
	107,800	Oasis Petroleum (a)		3,136
		Oil Producer in North Dakota
	115,000	Northern Oil & Gas (a)(b)		2,758
		Small E&P Company in North Dakota Bakken
	57,184	Petroleum Development Corporation (a)		2,008
		Oil & Gas Producer in U.S.
				37,683
		> Mining 0.9%
	85,000	Core Laboratories (Netherlands)		9,686
		Oil & Gas Reservoir Consulting

See accompanying notes to financial statements.

Columbia Acorn USA

Statement of Investments, continued

Number of Shares			Value (000)
		> Mining—continued
	600,000	Alexco Resource (a)	$	4,086
		Mining, Exploration & Environmental Services
	180,000	Augusta Resource (a)		558
		U.S. Copper/Molybdenum Mine
				14,330
Energy & Minerals: Total				124,974
Other Industries 6.5%
		> Real Estate 5.1%
	915,000	Extra Space Storage		22,170
		Self Storage Facilities
	739,200	BioMed Realty Trust		13,365
		Life Science-focused Office Buildings
	600,000	Associated Estates Realty		9,570
		Multi-family Properties
	870,000	Education Realty Trust		8,900
		Student Housing
	1,380,000	Kite Realty Group		6,224
		Community Shopping Centers
	159,000	Kilroy Realty		6,053
		West Coast Office and Industrial Properties
	958,000	DCT Industrial Trust		4,905
		Industrial Properties
	191,000	DuPont Fabros Technology (b)		4,626
		Technology-focused Office Buildings
	100,000	Post Properties		4,372
		Multifamily Properties
				80,185
		> Transportation 1.4%
	256,000	World Fuel Services		10,747
		Global Fuel Broker
	410,091	Rush Enterprises, Class A (a)		8,579
	115,000	Rush Enterprises, Class B (a)		1,975
		Truck Sales and Service
				21,301
Other Industries: Total				101,486
Total Equities: 99.7% (Cost: $1,151,332)				1,553,584

Number of Shares			Value (000)
Securities Lending Collateral 2.2%
	34,671,363	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (f)	$	34,671
Total Securities Lending Collateral: (Cost: $34,671)				34,671
Total Investments: 101.9% (Cost: $1,186,003)(g)(h)				1,588,255
Obligation to Return Collateral for Securities Loaned: (2.2)%				(34,671	)
Cash and Other Assets Less Liabilities: 0.3%				4,861
Total Net Assets: 100.0%			$	1,558,445

ADR - American Depositary Receipts

> 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, 2011. The total market value of securities on loan at December 31, 2011 was $33,589.

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
RCM Technologies		710,000		-		70,000		640,000	$	3,315	$	-
Total of Affiliated Transactions		710,000		-		70,000		640,000	$	3,315	$	-

See accompanying notes to financial statements.

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

The aggregate cost and value of this company at December 31, 2011, were $3,624 and $3,315, respectively. Investments in affiliated companies represented 0.21% of the Fund's total net assets at December 31, 2011.

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	$	27
				$	2,000	$	27

(e) Illiquid security.

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

(g) On December 31, 2011, the market value of foreign securities represented 1.18% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percent
Netherlands	$	9,686		0.62
Israel		8,681		0.56
Total Foreign Portfolio	$	18,367		1.18

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	484,893	$	-	$	-	$	484,893
Industrial Goods & Services		271,897		-		-		271,897
Consumer Goods & Services		231,008		-		-		231,008
Finance		185,101		-		-		185,101
Health Care		154,198		-		27		154,225
Energy & Minerals		124,974		-		-		124,974
Other Industries		101,486		-		-		101,486
Total Equities		1,553,557		-		27		1,553,584
Total Securities Lending Collateral		34,671		-		-		34,671
Total Investments	$	1,588,228	$	-	$	27	$	1,588,255

See accompanying notes to financial statements.

Columbia Acorn USA

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, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)			Change in Unrealized Appreciation (Depreciation)		Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Equities
Health Care	$	20	$	(1,556	)	$	1,563	$	-	$	-	$	-	$	-	$	27
	$	20	$	(1,556	)	$	1,563	$	-	$	-	$	-	$	-	$	27

The change in unrealized appreciation attributed to securities owned at December 31, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $9.

See accompanying notes to financial statements.

Columbia Acorn International Select

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Asia
> Singapore
Mapletree Industrial Trust		19,420,000		20,395,000
> Taiwan
CTCI Corp		0		2,789,400
Taiwan Mobile		0		1,179,000
> Indonesia
Archipelago Resources		6,886,399		8,808,000
Europe
> Netherlands
Imtech		235,519		277,519
Other Countries
> South Africa
Rand Merchant Insurance		7,209,798		7,415,000

	Number of Shares
	09/30/11		12/31/11
Sales
Asia
> Taiwan
Far Eastone Telecom		11,208,400		11,103,000
> China
Jiangsu Expressway		4,170,000		0
Zhaojin Mining Industry		6,276,000		4,146,000
> Korea
NHN		52,000		48,500
Europe
> United Kingdom
Chemring		1,480,000		810,000
Cobham		616,000		0
Intertek Group		312,000		210,000
JLT Group		1,014,600		665,000
Serco		850,000		659,000
Workspace Group		1,304,000		897,000
> Germany
Rheinmetall		115,500		109,500
Rhoen-Klinikum		270,000		175,000
> Netherlands
Aalberts Industries		242,103		0
AkzoNobel		166,000		0
Fugro		115,821		0
> Switzerland
Kuehne & Nagel		49,000		28,000
> Ireland
United Drug		1,930,000		1,329,400
> France
Neopost		32,657		0
Other Countries
> South Africa
Naspers		88,700		80,700
Latin America
> Colombia
Pacific Rubiales Energy		260,000		0

See accompanying notes to financial statements.

Columbia Acorn International Select

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 94.8%
Asia 50.6%
		> Japan 17.9%
	2,100,000	Kansai Paint	$	18,704
		Paint Producer in Japan, India, China and Southeast Asia
	6,753,000	Seven Bank		13,215
		ATM Processing Services
	8,970	Jupiter Telecommunications		9,080
		Largest Cable Service Provider in Japan
	528,000	Asahi Diamond Industrial		6,353
		Consumable Diamond Tools
	181,000	Gree		6,222
		Mobile Social Networking Game Developer/ Platform
	105,000	Ain Pharmaciez		5,053
		Dispensing Pharmacy/Drugstore Operator
				58,627
		> Singapore 13.1%
	13,130,000	Ascendas REIT		18,540
		Singapore Industrial Property Landlord
	20,395,000	Mapletree Industrial Trust		16,899
		Singapore Industrial Property Landlord
	11,142,000	Mapletree Logistics Trust		7,252
		Industrial Property Landlord
				42,691
		> Taiwan 8.7%
	11,103,000	Far Eastone Telecom		20,857
		Taiwan's 3rd Largest Mobile Operator
	2,789,400	CTCI Corp		3,801
		International Engineering Firm
	1,179,000	Taiwan Mobile		3,673
		Taiwan's 2nd Largest Mobile Operator
				28,331
		> China 4.2%
	4,146,000	Zhaojin Mining Industry		6,576
		Gold Mining and Refining in China
	84,000	NetEase.com - ADR (a)		3,767
		Chinese Online Gaming Services
	3,361,000	Want Want		3,348
		Chinese Branded Consumer Food Company
				13,691
		> Korea 3.8%
	48,500	NHN (a)		8,889
		Korean Online Search Services
	111,000	Woongjin Coway (a)		3,535
		South Korean Household Appliance Rental Service Provider
				12,424
		> Indonesia 2.9%
	8,808,000	Archipelago Resources (a)		9,456
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
				9,456
Asia: Total				165,220

Number of Shares			Value (000)
Europe 28.5%
		> United Kingdom 9.2%
	665,000	JLT Group (b)	$	7,121
		International Business Insurance Broker
	210,000	Intertek Group		6,637
		Testing, Inspection & Certification Services
	810,000	Chemring		5,030
		Defense Manufacturer of Countermeasures & Energetics
	659,000	Serco		4,851
		Facilities Management
	897,000	Workspace Group		3,145
		United Kingdom Real Estate
	432,000	Shaftesbury		3,134
		London Prime Retail REIT
				29,918
		> Germany 5.6%
	630,000	Wirecard		10,127
		Online Payment Processing & Risk Management
	109,500	Rheinmetall		4,852
		Defense & Automotive
	175,000	Rhoen-Klinikum		3,334
		Health Care Services
				18,313
		> Netherlands 3.3%
	277,519	Imtech (b)		7,189
		Electromechanical & ICT Installation & Maintenance
	32,000	Core Laboratories		3,646
		Oil & Gas Reservoir Consulting
				10,835
		> Sweden 3.0%
	658,666	Hexagon		9,848
		Design, Measurement & Visualization Software & Equipment
				9,848
		> Switzerland 2.2%
	24,000	Partners Group		4,188
		Private Markets Asset Management
	28,000	Kuehne & Nagel		3,145
		Freight Forwarding/Logistics
				7,333
		> Iceland 1.5%
	4,800,000	Marel (a)		4,910
		Largest Manufacturer of Poultry & Fish Processing Equipment
				4,910
		> Denmark 1.4%
	145,000	Novozymes		4,476
		Industrial Enzymes
				4,476
		> Belgium 1.2%
	74,000	EVS Broadcast Equipment		3,782
		Digital Live Mobile Production Software and Systems
				3,782

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Ireland 1.1%
	1,329,400	United Drug	$	3,527
		Irish Pharmaceutical Wholesaler & Outsourcer
				3,527
Europe: Total				92,942
Other Countries 14.9%
		> South Africa 7.7%
	7,415,000	Rand Merchant Insurance		12,308
		Directly Sold Property and Casualty Insurance; Holdings in Other Insurers
	1,220,200	Adcock Ingram Holdings		9,334
		Manufacturer of Pharmaceuticals and Medical Supplies
	80,700	Naspers		3,531
		Media in Africa, China, Russia & Other Emerging Markets
				25,173
		> Canada 3.4%
	210,400	CCL Industries		6,466
		Leading Global Label Manufacturer
	125,000	AG Growth		4,599
		Leading Manufacturer of Augers and Grain Handling Equipment
				11,065
		> United States 2.3%
	52,000	SM Energy		3,800
		Oil and Gas Producer
	94,000	Atwood Oceanics (a)		3,740
		Offshore Drilling Contractor
				7,540
		> Israel 1.5%
	460,000	Israel Chemicals		4,768
		Producer of Potash, Phosphates, Bromine & Specialty Chemicals
				4,768
Other Countries: Total				48,546
Latin America 0.8%
		> Argentina 0.6%
	183,333	Union Agriculture Group (a)(c)(d)		1,828
		Farmland Operator in Uruguay
				1,828
		> Colombia 0.2%
	18,800,000	Quetzal Energy (a)(c)		709
		Explores for Oil & Gas in Latin America
				709
Latin America: Total				2,537
Total Equities: 94.8% (Cost: $277,416)				309,245

Number of Shares			Value (000)
Securities Lending Collateral 1.2%
	3,949,607	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (e)	$	3,950
Total Securities Lending Collateral: (Cost: $3,950)				3,950
Total Investments: 96.0% (Cost: $281,366)(f)(g)				313,195
Obligation to Return Collateral for Securities Loaned: (1.2)%				(3,950	)
Cash and Other Assets Less Liabilities: 5.2%				17,138
Total Net Assets: 100.0%			$	326,383

See accompanying notes to financial statements.

Columbia Acorn International 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, 2011. The total market value of securities on loan at December 31, 2011 was $3,850.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost (000)		Value (000)
Union Agriculture Group	12/8/10-12/16/11		183,333	$	2,200	$	1,828
Quetzal Energy	1/14/11		18,800,000		2,376		709
				$	4,576	$	2,537

(d) Illiquid security.

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

(f) On December 31, 2011, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Japanese Yen	$	58,627		18.0
Singapore Dollar		42,691		13.1
Pound Sterling		39,374		12.1
Euro		32,811		10.0
Taiwan Dollar		28,331		8.7
South African Rand		25,173		7.7
U.S. Dollar		20,732		6.3
Other currencies less than 5% of total net assets		65,456		20.1
	$	313,195		96.0

At December 31, 2011, 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 Depreciation
USD				ZAR					169,376			$	20,000			1/13/12				$	(948	)

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

USD = United States Dollar

ZAR = South African Rand

Fair Value Measurements

• 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)

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

See accompanying notes to financial statements.

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	3,767	$	161,453		$	-	$	165,220
Europe		3,646		89,296			-		92,942
Other Countries		18,605		29,941			-		48,546
Latin America		-		709			1,828		2,537
Total Equities		26,018		281,399			1,828		309,245
Total Securities Lending Collateral		3,950		-			-		3,950
Total Investments	$	29,968	$	281,399		$	1,828	$	313,195
Unrealized Depreciation on Forward Foreign Currency Exchange Contracts		-		(948	)		-		(948	)
Total	$	29,968	$	280,451		$	1,828	$	312,247

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, in accordance with the policy adopted by the Board of Trustees, 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.

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, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Latin America
Argentina	$	2,200	$	-	$	(372	)	$	-	$	-	$	-	$	-	$	1,828
	$	2,200	$	-	$	(372	)	$	-	$	-	$	-	$	-	$	1,828

The change in unrealized depreciation attributed to securities owned at December 31, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $(372).

See accompanying notes to financial statements.

Columbia Acorn International Select

Portfolio Diversification

At December 31, 2011, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value (000)		Percentage of Net Assets
> Information
Mobile Communications	$	24,530		7.5
Internet Related		16,187		5.0
Financial Processors		10,127		3.1
Business Software		9,848		3.0
CATV		9,080		2.8
Gaming Equipment & Services		6,222		1.9
Computer Hardware & Related Equipment		3,782		1.2
		79,776		24.5
> Industrial Goods & Services
Industrial Materials & Specialty Chemicals		27,948		8.6
Machinery		20,714		6.4
Other Industrial Services		16,971		5.2
Electrical Components		5,030		1.5
Outsourcing Services		4,851		1.5
Construction		3,801		1.1
		79,315		24.3
> Other Industries
Real Estate		48,970		15.0
> Finance
Insurance		19,429		6.0
Banks		13,215		4.0
Brokerage & Money Management		4,188		1.3
		36,832		11.3
> Energy & Minerals
Mining		19,678		6.0
Oil & Gas Producers		4,509		1.4
Oil Services		3,740		1.1
Agricultural Commodities		1,828		0.6
		29,755		9.1

	Value (000)			Percentage of Net Assets
> Consumer Goods & Services
Nondurables	$	6,466			2.0
Retail		5,053			1.5
Other Consumer Services		3,535			1.1
Food & Beverage		3,348			1.0
		18,402			5.6
> Health Care
Pharmaceuticals		12,861			4.0
Health Care Services		3,334			1.0
		16,195			5.0
Total Equities:		309,245			94.8
Securities Lending Collateral:		3,950			1.2
Total Investments:		313,195			96.0
Obligation to Return Collateral for Securities Loaned		(3,950	)		(1.2	)
Cash and Other Assets Less Liabilities:		17,138			5.2
Net Assets:	$	326,383			100.0

See accompanying notes to financial statements.

Columbia Acorn Select

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Consumer Goods & Services
IFM Investments (Century 21 China RE) - ADR (China)		2,946,537		3,430,000
Information
Atmel		0		825,000
Globalstar		12,000,000		13,184,322
SBA Communications		730,000		1,100,000
VisionChina Media - ADR (China)		2,573,400		7,000,000
Finance
City National		0		630,000
Energy & Minerals
Continental Resources		0		65,000
Health Care
NPS Pharmaceuticals		2,200,000		2,600,000

	Number of Shares
	09/30/11		12/31/11
Sales
Consumer Goods & Services
Abercrombie & Fitch		950,000		830,000
Coach		875,000		650,000
Hertz		7,525,000		6,625,000
ITT Educational Services		315,000		300,000
lululemon athletica		565,000		417,900
Safeway		2,625,000		2,000,000
Skullcandy		266,300		0
Tiffany & Co.		240,000		200,000
Industrial Goods & Services
Ametek		1,660,000		1,550,000
Donaldson		735,000		700,000
Expeditors International of Washington		685,000		620,000
Kennametal		1,085,000		1,035,000
Pall		790,000		740,000
Quanta Services		1,500,000		1,470,000
Waste Management		650,000		500,000
Information
Amphenol		700,000		670,000
Crown Castle International		1,360,000		825,000
Finisar		324,000		0
Sanmina-SCI		6,275,000		6,100,000
WNS - ADR (India)		4,276,336		4,254,230
Finance
CNO Financial Group		11,650,000		9,100,000
Discover Financial Services		3,800,000		3,225,000
MF Global		4,900,000		0
SEI Investments		1,050,000		1,000,000
Energy & Minerals
Canacol (Colombia)		33,500,000		31,372,300
Eacom Timber (Canada)		38,000,000		36,000,000
Houston American Energy		1,309,500		1,060,000
Kirkland Lake Gold (Canada)		950,000		900,000
Pacific Rubiales Energy (Colombia)		2,255,000		2,150,000
Petrodorado (Colombia)		34,856,000		34,700,000
Other Industries
BioMed Realty Trust		1,800,000		1,720,000
JB Hunt Transport Services		1,140,000		115,000
Health Care
Horizon Pharma		195,000		0

See accompanying notes to financial statements.

Columbia Acorn Select

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 99.7%
Consumer Goods & Services 23.1%
		> Retail 9.0%
	2,000,000	Safeway	$	42,080
		Supermarkets
	830,000	Abercrombie & Fitch		40,537
		Teen Apparel Retailer
	417,900	lululemon athletica (a)(b)		19,500
		Premium Active Apparel Retailer
	200,000	Tiffany & Co.		13,252
		Luxury Good Retailer
				115,369
		> Travel 8.0%
	6,625,000	Hertz (a)		77,645
		Largest U.S. Rental Car Operator
	1,060,000	Gaylord Entertainment (a)		25,588
		Convention Hotels
				103,233
		> Apparel 3.1%
	650,000	Coach		39,676
		Designer & Retailer of Branded Leather Accessories
				39,676
		> Casinos & Gaming 1.5%
	300,000,000	RexLot Holdings (China)		19,637
		Lottery Equipment Supplier in China
				19,637
		> Educational Services 1.3%
	300,000	ITT Educational Services (a)(b)		17,067
		Post-secondary Degree Services
				17,067
		> Food & Beverage 0.1%
	1,850,000	GLG Life Tech (Canada) (a)(b)(c)		1,665
		Produce an All-Natural Sweetener Extracted from the Stevia Plant
				1,665
		> Other Consumer Services 0.1%
	3,430,000	IFM Investments (Century 21 China RE) - ADR (China) (a)(c)		1,098
		Provide Real Estate Services in China
				1,098
Consumer Goods & Services: Total				297,745
Industrial Goods & Services 23.0%
		> Machinery 15.4%
	1,550,000	Ametek		65,255
		Aerospace/Industrial Instruments
	700,000	Donaldson		47,656
		Industrial Air Filtration
	740,000	Pall		42,291
		Filtration & Fluids Clarification
	1,035,000	Kennametal		37,798
		Consumable Cutting Tools
	250,000	Oshkosh Corporation (a)		5,345
		Specialty Truck Manufacturer
				198,345

Number of Shares			Value (000)
		> Outsourcing Services 2.4%
	1,470,000	Quanta Services (a)	$	31,664
		Electrical & Telecom Construction Services
				31,664
		> Other Industrial Services 2.0%
	620,000	Expeditors International of Washington		25,395
		International Freight Forwarder
				25,395
		> Industrial Distribution 1.9%
	135,000	WW Grainger		25,271
		Industrial Distribution
				25,271
		> Waste Management 1.3%
	500,000	Waste Management		16,355
		U.S. Garbage Collection & Disposal
				16,355
Industrial Goods & Services: Total				297,030
Information 20.0%
		> Mobile Communications 7.1%
	1,100,000	SBA Communications (a)		47,256
		Communications Towers
	825,000	Crown Castle International (a)		36,960
		Communications Towers
	13,184,322	Globalstar (a)(b)		7,120
		Satellite Mobile Voice & Data Carrier
				91,336
		> Contract Manufacturing 4.4%
	6,100,000	Sanmina-SCI (a)(c)		56,791
		Electronic Manufacturing Services
				56,791
		> Computer Services 3.0%
	4,254,230	WNS - ADR (India) (a)(c)		38,246
		Offshore BPO (Business Process Outsourcing) Services
				38,246
		> Computer Hardware & Related Equipment 2.3%
	670,000	Amphenol		30,411
		Electronic Connectors
				30,411
		> Instrumentation 1.3%
	110,000	Mettler Toledo (a)		16,248
		Laboratory Equipment
				16,248
		> Business Software 0.7%
	182,000	Concur Technologies (a)		9,244
		Web Enabled Cost & Expense Management Software
				9,244
		> Advertising 0.7%
	7,000,000	VisionChina Media - ADR (China) (a)(c)		8,680
		Advertising on Digital Screens in China's Mass Transit System
				8,680

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Semiconductors & Related Equipment 0.5%
	825,000	Atmel (a)	$	6,682
		Microcontrollers, Radio Frequency, and Memory Semiconductors
				6,682
Information: Total				257,638
Finance 13.9%
		> Credit Cards 6.0%
	3,225,000	Discover Financial Services		77,400
		Credit Card Company
				77,400
		> Insurance 4.4%
	9,100,000	CNO Financial Group (a)		57,421
		Life, Long-term Care & Medical Supplement Insurance
				57,421
		> Banks 2.2%
	630,000	City National		27,833
		Bank & Asset Manager
				27,833
		> Brokerage & Money Management 1.3%
	1,000,000	SEI Investments		17,350
		Mutual Fund Administration & Investment Management
				17,350
Finance: Total				180,004
Energy & Minerals 12.8%
		> Oil & Gas Producers 8.4%
	2,150,000	Pacific Rubiales Energy (Colombia) (b)		39,528
		Oil Production & Exploration in Colombia
	31,372,300	Canacol (Colombia) (a)(c)		23,712
		Oil Producer in South America
	1,060,000	Houston American Energy (a)(b)		12,921
		Oil and Gas Exploration/Production in Colombia
	36,500,000	ShaMaran Petroleum (Iraq) (a)		12,719
		Oil Exploration in Kurdistan
	24,000,000	Canadian Overseas Petroleum (United Kingdom) (a)(c)(d)		7,965
	12,000,000	Canadian Overseas Petroleum - Warrants (United Kingdom) (a)(d)(e)		948
		Oil & Gas Exploration/Production in the North Sea
	34,700,000	Petrodorado (Colombia) (a)(c)		6,983
	17,144,000	Petrodorado - Warrants (Colombia) (a)(d)(e)		639
		Oil & Gas Exploration/Production in Colombia, Peru & Paraguay
	18,125,000	Petromanas (Canada) (a)		2,758
	6,562,500	Petromanas - Warrants (Canada) (a)(d)		48
		Exploring for Oil in Albania
				108,221
		> Agricultural Commodities 1.5%
	1,666,667	Union Agriculture Group (Argentina) (a)(d)(e)		16,617
		Farmland Operator in Uruguay

Number of Shares			Value (000)
	36,000,000	Eacom Timber (Canada) (a)(c)	$	2,473
		Canadian Lumber Producer
				19,090
		> Mining 1.4%
	900,000	Kirkland Lake Gold (Canada) (a)		13,623
		Gold Mining
	65,000	Continental Resources (a)		4,336
		Oil & Gas Producer in U.S.
				17,959
		> Alternative Energy 1.0%
	2,700,000	Canadian Solar (China) (a)(b)(c)		7,182
		Solar Cell & Module Manufacturer
	2,950,372	Synthesis Energy Systems (China) (a)(b)(c)		4,573
		Owner/Operator of Gasification Plants
	1,500,000	Real Goods Solar (a)(c)		2,145
		Residential Solar Energy Installer
				13,900
		> Oil Services 0.5%
	10,600,000	Tuscany International Drilling (Colombia) (a)		6,243
		South America Based Drilling Rig Contractor
				6,243
Energy & Minerals: Total				165,413
Other Industries 4.0%
		> Real Estate 2.4%
	1,720,000	BioMed Realty Trust		31,098
		Life Science-focused Office Buildings
				31,098
		> Regulated Utilities 1.2%
	450,000	Wisconsin Energy		15,732
		Wisconsin Utility
				15,732
		> Transportation 0.4%
	115,000	JB Hunt Transport Services		5,183
		Truck & Intermodal Carrier
				5,183
Other Industries: Total				52,013
Health Care 2.9%
		> Pharmaceuticals 1.6%
	1,802,464	Akorn (a)		20,043
		Develops, Manufactures & Sells Specialty Generic Drugs
				20,043
		> Biotechnology & Drug Delivery 1.3%
	2,600,000	NPS Pharmaceuticals (a)		17,134
		Orphan Drugs & Healthy Royalties
				17,134
Health Care: Total				37,177
Total Equities: 99.7% (Cost: $1,099,673)				1,287,020

See accompanying notes to financial statements.

Columbia Acorn Select

Statement of Investments, continued

Number of Shares			Value (000)
Securities Lending Collateral 2.6%
	33,620,749	Dreyfus Government Cash Management Fund (7 day yield of 0.00%) (f)	$	33,621
Total Securities Lending Collateral: (Cost: $33,621)				33,621
Total Investments: 102.3% (Cost: $1,133,294)(g)(h)				1,320,641
Obligation to Return Collateral for Securities Loaned: (2.6)%				(33,621	)
Cash and Other Assets Less Liabilities: 0.3%				3,601
Total Net Assets: 100.0%			$	1,290,621

ADR - American Depositary Receipts

> 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, 2011. The total market value of securities on loan at December 31, 2011 was $32,075.

Affiliates	Balance of Shares Held 12/31/10		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 12/31/11		Value		Dividend
Canacol Energy		36,240,000		-		4,867,700		31,372,300	$	23,712	$	-
Canadian Overseas Petroleum+		7,200,000		16,800,000		-		24,000,000		7,965		-
Canadian Solar		3,200,000		100,000		600,000		2,700,000		7,182		-
Eacom Timber		38,000,000		-		2,000,000		36,000,000		2,473		-
GLG Life Tech		1,000,000		850,000		-		1,850,000		1,665		-
Globalstar*		15,000,000		2,184,322		4,000,000		13,184,322		7,120		-
IFM Investments (Century 21 China RE) - ADR		2,300,000		1,131,400		1,400		3,430,000		1,098		-
Petrodorado		28,400,000		6,456,000		156,000		34,700,000		6,983		-
Real Goods Solar		1,500,000		100,000		100,000		1,500,000		2,145		-
Sanmina-SCI		7,100,000		-		1,000,000		6,100,000		56,791		-
ShaMaran Petroleum*		35,950,000		2,843,100		2,293,100		36,500,000		12,719		-
Synthesis Energy Systems		4,500,000		-		1,549,628		2,950,372		4,573		-
Tuscany International Drilling*		11,324,000		-		724,000		10,600,000		6,243
VisionChina Media - ADR		3,675,000		4,600,000		1,275,000		7,000,000		8,680		-
WNS - ADR		4,200,000		76,336		22,106		4,254,230		38,246		-
Total of Affiliated Transactions		199,589,000		35,141,158		18,588,934		216,141,224	$	187,595	$	-

+ Includes the effects of a corporate action.

* At December 31, 2011, the Fund owned less than five percent of the company's outstanding voting shares.

See accompanying notes to financial statements.

(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, 2011, the market value of these securities amounted to $26,217, which represented 2.03% of total net assets.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost		Value
Union Agriculture Group	12/8/10-12/16/11		1,666,667	$	20,000	$	16,617
Canadian Overseas Petroleum	11/24/10		24,000,000		10,260		7,965
Canadian Overseas Petroleum - Warrants	11/24/10		12,000,000		1,502		948
Petrodorado - Warrants	11/20/09		17,144,000		2,118		639
Petromanas - Warrants	5/20/10		6,562,500		380		48
				$	34,260	$	26,217

(e) Illiquid security.

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

(g) On December 31, 2011, the market value of foreign securities represented 16.14% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percent
Colombia	$	77,105		5.97
China		41,170		3.19
India		38,246		2.96
Canada		20,567		1.59
Argentina		16,617		1.29
Iraq		12,719		0.99
United Kingdom		8,913		0.69
Total Foreign Portfolio	$	208,354		16.68

Fair Value Measurements

• 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)

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

See accompanying notes to financial statements.

Columbia Acorn Select

Statement of Investments, continued

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	278,108	$	19,637	$	-	$	297,745
Industrial Goods & Services		297,030		-		-		297,030
Information		257,638		-		-		257,638
Finance		180,004		-		-		180,004
Energy & Minerals		139,196		9,600		16,617		165,413
Other Industries		52,013		-		-		52,013
Health Care		37,177		-		-		37,177
Total Equities		1,241,166		29,237		16,617		1,287,020
Total Securities Lending Collateral		33,621		-		-		33,621
Total Investments	$	1,274,787	$	29,237	$	16,617	$	1,320,641

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
$	63,267	$	-	$	-	$	63,267

Financial assets were transferred from Level 2 to Level 1 as resale restrictions no longer apply.

The following table reconciles asset balances for the year ending December 31, 2011, in which significant unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2010		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of December 31, 2011
Equities
Energy & Minerals	$	20,000	$	-	$	(3,383	)	$	-	$	-	$	-	$	-	$	16,617
	$	20,000	$	-	$	(3,383	)	$	-	$	-	$	-	$	-	$	16,617

The change in unrealized depreciation attributed to securities owned at December 31, 2011, which were valued using significant unobservable inputs (Level 3) amounted to $(3,383).

See accompanying notes to financial statements.

Columbia Thermostat Fund

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
		> Affiliated Stock Funds: 57.7%
	641,872	Columbia Acorn International Fund, Class I	$	22,035
	1,600,740	Columbia Dividend Income Fund, Class I		21,818
	594,621	Columbia Acorn Fund, Class I		16,394
	1,190,969	Columbia Contrarian Core Fund, Class I		16,388
	462,662	Columbia Acorn Select Fund, Class I		10,942
	906,270	Columbia Select Large Cap Growth Fund, Class I (a)		10,929
	882,190	Columbia Large Cap Enhanced Core Fund, Class I		10,904
Total Stock Funds (Cost: $97,291)				109,410

Number of Shares			Value (000)
		> Affiliated Bond Funds: 38.7%
	3,948,225	Columbia Intermediate Bond Fund, Class I	$	36,640
	2,359,650	Columbia Income Opportunities Fund, Class I		21,992
	1,243,623	Columbia U.S. Treasury Index Fund, Class I		14,662
Total Bond Funds (Cost: $71,486)				73,294
Total Investments: 96.4% (Cost: $168,777)(b)				182,704
Cash and Other Assets Less Liabilities: 3.6%				6,903
Total Net Assets: 100.0%			$	189,607

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

(a) Non-income producing security.

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	109,410	$	-	$	-	$	109,410
Total Bond Funds		73,294		-		-		73,294
Total Investments	$	182,704	$	-	$	-	$	182,704

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

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Asia
> Taiwan
Advantech		4,800		12,000
CTCI Corp		13,900		33,200
Far Eastone Telecom		25,902		43,700
Lung Yen		1,200		11,000
PC Home		0		3,900
St. Shine Optical		4,000		5,800
> Hong Kong
AAC Technologies		0		13,000
> China
Digital China		33,251		34,651
> Indonesia
Archipelago Resources		62,959		76,959
Jasa Marga		0		67,000
Surya Citra Media		0		44,000
Tower Bersama Infrastructure		0		241,000
> India
Jain Irrigation Systems		0		20,800
Manappuram Finance		0		35,100
Mundra Port & Special Economic Zone		0		12,250
United Breweries		0		4,180
> Cambodia
Nagacorp		219,935		229,035
> Thailand
Home Product Center		117,555		134,348
Other Countries
> Canada
Crew Energy		0		3,000
> United States
Hornbeck Offshore		0		1,000
Europe
> Italy
Pirelli		0		3,000

	Number of Shares
	09/30/11		12/31/11
Sales
Asia
> Taiwan
Formosa International Hotels		2,449		949
> China
China Yurun Food		3,065		0
Jiangsu Expressway		3,649		0
Noah Holdings - ADR		2,444		0
> India
EGShares India Small Cap ETF		10,727		0
Market Vectors India Small Cap Index ETF		37,812		0
Wisdomtree India Earnings Index ETF		3,000		0
Other Countries
> United States
Bristow		645		0

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 88.7%
Asia 50.4%
		> Taiwan 14.7%
	43,700	Far Eastone Telecom	$	82
		Taiwan's 3rd Largest Mobile Operator
	5,800	St. Shine Optical		61
		World's Leading Disposable Contact Lens OEM
	26,990	Chroma Ate		53
		Automatic Test Systems, Testing & Measurement Instruments
	33,200	CTCI Corp		45
		International Engineering Firm
	7,730	Simplo Technology		45
		Battery Packs for Notebook & Tablet PCs
	12,000	Advantech		33
		Industrial PC & Components
	11,277	Radiant Opto-Electronics		32
		Back Light Modules for LCDs
	11,000	Lung Yen		32
		Funeral Services and Columbaria
	15,385	Taiwan Hon Chuan		29
		Beverage Packaging (bottles, caps, labels) Manufacturer
	5,000	President Chain Store		27
		Taiwan's Number One Convenience Chain Store Operator
	3,900	PC Home		24
		Taiwanese Internet Retail Company
	949	Formosa International Hotels		13
		Hotel, Food & Beverage Operation & Hospitality Management Services
				476
		> Hong Kong 5.1%
	4,137	Melco Crown Entertainment - ADR (a)		40
		Macau Casino Operator
	16,865	Lifestyle International		37
		Mid- to High-end Department Store Operator in Hong Kong & China
	65,652	Sasa International		36
		Cosmetics Retailer
	13,000	AAC Technologies		29
		Miniature Acoustic Components
	33,000	Melco International (a)		24
		Macau Casino Operator
				166
		> China 7.1%
	34,651	Digital China		53
		IT Distribution & Systems Integration Services
	85,275	AMVIG Holdings		45
		Chinese Tobacco Packaging Material Supplier
	1,000	NetEase.com - ADR (a)		45
		Chinese Online Gaming Services
	741	51job - ADR (a)		31
		Integrated Human Resource Service
	451,892	RexLot Holdings		30
		Lottery Equipment Supplier in China
	7,538	ENN Energy		24
		China's Largest Private Gas Operator
				228

Number of Shares			Value (000)
		> Indonesia 9.2%
	76,959	Archipelago Resources (a)	$	83
		Gold Mining Projects in Indonesia, Vietnam & the Philippines
	178,989	Ace Indonesia		81
		Home Improvement Retailer
	241,000	Tower Bersama Infrastructure		63
		Communications Towers
	44,000	Surya Citra Media		38
		Free to Air TV in Indonesia
	67,000	Jasa Marga		31
		Largest Toll Road Operator in Indonesia
				296
		> India 4.0%
	20,800	Jain Irrigation Systems		34
		Agricultural Micro-Irrigation Systems & Food Processing
	35,100	Manappuram Finance		30
		Short-term Lending Collateralized by Household Gold
	4,180	United Breweries		30
		India's Largest Brewer
	12,250	Mundra Port & Special Economic Zone		28
		Indian West Coast Shipping Port
	2,200	Titan Industries		7
		Jewelry, Watches & Eyeglasses
				129
		> Philippines 3.9%
	189,156	SM Prime Holdings		58
		Shopping Mall Operator
	88,382	Manila Water Company		39
		Water Utility Company in the Philippines
	25,567	Int'l Container Terminal		31
		Container Handling Terminals & Port Management
				128
		> Cambodia 1.8%
	229,035	Nagacorp		58
		Casino/Entertainment Complex in Cambodia
				58
		> Thailand 1.5%
	134,348	Home Product Center		47
		Home Improvement Retailer
				47
		> Mongolia 1.1%
	48,909	Mongolian Mining (a)		37
		Coking Coal Mining in Mongolia
				37
		> Japan 1.1%
	3,860	Kansai Paint		34
		Paint Producer in Japan, India, China and Southeast Asia
				34
		> Singapore 0.9%
	27,403	Goodpack Limited		29
		International Bulk Container Leasing
				29
Asia: Total				1,628

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Statement of Investments, continued

Number of Shares			Value (000)
Other Countries 16.9%
		> South Africa 10.6%
	9,580	Adcock Ingram Holdings	$	73
		Manufacturer of Pharmaceuticals and Medical Supplies
	24,626	Coronation Fund Managers		69
		South African Fund Manager
	39,175	Rand Merchant Insurance		65
		Directly Sold Property and Casualty Insurance; Holdings in Other Insurers
	5,370	Mr. Price		53
		South African Retailer of Apparel, Household & Sporting Goods
	11,354	Northam Platinum		42
		Platinum Mining in South Africa
	1,945	Massmart Holdings		41
		General Merchandise, Food, and Home Improvement Stores; Wal-Mart Subsidiary
				343
		> Canada 3.3%
	3,565	Alliance Grain Traders		73
		Global Leader in Pulse Processing and Distribution
	3,000	Crew Energy (a)		33
		Canadian Oil and Gas Producer
				106
		> United States 3.0%
	1,200	Textainer Group Holdings		35
		Top International Container Leasor
	1,000	Hornbeck Offshore (a)		31
		Supply Vessel Operator in U.S. Gulf of Mexico
	752	Atwood Oceanics (a)		30
		Offshore Drilling Contractor
				96
Other Countries: Total				545
Europe 10.7%
		> Sweden 3.1%
	3,498	Hexagon		52
		Design, Measurement & Visualization Software & Equipment
	6,072	East Capital Explorer		48
		Sweden-based Russia/Central Eastern Europe Investment Fund
				100
		> Switzerland 1.9%
	675	Dufry Group (a)		62
		Operates Airport Duty Free and Duty Paid Shops
				62
		> Czech Republic 1.8%
	352	Komercni Banka		59
		Leading Czech Republic Universal Bank
				59
		> France 1.3%
	780	Rubis		41
		Tank Storage & Liquefied Petroleum Gas Distribution
				41

Number of Shares			Value (000)
		> Germany 1.1%
	824	Dürr	$	36
		Automotive Plant Engineering & Associated Capital Equipment
				36
		> Italy 0.8%
	3,000	Pirelli		25
		Global Tire Supplier
				25
		> Kazakhstan 0.6%
	4,332	Halyk Savings Bank of Kazakhstan - GDR (a)		21
		Largest Retail Bank & Insurer in Kazakhstan
				21
Europe: Total				344
Latin America 10.7%
		> Brazil 7.0%
	11,121	MRV Engenharia		64
		Brazilian Property Developer
	4,436	Localiza Rent A Car		61
		Car Rental
	4,617	Mills Estruturas e Servicos de Engenharia		44
		Civil Engineering & Construction
	1,884	Multiplus		32
		Loyalty Program Operator in Brazil
	7,431	Suzano		27
		Brazilian Pulp & Paper Producer
				228
		> Mexico 2.1%
	1,203	Grupo Aeroportuario del Sureste - ADR		67
		Mexican Airport Operator
				67
		> Argentina 1.6%
	56,433	Madalena Ventures (a)		51
		Oil and Gas Exploration in Argentina
				51
Latin America: Total				346
Total Equities: 88.7% (Cost: $2,997)				2,863
Total Investments: 88.7% (Cost: $2,997)(b)(c)				2,863
Cash and Other Assets Less Liabilities: 11.3%				366
Total Net Assets: 100.0%			$	3,229

ADR - American Depositary Receipts

GDR - Global Depositary Receipts

See accompanying notes to financial statements.

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

(a) Non-income producing security.

Currency	Value		Percentage of Net Assets
Taiwan Dollar	$	476		14.7
Hong Kong Dollar		374		11.6
South African Rand		344		10.7
U.S. Dollar		300		9.3
Brazilian Real		228		7.1
Indonesian Rupiah		213		6.6
Other currencies less than 5% of total net assets		928		28.7
	$	2,863		88.7

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	116	$	1,512	$	-	$	1,628
Other Countries		202		343		-		545
Europe		-		344		-		344
Latin America		346		-		-		346
Total Equities		664		2,199		-		2,863
Total Investments	$	664	$	2,199	$	-	$	2,863

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

See accompanying notes to financial statements.

Columbia Acorn Emerging Markets Fund

Portfolio Diversification

At December 31, 2011, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value (000)		Percentage of Net Assets
> Consumer Goods & Services
Retail	$	378		11.7
Casinos & Gaming		151		4.7
Other Consumer Services		101		3.1
Food & Beverage		63		1.9
Travel		61		1.9
Other Durable Goods		25		0.8
Other Entertainment		12		0.4
		791		24.5
> Information
Mobile Communications		145		4.5
Computer Hardware & Related Equipment		139		4.3
Electronics Distribution		54		1.7
Instrumentation		53		1.6
Business Software		52		1.6
Internet Related		45		1.4
TV Broadcasting		38		1.2
		526		16.3
> Energy & Minerals
Mining		161		5.0
Agricultural Commodities		99		3.0
Oil & Gas Producers		84		2.6
Oil Services		61		1.9
Oil Refining, Marketing & Distribution		41		1.3
		446		13.8
> Industrial Goods & Services
Industrial Materials & Specialty Chemicals		108		3.3
Construction		89		2.8
Machinery		70		2.2
Other Industrial Services		59		1.8
Industrial Distribution		29		0.9
		355		11.0
> Finance
Brokerage & Money Management		117		3.6
Banks		80		2.5
Finance Companies		65		2.0
Insurance		65		2.0
		327		10.1
> Other Industries
Real Estate		121		3.7
Transportation		99		3.1
Regulated Utilities		63		2.0
		283		8.8

	Value (000)		Percentage of Net Assets
> Health Care
Pharmaceuticals	$	74		2.3
Medical Supplies		61		1.9
		135		4.2
Total Equities:		2,863		88.7
Total Investments:		2,863		88.7
Cash and Other Assets Less Liabilities:		366		11.3
Net Assets:	$	3,229		100.0

See accompanying notes to financial statements.

Columbia Acorn European Fund

Major Portfolio Changes in the Fourth Quarter (Unaudited)

	Number of Shares
	09/30/11		12/31/11
Purchases
Europe
> United Kingdom
Shaftesbury		160		3,180
> Germany
Bertrandt		0		300
Stratec Biomedical Systems		0		420
> Sweden
Unibet		0		1,000
> Italy
Pirelli		0		2,000
> Iceland
Marel		400		43,750
> Norway
Atea		1,900		3,310
> Belgium
EVS Broadcast Equipment		300		630
> Czech Republic
Komercni Banka		0		140
> Poland
FX Energy		0		4,000
Other Countries
> Canada
Alliance Grain Traders		0		1,270
Asia
> Hong Kong
L'Occitane International		0		9,000

	Number of Shares
	09/30/11		12/31/11
Sales
Europe
> United Kingdom
Cobham		4,850		0
> France
1000 mercis		1,580		700
Neopost		590		352
Teleperformance		1,050		0
> Netherlands
Arcadis		1,910		1,280
Vopak		770		0
> Germany
Rhoen-Klinikum		800		0

See accompanying notes to financial statements.

Columbia Acorn European Fund

Statement of Investments, December 31, 2011

Number of Shares			Value (000)
			Equities: 96.7%
Europe 94.1%
		> United Kingdom 18.5%
	1,400	Intertek Group	$	44
		Testing, Inspection & Certification Services
	5,800	Chemring		36
		Defense Manufacturer of Countermeasures & Energetics
	2,927	JLT Group		31
		International Business Insurance Broker
	15,220	Charles Taylor		30
		Insurance Services
	6,480	GlobeOp Financial Services		29
		Hedge Fund Administrator
	3,180	Shaftesbury		23
		London Prime Retail REIT
	3,610	Domino's Pizza United Kingdom & Ireland		23
		Pizza Delivery in United Kingdom, Ireland and Germany
	5,830	Workspace Group		20
		United Kingdom Real Estate
	660	Rotork		20
		Valve Actuators for Oil & Water Pipelines
	2,480	Serco		18
		Facilities Management
	3,190	Abcam		18
		Online Sales of Antibodies
	2,870	Premier Oil (a)		16
		Oil and Gas Producer in Europe, Pakistan and Asia
	339	Greggs		3
		Bakery
				311
		> France 15.4%
	1,100	Gemalto		54
		Digital Security Solutions
	600	Eurofins Scientific		44
		Food, Pharmaceuticals & Materials Screening & Testing
	700	1000 mercis		41
		Interactive Advertising and Marketing
	360	Norbert Dentressangle		25
		Leading European Logistics & Transport Group
	352	Neopost		24
		Postage Meter Machines
	790	Saft Batteries		22
		Niche Battery Manufacturer
	600	Mersen		18
		Advanced Industrial Materials
	310	Rubis		16
		Tank Storage & Liquefied Petroleum Gas Distribution
	5,030	Hi-Media (a)		14
		Online Advertiser in Europe
				258

Number of Shares			Value (000)
		> Netherlands 14.2%
	430	Core Laboratories	$	49
		Oil & Gas Reservoir Consulting
	2,420	Aalberts Industries		41
		Flow Control & Heat Treatment
	1,530	UNIT4		36
		Business Software Development
	1,360	Imtech		35
		Electromechanical & ICT Installation & Maintenance
	1,210	Koninklijke TenCate		33
		Advanced Textiles & Industrial Fabrics
	410	Fugro		24
		Sub-sea Oilfield Services
	1,280	Arcadis		20
		Engineering Consultants
				238
		> Germany 12.6%
	3,080	Wirecard		49
		Online Payment Processing & Risk Management
	170	Rational		37
		Commercial Ovens
	560	Rheinmetall		25
		Defense & Automotive
	520	Dürr		23
		Automotive Plant Engineering & Associated Capital Equipment
	690	CTS Eventim		21
		Event Ticket Sales
	810	Elringklinger		20
		Automobile Components
	300	Bertrandt		20
		Outsourced Engineering
	420	Stratec Biomedical Systems		17
		Diagnostic Instrumentation
				212
		> Switzerland 7.1%
	250	Geberit (a)		48
		Plumbing Supplies
	15	Sika		28
		Chemicals for Construction & Industrial Applications
	160	Partners Group		28
		Private Markets Asset Management
	170	Dufry Group (a)		16
		Operates Airport Duty Free and Duty Paid Shops
				120
		> Sweden 5.7%
	2,570	Hexagon		39
		Design, Measurement & Visualization Software & Equipment
	4,070	Sweco		34
		Engineering Consultants
	1,000	Unibet		23
		European Online Gaming Operator
				96

See accompanying notes to financial statements.

Number of Shares			Value (000)
		> Italy 4.5%
	15,060	CIR	$	24
		Italian Holding Company
	6,400	Geox		18
		Apparel and Shoe Maker
	2,000	Pirelli		17
		Global Tire Supplier
	200	Tod's		16
		Leather Shoes & Bags
				75
		> Iceland 2.7%
	43,750	Marel (a)		45
		Largest Manufacturer of Poultry & Fish Processing Equipment
				45
		> Ireland 2.6%
	9,630	United Drug		26
		Irish Pharmaceutical Wholesaler & Outsourcer
	300	Paddy Power		17
		Irish Betting Services
				43
		> Portugal 2.2%
	13,480	Redes Energéticas Nacionais		37
		Portuguese Power Transmission & Gas Transportation
				37
		> Norway 2.0%
	3,310	Atea		33
		Leading Nordic IT Hardware/Software Re-seller & Installation Company
				33
		> Belgium 1.9%
	630	EVS Broadcast Equipment		32
		Digital Live Mobile Production Software and Systems
				32
		> Russia 1.5%
	1,000	Mail.ru - GDR (a)(b)		26
		Internet Social Networking & Games for Russian Speakers
				26
		> Czech Republic 1.4%
	140	Komercni Banka		24
		Leading Czech Republic Universal Bank
				24
		> Poland 1.1%
	4,000	FX Energy (a)		19
		Oil & Gas Producer in Poland
				19

Number of Shares			Value (000)
		> Greece 0.7%
	12,800	Intralot	$	11
		Lottery & Gaming Systems & Services
				11
Europe: Total				1,580
Other Countries 1.5%
		> Canada 1.5%
	1,270	Alliance Grain Traders		26
		Global Leader in Pulse Processing and Distribution
				26
Other Countries: Total				26
Asia 1.1%
		> Hong Kong 1.1%
	9,000	L'Occitane International		18
		Skin Care and Cosmetics Producer
				18
Asia: Total				18
Total Equities: 96.7% (Cost: $1,710)				1,624
Total Investments: 96.7% (Cost: $1,710)(c)(d)				1,624
Cash and Other Assets Less Liabilities: 3.3%				55
Total Net Assets: 100.0%			$	1,679

GDR – Global Depositary Receipts

See accompanying notes to financial statements.

Columbia Acorn European Fund

Statement of Investments, continued

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

(a) Non-income producing security.

(d) On December 31, 2011, the Fund's total investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Euro	$	858		51.1
British Pound		311		18.5
Swiss Franc		120		7.1
Swedish Krona		95		5.7
U.S. Dollar		94		5.6
Other currencies less than 5% of total net assets		146		8.7
	$	1,624		96.7

Fair Value Measurements

• 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)

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

The following table summarizes the inputs used, as of December 31, 2011, 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	$	68	$	1,512	$	-	$	1,580
Other Countries		26		-		-		26
Asia		-		18		-		18
Total Equities		94		1,530		-		1,624
Total Investments	$	94	$	1,530	$	-	$	1,624

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

See accompanying notes to financial statements.

Columbia Acorn European Fund

Portfolio Diversification

At December 31, 2011, 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	$	177		10.5
Machinery		173		10.3
Industrial Machinery & Specialty Chemicals		100		5.9
Conglomerates		65		3.9
Electrical Components		58		3.5
Construction		48		2.9
Outsourcing Services		38		2.3
		659		39.3
> Information
Computer Hardware & Related Equipment		86		5.1
Business Software		75		4.5
Financial Processors		50		3.0
Business Information & Marketing Services		41		2.4
Computer Services		33		2.0
Internet Related		26		1.6
Advertising		14		0.8
		325		19.4
> Energy & Minerals
Mining		49		2.9
Oil & Gas Producers		35		2.1
Agricultural Commodities		26		1.5
Oil Services		24		1.4
Oil Refining, Marketing & Distribution		16		1.0
		150		8.9
> Finance
Insurance		61		3.6
Brokerage & Money Management		57		3.4
Banks		23		1.4
		141		8.4
> Consumer Goods & Services
Casinos & Gaming		51		3.0
Nondurables		34		2.0
Restaurants		22		1.3
Other Entertainment		21		1.3
Apparel		18		1.1
Other Durable Goods		17		1.0
Retail		16		0.9
Food & Beverage		3		0.2
		182		10.8

	Value (000)		Percentage of Net Assets
> Other Industries
Real Estate	$	44		2.6
Regulated Utilities		37		2.2
Transportation		25		1.5
		106		6.3
> Health Care
Pharmaceuticals		26		1.5
Medical Equipment & Devices		17		1.0
Medical Supplies		18		1.1
		61		3.6
Total Equities:		1,624		96.7
Total Investments:		1,624		96.7
Cash and Other Assets Less Liabilities:		55		3.3
Net Assets:	$	1,679		100.0

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Assets and Liabilities

December 31, 2011	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select
(in thousands)
Assets:
Unaffiliated investments, at cost	$	8,636,867		$	4,524,775		$	1,182,379		$	281,366
Affiliated investments, at cost (See Note 4)		2,644,726			178,167			3,624			—
Unaffiliated investments, at value (including securities on loan: Columbia Acorn Fund $371,484; Columbia Acorn International $96,653; Columbia Acorn USA $33,589; Columbia Acorn International Select $3,850; Columbia Acorn Select $32,075; Columbia Thermostat Fund $—; Columbia Acorn Emerging Markets Fund $—; Columbia Acorn European Fund $—)	$	12,553,485		$	5,127,131		$	1,584,940		$	313,195
Affiliated investments, at value (See Note 4)		3,722,937			217,479			3,315			—
Cash		480,945			157,234			5,733			16,190
Foreign currency (cost: Columbia Acorn International $404)		—			404			—			—
Unrealized appreciation on forward foreign currency exchange contracts		—			4,539			—			—
Receivable for:
Investments sold		24,089			6,815			4,630			137
Fund shares sold		15,075			16,077			948			2,221
Dividends		9,889			6,101			721			257
Securities lending income		306			162			17			3
Foreign tax reclaims		166			2,615			—			136
Expense reimbursement due from Advisor		—			1			—			—
Trustees' Deferred Compensation
Investments		2,188			596			177			—
Other assets		177			60			18			4
Total Assets		16,809,257			5,539,214			1,600,499			332,143
Liabilities:
Collateral on securities loaned		382,045			99,418			34,671			3,950
Unrealized depreciation on forward foreign currency exchange contracts		—			—			—			948
Payable to advisor		—			—			—			—
Payable for:
Investments purchased		29,812			2,183			3,978			—
Fund shares redeemed		55,228			14,781			2,855			659
Management fee		289			113			37			8
Administration fee		18			6			2			—	*
12b-1 Service and Distribution fees		44			9			2			1
Reports to shareholders		617			367			109			48
Deferred Trustees' fees		2,188			596			177			—
Transfer agent fees		1,220			337			119			16
Trustees' fees		81			48			8			37
Registration and blue sky fees		5			7			5			4
Custody fees		75			482			3			37
Professional fee		489			216			78			49
Chief compliance officer expenses		93			31			9			3
Deferred foreign capital gains tax payable		—			2,321			—			—
Other liabilities		478			1,346			1			—	*
Total Liabilities		472,682			122,261			42,054			5,760
Net Assets	$	16,336,575		$	5,416,953		$	1,558,445		$	326,383
Composition of Net Assets:
Paid-in capital	$	11,198,023		$	5,139,384		$	1,154,235		$	299,340
Undistributed (overdistributed) net investment income (Accumulated net investment loss)		(32,074	)		(60,514	)		(167	)		(5,294	)
Accumulated net realized gain (loss)		175,809			(305,724	)		2,125			1,468
Net unrealized appreciation (depreciation) on:
Unaffiliated investments		3,916,618			602,356			402,561			31,829
Affiliated investments		1,078,211			39,312			(309	)		—
Foreign capital gains tax		—			(2,321	)		—			—
Foreign currency translations		(12	)		(79	)		—			(12	)
Forward foreign currency exchange contracts		—			4,539			—			(948	)
Net Assets	$	16,336,575		$	5,416,953		$	1,558,445		$	326,383
Net asset value per share – Class A (a)	$	26.63		$	34.15		$	25.94		$	24.26
(Net assets/shares)		($3,246,833/121,918)			($918,112/26,887)			($167,038/6,441)			($56,350/2,323)
Maximum offering price per share – Class A (b)	$	28.25		$	36.23		$	27.52		$	25.74
(Net asset value per share/front-end sales charge)		($26.63/0.9425)			($34.15/0.9425)			($25.94/0.9425)			($24.26/0.9425)
Net asset value and offering price per share – Class B (a)	$	24.53		$	33.17		$	23.98		$	23.27
(Net assets/shares)		($67,153/2,738)			($24,510/739)			($2,253/94)			($1,774/76)
Net asset value and offering price per share – Class C (a)	$	24.18		$	33.03		$	23.72		$	23.17
(Net assets/shares)		($721,446/29,834)			($97,328/2,946)			($30,584/1,289)			($8,704/376)
Net asset value and offering price per share – Class I (d)	$	27.57		$	34.33		$	27.00		$	24.45
(Net assets/shares)		($16,397/595)			($50,335/1,466)			($2,635/98)		($	2/—	**)
Net asset value and offering price per share – Class R (c)	$	—		$	34.11		$	—		$	—
(Net assets/shares)	($	—/—	)	($2,130/62)			($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class R5 (c)	$	—		$	34.31		$	—		$	—
(Net assets/shares)	($	—/—	)	($2,038/59)			($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class Z (d)	$	27.56		$	34.31		$	26.98		$	24.46
(Net assets/shares)		($12,284,746/445,806)			($4,322,500/126,000)			($1,355,935/50,253)			($259,553/10,613)

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

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

(d) Redemption price per share is equal to net asset value.

* Rounds to less than $500.

** Rounds to less than 500 shares.

See accompanying notes to financial statements.

December 31, 2011	Columbia Acorn Select			Columbia Thermostat Fund			Columbia Acorn Emerging Markets Fund			Columbia Acorn European Fund
(in thousands)
Assets:
Unaffiliated investments, at cost	$	866,336		$	—		$	2,997		$	1,710
Affiliated investments, at cost (See Note 4)		266,958			168,777			—			—
Unaffiliated investments, at value (including securities on loan: Columbia Acorn Fund $371,484; Columbia Acorn International $96,653; Columbia Acorn USA $33,589; Columbia Acorn International Select $3,850; Columbia Acorn Select $32,075; Columbia Thermostat Fund $—; Columbia Acorn Emerging Markets Fund $—; Columbia Acorn European Fund $—)	$	1,159,128		$	—		$	2,863		$	1,624
Affiliated investments, at value (See Note 4)		161,513			182,704			—			—
Cash		13,666			1,306			376			88
Foreign currency (cost: Columbia Acorn International $404)		—			—			—			—
Unrealized appreciation on forward foreign currency exchange contracts		—			—			—			—
Receivable for:
Investments sold		794			—			—			—
Fund shares sold		708			6,134			47			—
Dividends		1,409			224			3			2
Securities lending income		89			—			—			—
Foreign tax reclaims		20			—			—	*		—	*
Expense reimbursement due from Advisor		—			3			—	*		—	*
Trustees' Deferred Compensation
Investments		230			—			—			—
Other assets		19			1			57			55
Total Assets		1,337,576			190,372			3,346			1,769
Liabilities:
Collateral on securities loaned		33,621			—			—			—
Unrealized depreciation on forward foreign currency exchange contracts		—			—			—			—
Payable to advisor		—			—			27			34
Payable for:
Investments purchased		2,076			572			21			—
Fund shares redeemed		10,617			109			—			—
Management fee		30			1			—	*		—	*
Administration fee		1			—	*		—	*		—	*
12b-1 Service and Distribution fees		5			2			—	*		—	*
Reports to shareholders		137			27			10			10
Deferred Trustees' fees		230			—			—			—
Transfer agent fees		131			9			—	*		—	*
Trustees' fees		7			20			—	*		—	*
Registration and blue sky fees		6			2			7			7
Custody fees		2			—	*		21			8
Professional fee		81			22			30			30
Chief compliance officer expenses		11			1			—	*		—	*
Deferred foreign capital gains tax payable		—			—			1			—
Other liabilities		—	*		—	*		—	*		1
Total Liabilities		46,955			765			117			90
Net Assets	$	1,290,621		$	189,607		$	3,229		$	1,679
Composition of Net Assets:
Paid-in capital	$	1,100,909		$	196,559		$	3,419		$	1,776
Undistributed (overdistributed) net investment income (Accumulated net investment loss)		(324	)		471			(1	)		—	*
Accumulated net realized gain (loss)		2,689			(21,350	)		(54	)		(11	)
Net unrealized appreciation (depreciation) on:
Unaffiliated investments		292,792			—			(134	)		(86	)
Affiliated investments		(105,445	)		13,927			—			—
Foreign capital gains tax		—			—			(1	)		—
Foreign currency translations		—			—			—	*		—	*
Forward foreign currency exchange contracts		—			—			—			—
Net Assets	$	1,290,621		$	189,607		$	3,229		$	1,679
Net asset value per share – Class A (a)	$	22.95		$	12.82		$	9.26		$	9.43
(Net assets/shares)		($340,325/14,826)			($79,744/6,219)			($332/36)			($154/16)
Maximum offering price per share – Class A (b)	$	24.35		$	13.60		$	9.82		$	10.01
(Net asset value per share/front-end sales charge)		($22.95/0.9425)			($12.82/0.9425)			($9.26/0.9425)			($9.43/0.9425)
Net asset value and offering price per share – Class B (a)	$	21.40		$	12.91		$	—		$	—
(Net assets/shares)		($26,126/1,221)			($11,318/877)		($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class C (a)	$	21.20		$	12.91		$	9.24		$	9.44
(Net assets/shares)		($62,887/2,966)			($33,378/2,585)			($127/14)			($5/1)
Net asset value and offering price per share – Class I (d)	$	23.65		$	—		$	9.29		$	9.43
(Net assets/shares)		($10,944/463)		($	—/—	)		($5/1)			($5/1)
Net asset value and offering price per share – Class R (c)	$	—		$	—		$	—		$	—
(Net assets/shares)	($	—/—	)	($	—/—	)	($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class R5 (c)	$	—		$	—		$	—		$	—
(Net assets/shares)	($	—/—	)	($	—/—	)	($	—/—	)	($	—/—	)
Net asset value and offering price per share – Class Z (d)	$	23.62		$	12.67		$	9.28		$	9.44
(Net assets/shares)		($850,339/36,003)			($65,167/5,142)			($2,765/298)			($1,515/161)

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Operations For the Year Ended December 31, 2011

(in thousands)	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select
Investment Income:
Dividend income	$	114,994		$	139,245		$	8,706		$	9,725
Dividend income from affiliates (See Note 4)		12,906			4,877			—			—
Dividends from affiliated investment company shares (See Note 4)		—			—			—			—
Interest income		169			43			5			6
Securities lending income, net		3,532			900			286			24
		131,601			145,065			8,997			9,755
Foreign taxes withheld		(2,619	)		(12,305	)		(14	)		(782	)
Total Investment Income		128,982			132,760			8,983			8,973
Expenses:
Management fee		114,050			46,342			14,918			3,885
Administration fee		6,839			2,343			666			159
12b-1 Service and Distribution fees:
Class A		9,005			2,276			496			169
Class B		1,342			200			48			19
Class C		8,052			1,067			337			108
Class R		—			4			—			—
Transfer agent fees:
Class A		3,254			1,579			192			102
Class B		365			87			15			7
Class C		850			178			33			21
Class R		—			1			—			—
Class R5		—			—	*		—			—
Class Z		5,385			2,570			752			114
Custody fees		971			3,106			46			179
Trustees' fees		991			346			96			19
Registration and blue sky fees		194			143			94			74
Reports to shareholders		1,922			1,252			383			142
Audit fees		87			78			42			44
Legal fees		1,214			413			118			28
Chief compliance officer expenses (See Note 4)		752			257			74			18
Other expenses		567			283			56			28
Total Expenses		155,840			62,525			18,366			5,116
Less custody fees paid indirectly		—	*		—	*		—	*		—	*
Less reimbursement of expenses by Investment Advisor		—			(159	)		—			—
Net Expenses		155,840			62,366			18,366			5,116
Net Investment Income/(Loss)		(26,858	)		70,394			(9,383	)		3,857
Net Realized and Unrealized Gain/(Loss) on Portfolio Positions:
Net realized gain/(loss) on:
Unaffiliated investments		756,701			222,525			41,208			45,575
Affiliated investments (See Note 4)		(10,817	)		(3,603	)		(512	)		—
Foreign currency transactions		13			(4,273	)		—			(885	)
Forward foreign currency exchange contracts		—			7,872			—			1,262
Distributions from affiliated investment company shares		—			—			—			—
Reimbursement from affiliate (See Note 4)		—			174			—			—
Net realized gain/(loss)		745,897			222,695			40,696			45,952
Net change in net unrealized appreciation/(depreciation) on:
Unaffiliated investments		(1,530,752	)		(1,220,866	)		(112,790	)		(88,029	)
Affiliated investments (See Note 4)		(43,544	)		22,439			876			—
Foreign currency translations		(42	)		(1,536	)		—			(24	)
Forward foreign currency exchange contracts		—			(6,748	)		—			(948	)
Foreign capital gains tax		—			(1,814	)		—			—
Net change in unrealized depreciation		(1,574,338	)		(1,208,525	)		(111,914	)		(89,001	)
Net realized and unrealized gain/(loss)		(828,441	)		(985,830	)		(71,218	)		(43,049	)
Net Increase/(Decrease) in Net Assets resulting from Operations	$	(855,299	)	$	(915,436	)	$	(80,601	)	$	(39,192	)

* Rounds to less than $500.

See accompanying notes to financial statements.

(in thousands)	Columbia Acorn Select			Columbia Thermostat Fund			Columbia Acorn Emerging Markets Fund			Columbia Acorn European Fund
Investment Income:
Dividend income	$	12,579		$	—		$	17		$	6
Dividend income from affiliates (See Note 4)		—			—			—			—
Dividends from affiliated investment company shares (See Note 4)		—			3,668			—			—
Interest income		28			—	*		—			—
Securities lending income, net		579			—			—			—
		13,186			3,668			17			6
Foreign taxes withheld		(149	)		—			(1	)		—	*
Total Investment Income		13,037			3,668			16			6
Expenses:
Management fee		15,322			141			13			7
Administration fee		720			54			—	*		—	*
12b-1 Service and Distribution fees:
Class A		1,180			136			��	*		—	*
Class B		375			160			—			—
Class C		821			236			—	*		—	*
Class R		—			—			—			—
Transfer agent fees:
Class A		520			71			—	*		—	*
Class B		108			38			—			—
Class C		108			33			—	*		—	*
Class R		—			—			—			—
Class R5		—			—			—			—
Class Z		672			21			—	*		—	*
Custody fees		161			1			21			9
Trustees' fees		112			4			—	*		—	*
Registration and blue sky fees		94			69			32			32
Reports to shareholders		372			88			11			11
Audit fees		42			21			30			30
Legal fees		136			9			—	*		—	*
Chief compliance officer expenses (See Note 4)		83			6			—	*		—	*
Other expenses		183			12			90			94
Total Expenses		21,009			1,100			197			183
Less custody fees paid indirectly		—	*		—	*		—			—
Less reimbursement of expenses by Investment Advisor		—			(216	)		(182	)		(174	)
Net Expenses		21,009			884			15			9
Net Investment Income/(Loss)		(7,972	)		2,784			1			(3	)
Net Realized and Unrealized Gain/(Loss) on Portfolio Positions:
Net realized gain/(loss) on:
Unaffiliated investments		209,865			—			(54	)		(8	)
Affiliated investments (See Note 4)		(66,391	)		7,583			—			—
Foreign currency transactions		(69	)		—			(3	)		14
Forward foreign currency exchange contracts		—			—			—			—
Distributions from affiliated investment company shares		—			1,295			—			—
Reimbursement from affiliate (See Note 4)		—			—			—			—
Net realized gain/(loss)		143,405			8,878			(57	)		6
Net change in net unrealized appreciation/(depreciation) on:
Unaffiliated investments		(347,747	)		—			(134	)		(86	)
Affiliated investments (See Note 4)		(112,603	)		(4,866	)		—			—
Foreign currency translations		(1	)		—			—	*		—	*
Forward foreign currency exchange contracts		—			—			—			—
Foreign capital gains tax		—			—			(1	)		—
Net change in unrealized depreciation		(460,351	)		(4,866	)		(135	)		(86	)
Net realized and unrealized gain/(loss)		(316,946	)		4,012			(192	)		(80	)
Net Increase/(Decrease) in Net Assets resulting from Operations	$	(324,918	)	$	6,796		$	(191	)	$	(83	)

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Changes in Net Assets

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA						Columbia Acorn International Select
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2011			2010 (a)			2011 (b)			2010 (a)			2011			2010 (a)			2011			2010 (a)
Operations:
Net investment income/(loss)	$	(26,858	)	$	(7,374	)	$	70,394		$	45,340		$	(9,383	)	$	(5,972	)	$	3,857		$	2,667
Net realized gain/(loss) on investments, foreign currency transactions, forward foreign currency exchange contracts and foreign capital gains tax		756,714			971,334			226,124			276,374			41,208			96,553			45,952			42,527
Net realized gain/(loss) on affiliated investments and distributions from affiliated investment companies and affiliated investment company shares		(10,817	)		139,546			(3,603	)		5,786			(512	)		(1,208	)		—			—
Reimbursement from affiliate (See Note 4)		—			—			174			—			—			—			—			—
Net change in net unrealized appreciation/(depreciation) on investments, foreign currency translations, forward foreign currency exchange contracts and foreign capital gains tax		(1,530,794	)		1,864,571			(1,230,965	)		752,452			(112,790	)		224,623			(89,001	)		38,193
Net change in net unrealized appreciation/(depreciation) on affiliated investment companies and affiliated investment company shares		(43,544	)		758,959			22,440			6,050			876			4,434			—			—
Net Increase/(Decrease) from Operations		(855,299	)		3,727,036			(915,436	)		1,086,002			(80,601	)		318,430			(39,192	)		83,387
Distributions to Shareholders From:
Net investment income – Class A		(2,049	)		(2,387	)		(21,972	)		(12,578	)		—			—			(1,392	)		(776	)
Net realized gain – Class A		(144,445	)		(100,919	)		—			—			(1,096	)		—			(901	)		—
Net investment income – Class B		—			—			(600	)		(290	)		—			—			(23	)		(25	)
Net realized gain – Class B		(4,964	)		(9,116	)		—			—			(21	)		—			(31	)		—
Net investment income – Class C		—			—			(2,369	)		(714	)		—			—			(70	)		(65	)
Net realized gain – Class C		(35,291	)		(25,102	)		—			—			(217	)		—			(150	)		—
Net investment income – Class I		(34	)		—	*		(676	)		(9	)		—			—			—	*		—
Net realized gain – Class I		(670	)		—	*		—			—			(16	)		—			—	*		—
Net investment income – Class Z		(36,823	)		(18,634	)		(131,455	)		(109,328	)		—			—			(9,039	)		(5,241	)
Net realized gain – Class Z		(521,915	)		(361,156	)		—			—			(8,481	)		—			(4,186	)		—
Total Distributions to Shareholders		(746,191	)		(517,314	)		(157,072	)		(122,919	)		(9,831	)		—			(15,792	)		(6,107	)
Share Transactions:
Subscriptions – Class A		881,347			843,928			302,659			317,458			41,839			55,029			18,154			18,214
Distributions reinvested – Class A		134,125			94,158			18,983			10,862			993			—			2,039			675
Net assets of shares issued in connection with Merger – Class A		—			—			204,930			—			—			—			—			—
Redemptions – Class A		(1,072,697	)		(866,166	)		(251,677	)		(221,501	)		(80,479	)		(59,786	)		(26,422	)		(23,778	)
Net Increase/(Decrease) – Class A		(57,225	)		71,920			274,895			106,819			(37,647	)		(4,757	)		(6,229	)		(4,889	)
Subscriptions – Class B		543			989			64			35			9			2			5			—	*
Distributions reinvested – Class B		4,234			7,325			494			260			18			—			46			22
Net assets of shares issued in connection with Merger – Class B		—			—			12,517			—			—			—			—			—
Redemptions – Class B		(215,636	)		(312,686	)		(13,183	)		(15,278	)		(6,779	)		(13,951	)		(1,017	)		(1,418	)
Net Increase/(Decrease) – Class B		(210,859	)		(304,372	)		(108	)		(14,983	)		(6,752	)		(13,949	)		(966	)		(1,396	)
Subscriptions – Class C		101,181			76,903			19,819			24,476			2,255			1,669			966			1,883
Distributions reinvested – Class C		27,313			19,273			1,845			590			193			—			188			55
Net assets of shares issued in connection with Merger – Class C		—			—			25,563			—			—			—			—			—
Redemptions – Class C		(154,450	)		(145,469	)		(42,187	)		(17,799	)		(5,937	)		(4,671	)		(2,975	)		(3,121	)
Net Increase/(Decrease) – Class C		(25,956	)		(49,293	)		5,040			7,267			(3,489	)		(3,002	)		(1,821	)		(1,183	)
Subscriptions – Class I		17,610			13,063			27,930			66,675			11,070			28,852			—			3
Distributions reinvested – Class I		704			—			676			9			16			—			—			—
Net assets of shares issued in connection with Merger – Class I		—			—			152,987			—			—			—			—			—
Redemptions – Class I		(13,595	)		(1,538	)		(184,760	)		(2,003	)		(38,709	)		(293	)		—			—
Net Increase/(Decrease) – Class I		4,719			11,525			(3,167	)		64,681			(27,623	)		28,559			—			3
Subscriptions – Class R		—			—			370			—			—			—			—			—
Net assets of shares issued in connection with Merger – Class R		—			—			2,027			—			—			—			—			—
Redemptions – Class R		—			—			(77	)		—			—			—			—			—
Net Increase – Class R		—			—			2,320			—			—			—			—			—

(a) Class I shares reflect activity for the period September 27, 2010 (commencement of operations) through December 31, 2010.

(b) Class R and Class R5 shares reflect activity for the period August 15, 2011 (commencement of operations) through December 31, 2011.

* Rounds to less than $500.

See accompanying notes to financial statements.

	Columbia Acorn Select						Columbia Thermostat Fund						Columbia Acorn Emerging Markets Fund					Columbia Acorn European Fund
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,					Year ended December 31,
(in thousands)	2011			2010 (a)			2011			2010			2011 (c)			2010		2011 (c)			2010
Operations:
Net investment income/(loss)	$	(7,972	)	$	(11,783	)	$	2,784		$	1,806		$	1		$	—	$	(3	)	$	—
Net realized gain/(loss) on investments, foreign currency transactions, forward foreign currency exchange contracts and foreign capital gains tax		209,796			59,672			—			—			(57	)		—		6			—
Net realized gain/(loss) on affiliated investments and distributions from affiliated investment companies and affiliated investment company shares		(66,391	)		(38,281	)		8,878			(1,976	)		—			—		—			—
Reimbursement from affiliate (See Note 4)		—			—			—			—			—			—		—			—
Net change in net unrealized appreciation/(depreciation) on investments, foreign currency translations, forward foreign currency exchange contracts and foreign capital gains tax		(347,748	)		283,123			—			—			(135	)		—		(86	)		—
Net change in net unrealized appreciation/(depreciation) on affiliated investment companies and affiliated investment company shares		(112,603	)		123,090			(4,866	)		19,741			—			—		—			—
Net Increase/(Decrease) from Operations		(324,918	)		415,821			6,796			19,571			(191	)		—		(83	)		—
Distributions to Shareholders From:
Net investment income – Class A		(7,162	)		—			(1,706	)		(678	)		—			—		(1	)		—
Net realized gain – Class A		—			—			—			—			—			—		—	*		—
Net investment income – Class B		(500	)		—			(351	)		(239	)		—			—		—			—
Net realized gain – Class B		—			—			—			—			—			—		—			—
Net investment income – Class C		(672	)		—			(405	)		(124	)		—			—		—	*		—
Net realized gain – Class C		—			—			—			—			—			—		—	*		—
Net investment income – Class I		(141	)		—			—			—			—			—		—	*		—
Net realized gain – Class I		—			—			—			—			—			—		—	*		—
Net investment income – Class Z		(22,715	)		—			(1,460	)		(625	)		—			—		(11	)		—
Net realized gain – Class Z		—			—			—			—			—			—		(3	)		—
Total Distributions to Shareholders		(31,190	)		—			(3,922	)		(1,666	)		—			—		(15	)		—
Share Transactions:
Subscriptions – Class A		72,441			115,498			44,385			8,937			351			—		164			—
Distributions reinvested – Class A		6,307			—			1,391			609			—			—		1			—
Net assets of shares issued in connection with Merger – Class A		—			—			—			—			—			—		—			—
Redemptions – Class A		(203,499	)		(187,411	)		(11,539	)		(13,847	)		(13	)		—		—			—
Net Increase/(Decrease) – Class A		(124,751	)		(71,913	)		34,237			(4,301	)		338			—		165			—
Subscriptions – Class B		73			34			120			4			—			—		—			—
Distributions reinvested – Class B		391			—			261			218			—			—		—			—
Net assets of shares issued in connection with Merger – Class B		—			—			—			—			—			—		—			—
Redemptions – Class B		(37,412	)		(30,406	)		(18,369	)		(8,516	)		—			—		—			—
Net Increase/(Decrease) – Class B		(36,948	)		(30,372	)		(17,988	)		(8,294	)		—			—		—			—
Subscriptions – Class C		3,603			6,743			15,268			3,195			138			—		5			—
Distributions reinvested – Class C		494			—			313			109			—			—		—	*		—
Net assets of shares issued in connection with Merger – Class C		—			—			—			—			—			—		—			—
Redemptions – Class C		(23,948	)		(19,302	)		(4,725	)		(5,530	)		(10	)		—		—			—
Net Increase/(Decrease) – Class C		(19,851	)		(12,559	)		10,856			(2,226	)		128			—		5			—
Subscriptions – Class I		12,447			8,577			—			—			5			—		5			—
Distributions reinvested – Class I		141			—			—			—			—			—		—	*		—
Net assets of shares issued in connection with Merger – Class I		—			—			—			—			—			—		—			—
Redemptions – Class I		(8,782	)		(931	)		—			—			—			—		—			—
Net Increase/(Decrease) – Class I		3,806			7,646			—			—			5			—		5			—
Subscriptions – Class R		—			—			—			—			—			—		—			—
Net assets of shares issued in connection with Merger – Class R		—			—			—			—			—			—		—			—
Redemptions – Class R		—			—			—			—			—			—		—			—
Net Increase – Class R		—			—			—			—			—			—		—			—

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Changes in Net Assets, continued

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA						Columbia Acorn International Select
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2011			2010 (a)			2011 (b)			2010 (a)			2011			2010 (a)			2011			2010 (a)
Subscriptions – Class R5		—			—			3			—			—			—			—			—
Net assets of shares issued in connection with Merger – Class R5		—			—			2,232			—			—			—			—			—
Redemptions – Class R5		—			—			—	*		—			—			—			—			—
Net Increase – Class R5		—			—			2,235			—			—			—			—			—
Subscriptions – Class Z		2,172,346			2,077,687			965,616			1,216,447			349,841			260,284			45,936			67,172
Distributions reinvested – Class Z		471,639			324,149			91,324			76,344			7,534			—			5,069			1,451
Redemptions – Class Z		(2,515,311	)		(1,969,788	)		(973,865	)		(726,019	)		(331,533	)		(276,628	)		(113,289	)		(96,502	)
Net Increase/(Decrease) – Class Z		128,674			432,058			83,075			566,772			25,842			(16,344	)		(62,284	)		(27,879	)
Net Increase/(Decrease) from Share Transactions		(160,647	)		161,838			364,290			730,556			(49,669	)		(9,493	)		(71,300	)		(35,344	)
Redemption Fees		—			—			—			239			—			—			—			10
Increase from regulatory settlements		—			1			108			447			—			—			—			46
Increase from contribution from affiliate		—			—			—			—			—			—			—			—
Total Increase/(Decrease) in Net Assets		(1,762,137	)		3,371,561			(708,110	)		1,694,325			(140,101	)		308,937			(126,284	)		41,992
Net Assets:
Beginning of period		18,098,712			14,727,151			6,125,063			4,430,738			1,698,546			1,389,609			452,667			410,675
End of period	$	16,336,575		$	18,098,712		$	5,416,953		$	6,125,063		$	1,558,445		$	1,698,546		$	326,383		$	452,667
Undistributed (Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(32,074	)	$	(48,598	)	$	(60,514	)	$	5,502		$	(167	)	$	(238	)	$	(5,294	)	$	(1,132	)

(a) Class I shares reflect activity for the period September 27, 2010 (commencement of operations) through December 31, 2010.

(b) Class R and Class R5 shares reflect activity for the period August 15, 2011 (commencement of operations) through December 31, 2011.

* Rounds to less than $500.

See accompanying notes to financial statements.

	Columbia Acorn Select						Columbia Thermostat Fund						Columbia Acorn Emerging Markets Fund					Columbia Acorn European Fund
Increase (Decrease) in Net Assets	Year ended December 31,						Year ended December 31,						Year ended December 31,					Year ended December 31,
(in thousands)	2011			2010 (a)			2011			2010			2011 (c)			2010		2011 (c)			2010
Subscriptions – Class R5		—			—			—			—			—			—		—			—
Net assets of shares issued in connection with Merger – Class R5		—			—			—			—			—			—		—			—
Redemptions – Class R5		—			—			—			—			—			—		—			—
Net Increase – Class R5		—			—			—			—			—			—		—			—
Subscriptions – Class Z		177,362			358,116			42,102			7,895			2,949			—		1,589			—
Distributions reinvested – Class Z		17,488			—			1,165			560			—			—		13			—
Redemptions – Class Z		(653,289	)		(328,729	)		(14,914	)		(18,853	)		—	*		—		—	*		—
Net Increase/(Decrease) – Class Z		(458,439	)		29,387			28,353			(10,398	)		2,949			—		1,602			—
Net Increase/(Decrease) from Share Transactions		(636,183	)		(77,811	)		55,458			(25,219	)		3,420			—		1,777			—
Redemption Fees		—			—			—			—			—			—		—			—
Increase from regulatory settlements		—			—			—			—			—			—		—			—
Increase from contribution from affiliate		57			—			—			—			—			—		—			—
Total Increase/(Decrease) in Net Assets		(992,234	)		338,010			58,332			(7,314	)		3,229			—		1,679			—
Net Assets:
Beginning of period		2,282,855			1,944,845			131,275			138,589			—			—		—			—
End of period	$	1,290,621		$	2,282,855		$	189,607		$	131,275		$	3,229		$	—	$	1,679		$	—
Undistributed (Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(324	)	$	(17,217	)	$	471		$	1,479		$	(1	)	$	—	$	—	*	$	—

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Statements of Changes in Net Assets, continued

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA						Columbia Acorn International Select
Changes in Shares of Beneficial Interest:	Year ended December 31,						Year ended December 31,						Year ended December 31,						Year ended December 31,
(in thousands)	2011			2010 (a)			2011 (b)			2010 (a)			2011			2010 (a)			2011			2010 (a)
Subscriptions – Class A		30,309			32,735			7,713			8,744			1,507			2,334			666			746
Shares issued in reinvestment and capital gains – Class A		4,849			3,306			463			325			38			—			78			31
Shares issued in connection with merger – Class A		—			—			5,467			—			—			—			—			—
Less shares redeemed – Class A		(37,725	)		(34,053	)		(6,592	)		(6,188	)		(2,879	)		(2,521	)		(980	)		(982	)
Net Increase/(Decrease) – Class A		(2,567	)		1,988			7,051			2,881			(1,334	)		(187	)		(236	)		(205	)
Subscriptions – Class B		21			38			2			1			—	*		—	*		—	*		—	*
Shares issued in reinvestment and capital gains – Class B		164			276			12			9			1			—			2			1
Shares issued in connection with merger – Class B		—			—			343			—			—			—			—			—
Less shares redeemed – Class B		(8,046	)		(13,126	)		(353	)		(444	)		(267	)		(636	)		(39	)		(62	)
Net Increase/(Decrease) – Class B		(7,861	)		(12,812	)		4			(434	)		(266	)		(636	)		(37	)		(61	)
Subscriptions – Class C		3,779			3,197			519			700			90			76			36			83
Shares issued in reinvestment and capital gains – Class C		1,086			733			46			19			8			—			8			2
Shares issued in connection with merger – Class C		—			—			703			—			—			—			—			—
Less shares redeemed – Class C		(5,913	)		(6,190	)		(1,110	)		(519	)		(231	)		(214	)		(115	)		(138	)
Net Increase/(Decrease) – Class C		(1,048	)		(2,260	)		158			200			(133	)		(138	)		(71	)		(53	)
Subscriptions – Class I		639			436			764			1,677			371			1,025			—			—	*
Shares issued in reinvestment and capital gains – Class I		25			—			17			—	*		1			—			—			—
Shares issued in connection with merger – Class I		—			—			4,062			—			—			—			—			—
Less shares redeemed – Class I		(454	)		(51	)		(5,004	)		(50	)		(1,289	)		(10	)		—			—
Net Increase/(Decrease) – Class I		210			385			(161	)		1,627			(917	)		1,015			—			—	*
Subscriptions – Class R		—			—			10			—			—			—			—			—
Shares issued in connection with merger – Class R		—			—			54			—			—			—			—			—
Less shares redeemed – Class R		—			—			(2	)		—			—			—			—			—
Net Increase – Class R		—			—			62			—			—			—			—			—
Subscriptions – Class R5		—			—			—	*		—			—			—			—			—
Shares issued in connection with merger – Class R5		—			—			59			—			—			—			—			—
Net Increase – Class R5		—			—			59			—			—			—			—			—
Subscriptions – Class Z		72,817			78,950			24,482			33,971			12,164			10,643			1,655			2,699
Shares issued in reinvestment and capital gains – Class Z		16,442			11,048			2,222			2,239			274			—			192			66
Less shares redeemed – Class Z		(85,040	)		(74,926	)		(25,537	)		(20,195	)		(11,564	)		(11,173	)		(4,157	)		(3,845	)
Net Increase/(Decrease) – Class Z		4,219			15,072			1,167			16,015			874			(530	)		(2,310	)		(1,080	)
Net Increase/(Decrease) in Shares of Beneficial Interest		(7,047	)		2,373			8,340			20,289			(1,776	)		(476	)		(2,654	)		(1,399	)

(a) Class I shares reflect activity for the period September 27, 2010 (commencement of operations) through December 31, 2010.

(b) Class R and Class R5 shares reflect activity for the period August 15, 2011 (commencement of operations) through December 31, 2011.

* Rounds to less than 500 shares.

See accompanying notes to financial statements.

	Columbia Acorn Select						Columbia Thermostat Fund						Columbia Acorn Emerging Markets Fund					Columbia Acorn European Fund
Changes in Shares of Beneficial Interest:	Year ended December 31,						Year ended December 31,						Year ended December 31,					Year ended December 31,
(in thousands)	2011			2010 (a)			2011			2010			2011 (c)			2010		2011 (c)			2010
Subscriptions – Class A		2,804			4,815			3,467			765			37			—		16			—
Shares issued in reinvestment and capital gains – Class A		242			—			109			56			—			—		—	*		—
Shares issued in connection with merger – Class A		—			—			—			—			—			—		—			—
Less shares redeemed – Class A		(8,092	)		(7,851	)		(898	)		(1,223	)		(1	)		—		—			—
Net Increase/(Decrease) – Class A		(5,046	)		(3,036	)		2,678			(402	)		36			—		16			—
Subscriptions – Class B		3			2			10			—	*		—			—		—			—
Shares issued in reinvestment and capital gains – Class B		16			—			20			21			—			—		—			—
Shares issued in connection with merger – Class B		—			—			—			—			—			—		—			—
Less shares redeemed – Class B		(1,569	)		(1,342	)		(1,427	)		(744	)		—			—		—			—
Net Increase/(Decrease) – Class B		(1,550	)		(1,340	)		(1,397	)		(723	)		—			—		—			—
Subscriptions – Class C		145			299			1,196			275			15			—		1			—
Shares issued in reinvestment and capital gains – Class C		21			—			24			10			—			—		—	*		—
Shares issued in connection with merger – Class C		—			—			—			—			—			—		—			—
Less shares redeemed – Class C		(1,011	)		(870	)		(368	)		(485	)		(1	)		—		—			—
Net Increase/(Decrease) – Class C		(845	)		(571	)		852			(200	)		14			—		1			—
Subscriptions – Class I		520			305			—			—			1			—		1			—
Shares issued in reinvestment and capital gains – Class I		5			—			—			—			—			—		—	*		—
Shares issued in connection with merger – Class I		—			—			—			—			—			—		—			—
Less shares redeemed – Class I		(335	)		(32	)		—			—			—			—		—			—
Net Increase/(Decrease) – Class I		190			273			—			—			1			—		1			—
Subscriptions – Class R		—			—			—			—			—			—		—			—
Shares issued in connection with merger – Class R		—			—			—			—			—			—		—			—
Less shares redeemed – Class R		—			—			—			—			—			—		—			—
Net Increase – Class R		—			—			—			—			—			—		—			—
Subscriptions – Class R5		—			—			—			—			—			—		—			—
Shares issued in connection with merger – Class R5		—			—			—			—			—			—		—			—
Net Increase – Class R5		—			—			—			—			—			—		—			—
Subscriptions – Class Z		6,576			14,221			3,338			697			298			—		159			—
Shares issued in reinvestment and capital gains – Class Z		654			—			92			51			—			—		2			—
Less shares redeemed – Class Z		(25,141	)		(13,400	)		(1,192	)		(1,710	)		—	*		—		—	*		—
Net Increase/(Decrease) – Class Z		(17,911	)		821			2,238			(962	)		298			—		161			—
Net Increase/(Decrease) in Shares of Beneficial Interest		(25,162	)		(3,853	)		4,371			(2,287	)		349			—		179			—

See accompanying notes to financial statements.

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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	29.24		$	23.98		$	17.22		$	28.87		$	29.02
Income from Investment Operations
Net investment income/(loss) (a)		(0.10	)		(0.06	)		(0.02	)		(0.01	)		0.05	(b)
Net realized and unrealized gain/(loss)		(1.30	)		6.18			6.78			(10.98	)		2.13
Total from Investment Operations		(1.40	)		6.12			6.76			(10.99	)		2.18
Less Distributions to Shareholders
From net investment income		(0.02	)		(0.02	)		—			—			(0.03	)
From net realized gains		(1.19	)		(0.84	)		—			(0.66	)		(2.30	)
Total Distributions to Shareholders		(1.21	)		(0.86	)		—			(0.66	)		(2.33	)
Increase from regulatory settlements		—			0.00	(c)		0.00	(c)		—			—
Net Asset Value, End of Period	$	26.63		$	29.24		$	23.98		$	17.22		$	28.87
Total Return (d)		(4.91	)%		25.61	%		39.26	%		(38.72	)%		7.39	%(e)(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.06	%		1.07	%		1.07	%		1.05	%		1.02	%
Net investment income/(loss) (g)		(0.33	)%		(0.22	)%		(0.12	)%		(0.04	)%		0.17	%
Waiver/Reimbursement		—			—			—			—			0.01	%
Portfolio turnover rate		18	%		28	%		27	%		21	%		20	%
Net assets at end of period (000s)	$	3,246,833		$	3,639,788		$	2,937,761		$	2,221,100		$	4,300,920

(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.

(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.

(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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	27.14		$	22.43		$	16.21		$	27.39		$	27.78
Income from Investment Operations
Net investment loss (a)		(0.27	)		(0.21	)		(0.14	)		(0.15	)		(0.11	)(b)
Net realized and unrealized gain/(loss)		(1.15	)		5.76			6.36			(10.37	)		2.02
Total from Investment Operations		(1.42	)		5.55			6.22			(10.52	)		1.91
Less Distributions to Shareholders
From net realized gains		(1.19	)		(0.84	)		—			(0.66	)		(2.30	)
Total Distributions to Shareholders		(1.19	)		(0.84	)		—			(0.66	)		(2.30	)
Increase from regulatory settlements		—			0.00	(c)		0.00	(c)		—			—
Net Asset Value, End of Period	$	24.53		$	27.14		$	22.43		$	16.21		$	27.39
Total Return (d)		(5.34	)%		24.81	%		38.37	%		(39.11	)%		6.76	%(e)(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.67	%		1.69	%		1.74	%		1.65	%		1.59	%
Net investment loss (g)		(0.98	)%		(0.88	)%		(0.77	)%		(0.64	)%		(0.39	)%
Waiver/Reimbursement		—			—			—			—			0.01	%
Portfolio turnover rate		18	%		28	%		27	%		21	%		20	%
Net assets at end of period (000s)	$	67,153		$	287,650		$	525,072		$	581,587		$	1,270,292

(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.

(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.

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

See accompanying notes to financial statements.

Class C Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	26.85		$	22.23		$	16.09		$	27.25		$	27.70
Income from Investment Operations
Net investment loss (a)		(0.29	)		(0.24	)		(0.17	)		(0.19	)		(0.18	)(b)
Net realized and unrealized gain/(loss)		(1.19	)		5.70			6.31			(10.31	)		2.03
Total from Investment Operations		(1.48	)		5.46			6.14			(10.50	)		1.85
Less Distributions to Shareholders
From net realized gains		(1.19	)		(0.84	)		—			(0.66	)		(2.30	)
Total Distributions to Shareholders		(1.19	)		(0.84	)		—			(0.66	)		(2.30	)
Increase from regulatory settlements		—			0.00	(c)		0.00	(c)		—			—
Net Asset Value, End of Period	$	24.18		$	26.85		$	22.23		$	16.09		$	27.25
Total Return (d)		(5.63	)%		24.63	%		38.16	%		(39.23	)%		6.56	%(e)(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.82	%		1.85	%		1.89	%		1.83	%		1.79	%
Net investment loss (g)		(1.10	)%		(1.00	)%		(0.93	)%		(0.82	)%		(0.60	)%
Waiver/Reimbursement		—			—			—			—			0.00	%(h)
Portfolio turnover rate		18	%		28	%		27	%		21	%		20	%
Net assets at end of period (000s)	$	721,446		$	829,181		$	736,818		$	622,665		$	1,312,243

(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.

(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.

(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	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010 (a)
Net Asset Value, Beginning of Period	$	30.19		$	26.80
Income from Investment Operations
Net investment income/(loss) (b)		0.01			(0.01	)
Net realized and unrealized gain/(loss)		(1.35	)		4.26
Total from Investment Operations		(1.34	)		4.25
Less Distributions to Shareholders
From net investment income		(0.09	)		(0.02	)
From net realized gains		(1.19	)		(0.84	)
Total Distributions to Shareholders		(1.28	)		(0.86	)
Net Asset Value, End of Period	$	27.57		$	30.19
Total Return (c)		(4.57	)%		15.94	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		0.72	%		0.71	%(f)
Net investment income/(loss) (e)		0.02	%		(0.13	)%(f)
Portfolio turnover rate		18	%		28	%(d)
Net assets at end of period (000s)	$	16,397		$	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.

(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.

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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	40.87		$	34.13		$	23.03		$	43.42		$	40.07
Income from Investment Operations
Net investment income (a)		0.32			0.22			0.23			0.47			0.27
Net realized and unrealized gain/(loss)		(6.02	)		7.21			11.27			(20.20	)		6.52
Reimbursement from affiliate		0.00	(b)		—			—			—			—
Total from Investment Operations		(5.70	)		7.43			11.50			(19.73	)		6.79
Less Distributions to Shareholders
From net investment income		(1.02	)		(0.69	)		(0.41	)		(0.06	)		(0.08	)
From net realized gains		—			—			—			(0.60	)		(3.36	)
Total Distributions to Shareholders		(1.02	)		(0.69	)		(0.41	)		(0.66	)		(3.44	)
Redemption Fees
Redemption fees added to paid in capital (a)		—			0.00	(b)		0.00	(b)		0.00	(b)		0.00	(b)
Increase from regulatory settlements		0.00	(b)		0.00	(b)		0.01			—			—
Net Asset Value, End of Period	$	34.15		$	40.87		$	34.13		$	23.03		$	43.42
Total Return (c)		(14.37	)%(d)(e)		22.23	%		50.40	%		(46.09	)%		16.90	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		1.30	%		1.35	%		1.36	%		1.31	%		1.23	%
Net investment income (f)		0.84	%		0.62	%		0.85	%		1.36	%		0.60	%
Waiver/Reimbursement		0.02	%		—			—			—			0.00	%(g)
Portfolio turnover rate		32	%		25	%		31	%		38	%		28	%
Net assets at end of period (000s)	$	918,112		$	810,603		$	578,599		$	366,820		$	622,901

(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) During the year ended December 31, 2011, Columbia Management reimbursed the Fund for a loss on a trading error. Had the Fund not received this reimbursement total return would have been lower by less than 0.01%.

(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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	39.96		$	33.22		$	22.41		$	42.46		$	39.39
Income from Investment Operations
Net investment income (a)		0.06			0.03			0.08			0.27			0.04
Net realized and unrealized gain/(loss)		(5.85	)		7.02			10.92			(19.72	)		6.39
Reimbursement from affiliate		0.00	(b)		—			—			—			—
Total from Investment Operations		(5.79	)		7.05			11.00			(19.45	)		6.43
Less Distributions to Shareholders
From net investment income		(1.00	)		(0.31	)		(0.20	)		—			(0.00	)(b)
From net realized gains		—			—			—			(0.60	)		(3.36	)
Total Distributions to Shareholders		(1.00	)		(0.31	)		(0.20	)		(0.60	)		(3.36	)
Redemption Fees
Redemption fees added to paid in capital (a)		—			0.00	(b)		0.00	(b)		0.00	(b)		0.00	(b)
Increase from regulatory settlements		0.00	(b)		0.00	(b)		0.01			—			—
Net Asset Value, End of Period	$	33.17		$	39.96		$	33.22		$	22.41		$	42.46
Total Return (c)		(14.92	)%(d)(e)		21.49	%		49.36	%		(46.41	)%		16.25	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		1.96	%		1.96	%		2.03	%		1.90	%		1.81	%
Net investment income (f)		0.15	%		0.08	%		0.29	%		0.77	%		0.08	%
Waiver/Reimbursement		0.02	%		—			—			—			0.01	%
Portfolio turnover rate		32	%		25	%		31	%		38	%		28	%
Net assets at end of period (000s)	$	24,510		$	29,368		$	38,835		$	39,153		$	103,631

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

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

(d) 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.

Class C Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	39.79		$	33.08		$	22.30		$	42.32		$	39.35
Income from Investment Operations
Net investment income/(loss) (a)		0.04			(0.05	)		0.02			0.21			(0.06	)
Net realized and unrealized gain/(loss)		(5.86	)		7.03			10.89			(19.63	)		6.39
Reimbursement from affiliate		0.00	(b)		—			—			—			—
Total from Investment Operations		(5.82	)		6.98			10.91			(19.42	)		6.33
Less Distributions to Shareholders
From net investment income		(0.94	)		(0.27	)		(0.14	)	��	—			(0.00	)(b)
From net realized gains		—			—			—			(0.60	)		(3.36	)
Total Distributions to Shareholders		(0.94	)		(0.27	)		(0.14	)		(0.60	)		(3.36	)
Redemption Fees
Redemption fees added to paid in capital (a)		—			0.00	(b)		0.00	(b)		0.00	(b)		0.00	(b)
Increase from regulatory settlements		0.00	(b)		0.00	(b)		0.01			—			—
Net Asset Value, End of Period	$	33.03		$	39.79		$	33.08		$	22.30		$	42.32
Total Return (c)		(15.02	)%(d)(e)		21.34	%		49.12	%		(46.50	)%		16.01	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		2.06	%		2.11	%		2.17	%		2.08	%		1.99	%
Net investment income/(loss) (f)		0.10	%		(0.13	)%		0.07	%		0.60	%		(0.14	)%
Waiver/Reimbursement		0.01	%		—			—			—			0.00	%(g)
Portfolio turnover rate		32	%		25	%		31	%		38	%		28	%
Net assets at end of period (000s)	$	97,328		$	110,931		$	85,625		$	62,906		$	153,416

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

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

(d) 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 I Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010 (a)
Net Asset Value, Beginning of Period	$	40.92		$	37.69
Income from Investment Operations
Net investment income (b)		0.37			0.08
Net realized and unrealized gain/(loss)		(5.94	)		3.49
Reimbursement from affiliate		0.00	(c)		—
Total from Investment Operations		(5.57	)		3.57
Less Distributions to Shareholders
From net investment income		(1.02	)		(0.34	)
Total Distributions to Shareholders		(1.02	)		(0.34	)
Redemption Fees
Redemption fees added to paid in capital (b)		—			0.00	(c)
Increase from regulatory settlements		0.00	(c)		—
Net Asset Value, End of Period	$	34.33		$	40.92
Total Return (d)		(14.02	)%(e)		9.50	%(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		0.91	%		0.94	%(h)
Net investment income (g)		0.99	%		0.77	%(h)
Portfolio turnover rate		32	%		25	%(f)
Net assets at end of period (000s)	$	50,335		$	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.

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

(f) Not annualized.

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

(h) Annualized.

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

Financial Highlights, continued

Class R Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	40.11
Income from Investment Operations
Net investment income (b)		(0.00	)(c)
Net realized and unrealized loss		(6.00	)
Reimbursement from affiliate		0.00	(c)
Total from Investment Operations		(6.00	)
Increase from regulatory settlements		0.00	(c)
Net Asset Value, End of Period	$	34.11
Total Return (d)(e)(f)		(14.96	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.59	%(h)
Net investment loss (g)		(0.02	)%(h)
Portfolio turnover rate (e)		32	%
Net assets at end of period (000s)	$	2,130

(a) Class R shares commenced operations on August 2, 2011. 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.

(d) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(e) Not annualized.

(f) During the year ended December 31, 2011, Columbia Management reimbursed the Fund for a loss on a trading error. Had the Fund not received this reimbursement total return would have been lower by less than 0.01%.

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

(h) Annualized.

Class R5 Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	40.24
Income from Investment Operations
Net investment income (b)		0.09
Net realized and unrealized loss		(6.02	)
Reimbursement from affiliate		0.00	(c)
Total from Investment Operations		(5.93	)
Increase from regulatory settlements		0.00	(c)
Net Asset Value, End of Period	$	34.31
Total Return (d)(e)(f)		(14.74	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		0.91	%(h)
Net investment income (g)		0.65	%(h)
Portfolio turnover rate (e)		32	%
Net assets at end of period (000s)	$	2,038

(a) Class R5 shares commended operations on August 2, 2011. 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.

(d) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(e) Not annualized.

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

(h) Annualized.

See accompanying notes to financial statements.

100

Columbia Acorn USA

Class A Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	27.54		$	22.43		$	15.90		$	27.23		$	28.02
Income from Investment Operations
Net investment loss (a)		(0.22	)		(0.15	)		(0.11	)		(0.14	)		(0.09	)(b)
Net realized and unrealized gain/(loss)		(1.21	)		5.26			6.64			(10.23	)		1.01
Total from Investment Operations		(1.43	)		5.11			6.53			(10.37	)		0.92
Less Distributions to Shareholders
From net realized gains		(0.17	)		—			—			(0.96	)		(1.71	)
Total Distributions to Shareholders		(0.17	)		—			—			(0.96	)		(1.71	)
Increase from regulatory settlements		—			—			0.00	(c)		—			—
Net Asset Value, End of Period	$	25.94		$	27.54		$	22.43		$	15.90		$	27.23
Total Return (d)		(5.21	)%		22.78	%		41.07	%		(39.38	)%		3.18	%(e)(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.30	%		1.30	%		1.32	%		1.29	%		1.25	%
Net investment loss (g)		(0.78	)%		(0.64	)%		(0.64	)%		(0.60	)%		(0.29	)%
Waiver/Reimbursement		—			—			—			—			0.00	%(h)
Portfolio turnover rate		20	%		32	%		28	%		23	%		21	%
Net assets at end of period (000s)	$	167,038		$	214,097		$	178,605		$	136,597		$	245,085

(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.

(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.

(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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	25.60		$	20.99		$	14.98		$	25.87		$	26.87
Income from Investment Operations
Net investment loss (a)		(0.37	)		(0.30	)		(0.22	)		(0.27	)		(0.25	)(b)
Net realized and unrealized gain/(loss)		(1.08	)		4.91			6.23			(9.66	)		0.96
Total from Investment Operations		(1.45	)		4.61			6.01			(9.93	)		0.71
Less Distributions to Shareholders
From net realized gains		(0.17	)		—			—			(0.96	)		(1.71	)
Total Distributions to Shareholders		(0.17	)		—			—			(0.96	)		(1.71	)
Increase from regulatory settlements		—			—			0.00	(c)		—			—
Net Asset Value, End of Period	$	23.98		$	25.60		$	20.99		$	14.98		$	25.87
Total Return (d)		(5.68	)%		21.96	%		40.12	%		(39.75	)%		2.53	%(e)(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.92	%		1.98	%		2.02	%		1.92	%		1.85	%
Net investment loss (g)		(1.42	)%		(1.37	)%		(1.33	)%		(1.24	)%		(0.87	)%
Waiver/Reimbursement		—			—			—			—			0.01	%
Portfolio turnover rate		20	%		32	%		28	%		23	%		21	%
Net assets at end of period (000s)	$	2,253		$	9,222		$	20,903		$	23,633		$	53,820

(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.

(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.

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

See accompanying notes to financial statements.

101

Columbia Acorn Family of Funds

Financial Highlights, continued

Class C Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	25.39		$	20.84		$	14.89		$	25.77		$	26.81
Income from Investment Operations
Net investment loss (a)		(0.39	)		(0.31	)		(0.24	)		(0.30	)		(0.30	)(b)
Net realized and unrealized gain/(loss)		(1.11	)		4.86			6.19			(9.62	)		0.97
Total from Investment Operations		(1.50	)		4.55			5.95			(9.92	)		0.67
Less Distributions to Shareholders
From net realized gains		(0.17	)		—			—			(0.96	)		(1.71	)
Total Distributions to Shareholders		(0.17	)		—			—			(0.96	)		(1.71	)
Increase from regulatory settlements		—			—			0.00	(c)		—			—
Net Asset Value, End of Period	$	23.72		$	25.39		$	20.84		$	14.89		$	25.77
Total Return (d)		(5.92	)%		21.83	%		39.96	%		(39.87	)%		2.39	%(e)(f)
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		2.05	%		2.08	%		2.13	%		2.08	%		2.03	%
Net investment loss (g)		(1.53	)%		(1.41	)%		(1.45	)%		(1.39	)%		(1.07	)%
Waiver/Reimbursement		—			—			—			—			0.00	%(h)
Portfolio turnover rate		20	%		32	%		28	%		23	%		21	%
Net assets at end of period (000s)	$	30,584		$	36,101		$	32,508		$	25,899		$	50,743

(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.

(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.

(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	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010 (a)
Net Asset Value, Beginning of Period	$	28.56		$	24.24
Income from Investment Operations
Net investment loss (b)		(0.14	)		(0.03	)
Net realized and unrealized gain/(loss)		(1.25	)		4.35
Total from Investment Operations		(1.39	)		4.32
Less Distributions to Shareholders
From net realized gains		(0.17	)		—
Total Distributions to Shareholders		(0.17	)		—
Net Asset Value, End of Period	$	27.00		$	28.56
Total Return (c)		(4.88	)%		17.82	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		0.94	%		0.94	%(f)
Net investment loss (e)		(0.47	)%		(0.35	)%(f)
Portfolio turnover rate		20	%		32	%(d)
Net assets at end of period (000s)	$	2,635		$	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.

(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.

102

Columbia Acorn International Select

Class A Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	28.01		$	23.39		$	17.99		$	31.74		$	27.68
Income from Investment Operations
Net investment income (a)		0.18			0.08			0.10			0.20			0.04	(b)
Net realized and unrealized gain/(loss)		(2.95	)		4.84			5.43			(13.41	)		5.91
Total from Investment Operations		(2.77	)		4.92			5.53			(13.21	)		5.95
Less Distributions to Shareholders
From net investment income		(0.59	)		(0.30	)		(0.15	)		—			(0.12	)
From net realized gains		(0.39	)		—			—			(0.54	)		(1.77	)
Total Distributions to Shareholders		(0.98	)		(0.30	)		(0.15	)		(0.54	)		(1.89	)
Redemption Fees
Redemption fees added to paid in capital (a)		—			0.00	(c)		0.00	(c)		0.00	(c)		0.00	(c)
Increase from regulatory settlements		—			0.00	(c)		0.02			—			—
Net Asset Value, End of Period	$	24.26		$	28.01		$	23.39		$	17.99		$	31.74
Total Return (d)		(10.11	)%		21.41	%		31.01	%		(42.30	)%		21.50	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		1.51	%		1.56	%		1.56	%		1.54	%		1.49	%
Net investment income (f)		0.66	%		0.33	%		0.53	%		0.78	%		0.11	%
Waiver/Reimbursement		—			—			—			—			0.00	%(g)
Portfolio turnover rate		44	%		42	%		56	%		68	%		57	%
Net assets at end of period (000s)	$	56,350		$	71,668		$	64,664		$	46,522		$	48,538

(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.

(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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	26.72		$	22.34		$	17.16		$	30.50		$	26.73
Income from Investment Operations
Net investment income/(loss) (a)		0.01			(0.06	)		(0.01	)		0.04			(0.13	)(b)
Net realized and unrealized gain/(loss)		(2.82	)		4.62			5.17			(12.84	)		5.67
Total from Investment Operations		(2.81	)		4.56			5.16			(12.80	)		5.54
Less Distributions to Shareholders
From net investment income		(0.25	)		(0.18	)		—			—			—
From net realized gains		(0.39	)		—			—			(0.54	)		(1.77	)
Total Distributions to Shareholders		(0.64	)		(0.18	)		—			(0.54	)		(1.77	)
Redemption Fees
Redemption fees added to paid in capital (a)		—			0.00	(c)		0.00	(c)		0.00	(c)		0.00	(c)
Increase from regulatory settlements		—			0.00	(c)		0.02			—			—
Net Asset Value, End of Period	$	23.27		$	26.72		$	22.34		$	17.16		$	30.50
Total Return (d)		(10.64	)%		20.63	%(e)		30.19	%(e)		(42.68	)%		20.69	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		2.14	%		2.20	%		2.20	%		2.17	%		2.10	%
Net investment income/(loss) (f)		0.04	%		(0.27	)%		(0.05	)%		0.16	%		(0.45	)%
Waiver/Reimbursement		—			0.04	%		0.12	%		—			0.01	%
Portfolio turnover rate		44	%		42	%		56	%		68	%		57	%
Net assets at end of period (000s)	$	1,774		$	3,030		$	3,887		$	4,444		$	11,941

(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.

(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.

103

Columbia Acorn Family of Funds

Financial Highlights, continued

Class C Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	26.58		$	22.21		$	17.08		$	30.42		$	26.70
Income from Investment Operations
Net investment income/(loss) (a)		(0.04	)		(0.10	)		(0.06	)		0.00	(b)		(0.20	)(c)
Net realized and unrealized gain/(loss)		(2.81	)		4.60			5.17			(12.80	)		5.69
Total from Investment Operations		(2.85	)		4.50			5.11			(12.80	)		5.49
Less Distributions to Shareholders
From net investment income		(0.17	)		(0.13	)		—			—			—
From net realized gains		(0.39	)		—			—			(0.54	)		(1.77	)
Total Distributions to Shareholders		(0.56	)		(0.13	)		—			(0.54	)		(1.77	)
Redemption Fees
Redemption fees added to paid in capital (a)		—			0.00	(b)		0.00	(b)		0.00	(b)		0.00	(b)
Increase from regulatory settlements		—			0.00	(b)		0.02			—			—
Net Asset Value, End of Period	$	23.17		$	26.58		$	22.21		$	17.08		$	30.42
Total Return (d)		(10.81	)%		20.45	%		30.04	%		(42.79	)%		20.53	%(e)
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		2.31	%		2.36	%		2.42	%		2.34	%		2.29	%
Net investment income/(loss) (f)		(0.14	)%		(0.45	)%		(0.30	)%		0.01	%		(0.68	)%
Waiver/Reimbursement		—			—			—			—			0.01	%
Portfolio turnover rate		44	%		42	%		56	%		68	%		57	%
Net assets at end of period (000s)	$	8,704		$	11,885		$	11,096		$	9,747		$	13,023

(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	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010 (a)
Net Asset Value, Beginning of Period	$	28.33		$	26.11
Income from Investment Operations
Net investment income (b)		0.31			0.03
Net realized and unrealized gain/(loss)		(2.97	)		2.19
Total from Investment Operations		(2.66	)		2.22
Less Distributions to Shareholders
From net investment income		(0.83	)		—
From net realized gains		(0.39	)		—
Total Distributions to Shareholders		(1.22	)		—
Net Asset Value, End of Period	$	24.45		$	28.33
Total Return (c)		(9.68	)%		8.50	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.04	%		1.14	%(f)
Net investment income (e)		1.12	%		0.44	%(f)
Portfolio turnover rate		44	%		42	%(d)
Net assets at end of period (000s)	$	2		$	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.

(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.

104

Columbia Acorn Select

Class A Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	27.94		$	22.81		$	13.77		$	27.89		$	26.18
Income from Investment Operations
Net investment loss (a)		(0.15	)		(0.18	)		(0.14	)		(0.18	)		(0.15	)
Net realized and unrealized gain/(loss)		(4.46	)		5.31			9.18			(13.25	)		2.50
Total from Investment Operations		(4.61	)		5.13			9.04			(13.43	)		2.35
Less Distributions to Shareholders
From net investment income		(0.38	)		—			—			—			—
From net realized gains		—			—			—			(0.69	)		(0.64	)
Total Distributions to Shareholders		(0.38	)		—			—			(0.69	)		(0.64	)
Net Asset Value, End of Period	$	22.95		$	27.94		$	22.81		$	13.77		$	27.89
Total Return (b)		(16.65	)%		22.49	%		65.65	%		(49.31	)%(c)		8.92	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.28	%		1.28	%		1.30	%		1.24	%		1.19	%
Net investment loss (e)		(0.57	)%		(0.73	)%		(0.78	)%		(0.80	)%		(0.52	)%
Waiver/Reimbursement		—			—			—			—			0.00	%(f)
Portfolio turnover rate		21	%		28	%		19	%		28	%		14	%
Net assets at end of period (000s)	$	340,325		$	555,263		$	522,443		$	395,794		$	1,117,941

(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 Advisor 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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	26.06		$	21.41		$	13.02		$	26.57		$	25.13
Income from Investment Operations
Net investment loss (a)		(0.30	)		(0.31	)		(0.24	)		(0.31	)		(0.31	)
Net realized and unrealized gain/(loss)		(4.13	)		4.96			8.63			(12.55	)		2.39
Total from Investment Operations		(4.43	)		4.65			8.39			(12.86	)		2.08
Less Distributions to Shareholders
From net investment income		(0.23	)		—			—			—			—
From net realized gains		—			—			—			(0.69	)		(0.64	)
Total Distributions to Shareholders		(0.23	)		—			—			(0.69	)		(0.64	)
Net Asset Value, End of Period	$	21.40		$	26.06		$	21.41		$	13.02		$	26.57
Total Return (b)		(17.11	)%		21.72	%		64.44	%		(49.62	)%(c)		8.22	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.88	%		1.92	%		2.01	%		1.87	%		1.79	%
Net investment loss (e)		(1.21	)%		(1.39	)%		(1.49	)%		(1.43	)%		(1.12	)%
Waiver/Reimbursement		—			—			—			—			0.01	%
Portfolio turnover rate		21	%		28	%		19	%		28	%		14	%
Net assets at end of period (000s)	$	26,126		$	72,203		$	88,004		$	73,152		$	199,182

(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.

(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.

105

Columbia Acorn Family of Funds

Financial Highlights, continued

Class C Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	25.83		$	21.25		$	12.94		$	26.46		$	25.07
Income from Investment Operations
Net investment loss (a)		(0.32	)		(0.34	)		(0.26	)		(0.34	)		(0.36	)
Net realized and unrealized gain/(loss)		(4.12	)		4.92			8.57			(12.49	)		2.39
Total from Investment Operations		(4.44	)		4.58			8.31			(12.83	)		2.03
Less Distributions to Shareholders
From net investment income		(0.19	)		—			—			—			—
From net realized gains		—			—			—			(0.69	)		(0.64	)
Total Distributions to Shareholders		(0.19	)		—			—			(0.69	)		(0.64	)
Net Asset Value, End of Period	$	21.20		$	25.83		$	21.25		$	12.94		$	26.46
Total Return (b)		(17.27	)%		21.55	%		64.22	%		(49.71	)%(c)		8.04	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		2.05	%		2.07	%		2.14	%		2.04	%		1.98	%
Net investment loss (e)		(1.34	)%		(1.52	)%		(1.62	)%		(1.60	)%		(1.31	)%
Waiver/Reimbursement		—			—			—			—			0.00	%(f)
Portfolio turnover rate		21	%		28	%		19	%		28	%		14	%
Net assets at end of period (000s)	$	62,887		$	98,445		$	93,121		$	70,962		$	197,100

(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.

(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	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010 (a)
Net Asset Value, Beginning of Period	$	28.74		$	24.74
Income from Investment Operations
Net investment income/(loss) (b)		(0.03	)		0.01
Net realized and unrealized gain/(loss)		(4.59	)		3.99
Total from Investment Operations		(4.62	)		4.00
Less Distributions to Shareholders
From net investment income		(0.47	)		—
Total Distributions to Shareholders		(0.47	)		—
Net Asset Value, End of Period	$	23.65		$	28.74
Total Return (c)		(16.25	)%		16.17	%(d)
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		0.92	%		0.91	%(f)
Net investment income/(loss) (e)		(0.12	)%		0.18	%(f)
Portfolio turnover rate		21	%		28	%(d)
Net assets at end of period (000s)	$	10,944		$	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.

(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.

106

Columbia Thermostat Fund

Class A Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	12.58		$	10.90		$	8.26		$	12.31		$	12.59
Income from Investment Operations
Net investment income (a)		0.28			0.19			0.11			0.22			0.49
Net realized and unrealized gain/(loss)		0.30			1.67			2.53			(3.98	)		0.53
Total from Investment Operations		0.58			1.86			2.64			(3.76	)		1.02
Less Distributions to Shareholders
From net investment income		(0.34	)		(0.18	)		(0.00	)(b)		(0.22	)		(0.51	)
From net realized gains		—			—			—			(0.07	)		(0.79	)
Total Distributions to Shareholders		(0.34	)		(0.18	)		(0.00	)(b)		(0.29	)		(1.30	)
Net Asset Value, End of Period	$	12.82		$	12.58		$	10.90		$	8.26		$	12.31
Total Return (c)(d)		4.62	%		17.28	%		31.98	%		(30.67	)%		8.19	%
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)		2.17	%		1.64	%		1.17	%		1.99	%		3.75	%
Waiver/Reimbursement		0.17	%		0.22	%		0.28	%		0.18	%		0.18	%
Portfolio turnover rate		130	%		118	%		17	%		130	%		128	%
Net assets at end of period (000s)	$	79,744		$	44,527		$	42,976		$	41,032		$	53,246

(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) In addition to the fees and expenses which the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of the affiliated funds in which it invests. Such indirect expenses are not included in the reported expense ratios.

(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}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	12.64		$	10.93		$	8.32		$	12.38		$	12.62
Income from Investment Operations
Net investment income (a)		0.15			0.13			0.06			0.16			0.42
Net realized and unrealized gain/(loss)		0.38			1.67			2.55			(4.00	)		0.54
Total from Investment Operations		0.53			1.80			2.61			(3.84	)		0.96
Less Distributions to Shareholders
From net investment income		(0.26	)		(0.09	)		—			(0.15	)		(0.41	)
From net realized gains		—			—			—			(0.07	)		(0.79	)
Total Distributions to Shareholders		(0.26	)		(0.09	)		—			(0.22	)		(1.20	)
Net Asset Value, End of Period	$	12.91		$	12.64		$	10.93		$	8.32		$	12.38
Total Return (b)(c)		4.19	%		16.64	%		31.37	%		(31.10	)%		7.71	%
Ratios to Average Net Assets/Supplemental Data
Net expenses (d)(e)		1.00	%		1.00	%		1.00	%		1.00	%		1.00	%
Net investment income (e)		1.18	%		1.10	%		0.64	%		1.45	%		3.25	%
Waiver/Reimbursement		0.23	%		0.28	%		0.32	%		0.20	%		0.19	%
Portfolio turnover rate		130	%		118	%		17	%		130	%		128	%
Net assets at end of period (000s)	$	11,318		$	28,752		$	32,758		$	36,673		$	67,709

(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.

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

See accompanying notes to financial statements.

107

Columbia Acorn Family of Funds

Financial Highlights, continued

Class C Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011			2010			2009			2008			2007
Net Asset Value, Beginning of Period	$	12.62		$	10.91		$	8.33		$	12.37		$	12.62
Income from Investment Operations
Net investment income (a)		0.18			0.10			0.03			0.13			0.39
Net realized and unrealized gain/(loss)		0.31			1.68			2.55			(3.97	)		0.53
Total from Investment Operations		0.49			1.78			2.58			(3.84	)		0.92
Less Distributions to Shareholders
From net investment income		(0.20	)		(0.07	)		—			(0.13	)		(0.38	)
From net realized gains		—			—			—			(0.07	)		(0.79	)
Total Distributions to Shareholders		(0.20	)		(0.07	)		—			(0.20	)		(1.17	)
Net Asset Value, End of Period	$	12.91		$	12.62		$	10.91		$	8.33		$	12.37
Total Return (b)(c)		3.87	%		16.43	%		30.97	%		(31.20	)%		7.36	%
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)		1.40	%		0.88	%		0.39	%		1.23	%		3.02	%
Waiver/Reimbursement		0.18	%		0.24	%		0.30	%		0.20	%		0.19	%
Portfolio turnover rate		130	%		118	%		17	%		130	%		128	%
Net assets at end of period (000s)	$	33,378		$	21,866		$	21,090		$	24,383		$	26,908

(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.

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

Columbia Acorn Emerging Markets Fund

Class A Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	10.00
Income from Investment Operations
Net investment income (b)		(0.00	)(c)
Net realized and unrealized loss		(0.74	)
Total from Investment Operations		(0.74	)
Net Asset Value, End of Period	$	9.26
Total Return (d)(e)(f)		(7.40	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (g)		1.85	%
Net investment loss (g)		(0.01	)%
Waiver/Reimbursement		18.28	%
Portfolio turnover rate (f)		9	%
Net assets at end of period (000s)	$	332

(a) Class A shares commenced operations on August 19, 2011. 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.

(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) Not annualized.

(g) Annualized.

See accompanying notes to financial statements.

108

Class C Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	10.00
Income from Investment Operations
Net investment loss (b)		(0.02	)
Net realized and unrealized loss		(0.74	)
Total from Investment Operations		(0.76	)
Net Asset Value, End of Period	$	9.24
Total Return (c)(d)(e)		(7.60	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		2.60	%
Net investment loss (f)		(0.68	)%
Waiver/Reimbursement		22.46	%
Portfolio turnover rate (e)		9	%
Net assets at end of period (000s)	$	127

(a) Class C shares commenced operations on August 19, 2011. 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.

(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) Not annualized.

(f) Annualized.

Class I Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	10.00
Income from Investment Operations
Net investment income (b)		0.01
Net realized and unrealized loss		(0.72	)
Total from Investment Operations		(0.71	)
Net Asset Value, End of Period	$	9.29
Total Return (c)(d)		(7.10	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (e)		1.41	%
Net investment income (e)		0.17	%
Waiver/Reimbursement		17.90	%
Portfolio turnover rate (d)		9	%
Net assets at end of period (000s)	$	5

(a) Class I shares commenced operations on August 19, 2011. 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.

(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) Not annualized.

(f) Annualized.

See accompanying notes to financial statements.

109

Columbia Acorn Family of Funds

Financial Highlights, continued

Columbia Acorn European Fund

Class A Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	10.00
Income from Investment Operations
Net investment loss (b)		(0.03	)
Net realized and unrealized loss		(0.46	)
Total from Investment Operations		(0.49	)
Less Distributions to Shareholders
From net investment income		(0.06	)
From net realized gains		(0.02	)
Total Distributions to Shareholders		(0.08	)
Net Asset Value, End of Period	$	9.43
Total Return (c)(d)(e)		(4.97	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		1.75	%
Net investment loss (f)		(0.84	)%
Waiver/Reimbursement		31.84	%
Portfolio turnover rate (e)		17	%
Net assets at end of period (000s)	$	154

(a) Class A shares commenced operations on August 19, 2011. 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.

(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) Not annualized.

(f) Annualized.

Class C Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	10.00
Income from Investment Operations
Net investment loss (b)		(0.06	)
Net realized and unrealized loss		(0.45	)
Total from Investment Operations		(0.51	)
Less Distributions to Shareholders
From net investment income		(0.03	)
From net realized gains		(0.02	)
Total Distributions to Shareholders		(0.05	)
Net Asset Value, End of Period	$	9.44
Total Return (c)(d)(e)		(5.14	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		2.50	%
Net investment loss (f)		(1.66	)%
Waiver/Reimbursement		33.29	%
Portfolio turnover rate (e)		17	%
Net assets at end of period (000s)	$	5

(a) Class C shares commenced operations on August 19, 2011. 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.

(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) Not annualized.

(f) Annualized.

See accompanying notes to financial statements.

110

Class I Shares	Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2011 (a)
Net Asset Value, Beginning of Period	$	10.00
Income from Investment Operations
Net investment loss (b)		(0.02	)
Net realized and unrealized loss		(0.46	)
Total from Investment Operations		(0.48	)
Less Distributions to Shareholders
From net investment income		(0.07	)
From net realized gains		(0.02	)
Total Distributions to Shareholders		(0.09	)
Net Asset Value, End of Period	$	9.43
Total Return (c)(d)(e)		(4.81	)%
Ratios to Average Net Assets/Supplemental Data
Net expenses (f)		1.31	%
Net investment loss (f)		(0.47	)%
Waiver/Reimbursement		28.69	%
Portfolio turnover rate (d)		17	%
Net assets at end of period (000s)	$	5

(a) Class I shares commenced operations on August 19, 2011. 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.

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

(d) Not annualized.

(f) Annualized.

See accompanying notes to financial statements.

111

Columbia Acorn Family of Funds

Notes to Financial Statements

1. Nature of Operations

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 affiliated stock and bond mutual funds (underlying 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. Columbia Acorn Fund, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select each currently offers Class A, Class B, Class C, Class I and Class Z shares. Columbia Acorn International currently offers Class A, Class B, Class C, Class I, Class R, Class R5 and Class Z shares. Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund each currently offers Class A, Class C, Class I and Class Z shares. Columbia Thermostat Fund currently offers Class A, Class B, Class C and Class Z shares. Effective February 29, 2008, the Funds generally no longer accept investments by new or existing investors in the Fund's Class B shares, except in connection with the reinvestment of any dividend and/or capital gain distributions in Class B shares of the Funds and exchanges by existing Class B shareholders of certain other funds within the Columbia Family of Funds.

Class B shares are subject to 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 at net asset value. There are certain restrictions on who may purchase Class I shares.

The financial highlights for the Fund's Class Z shares are presented in a separate annual report.

2. Significant Accounting Policies

>Security valuation

112

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.

Short-term investments maturing in 60 days or less are valued at amortized cost, which approximates market value.

Forward foreign currency exchange contracts are marked-to-market based upon foreign currency exchange rates provided by a pricing service.

>Foreign currency translations

>Repurchase agreements

>Restricted securities

>Derivative Instruments

>Forward Foreign Currency Exchange Contracts

The use of forward foreign currency exchange contracts does not eliminate fluctuations in the prices of the Funds' portfolio securities. The risks of forward foreign currency

113

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

>Effects of Derivative Transactions in the Financial Statements

During the year ended December 31, 2011, Columbia Acorn International entered into 104 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, 2011.

Fair Value of Derivative Instruments

Asset

Liability

Statement of Assets
and Liabilities

Fair
Value

Statement of Assets
and Liabilities

Fair
Value

(in thousands)

Unrealized
appreciation
on forward foreign
currency exchange
contracts

$4,539

Unrealized
depreciation
on forward foreign
currency exchange
contracts

$—

The effect of derivative instruments on Columbia Acorn International's Statement of Operations for the year ended December 31, 2011 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	$	7,872	$	(6,748	)

During the year ended December 31, 2011, Columbia Acorn International Select entered into four forward foreign currency exchange contracts.

The following table is a summary of the value of Columbia Acorn International Select's derivative Instruments as of December 31, 2011.

Fair Value of Derivative Instruments

Asset

Liability

Statement of Assets
and Liabilities

Fair
Value

Statement of Assets
and Liabilities

Fair
Value

(in thousands)

Unrealized
appreciation
on forward foreign
currency exchange
contracts

—

Unrealized
depreciation
on forward foreign
currency exchange
contracts

948

The effect of derivative instruments on Columbia Acorn International Select's Statement of Operations for the year ended December 31, 2011 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	$	1,262	$	(948	)

>Security transactions and investment income

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

114

longer owned, any distributions received in excess of income are recorded as realized gains.

>Fund share valuation

>Securities lending

The net lending income earned as of December 31, 2011 by each Fund is included in the Statements of Operations.

>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

>Foreign capital gains taxes

>Distributions to shareholders

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

>Indemnification

>Recent Accounting Pronouncement

Fair Value Measurements and Disclosures

Specifically, ASU No. 2011-04 requires reporting entities to disclose i) the amounts of any transfers between Level 1 and

115

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

Level 2, and the reasons for the transfers, ii) for Level 3 fair value measurements, a) quantitative information about significant unobservable inputs used, b) a description of the valuation processes used by the reporting entity and c) a narrative description of the sensitivity of the fair value measurement to changes in unobservable inputs if a change in those inputs might result in a significantly higher or lower fair value measurement. The effective date of ASU No. 2011-04 is for interim and annual periods beginning after December 15, 2011. At this time, management is evaluating the implications of this guidance and the impact it will have on the financial statement amounts and footnote disclosures, if any.

3. Federal Tax Information

	Undistributed/ (Overdistributed) or Accumulated Net Investment Income (Loss)			Accumulated Net Realized Gain/(Loss)			Paid-In Capital
(in thousands)
Columbia Acorn Fund	$	82,288		$	(31,818	)	$	(50,470	)
Columbia Acorn International		34,709			50,375			(85,084	)
Columbia Acorn USA		9,454			—			(9,454	)
Columbia Acorn International Select		2,505			(2,505	)		—
Columbia Acorn Select		56,056			(20,699	)		(35,357	)
Columbia Thermostat Fund		130			(130	)		—
Columbia Acorn Emerging Markets Fund		(2	)		3			(1	)
Columbia Acorn European Fund		15			(14	)		(1	)

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, 2011 and December 31, 2010 was as follows:

	December 31, 2011				December 31, 2010
Fund	Ordinary Income*		Long-term Capital Gains		Ordinary Income*		Long-term Capital Gains
(in thousands)
Columbia Acorn Fund	$	38,838	$	707,353	$	21,020	$	496,293
Columbia Acorn International		157,072		—		122,919		—
Columbia Acorn USA		—		9,831		—		—
Columbia Acorn International Select		10,288		5,504		6,107		—
Columbia Acorn Select		31,148		42		—		—
Columbia Thermostat Fund		3,922		—		1,666		—
Columbia Acorn Emerging Markets Fund		—		—		N/A		N/A
Columbia Acorn European Fund		15		—		N/A		N/A

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

116

As of December 31, 2011, the components of distributable earnings on a tax basis were as follows:

Fund	Undistributed Ordinary Income		Undistributed Long-term Capital Gains		Unrealized Appreciation (Depreciation)
(in thousands)
Columbia Acorn Fund	$	—	$	255,805	$	4,943,887
Columbia Acorn International		27,270		—		553,374
Columbia Acorn USA		—		5,790		401,645
Columbia Acorn International Select		—		4,603		28,246
Columbia Acorn Select		—		26,965		166,244
Columbia Thermostat Fund		490		—		13,265
Columbia Acorn Emerging Markets Fund		1		—		(136	)
Columbia Acorn European Fund		2		—		(91	)

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

The following capital loss carryforwards, determined as of December 31, 2011, 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
	2015		2016		2017		2018		Unlimited		Total
(in thousands)
Columbia Acorn International	$	15,640	$	82,683	$	189,008	$	—	$	—	$	287,331
Columbia Thermostat Fund		—		—		17,733		2,955		—		20,688
Columbia Acorn Emerging Markets Fund		—		—		—		—		11		11

Capital loss carryforwards that were utilized and expired for the Funds during the year ended December 31, 2011, were as follows:

	Utilized		Expired
(in thousands)
Columbia Acorn International	$	211,304	$	82,542
Columbia Acorn USA		28,408		—
Columbia Acorn International Select		36,610		—
Columbia Acorn Select		119,037		—
Columbia Thermostat Fund		9,197		—

Fund	Late-year ordinary losses		Post-October capital losses
(in thousands)
Columbia Acorn Fund	$	9,350	$	50,163
Columbia Acorn International		—		12,775
Columbia Acorn USA		—		3,057
Columbia Acorn International Select		2,622		3,120
Columbia Acorn Select		107		3,172
Columbia Acorn Emerging Markets Fund		—		42
Columbia Acorn European Fund		2		7

4. Transactions with Affiliates

117

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

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	%

Columbia Acorn Emerging Markets Fund

Average Daily Net Assets	Annual Fee Rate
Up to $100 million		1.25	%
$100 million to $500 million		1.00	%
$500 million and over		0.80	%

Columbia Acorn European Fund

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	%

For the year ended December 31, 2011, the effective investment advisory fee rates were as follows:

Fund
Columbia Acorn Fund	0.64	%
Columbia Acorn International	0.76	%
Columbia Acorn USA	0.86	%
Columbia Acorn International Select	0.94	%
Columbia Acorn Select	0.82	%
Columbia Thermostat Fund	0.10	%
Columbia Acorn Emerging Markets Fund	1.25	%
Columbia Acorn European Fund	1.19	%

>Expense Limit

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 Acorn Emerging Markets Fund and Columbia Acorn European Fund through April 30, 2013, so that the ordinary operating expenses (exclusive of interest and fees on borrowings, and expenses associated with each Fund's investment in other investment companies, if any), do not exceed the following annual rates based on each Fund's average daily net assets:

Fund	Class A			Class C			Class I
Columbia Acorn Emerging Markets Fund		1.85	%		2.60	%		1.41	%
Columbia Acorn European Fund		1.75	%		2.50	%		1.31	%

118

There is no guarantee that these arrangements will continue after April 30, 2013.

Effective August 15, 2011, CWAM and its affiliates have contractually agreed to waive a portion of total annual Fund operating expenses incurred by Class A shares, Class B shares and Class C shares of Columbia Acorn International such that the Fund's total annual Fund operating expenses will be reduced by 0.04%, 0.03% and 0.02% for Class A, Class B and Class C shares of the Fund, respectively through August 14, 2013. There is no guarantee that this arrangement will continue thereafter.

Expenses reimbursed by CWAM and its affiliates for the year ended December 31, 2011, were as follows:

Fund	Expenses reimbursed
(in thousands)
Columbia Acorn International	$	159
Columbia Thermostat Fund	$	216
Columbia Acorn Emerging Markets Fund	$	217
Columbia Acorn European Fund	$	218

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	%

Columbia Management Investment Distributors, Inc. (CMID), an indirect wholly owned subsidiary of Ameriprise Financial, is the distributor of the Funds.

For the year ended December 31, 2011, the Funds have been advised that CMID retained underwriting discounts in connection with redemptions of Class A shares and received CDSCs in connection with Class A, Class B and Class C share redemptions as follows:

	Underwriting Discounts		CDSCs
	Class A		Class A			Class B		Class C
(in thousands) (Unaudited)
Columbia Acorn Fund	$	862	$	4		$	16	$	31
Columbia Acorn International		181		7			11		6
Columbia Acorn USA		77		—			2		1
Columbia Acorn International Select		42		—	*		2		1
Columbia Acorn Select		137		—			9		2
Columbia Thermostat Fund		481		—			6		1
Columbia Acorn Emerging Markets Fund		3		—			—		—	*
Columbia Acorn European Fund		1		—			—		—

* Rounds to less than $500.

Columbia Management Investment Services Corp. (CMIS), a wholly owned subsidiary of Ameriprise Financial, is the transfer agent of the Funds. For its services, each Fund pays CMIS a monthly fee at the annual rate of $17.00 per open account. CMIS also receives reimbursement from the Fund's for certain out-of-pocket expenses. Class I shares do not pay transfer agent fees.

119

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

and RiverSource Partners International Select Growth Fund, respectively, in previous years. The lease and the Guaranty expire in January 2019. At December 31, 2011, Columbia Acorn International's total potential future obligation over the life of the Guaranty was $140,903. The liability remaining at December 31, 2011 for non-recurring charges associated with the lease amounted to $97,731 and is included within other accrued expenses in the Statements of Assets and Liabilities.

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.

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, 2011, 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 39, 40, 51, 60, 61, 72 and 73, respectively.

	Purchases		Sales
(in thousands)
Columbia Acorn Fund	$	24,382	$	—
Columbia Acorn International		35,187		—
Columbia Acorn USA		578		—
Columbia Acorn International Select		213		—
Columbia Acorn Select		—		23,766
Columbia Acorn European Fund		53		10

During the year ended December 31, 2011, Columbia Management reimbursed Columbia Acorn International $174,055 for a loss on a trading error.

5. Borrowing Arrangements

Effective July 22, 2011, the Trust participates in a $150 million credit facility with JPMorgan Chase Bank, N.A., 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 0.10% per annum of the unutilized line of credit is 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. The Trust enters into this line of credit for one year durations.

No amounts were borrowed by the Funds under either facility during the year ended December 31, 2011.

6. Investment Transactions

The aggregate cost of purchases and proceeds from sales, other than short-term obligations, for the year ended December 31, 2011, were:

	Purchases		Proceeds from Sales
(in thousands)
Columbia Acorn Fund	$	3,205,101	$	4,069,128
Columbia Acorn International		2,350,871		1,899,789
Columbia Acorn USA		343,125		407,720
Columbia Acorn International Select		169,127		246,489
Columbia Acorn Select		386,396		951,396
Columbia Thermostat Fund		235,550		186,041
Columbia Acorn Emerging Markets Fund		3,285		234
Columbia Acorn European Fund		1,983		264

120

7. Regulatory Settlements with Third Parties

8. Fund Merger

The aggregate net assets of Columbia Acorn International immediately before the acquisitions were $5,887,634,436 and the combined net assets immediately after the acquisitions were $6,287,891,195.

In exchange for RiverSource Partners International Select Growth and RiverSource Partners International Small Cap Fund shares, Columbia Acorn International issued the following number of shares:

	RiverSource Partners International Select Growth Fund		RiverSource Partners International Small Cap Fund
Class A		3,800,227		1,666,707
Class B		267,259		75,499
Class C		183,761		518,779
Class I		4,010,380		51,634
Class R		35,341		48,348
Class R5		5,711		23,983

9. Shareholder Concentration

At December 31, 2011, one unaffiliated shareholder account owned 18.0% of the outstanding shares of Columbia Acorn International, three unaffiliated shareholder accounts owned 47.3% of the outstanding shares of Columbia Acorn USA, one unaffiliated shareholder account owned 45.2% of the outstanding shares of Columbia Acorn International Select, two unaffiliated shareholder accounts owned 26.2% of the outstanding shares of Columbia Acorn Select, one unaffiliated shareholder account owned 15.7% of the outstanding shares of Columbia Thermostat Fund. Affiliated shareholder accounts owned 28.9% of the outstanding shares of Columbia Acorn Emerging Markets Fund and 66.3% of the outstanding shares of Columbia Acorn European Fund. The Funds have no knowledge about whether any portion of those shares was owned beneficially. Subscription and redemption activity of these accounts may have a significant effect on the operations of the Funds.

10. Subsequent Events

121

Columbia Acorn Family of Funds

Notes to Financial Statements, continued

11. 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 mutual funds (branded as Columbia) 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 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 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 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 response to the plaintiffs' opening appellate brief filed on March 18, 2011, the defendants filed a response brief on May 4, 2011 with the Eighth Circuit. The plaintiffs filed a reply brief on May 26, 2011 and oral arguments took place on November 17, 2011.

122

Report of Independent Registered Public Accounting Firm

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

PricewaterhouseCoopers LLP
Chicago, Illinois
February 17, 2012

123

Columbia Acorn Family of Funds

Federal Income Tax Information (in thousands) (Unaudited) — Class A, B, C, I, R, R5 and Z shares

Columbia Acorn Fund

100.00% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2011 qualified for the corporate dividends received deduction.

Columbia Acorn International

Gross income derived from sources within foreign countries was $143,798 ($0.91 per share) for the fiscal year ended December 31, 2011.

Columbia Acorn USA

Columbia Acorn International Select

Gross income derived from sources within foreign countries was $9,719 ($0.73 per share) for the fiscal year ended December 31, 2011.

Columbia Acorn Select

30.25% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2011 qualified for the corporate dividends received deduction.

Columbia Thermostat Fund

53.13% of the ordinary income distributed by the Fund, for the fiscal year ended December 31, 2011 qualified for the corporate dividends received deduction.

Columbia Acorn Emerging Markets Fund

Gross income derived from sources within foreign countries was $16 ($0.05 per share) for the fiscal year ended December 31, 2011.

Columbia Acorn European Fund

Gross income derived from sources within foreign countries was $6 ($0.03 per share) for the fiscal year ended December 31, 2011.

124

Board of Trustees and Management of
Columbia Acorn Funds

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, 2011

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, 46,
Trustee and Chair

2007

Wanger Advisors Trust

Michelle L. Collins, 51,
Trustee

2008

Maureen M. Culhane, 63,
Trustee

2007

Wanger Advisors Trust

Margaret M. Eisen, 58,
Trustee

2002

Chief Investment Officer, EAM International LLC (corporate finance and asset management) since 2003; Managing Director, CFA Institute, 2005-2008.

Wanger Advisors Trust; Antigenics, Inc. (biotechnology and pharmaceuticals) until June 2009.

John C. Heaton, 52,
Trustee

2010

Wanger Advisors Trust

Steven N. Kaplan, 52,
Trustee and Vice Chair

1999

Neubauer Family Professor of Entrepreneurship and Finance, University of Chicago Booth School of Business; faculty member of the University of Chicago Booth School of Business since 1988.

Wanger Advisors Trust; Accretive Health, Inc. (healthcare management services provider); Morningstar, Inc. (provider of independent investment research).

Allan B. Muchin, 75,
Trustee⁽¹⁾

1998

Chairman Emeritus, Katten Muchin Rosenman LLP (law firm).

Wanger Advisors Trust

David J. Rudis, 58,
Trustee⁽²⁾

2010

National Checking and Debit Executive, and Illinois President, Bank of America, 2007-2009; President, Consumer Banking Group, LaSalle National Bank, 2004-2007.

Wanger Advisors Trust

David B. Small, 55,
Trustee

2010

Managing Director, Grosvenor Capital Management, L.P. (investment adviser) since 1994; Adjunct Associate Professor of Finance, University of Chicago Booth School of Business.

Wanger Advisors Trust

Trustees who are interested persons of Columbia Acorn Trust:

Charles P. McQuaid, 58,
Trustee and President⁽³⁾

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.

Wanger Advisors Trust

125

Name, Position(s)
with Columbia Acorn
Trust and Age at
December 31, 2011

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

Trustee Emeritus

Ralph Wanger, 77,
Trustee Emeritus⁽⁴⁾

1970

Wanger Advisors Trust

Officers of Columbia Acorn Trust:

Ben Andrews, 45,
Vice President

2004

Portfolio manager and analyst, CWAM or its predecessors, since 1998; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2004.

None

Robert A. Chalupnik, 45,
Vice President

2011

Portfolio manager and analyst, CWAM or its predecessors since 1998. Vice President Columbia Acorn Trust and Wanger Advisors Trust since May 2011.

None

Michael G. Clarke, 42,
Assistant Treasurer

2004

None

Joseph F. DiMaria, 44,
Assistant Treasurer

2010

None

P. Zachary Egan, 43,
Vice President

2003

None

Fritz Kaegi, 40,
Vice President

2011

Portfolio manager and analyst, CWAM or its predecessors since 2004. Vice President Columbia Acorn Trust and Wanger Advisors Trust since September 2011.

None

John Kunka, 41,
Assistant Treasurer

2006

None

Stephen Kusmierczak, 44,
Vice President

2011

Portfolio manager and analyst, CWAM or its predecessors since 2001. Vice President Columbia Acorn Trust and Wanger Advisors Trust since September 2011.

None

Joseph C. LaPalm, 42,
Vice President

2006

Chief Compliance Officer, CWAM since 2005; prior thereto, compliance officer, William Blair & Company (investment firm).

None

Bruce H. Lauer, 54,
Vice President, Secretary and Treasurer

1995

None

126

Name, Position(s)
with Columbia Acorn
Trust and Age at
December 31, 2011

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)

Louis J. Mendes III, 47,
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.

None

Robert A. Mohn, 50,
Vice President

1997

None

Christopher J. Olson, 47,
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.

None

Scott R. Plummer, 52,
Assistant Secretary

2010

None

Christopher O. Petersen, 42,
Assistant Secretary

2010

None

Robert P. Scales, 59,
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.

None

Andreas Waldburg-Wolfegg, 45,
Vice President

2011

Portfolio Manager and analyst of CWAM since 2002. Vice President Columbia Acorn Trust and Wanger Advisors Trust since September 2011

None

Linda Roth-Wiszowaty, 42,
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.

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. Muchin retired at the end of calendar year 2011.

(3) 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.

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

127

Columbia Acorn Family of Funds

Fourth Quarter Class A, B, C, I, R and R5 Expense Information (Unaudited)

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		0.17	%		0.28	%		0.18	%		0.08	%
Net Expense Ratio		1.06	%		1.67	%		1.82	%		0.72	%
Columbia Acorn International	Class A			Class B*			Class C			Class I			Class R†			Class R5†
Management Fees		0.76	%		0.76	%		0.76	%		0.76	%		0.76	%		0.76	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%		0.50	%		0.00	%
Other Expenses		0.29	%		0.45	%		0.29	%		0.14	%		0.33	%		0.15	%
Net Expense Ratio		1.30	%		1.96	%		2.05	%		0.90	%		1.59	%		0.91	%
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	%		0.31	%		0.19	%		0.08	%
Net Expense Ratio		1.30	%		1.92	%		2.05	%		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		0.32	%		0.45	%		0.37	%		0.10	%
Net Expense Ratio		1.51	%		2.14	%		2.31	%		1.04	%
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	%		0.31	%		0.23	%		0.10	%
Net Expense Ratio		1.28	%		1.88	%		2.05	%		0.92	%
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	%
Columbia Acorn Emerging Markets Fund	Class A			Class C			Class I
Management Fees		1.25	%		1.25	%		1.25	%
Distribution and Service (12b-1) Fees		0.25	%		1.00	%		0.00	%
Other Expenses		0.35	%		0.35	%		0.16	%
Net Expense Ratio		1.85	%		2.60	%		1.41	%
Columbia Acorn European Fund	Class A			Class C			Class I
Management Fees		1.19	%		1.19	%		1.19	%
Distribution and Service (12b-1) Fees		0.25	%		1.00	%		0.00	%
Other Expenses		0.31	%		0.31	%		0.12	%
Net Expense Ratio		1.75	%		2.50	%		1.31	%

See the Funds' prospectuses for information on minimum initial investment amounts and other details of buying, selling and exchanging shares of the Funds.

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, 2012. There is no guarantee that this arrangement will continue thereafter.

The fees and expenses of Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund also include the effect of fee waivers/reimbursement. CWAM has contractually undertaken to waive fees and/or reimburse Columbia Acorn Emerging Markets Fund so that the Fund's ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund's investment in other investment companies, if any) do not exceed the annual rates of 1.85%, 2.60% and 1.41% of the Fund's average daily net assets attributable to Class A, Class C and Class I shares, respectively, through April 30, 2013. There is no guarantee that this arrangement will continue thereafter. CWAM has contractually undertaken to waive fees and/or reimburse Columbia Acorn European Fund so that the Fund's ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund's investment in other investment companies, if any) do not exceed the annual rates of 1.75%, 2.50% and 1.31% of the Fund's average daily net assets attributable to Class A, Class C and Class I shares, respectively, through April 30, 2013. There is no guarantee that this arrangement will continue thereafter.

Columbia Acorn International's fees and expenses include the effect of the contractual undertaking by CWAM and its affiliates, effective August 15, 2011, to waive a portion of total annual Fund operating expenses incurred by Class A, Class B and Class C shares of Columbia Acorn International such that the Fund's total annual Fund operating expenses will be reduced by 0.04%, 0.03% and 0.02% for Class A, Class B and Class C shares of the Fund, respectively, through August 14, 2013. There is no guarantee that this arrangement will continue thereafter.

* The Funds generally no longer accept investments by new or existing investors in Class B shares, except in connection with the reinvestment of any dividend and/or capital gain distributions in Class B shares of the Funds and exchanges by existing Class B shareholders of certain other funds within the Columbia Family of Funds.

** Does not include estimated fees and expenses of 0.65% incurred by the Fund from the underlying portfolio funds in which it invests.

† Class R and Class R5 shares of Columbia Acorn International commenced operations on August 15, 2011, in connection with the completed merger of two series of RiverSource International Managers Series, Inc. into Columbia Acorn International.

128

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129

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.
225 Franklin Street
Boston, Massachusetts 02110

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

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

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

130

Columbia Management^®

Columbia Acorn Family of Funds
Class A, B, C, I, R and R5 Shares

Annual Report, December 31, 2011

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

Prospectuses and the Statement of Additional Information (SAI)

Information Provided by the SEC

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

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1446 C (2/12) 132752

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 Michelle L. Collins, Maureen M. Culhane and John C. Heaton, each of whom are members of the registrant’s Board of Trustees and Audit Committee, each qualify as an audit committee financial expert. Ms. Collins, Ms. Culhane and Mr. Heaton 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, 2011 and December 31, 2010 are approximately as follows:

2011		2010
$	286,000	$	219,500

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, 2011 and December 31, 2010 are approximately as follows:

2011		2010
$	74,100	$	15,800

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 2011 and 2010, Audit-Related Fees consist of agreed-upon procedures performed for other audit-related additional testing. Fiscal years 2011 and 2010 also include Audit-Related Fees for agreed-upon procedures related to a fund merger. Fiscal year 2011 also includes agreed-upon procedures for fund accounting and custody conversions.

During the fiscal years ended December 31, 2011 and December 31, 2010, 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, 2011 and December 31, 2010 are approximately as follows:

2011		2010
$	49,300	$	41,500

Tax Fees incurred in both fiscal years 2011 and 2010 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, 2011 and December 31, 2010, 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, 2011 and December 31, 2010 are as follows:

2011		2010
$	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, 2011 and December 31, 2010 are approximately as follows:

2011		2010
$	65,000	$	135,000

In both fiscal years 2011 and 2010, 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, 2011 and December 31, 2010 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, 2011 and December 31, 2010 are approximately as follows:

2011		2010
$	188,400	$	192,300

(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/ Charles P. McQuaid
				Charles P. McQuaid, President


Date				February 21, 2012

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/ Charles P. McQuaid
			Charles P. McQuaid, President


Date			February 21, 2012

By (Signature and Title)			/s/ Bruce H. Lauer
			Bruce H. Lauer, Treasurer


Date			February 21, 2012

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