William Blair Funds NCSRS Certified semi-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 811-5344

William Blair Funds

(Exact name of registrant as specified in charter)

150 North Riverside Plaza, Chicago, IL		60606
(Address of principal executive offices)		(Zip Code)

Stephanie G. Braming, Principal Executive Officer
William Blair Funds
150 North Riverside Plaza, Chicago, IL 60606
(Name and address of agent for service)

Registrant’s telephone number, including area code: 312-236-1600

Date of fiscal year end: December 31

Date of reporting period: June 30, 2020

Item 1. June 30, 2020 Semiannual Reports transmitted to shareholders.

		June 30, 2020













William Blair Funds
Semiannual Report




	IMPORTANT NOTE: Beginning on January 1, 2021, as permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the William Blair Funds’ (the “Funds”) annual and semi-annual shareholder reports will no longer be sent by mail, unless you specifically request paper copies of the shareholder reports from the Funds or from your financial intermediary, such as a broker-dealer or bank. Instead, shareholder reports will be available on the Funds’ website (https://www.williamblairfunds.com/investor_services/prospectus_reports_forms.fs), and you will be notified by mail each time a report is posted and provided with a website link to access the report.
	If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the Funds electronically by notifying your financial intermediary or, if you are a direct investor, by calling 1-800-635-2886.
	You may elect to receive all future shareholder reports in paper free of charge. You can inform your financial intermediary that you wish to continue receiving paper copies of your shareholder reports, or if you are a direct investor, by calling 1-800-635-2886. Your election to receive reports in paper will apply to all Funds you hold directly or through your financial intermediary, as applicable.

Table of Contents


U.S. Growth Market Review and Outlook	3

U.S. Value Market Review and Outlook	4

Growth Fund
An Overview from the Portfolio Manager	5
Portfolio of Investments	7

Large Cap Growth Fund
An Overview from the Portfolio Managers	8
Portfolio of Investments	10

Mid Cap Growth Fund
An Overview from the Portfolio Managers	11
Portfolio of Investments	13

Small-Mid Cap Core Fund
An Overview from the Portfolio Managers	14
Portfolio of Investments	16

Small-Mid Cap Growth Fund
An Overview from the Portfolio Managers	17
Portfolio of Investments	19

Small-Mid Cap Value Fund
An Overview from the Portfolio Managers	20
Portfolio of Investments	22

Small Cap Growth Fund
An Overview from the Portfolio Managers	23
Portfolio of Investments	25

Small Cap Value Fund
An Overview from the Portfolio Managers	27
Portfolio of Investments	29

Global Markets Review and Outlook	31

Global Leaders Fund
An Overview from the Portfolio Managers	33
Portfolio of Investments	35

International Leaders Fund
An Overview from the Portfolio Managers	37
Portfolio of Investments	39

International Growth Fund
An Overview from the Portfolio Managers	41
Portfolio of Investments	43

Institutional International Growth Fund
An Overview from the Portfolio Managers	47
Portfolio of Investments	49

International Small Cap Growth Fund
An Overview from the Portfolio Managers	53
Portfolio of Investments	55

Emerging Markets Leaders Fund
An Overview from the Portfolio Managers	58
Portfolio of Investments	60

June 30, 2020

William Blair Funds

The views expressed in the commentary for each Fund reflect those of the portfolio management team only through the end of the period of the report as stated on the cover. The portfolio management team’s views are subject to change at any time based on market and other conditions and should not be construed as a recommendation. Statements involving predictions, assessments, analyses, or outlook for individual securities, industries, market sectors, and/or markets involve risks and uncertainties, and there is no guarantee they will come to pass.

This report is submitted for the general information of the shareholders of William Blair Funds. It is not authorized for distribution to prospective Fund investors unless accompanied or preceded by the Fund’s prospectus. Please carefully consider a Fund’s investment objectives, risks, charges, and expenses before investing. This and other information is contained in the Fund’s prospectus, which you may obtain by calling 1-800-742-7272. Read it carefully before you invest or send money.

Semiannual Report

June 30, 2020

U.S. Growth Market Review and Outlook

While COVID-19 was the dominant force affecting the economy and equities year-to-date, the tenor of the market was dramatically different in the first and second quarters of the year.

During the first quarter, equities declined rapidly as market participants digested the magnitude of the economic impact of COVID-19. Stay-at-home directives effectively shut down many segments of the economy. First quarter GDP declined 5% and the unemployment rate spiked to almost 15%. This was the most dramatic decline in GDP and the sharpest rise in unemployment in the post-World War II period.

After bottoming in mid-March, equity returns were robust during the second quarter. This was predominately the result of massive amounts of fiscal and monetary stimulus, coupled with improving COVID-19 trends, optimism regarding vaccine development and progress toward re-opening the economy. The Federal Reserve (Fed) responded quickly and dramatically in an attempt to limit economic damage. With the federal funds rate near zero and purchases of both government and corporate bonds, the Fed balance sheet has expanded by over $3 trillion since the pandemic began. The Fed’s actions, paired with unprecedented levels of fiscal stimulus, supported strong demand for equities and a decline in fixed income spreads.

The strength of the recovery brought several market indices into positive territory for the first half of the year. The S&P 500 was down close to 20% in the first quarter and regained nearly all of the lost ground, returning over 20% during the second quarter - its highest quarterly gain since 1998.

Despite the recovery of the equity market, significant uncertainty remains as we emerge from an economic shutdown amidst an ongoing global health pandemic. The economic trajectory of the U.S. is unclear as some states begin to re-open while others retrench in response to rising COVID-19 infections. Early signs of economic improvement could prove fleeting as unemployment benefits expire and potential structural changes could leave some workers permanently out of work. Possible offsets to these challenges include the development of a vaccine and the lagged impact of monetary and fiscal stimulus. These factors, together with social unrest and a contentious forthcoming U.S. presidential election, leave corporate management teams with limited certainty.

As long-term investors, we are reminded more than ever that companies with superior management, high barriers to entry, differentiated products or services, and the financial flexibility to invest through uncertainty should ultimately prevail. We continually seek to identify companies that we believe will come out the other side of this unprecedented period stronger, with increased market share and profitability, regardless of the shape and duration of the broader recovery. While non-fundamental factors can create short-term volatility, the foundational belief upon which our portfolio is built is that earnings and cash flows are the determinants of long-term value creation and stock performance.

June 30, 2020

William Blair Funds

U.S. Value Market Review and Outlook

While COVID-19 was the dominant force impacting the economy and equities during the first half of 2020, market sentiment was dramatically different between the first and second quarters of the year.

During the first quarter, equities declined dramatically as economic activity was brought to an abrupt halt due to the implementation of shelter-in-place directives in an effort to curb the spread of the virus. With a large percentage of the U.S. economy essentially closed due to this health care related shock, first quarter GDP declined 5% and the unemployment rate spiked to almost 15%. This was the most dramatic decline in GDP and the sharpest rise in unemployment in the post-World War II period.

After the market bottomed in mid-March, equity returns rebounded swiftly in the second quarter. The dramatic reversal in the equity market was a function of massive amounts fiscal and monetary stimulus, improving virus trends, positive health care news on potential vaccines, and optimism regarding economic re-opening, and the hope that the recession would be short-lived.

Policymaker response to this pandemic has been unprecedented in many respects. The Federal Reserve (Fed) has been particularly aggressive in escalating the degree of support broadly across asset classes. These moves seem to have provided more economic support and market liquidity than initially anticipated. While the re-opening of the U.S. economy has provided some positive economic data-points, the Fed appears fully committed to employing any means necessary to provide market liquidity and mitigate the economic fallout from the COVID-19 pandemic.

Despite the swift recovery in the equity market, it is impossible to predict how this COVID-driven recession will play out. Investor confidence will likely hinge on additional fiscal and monetary stimulus efforts and the availability of forward guidance from company management regarding how the shutdown will impact future earnings. We believe that there are numerous risks that are likely to impact the pace and duration of the domestic economy recovery, including the upcoming U.S. presidential election, further increase in virus cases, mass unemployment, corporate bankruptcies, re-emergence of U.S.-China tensions, civil unrest, and vaccine delays.

The pandemic-related lockdowns are starving many businesses of revenue and, where corporate debt levels are high, inability to service debt may likely result in an escalation in the number of corporate bankruptcies. Although all fifty states have taken measures to ease lockdowns, some have retrenched in response to rising COVID-19 infections. This causes us to question the strength of any subsequent economic rebound and the potential longer-term impacts due to fundamental changes in social behavior.

We continue to focus on companies with increasingly stronger balance sheets given our concern about corporate debt levels and expectations for increased market volatility. We believe these companies will be able to endure this unprecedented period and emerge from this crisis stronger and with increased market share, regardless of the trajectory of the broader economic recovery. While non-fundamental factors can create short-term volatility, the foundational belief upon which our Fund is built is that superior capital stewardship, as characterized by strong cash flows and improving or sustainable return on invested capital, are the determinants of long-term value creation and stock performance.

Semiannual Report

June 30, 2020

	Growth Fund

	The Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGER

David C. Fording	The William Blair Growth Fund (Class N shares) posted a 7.72% increase, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the Russell 3000^® Growth Index (the “Index”), increased 8.98%. Despite adding value during the first quarter market sell off, the Fund trailed its benchmark on a year-to-date basis due to a combination of style dynamics and stock-specific factors. From a style perspective, our typical underweight to larger market capitalization stocks, specifically mega caps, relative to the Index was a headwind during the quarter as mega cap stocks outperformed. This headwind was partially offset by our higher growth bias as stocks with higher growth profiles generally outperformed during the period. From a stock-specific perspective, our top detractors included Brink’s Company (Industrials), Coca-Cola (Consumer Staples), Laureate Education (Consumer Discretionary) and Raytheon (Industrials). COVID-19 related closures weighed on Brink’s Company, a global cash management services company, most notably as it related to revenues derived from retail locations that were either temporarily closed or operating on a limited basis. Beverage company Coca-Cola lagged as it continued to face revenue headwinds resulting from COVID-19 driven store and restaurant closures. Stock selection in Information Technology, including our position in Sabre Corp and not owning Apple, one of the largest positions in the benchmark, created a significant headwind to relative performance. We believe the high-end smart phone, tablet and PC markets, which are significant sources of revenue for the company, have largely matured, limiting Apple’s ability to materially grow revenues and operating profits over the longer term, notwithstanding its near-term opportunity for a 5G driven upgrade cycle, also detracted from the Fund’s relative returns. Conversely, our top individual contributor during the period was Amazon (Consumer Discretionary). E-commerce website Amazon continued to benefit from COVID-19 related tailwinds, including increased consumer demand and the rapid shift to e-commerce and online shopping. Other top contributors included Horizon Therapeutics (Health Care), which benefitted from robust growth of the company’s newly launched drug Tepezza (as well as broad based strength across the rest of the business), BJ’s Wholesale Club (Consumer Staples), Etsy (Consumer Discretionary) and Virtu Financial (Financials). Please refer to the U.S. Growth Market Review and Outlook relating to the Fund on page 3.

June 30, 2020

William Blair Funds

Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year			Since Inception(a)
Class N		7.72	%		16.17	%		18.66	%		13.46	%		14.65	%		—
Class I		7.91			16.47			18.98			13.80			15.01			—
Class R6		7.99			16.65			—			—			—			16.61	%
Russell 3000^® Growth Index		8.98			21.94			18.21			15.23			16.92			19.35
S&P 500^® Index		(3.08	)		7.51			10.73			10.73			13.99			7.31

(a)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Russell 3000^®Growth Index consists of large, medium, and small capitalization companies with above average price-to-book ratios and forecasted growth rates. The index is weighted by market capitalization and large/medium/small companies make up approximately 80%/15%/5% of the index.

The S&P 500^®Index indicates broad larger capitalization equity market performance.

This report identifies the Fund’s investments on June 30, 2020. These holdings are subject to change. Not all stocks in the Fund performed the same, nor is there any guarantee that these stocks will perform as well in the future. Market forecasts provided in this report may not necessarily come to pass.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks
	Information Technology—37.5%
*	Adobe, Inc.		17,532	$	7,632
*	Advanced Micro Devices, Inc.		65,822		3,463
*	Alarm.com Holdings, Inc.		31,712		2,055
*	Arista Networks, Inc.		20,623		4,331
	Dolby Laboratories, Inc.		34,533		2,275
	Fidelity National Information Services, Inc.		40,947		5,491
*	Inphi Corporation		14,404		1,692
	Mastercard, Inc. Class “A”		35,743		10,569
	Microsoft Corporation		122,155		24,860
*	MongoDB, Inc.		8,437		1,910
	National Instruments Corporation		81,576		3,158
*	Nice, Ltd. - ADR		13,668		2,586
*	PayPal Holdings, Inc.		36,405		6,343
	Perspecta, Inc.		99,820		2,319
*	Pure Storage, Inc.		249,468		4,323
	Texas Instruments, Inc.		44,270		5,621
*	Verra Mobility Corporation		117,183		1,205
*	Workday, Inc.		19,604		3,673
					93,506
	Health Care—14.9%
	Abbott Laboratories		44,724		4,089
	Agilent Technologies, Inc.		45,389		4,011
*	Codexis, Inc.		61,640		703
*	Horizon Therapeutics plc†		84,259		4,683
*	Illumina, Inc.		7,106		2,632
*	Penumbra, Inc.		8,981		1,606
*	Quidel Corporation		7,197		1,610
	STERIS plc†		12,217		1,875
	Stryker Corporation		16,269		2,931
	Teleflex, Inc.		5,141		1,871
	UnitedHealth Group, Inc.		27,608		8,143
	Zoetis, Inc.		22,226		3,046
					37,200
	Consumer Discretionary—13.9%
	Advance Auto Parts, Inc.		20,170		2,873
*	Amazon.com, Inc.		7,912		21,828
*	Burlington Stores, Inc.		11,370		2,239
*	Etsy, Inc.		23,284		2,474
*	Grand Canyon Education, Inc.		19,656		1,779
*	Laureate Education, Inc.		142,194		1,417
*	Ulta Beauty, Inc.		10,281		2,091
					34,701
	Communication Services—9.4%
	Activision Blizzard, Inc.		62,172		4,719
*	Alphabet, Inc. Class “A”		10,727		15,211
*	Live Nation Entertainment, Inc.		33,052		1,465
*	Take-Two Interactive Software, Inc.		15,059		2,102
					23,497
	Industrials—8.5%
	BWX Technologies, Inc.		69,905		3,959

		Shares or
		Principal
	Issuer	Amount		Value

	Common Stocks—(continued)
	Industrials—(continued)
*	Copart, Inc.		48,534	$	4,041
*	CoStar Group, Inc.		5,770		4,101
	Fortive Corporation		46,750		3,163
	Luxfer Holdings plc†		101,664		1,439
	The Brink’s Co.		45,087		2,052
*	Trex Co., Inc.		19,172		2,494
					21,249
	Consumer Staples—6.0%
*	BJ’s Wholesale Club Holdings, Inc.		89,221		3,325
	Costco Wholesale Corporation		12,156		3,686
	The Coca-Cola Co.		105,001		4,692
	The Estee Lauder Cos., Inc. Class “A”		16,511		3,115
					14,818
	Financials—3.5%
	Aon plc†		16,269		3,133
	Ares Management Corporation		69,157		2,746
	Virtu Financial, Inc.		118,190		2,789
					8,668
	Materials—3.1%
	Ball Corporation		66,073		4,591
	Linde plc†		14,696		3,117
					7,708
	Real Estate—1.4%
	SBA Communications Corporation		11,975		3,568
	Energy—1.1%
	Cameco Corporation†		273,623		2,805
	Total Common Stocks—99.3% (cost $148,062)				247,720

	Repurchase Agreement
	Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $1,884, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $1,922		$1,884		1,884
	Total Repurchase Agreement—0.8% (cost $1,884)				1,884
	Total Investments—100.1% (cost $149,946)				249,604
	Liabilities, plus cash and other assets—(0.1)%				(271	)
	Net assets—100.0%			$	249,333

ADR = American Depository Receipt

* = Non-income producing security

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

	Large Cap Growth Fund

	The Large Cap Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

James S. Golan David P. Ricci	The William Blair Large Cap Growth Fund (Class N shares) posted a 9.63% increase, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the Russell 1000^®Growth Index (the “Index”), increased 9.81%. As a result of adding value during the first quarter market sell off, the Fund modestly outperformed its benchmark during the year-to-date period due to a combination of style dynamics and stock specific factors. From a style perspective, our higher valuation exposure, driven by the Fund’s secular growth bias, was a tailwind as stocks with higher valuations generally outperformed during the period. From a stock-specific perspective, our top two contributors were PayPal Holdings (Information Technology), which reported strong revenue acceleration and record levels of new client additions and transactions as it continued to benefit from the rapid transition to e-commerce and digital payments, and Amazon (Consumer Discretionary). E-commerce website Amazon continued to benefit from COVID-19 related tailwinds including increased consumer demand and the rapid shift to e-commerce and online shopping. Other notable contributors included Activision Blizzard (Communication Services), Veeva Systems (Health Care) and Adobe (Information Technology). Additionally, not owning Apple was the largest detractor from relative returns during the period. We believe the high-end smart phone, tablet and PC markets, which are significant sources of revenue for the company, have largely matured, limiting Apple’s ability to materially grow revenues and operating profits over the longer term. Conversely, our top detractors included Live Nation Entertainment (Communication Services), Starbucks Corporation (Consumer Discretionary), Coca-Cola (Consumer Staples), Stryker (Health Care) and Fortive Corp. (Industrials). Live Nation, a global leader in live entertainment, lagged as social distancing measures negatively impacted the company’s ability to conduct live events. COVID-19 related store closures weighed on Starbucks, impacting the company’s revenues during the period. Please refer to the U.S. Growth Market Review and Outlook relating to the Fund on page 3.

Semiannual Report

June 30, 2020

Large Cap Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year			Since Inception(a)
Class N		9.63	%		20.14	%		22.15	%		16.15	%		17.24	%		—
Class I		9.76			20.45			22.44			16.44			17.54			—
Class R6		9.83			20.50			—			—			—			21.42	%
Russell 1000^®Growth Index		9.81			23.28			18.99			15.89			17.23			20.47

(a)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Russell 1000^®Growth Index consists of large capitalization companies with above average price-to-book ratios and forecasted growth rates.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

June 30, 2020

William Blair Funds

Large Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks
	Information Technology—41.9%
	Accenture plc†		84,890	$	18,228
*	Adobe, Inc.		44,380		19,319
*	Advanced Micro Devices, Inc.		263,228		13,848
	Fidelity National Information Services, Inc.		84,700		11,357
*	Guidewire Software, Inc.		77,230		8,561
	Intuit, Inc.		44,760		13,258
	Lam Research Corporation		39,000		12,615
	Mastercard, Inc. Class “A”		82,700		24,454
	Microsoft Corporation		266,900		54,317
*	PayPal Holdings, Inc.		144,230		25,129
	Texas Instruments, Inc.		131,540		16,702
					217,788
	Consumer Discretionary—15.9%
*	Amazon.com, Inc.		16,490		45,493
	Marriott International, Inc.		63,480		5,442
	NIKE, Inc. Class “B”		169,830		16,652
	Starbucks Corporation		203,860		15,002
					82,589
	Health Care—13.7%
	Abbott Laboratories		135,850		12,421
*	Illumina, Inc.		29,870		11,062
	Stryker Corporation		84,180		15,168
	UnitedHealth Group, Inc.		70,330		20,744
	Zoetis, Inc.		87,590		12,003
					71,398
	Communication Services—9.9%
	Activision Blizzard, Inc.		182,310		13,837
*	Alphabet, Inc. Class “A”		19,260		27,312
*	Alphabet, Inc. Class “C”		816		1,154
*	Live Nation Entertainment, Inc.		213,270		9,454
					51,757
	Industrials—7.4%
*	Copart, Inc.		175,830		14,641
	Equifax, Inc.		73,970		12,714
	Fortive Corporation		162,220		10,976
					38,331
	Consumer Staples—5.4%
	Costco Wholesale Corporation		24,480		7,423
	The Coca-Cola Co.		278,210		12,430
	The Estee Lauder Cos., Inc. Class “A”		42,590		8,036
					27,889
	Financials—3.7%
	Aon plc†		45,230		8,711
	Apollo Global Management, Inc.		212,890		10,628
					19,339
	Materials—1.7%
	Linde plc†		40,980		8,692
	Total Common Stocks—99.6% (cost $402,992)				517,783


	Principal
Issuer	Amount		Value

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $4,290, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $4,376		$4,290	$	4,290
Total Repurchase Agreement—0.8% (cost $4,290)				4,290
Total Investments—100.4% (cost $407,282)				522,073
Liabilities, plus cash and other assets—(0.4)%				(1,838	)
Net assets—100.0%			$	520,235

† = U.S. listed foreign security

* = Non-income producing security

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	Mid Cap Growth Fund

	The Mid Cap Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Daniel Crowe James E. Jones Robert C. Lanphier, IV	The William Blair Mid Cap Growth Fund (Class N shares) posted a 1.36% decrease, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the Russell Midcap^®Growth Index (the “Index”), increased 4.16%. Despite holding up better than its benchmark during the first quarter market sell off, the Fund trailed the Index on a year-to-date basis due to a combination of style headwinds and stock specific factors. From a style perspective, our bias toward more consistent business models did not provide its typical, down market benefit during the first quarter. The unique nature of the sell-off caused by COVID-19 impacted performance in some unexpected ways as stocks of companies with low fundamental volatility and low cyclicality were not necessarily rewarded. From a stock specific standpoint, selection in Information Technology, including our positions in Euronet Worldwide and WEX, and our underweight to the most expensive stocks in the sector (e.g., Software), which materially outperformed, detracted from relative returns. Electronic payment and transaction processor Euronet Worldwide lagged as COVID-19 related social distancing measures caused a decline in global travel volumes, negatively affecting the company’s ATM business. Stock selection in Consumer Discretionary, including our positions in Wayfair and Ross Stores, also was a detractor during the period. Home furnishings retailer Wayfair experienced headwinds as the COVID-19 pandemic resulted in a decline in consumer spending and supply chain disruptions. Communication Services holding Live Nation Entertainment also underperformed during the period. Conversely, our top contributors included Horizon Therapeutics (Health Care), which benefitted from robust growth of the company’s newly launched drug Tepezza as well as broad based strength across the rest of the business, BJ’s Wholesale Club (Consumer Staples), SBA Communications (Real Estate) and Autodesk (Information Technology). BJ’s, the third largest wholesale club retailer, benefitted from an unexpected increase in new memberships during the period. Stock selection in Industrials, including our position in CoStar Group, contributed positively to relative returns. Please refer to the U.S. Growth Market Review and Outlook relating to the Fund on page 3.

June 30, 2020

William Blair Funds

Mid Cap Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020

	Year to Date			1 Year			3 Year			5 Year			10 Year			Since Inception(a)
Class N		(1.36	)%		5.31	%		13.29	%		8.90	%		12.28	%		—
Class I		(1.17	)		5.60			13.57			9.18			12.57			—
Class R6		(1.17	)		5.69			—			—			—			6.68	%
Russell Midcap^® Growth Index		4.16			11.91			14.76			11.60			15.09			12.00

(a)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in medium capitalization companies involves special risks, including higher volatility and lower liquidity. Medium capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Russell Midcap^®Growth Index is an index that is constructed to provide a comprehensive and unbiased barometer of the mid-cap growth market.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

Mid Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks
	Information Technology—31.9%
*	Arista Networks, Inc.		7,190	$	1,510
*	Aspen Technology, Inc.		7,180		744
	Booz Allen Hamilton Holding Corporation		18,359		1,428
*	Cadence Design Systems, Inc.		20,730		1,989
*	Coupa Software, Inc.		3,920		1,086
	Dolby Laboratories, Inc.		19,230		1,267
*	EPAM Systems, Inc.		5,675		1,430
*	Euronet Worldwide, Inc.		12,375		1,186
	Global Payments, Inc.		5,915		1,003
*	GoDaddy, Inc.		19,600		1,437
	j2 Global, Inc.		9,803		620
	MAXIMUS, Inc.		11,310		797
	Microchip Technology, Inc.		15,790		1,663
*	MongoDB, Inc.		5,420		1,227
*	Nice, Ltd.—ADR		5,365		1,015
*	Pure Storage, Inc.		77,980		1,352
*	WEX, Inc.		6,625		1,093
*	Workday, Inc.		5,480		1,027
*	Zendesk, Inc.		8,710		771
					22,645
	Health Care—19.3%
*	ABIOMED, Inc.		4,718		1,140
	Agilent Technologies, Inc.		24,660		2,179
*	Align Technology, Inc.		4,015		1,102
*	Centene Corporation		19,235		1,222
	Encompass Health Corporation		20,913		1,295
*	Exact Sciences Corporation		10,660		927
*	Horizon Therapeutics plc†		31,195		1,734
*	Insulet Corporation		3,620		703
*	Mettler-Toledo International, Inc.		1,040		838
	STERIS plc†		4,815		739
	Teleflex, Inc.		4,935		1,796
					13,675
	Industrials—14.5%
	BWX Technologies, Inc.		39,349		2,229
*	Copart, Inc.		27,722		2,308
*	CoStar Group, Inc.		3,609		2,565
	Equifax, Inc.		5,000		859
	Fortive Corporation		11,515		779
*	Teledyne Technologies, Inc.		2,095		652
	Waste Connections, Inc.†		9,975		936
					10,328
	Consumer Discretionary—10.2%
	Advance Auto Parts, Inc.		10,113		1,441
	Aptiv plc†		10,375		809
*	Bright Horizons Family Solutions, Inc.		5,625		659
*	Burlington Stores, Inc.		6,145		1,210
	Domino’s Pizza, Inc.		1,698		627
	Ross Stores, Inc.		10,960		934
	Service Corporation International		19,525		759
*	Ulta Beauty, Inc.		3,800		773
					7,212

		Shares or
		Principal
	Issuer	Amount		Value

	Common Stocks—(continued)
	Materials—5.9%
	Ball Corporation		31,065	$	2,158
	Celanese Corporation		3,820		330
	Vulcan Materials Co.		14,715		1,705
					4,193
	Communication Services—5.8%
	Cable One, Inc.		335		594
*	Live Nation Entertainment, Inc.		18,069		801
*	Take-Two Interactive Software, Inc.		11,020		1,538
*	Zynga, Inc.		123,960		1,183
					4,116
	Consumer Staples—4.2%
*	BJ’s Wholesale Club Holdings, Inc.		26,864		1,001
	Conagra Brands, Inc.		30,625		1,077
	Lamb Weston Holdings, Inc.		13,622		871
					2,949
	Financials—3.1%
	Arthur J Gallagher & Co.		16,570		1,615
*	SVB Financial Group		2,760		595
					2,210
	Real Estate—1.9%
	SBA Communications Corporation		4,530		1,350
	Total Common Stocks—96.8% (cost $55,389)				68,678

	Repurchase Agreement
	Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $1,769, collateralized by U.S. Treasury Note, 1.625% due 2/15/26, valued at $1,805		$1,769		1,769
	Total Repurchase Agreement—2.5% (cost $1,769)				1,769
	Total Investments—99.3% (cost $57,158)				70,447
	Cash and other assets, less liabilities—0.7%				501
	Net assets—100.0%			$	70,948

ADR = American Depository Receipt

* = Non-income producing security

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Small-Mid Cap Core Fund

The Small-Mid Cap Core Fund seeks long-term capital appreciation.

AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Daniel Crowe

Robert C. Lanphier, IV

Ward D. Sexton

The William Blair Small-Mid Cap Core Fund (Class I shares) posted a 10.49% decrease, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the Russell 2500^TMIndex (the “Index”), decreased 11.05%.

As a result of adding value during the first quarter market sell off, the Fund outperformed its benchmark on a year-to-date basis primarily driven by stock specific factors. Top individual contributors for the period were Horizon Therapeutics (Health Care), which benefitted from robust growth of the company’s newly launched drug Tepezza, as well as broad based strength across the rest of the business, and BJ’s Wholesale Clubs (Consumer Staples), which benefitted from higher consumer demand amid the pandemic. Stock selection was positive in several sectors, most notably Financials, including our position in Virtu Financial. Other notable performers included Merit Medical Systems (Health Care) and Nice Ltd (Information Technology). Conversely, selection in Information Technology, including our underweight to the most expensive stocks in the sector (e.g., Software) which outperformed, dampened relative returns. Top detractors during the period were Brink’s Company (Industrials), whose COVID-19 related closures weighed on cash management services, most notably as it relates to revenues derived from retail locations that were either temporarily closed or operating on a limited basis, and Western Alliance Bancorp (Financials), due to the potential impact of COVID-19 on the company’s hotel loan book combined with a lower interest rate environment. Our positions in Boot Barn (Consumer Discretionary), Hanger (Health Care) and Orion Engineered Carbons (Materials) also underperformed. From a style perspective, year-to-date dynamics were similar to those of the second quarter wherein the most volatile and lowest return on invested capital quintiles of the benchmark were the best performers. While these dynamics persisted across our benchmark, they are exemplified by Biotechnology, which, in the small/mid space, consists mostly of speculative companies without approved products and outperformed year-to-date. Our underweight to these types of companies was a relative headwind.

Please refer to the U.S. Growth Market Review and Outlook relating to the Fund on page 3.

Semiannual Report

June 30, 2020

Small-Mid Cap Core Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year			Since
	to Date			Inception(a)
Class I		(10.49	)%		(4.34	)%
Class R6		(10.39	)		(4.23	)
Russell 2500^TMIndex		(11.05	)		(3.46	)

(a)	Since inception is for the period from October 1, 2019 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in smaller and medium capitalization companies involves special risks, including higher volatility and lower liquidity. Smaller and medium capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Russell 2500^TMIndex measures the performance of those Russell 2500 companies with above average price-to-book ratios and forecasted growth rates.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

June 30, 2020

William Blair Funds

Small-Mid Cap Core Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value
	Common Stocks
	Health Care—17.8%
*	Codexis, Inc.		171,142	$	1,951
	Encompass Health Corporation		43,479		2,693
*	Hanger, Inc.		155,704		2,578
*	HealthEquity, Inc.		25,784		1,513
*	Horizon Therapeutics plc†		82,903		4,608
*	LHC Group, Inc.		20,144		3,512
*	Mednax, Inc.		153,973		2,633
*	Merit Medical Systems, Inc.		114,425		5,223
*	Quidel Corporation		7,961		1,781
	STERIS plc†		17,936		2,752
*	Tabula Rasa HealthCare, Inc.		46,327		2,535
	Teleflex, Inc.		5,796		2,110
*	Veracyte, Inc.		59,332		1,537
					35,426
	Information Technology—17.6%
	Booz Allen Hamilton Holding Corporation		22,076		1,717
	Brooks Automation, Inc.		49,248		2,179
*	Cree, Inc.		26,513		1,569
	Dolby Laboratories, Inc.		41,170		2,712
	Entegris, Inc.		27,965		1,651
*	Euronet Worldwide, Inc.		26,130		2,504
	j2 Global, Inc.		33,957		2,146
*	Knowles Corporation		117,231		1,789
	MAXIMUS, Inc.		21,870		1,541
*	Nice, Ltd.—ADR		23,348		4,418
	Perspecta, Inc.		111,793		2,597
*	Pure Storage, Inc.		146,510		2,539
*	Rogers Corporation		12,806		1,596
*	SolarEdge Technologies, Inc.		16,499		2,290
*	Verra Mobility Corporation		214,086		2,201
*	WEX, Inc.		9,620		1,587
					35,036
	Industrials—12.6%
	Armstrong World Industries, Inc.		14,436		1,126
*	Blue Bird Corporation		96,108		1,441
	BWX Technologies, Inc.		89,250		5,055
	Douglas Dynamics, Inc.		49,976		1,755
*	Generac Holdings, Inc.		16,298		1,987
*	IAA, Inc.		34,848		1,344
	John Bean Technologies Corporation		14,124		1,215
	Lincoln Electric Holdings, Inc.		18,103		1,525
	Luxfer Holdings plc†		99,356		1,406
*	Teledyne Technologies, Inc.		3,879		1,206
	The Brink’s Co.		50,504		2,299
	The Toro Co.		20,683		1,372
*	Trex Co., Inc.		25,965		3,377
					25,108
	Financials—12.3%
	Ares Management Corporation		70,963		2,817
	Arthur J Gallagher & Co.		15,931		1,553
	Cboe Global Markets, Inc.		19,185		1,790
*	Encore Capital Group, Inc.		59,921		2,048
	FirstCash, Inc.		22,858		1,542
	LPL Financial Holdings, Inc.		38,938		3,053
*	SVB Financial Group		18,192		3,921
	Virtu Financial, Inc.		74,059		1,748
	Western Alliance Bancorp		105,753		4,005
	Wintrust Financial Corporation		48,209		2,103
					24,580
	Consumer Discretionary—9.7%
	Advance Auto Parts, Inc.		29,937		4,264
*	Boot Barn Holdings, Inc.		137,711		2,969
*	Burlington Stores, Inc.		11,936		2,351

		Shares or
		Principal
	Issuer	Amount		Value
	Common Stocks—(continued)
	Consumer Discretionary—(continued)
*	Grand Canyon Education, Inc.		51,904	$	4,699
*	National Vision Holdings, Inc.		87,849		2,681
	Service Corporation International		60,415		2,350
					19,314
	Real Estate—8.1%
	Americold Realty Trust		92,393		3,354
	CoreSite Realty Corporation		18,135		2,195
	Douglas Emmett, Inc.		87,146		2,672
	Equity LifeStyle Properties, Inc.		39,540		2,470
	Healthcare Realty Trust, Inc.		82,686		2,422
	Jones Lang LaSalle, Inc.		17,405		1,801
	Sunstone Hotel Investors, Inc.		151,385		1,234
					16,148
	Materials—7.0%
	Avery Dennison Corporation		18,029		2,057
*	Crown Holdings, Inc.		56,044		3,650
	Eagle Materials, Inc.		29,792		2,092
	FMC Corporation		15,797		1,574
	Martin Marietta Materials, Inc.		10,300		2,127
	Orion Engineered Carbons S.A.†		222,757		2,359
					13,859
	Consumer Staples—5.5%
*	BJ’s Wholesale Club Holdings, Inc.		108,339		4,038
	Lamb Weston Holdings, Inc.		46,008		2,941
	Primo Water Corporation†		144,297		1,984
	Spectrum Brands Holdings, Inc.		42,616		1,956
					10,919
	Communication Services—4.3%
	Cable One, Inc.		1,270		2,254
*	Live Nation Entertainment, Inc.		41,248		1,828
*	Take-Two Interactive Software, Inc.		13,901		1,940
*	Zynga, Inc.		271,238		2,588
					8,610
	Energy—2.9%
	Cameco Corporation†		272,737		2,796
*	Oceaneering International, Inc.		129,684		829
	Parsley Energy, Inc.		122,477		1,308
*	Talos Energy, Inc.		88,414		813
					5,746
	Utilities—1.3%
	IDACORP, Inc.		28,867		2,521
	Total Common Stocks—99.1% (cost $210,215)				197,267
	Repurchase Agreement
	Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $2,170, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $2,213		$2,170		2,170
	Total Repurchase Agreement—1.1% (cost $2,170)				2,170
	Total Investments—100.2% (cost $212,385)				199,437
	Liabilities, plus cash and other assets—(0.2)%				(339	)
	Net assets—100.0%			$	199,098

ADR = American Depository Receipt

* = Non-income producing security

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	Small-Mid Cap Growth Fund

	The Small-Mid Cap Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Daniel Crowe James E. Jones Robert C. Lanphier, IV	The William Blair Small-Mid Cap Growth Fund (Class N shares) posted a 0.67% increase, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the Russell 2500^TMGrowth Index (the “Index”), increased 2.02%. Despite adding value during the first quarter market sell off, the portfolio trailed its benchmark on a year-to-date basis due to a combination of style headwinds and stock specific factors. From a style perspective, year-to-date dynamics were similar to those of the second quarter wherein the most volatile, highest beta and lowest Return on Invested Capital quintiles of the benchmark were the best performers. While these dynamics persisted across our benchmark, we believe that they are exemplified by Biotechnology, which, in the small/mid space, consists mostly of speculative companies without approved products and outperformed year-to-date. Our underweight to these types of companies was a relative headwind. Partly offsetting this headwind was our typical larger market cap profile relative to the Index as the largest stocks in our universe outperformed year-to-date. From a stock specific standpoint, selection in Information Technology, including our position in Euronet Worldwide, and our underweight to the most expensive stocks in the sector (e.g., Software) detracted from relative returns. Top individual stock detractors were Brink’s Company (Industrials), whose COVID-19 related closures weighed on this cash management services provider, most notably as it relates to revenues derived from retail locations that were either temporarily closed or operating on a limited basis, and Live Nation Entertainment (Communication Services), due to the negative impact social-distancing measures had on the company’s ability to conduct live events. Other notable underperforming holdings were Martin Marietta (Materials) and Jones Lang LaSalle (Real Estate). Conversely, top contributors included Horizon Therapeutics (Health Care) and Etsy (Consumer Discretionary), which added new buyers to its platform amid COVID-19 retail disruption, which we believe could sustainably increase longer-term sales potential for the company, as well as BJ’s Wholesale Club (Consumer Staples) and Zynga (Communication Services). Stock selection in Industrials, including our position in Trex Company, also added value. Please refer to the U.S. Growth Market Review and Outlook relating to the Fund on page 3.

June 30, 2020

William Blair Funds

Small-Mid Cap Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year			Since Inception(a)
Class N		0.67	%		5.64	%		12.47	%		10.98	%		14.82	%		—
Class I		0.78			5.89			12.73			11.27			15.11			—
Class R6		0.81			5.96			—			—			—			7.73	%
Russell 2500^TM Growth Index		2.02			9.21			12.10			9.57			14.45			9.51


(a)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in smaller and medium capitalization companies involves special risks, including higher volatility and lower liquidity. Smaller and medium capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Russell 2500^TMGrowth Index measures the performance of those Russell 2500 companies with above average price-to-book ratios and forecasted growth rates.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

Small-Mid Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks
	Information Technology—28.1%
*	Alarm.com Holdings, Inc.		455,200	$	29,501
*	Aspen Technology, Inc.		387,267		40,125
*	Avalara, Inc.		343,615		45,732
	Booz Allen Hamilton Holding Corporation		504,207		39,222
	Brooks Automation, Inc.		773,342		34,213
*	Coupa Software, Inc.		107,222		29,705
*	Cree, Inc.		503,938		29,828
	Entegris, Inc.		384,583		22,710
*	Euronet Worldwide, Inc.		490,562		47,006
*	GoDaddy, Inc.		584,560		42,866
*	j2 Global, Inc.		404,491		25,568
	MAXIMUS, Inc.		283,184		19,950
*	MongoDB, Inc.		130,769		29,598
	National Instruments Corporation		903,275		34,966
*	Nice, Ltd.—ADR		331,492		62,731
*	Novanta, Inc.†		236,981		25,302
	Perspecta, Inc.		997,557		23,173
*	Proofpoint, Inc.		250,218		27,804
*	Pure Storage, Inc.		3,178,226		55,079
*	Rogers Corporation		185,631		23,130
*	SolarEdge Technologies, Inc.		320,680		44,504
*	Varonis Systems, Inc.		287,056		25,399
*	WEX, Inc.		189,785		31,316
					789,428
	Health Care—23.5%
*	ABIOMED, Inc.		130,971		31,637
*	Amedisys, Inc.		233,952		46,449
	Encompass Health Corporation		927,606		57,447
*	Exact Sciences Corporation		419,811		36,499
*	Halozyme Therapeutics, Inc.		1,466,206		39,309
*	HealthEquity, Inc.		578,815		33,959
*	Horizon Therapeutics plc†		1,596,174		88,715
*	Insulet Corporation		218,635		42,472
*	iRhythm Technologies, Inc.		319,525		37,030
*	Ligand Pharmaceuticals, Inc.		324,998		36,351
*	Masimo Corporation		117,464		26,781
*	Penumbra, Inc.		292,841		52,366
*	Quidel Corporation		113,121		25,310
	STERIS plc†		270,968		41,577
	Teleflex, Inc.		116,521		42,411
*	Veracyte, Inc.		865,726		22,422
					660,735
	Industrials—16.2%
	BWX Technologies, Inc.		1,540,431		87,250
*	Copart, Inc.		328,757		27,376
*	Generac Holdings, Inc.		225,097		27,446
	HEICO Corporation		355,105		28,849
	Lincoln Electric Holdings, Inc.		246,796		20,790
*	Mercury Systems, Inc.		485,707		38,206
	Ritchie Bros Auctioneers, Inc.†		999,891		40,845
*	Teledyne Technologies, Inc.		147,428		45,843
	The Brink’s Co.		778,699		35,439
	TransUnion		521,267		45,371
*	Trex Co., Inc.		447,224		58,170
					455,585
	Consumer Discretionary—13.1%
	Advance Auto Parts, Inc.		281,088		40,041
*	Bright Horizons Family Solutions, Inc.		369,018		43,249

		Shares or
		Principal
	Issuer	Amount		Value

	Common Stocks—(continued)
	Consumer Discretionary—(continued)
*	Burlington Stores, Inc.		209,395	$	41,236
*	Etsy, Inc.		523,572		55,619
*	Grand Canyon Education, Inc.		915,184		82,852
*	Helen of Troy, Ltd.†		157,280		29,657
*	National Vision Holdings, Inc.		904,559		27,607
*	Planet Fitness, Inc.		488,161		29,568
*	Ulta Beauty, Inc.		89,463		18,198
					368,027
	Communication Services—4.9%
	Cable One, Inc.		26,955		47,841
*	Live Nation Entertainment, Inc.		767,164		34,009
*	Zynga, Inc.		5,775,077		55,094
					136,944
	Materials—4.0%
*	Crown Holdings, Inc.		774,764		50,460
	Martin Marietta Materials, Inc.		298,916		61,747
					112,207
	Financials—3.2%
	Ares Management Corporation		647,771		25,716
	FirstCash, Inc.		446,051		30,100
	Virtu Financial, Inc.		1,483,507		35,011
					90,827
	Consumer Staples—3.2%
*	BJ’s Wholesale Club Holdings, Inc.		1,358,938		50,648
	Lamb Weston Holdings, Inc.		617,165		39,455
					90,103
	Real Estate—1.8%
	FirstService Corporation†		300,222		30,247
	Jones Lang LaSalle, Inc.		212,565		21,992
					52,239
	Energy—1.1%
	Cameco Corporation†		3,037,700		31,136
	Total Common Stocks—99.1% (cost $2,239,412)				2,787,231

	Repurchase Agreement
	Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $24,418, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $24,906	$	24,418		24,418
	Total Repurchase Agreement—0.9% (cost $24,418)				24,418
	Total Investments—100.0% (cost $2,263,830)				2,811,649
	Liabilities, plus cash and other assets—(0.0)%				(849	)
	Net assets—100.0%			$	2,810,800

ADR = American Depository Receipt

* = Non-income producing security

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

	Small-Mid Cap Value Fund

	The Small-Mid Cap Value Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Chad M. Kilmer Mark T. Leslie David S. Mitchell	The William Blair Small-Mid Cap Value Fund (Class N shares) posted a 23.89% decrease, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the Russell 2500^TMValue Index (the “Index”), decreased 21.18%. The relative underperformance of the Fund during the period was the result of stock selection. At the sector level, Energy was the most significant detractor from relative performance due to stock selection within Oil, Gas & Consumable Fuels. More specifically, stock selection within Exploration & Production was the main driver of the relative underperformance within the sector as all Energy sectors were faced with lower commodity prices during the period. The relative underperformance within Health Care, the best performing sector of the market, was driven by the lack of exposure to Biotechnology and Pharmaceutical stocks. The relative outperformance within Technology was the result of strong stock selection within IT Services and Communications Equipment. Looking specifically at stock selection, the Fund’s largest detractors during the period were EPR Properties (Real Estate), Patterson-UTI (Energy) and WPX Energy (Energy). Somewhat offsetting these detractors were our investments in Booz Allen Hamilton (Information Technology), FTI Consulting (Industrials) and Cadence Design Systems (Information Technology). Please refer to the U.S. Value Market Review and Outlook relating to the Fund on page 4.


20	Semiannual Report	June 30, 2020

Small-Mid Cap Value Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020

	Year												Since
	to Date			1 Year			3 Year			5 Year			Inception
Class N(a)		(23.89	)%		(19.90	)%		(4.73	)%		(0.10	)%		6.35	%
Class I(a)		(23.63	)		(19.57	)		(4.43	)		0.19			6.65
Russell 2500^TMValue Index(a)		(21.18	)		(15.50	)		(2.60	)		1.85			8.30
Class R6(b)		(23.81	)		(19.82	)		—			—			(18.19	)
Russell 2500^TMValue Index(b)		(21.18	)		(15.50	)		—			—			(13.98	)


(a)	Since inception is for the period from December 15, 2011 (Commencement of Operations) to June 30, 2020.
(b)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in smaller and medium capitalization companies involves special risks, including higher volatility and lower liquidity. Smaller and medium capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Russell 2500^TMValue Index consists of small to mid-capitalization companies with below average price-to-book ratios and forecasted growth rates.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

June 30, 2020

William Blair Funds

Small-Mid Cap Value Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks
	Financials—18.8%
	American Financial Group, Inc.		159	$	10
	CNO Financial Group, Inc.		736		11
	East West Bancorp, Inc.		394		14
	First American Financial Corporation		288		14
	FNB Corporation		1,525		11
	Hancock Whitney Corporation		497		11
	Home BancShares, Inc.		849		13
	National Bank Holdings Corporation		426		12
	PacWest Bancorp		769		15
	Radian Group, Inc.		806		13
	Selective Insurance Group, Inc.		331		17
*	SVB Financial Group		69		15
	The Hanover Insurance Group, Inc.		178		18
	Umpqua Holdings Corporation		1,379		15
	Voya Financial, Inc.		419		20
	Western Alliance Bancorp		450		17
					226
	Industrials—17.0%
	Brady Corporation		510		24
	Curtiss-Wright Corporation		210		19
*	FTI Consulting, Inc.		171		20
	IDEX Corporation		195		31
	Kansas City Southern		163		24
	Simpson Manufacturing Co., Inc.		255		21
	The Toro Co.		364		24
	Watts Water Technologies, Inc.		186		15
	Westinghouse Air Brake Technologies Corporation		448		26
					204
	Real Estate—12.8%
	American Assets Trust, Inc.		619		17
	American Campus Communities, Inc.		372		13
	Americold Realty Trust		424		15
	CoreSite Realty Corporation		47		6
	Douglas Emmett, Inc.		581		18
	Equity LifeStyle Properties, Inc.		359		22
	Healthcare Realty Trust, Inc.		783		23
	Life Storage, Inc.		222		21
	Terreno Realty Corporation		358		19
					154
	Consumer Discretionary—12.0%
*	Deckers Outdoor Corporation		89		18
	Dunkin’ Brands Group, Inc.		319		21
*	Helen of Troy, Ltd.†		112		21
*	Murphy USA, Inc.		149		17
	PulteGroup, Inc.		600		20
	Service Corporation International		445		17
	Strategic Education, Inc.		73		11
*	TopBuild Corporation		167		19
					144



	Issuer	Shares		Value

	Common Stocks—(continued)
	Information Technology—8.5%
*	Arista Networks, Inc.		75	$	16
	Booz Allen Hamilton Holding Corporation		212		16
*	Cadence Design Systems, Inc.		177		17
*	Ciena Corporation		380		21
*	Inphi Corporation		104		12
	MAXIMUS, Inc.		291		21
					103
	Health Care—6.8%
*	Bio-Rad Laboratories, Inc.		29		13
	CONMED Corporation		147		11
	Encompass Health Corporation		295		18
*	Hologic, Inc.		332		19
	PerkinElmer, Inc.		214		21
					82
	Materials—6.3%
	FMC Corporation		264		26
	PolyOne Corporation		509		13
	Sensient Technologies Corporation		208		11
	Silgan Holdings, Inc.		351		11
	Steel Dynamics, Inc.		556		15
					76
	Utilities—4.4%
	Alliant Energy Corporation		334		16
	Atmos Energy Corporation		192		19
	IDACORP, Inc.		208		18
					53
	Consumer Staples—3.8%
*	BJ’s Wholesale Club Holdings, Inc.		326		12
	Casey’s General Stores, Inc.		40		6
	J&J Snack Foods Corporation		98		12
	Lamb Weston Holdings, Inc.		248		16
					46
	Energy—3.8%
*	CNX Resources Corporation		897		8
	Diamondback Energy, Inc.		269		11
	Helmerich & Payne, Inc.		308		6
	Parsley Energy, Inc.		849		9
	Valero Energy Corporation		196		12
					46
	Communication Services—3.1%
	The Interpublic Group of Cos., Inc.		1,310		23
*	Zynga, Inc.		1,499		14
					37
	Total Common Stocks—97.3% (cost $996)				1,171
	Total Investments—97.3% (cost $996)				1,171
	Cash and other assets, less liabilities—2.7%				33
	Net assets—100.0%			$	1,204

* = Non-income producing security

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	Small Cap Growth Fund

	The Small Cap Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Michael P. Balkin Ward D. Sexton	The William Blair Small Cap Growth Fund (Class N shares) posted a 2.88% decrease, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the Russell 2000^®Growth Index (the “Index”), decreased 3.06%. As a result of adding value during the first quarter market sell off, the Fund outperformed its benchmark on a year-to-date basis primarily driven by stock specific factors. Top individual contributors for the period were Etsy (Consumer Discretionary) and Horizon Therapeutics (Health Care). E-commerce marketplace Etsy added new buyers to its platform amid COVID-19 retail disruption, which we believe could sustainably increase longer-term sales potential for the company. Horizon Therapeutics benefitted from robust growth of the company’s newly launched drug Tepezza, as well as broad based strength across the rest of the business. Other top performers included Simulations Plus (Health Care), Virtu Financial (Financials) and Avalara (Information Technology). Conversely, top detractors were Hanger (Health Care), as demand for orthotic and prosthetic services paused amid the COVID-19 outbreak, and Brink’s Company (Industrials). COVID-19 related closures weighed on Brink’s Company, most notably as it relates to revenues derived from retail locations that were either temporarily closed or operating on a limited basis. Other laggards included Laureate Education (Consumer Discretionary), Boot Barn (Consumer Discretionary) and Euronet Worldwide (Information Technology). From a style perspective, year-to-date dynamics were similar to those of the second quarter wherein our typical underweights to Biotechnology and the most expensive stocks in the benchmark were headwinds. Please refer to the U.S. Growth Market Review and Outlook relating to the Fund on page 3.

June 30, 2020

William Blair Funds

Small Cap Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year			Since Inception(a)
Class N		(2.88	)%		(0.21	)%		8.44	%		10.12	%		12.47	%		—
Class I		(2.73	)		0.04			8.72			10.40			12.75			—
Class R6		(2.72	)		0.08			—			—			—			(0.05	)%
Russell 2000^® Growth Index		(3.06	)		3.48			7.86			6.86			12.92			3.65

(a)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in smaller companies involves special risks, including higher volatility and lower liquidity. Smaller capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Russell 2000^®Growth Index is an unmanaged composite of the smallest 2000 stocks of the Russell 3000^®Growth Index.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks
	Health Care—27.2%
*	Aerie Pharmaceuticals, Inc.		432,011	$	6,376
*	Amedisys, Inc.		26,965		5,354
*	AxoGen, Inc.		313,450		2,896
*	CareDx, Inc.		76,478		2,710
*	Codexis, Inc.		426,428		4,861
*	CryoLife, Inc.		241,042		4,621
	Encompass Health Corporation		104,631		6,480
*	GenMark Diagnostics, Inc.		198,750		2,923
*	Halozyme Therapeutics, Inc.		292,920		7,853
*	Hanger, Inc.		384,270		6,363
*	Health Catalyst, Inc.		206,878		6,035
*	HealthEquity, Inc.		64,495		3,784
*	Horizon Therapeutics plc†		139,152		7,734
*	Insmed, Inc.		257,880		7,102
*	iRhythm Technologies, Inc.		61,895		7,173
*	LHC Group, Inc.		41,533		7,240
*	Ligand Pharmaceuticals, Inc.		73,918		8,268
*	Merit Medical Systems, Inc.		155,490		7,098
*	Penumbra, Inc.		38,243		6,839
*	Quidel Corporation		19,025		4,257
	Simulations Plus, Inc.		110,270		6,596
*	Tabula Rasa HealthCare, Inc.		98,084		5,368
*	Twist Bioscience Corporation		175,586		7,954
*	Veracyte, Inc.		205,860		5,332
					141,217
	Information Technology—23.6%
*	Agilysys, Inc.		244,605		4,388
*	Alarm.com Holdings, Inc.		128,390		8,321
	American Software, Inc.		239,650		3,777
*	Avalara, Inc.		40,898		5,443
	Brooks Automation, Inc.		142,815		6,318
	Computer Services, Inc.		98,029		5,245
*	Euronet Worldwide, Inc.		52,830		5,062
*	Grid Dynamics Holdings, Inc.		706,991		4,878
*	Inphi Corporation		38,870		4,567
*	j2 Global, Inc.		88,912		5,620
*	Knowles Corporation		268,830		4,102
	Littelfuse, Inc.		35,313		6,026
*	LivePerson, Inc.		95,347		3,950
*	Novanta, Inc.†		34,220		3,654
*	PDF Solutions, Inc.		150,872		2,951
	Perspecta, Inc.		261,440		6,073
*	Pure Storage, Inc.		467,276		8,098
*	Qualys, Inc.		34,220		3,560
*	Rogers Corporation		29,897		3,725
*	SiTime Corporation		125,468		5,948
*	SolarEdge Technologies, Inc.		31,760		4,408
*	Varonis Systems, Inc.		50,890		4,503
*	Verra Mobility Corporation		502,749		5,168
*	WNS Holdings, Ltd.—ADR		122,092		6,713
					122,498



	Issuer	Shares		Value

	Common Stocks—(continued)
	Industrials—21.3%
	Albany International Corporation		91,435	$	5,368
	Armstrong World Industries, Inc.		27,653		2,156
*	Blue Bird Corporation		260,441		3,904
	BWX Technologies, Inc.		213,529		12,094
*	Casella Waste Systems, Inc.		166,720		8,689
	Douglas Dynamics, Inc.		151,413		5,318
*	Ducommun, Inc.		234,279		8,169
	ESCO Technologies, Inc.		47,906		4,050
*	Forrester Research, Inc.		132,993		4,261
*	IAA, Inc.		90,070		3,474
	John Bean Technologies Corporation		52,830		4,544
	Lincoln Electric Holdings, Inc.		45,170		3,805
	Luxfer Holdings plc†		391,695		5,543
*	Mercury Systems, Inc.		83,936		6,602
*	PAE, Inc.		886,258		8,473
	Ritchie Bros Auctioneers, Inc.†		149,475		6,106
	The Brink’s Co.		193,406		8,802
*	Trex Co., Inc.		44,350		5,769
*	Willdan Group, Inc.		123,108		3,079
					110,206
	Consumer Discretionary—9.9%
	Aaron’s, Inc.		161,297		7,323
*	Boot Barn Holdings, Inc.		371,924		8,019
*	Etsy, Inc.		48,512		5,153
*	Grand Canyon Education, Inc.		99,812		9,036
*	Laureate Education, Inc.		610,423		6,083
	Lithia Motors, Inc.		34,749		5,258
*	National Vision Holdings, Inc.		244,468		7,461
*	Revolve Group, Inc.		187,800		2,791
					51,124
	Financials—5.1%
*	Encore Capital Group, Inc.		127,105		4,344
	FirstCash, Inc.		105,118		7,093
	Home BancShares, Inc.		233,931		3,598
	LPL Financial Holdings, Inc.		55,850		4,379
*	Open Lending Corporation		246,467		3,722
	Virtu Financial, Inc.		132,666		3,131
					26,267
	Real Estate—3.3%
	Colliers International Group, Inc.†		110,408		6,327
	CoreSite Realty Corporation		26,004		3,148
	FirstService Corporation†		78,427		7,902
					17,377
	Consumer Staples— 2.8%
*	BJ’s Wholesale Club Holdings, Inc.		196,830		7,336
*	Darling Ingredients, Inc.		288,180		7,095
					14,431
	Communication Services—1.6%
*	QuinStreet, Inc.		784,860		8,209

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

	Shares or
	Principal
Issuer	Amount		Value

Common Stocks—(continued)
Energy—1.3%
Cameco Corporation†		497,960	$	5,104
Parsley Energy, Inc.		140,160		1,497
				6,601
Materials—1.0%
Orion Engineered Carbons S.A.†		482,417		5,109
Total Common Stocks—97.1% (cost $419,618)				503,039

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $10,600, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $10,812		$10,600		10,600
Total Repurchase Agreement—2.0% (cost $10,600)				10,600
Total Investments—99.1% (cost $430,218)				513,639
Cash and other assets, less liabilities—0.9%				4,549
Net assets—100.0%			$	518,188

ADR = American Depository Receipt

* = Non-income producing security

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	Small Cap Value Fund

	The Small Cap Value Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Chad M. Kilmer Mark T. Leslie David S. Mitchell	The William Blair Small Cap Value Fund (Class N shares) posted a 26.37% decrease, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the Russell 2000^®Value Index (the “Index”), decreased 23.50%. The relative underperformance of the Fund during the period was the result of stock selection. At the sector level, Health Care was the most significant detractor from relative performance due to the Fund’s lack of exposure to Biotechnology. This lack of exposure more than offset positive stock selection within Health Care Providers & Services. The relative underperformance within Energy, the worst performing sector of the market, was primarily due to stock selection within Oil, Gas & Consumable Fuels; more specifically, stock selection within Exploration & Production. Within Consumer Discretionary, stock selection within Hotels, Restaurants & Leisure and the lack of exposure to Internet & Direct Marketing Retail contributed to the relative underperformance within the sector. The relative outperformance within Industrials was due to broad-based stock selection throughout most industries. Within the sector, stock selection within Professional Services and Commercial Services & Supplies were the main contributors to relative returns. Within Communication Services, our lack of exposure to Media stocks was the main contributor to relative performance within the sector. Looking specifically at stock selection, the Fund’s largest detractors during the period were EPR Properties (Real Estate), Pebblebrook Hotel Trust (Real Estate) and Helix Energy Solutions (Energy). More than offsetting these detractors were our investments in Inphi (Information Technology), FTI Consulting (Industrials) and Americold Realty Trust (Real Estate). Please refer to the U.S. Value Market Review and Outlook relating to the Fund on page 4.

June 30, 2020

William Blair Funds

Small Cap Value Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year			Since Inception(a)
Class N		(26.37	)%		(23.93	)%		(7.00	)%		(1.15	)%		6.54	%		—
Class I		(26.34	)		(23.77	)		(6.78	)		(0.91	)		6.80			—
Class R6		(26.27	)		(23.70	)		—			—			—			(21.26	)%
Russell 2000^® Value Index		(23.50	)		(17.48	)		(4.35	)		1.26			7.82			(16.29	)

(a)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in smaller companies involves special risks, including higher volatility and lower liquidity. Smaller capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Russell 2000^®Value Index consists of small-capitalization companies with below average price-to-book ratios and forecasted growth rates.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

Small Cap Value Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks
	Financials—25.7%
	Banc of California, Inc.		72,707	$	787
	Banner Corporation		27,015		1,027
	Boston Private Financial Holdings, Inc.		165,828		1,141
	CNO Financial Group, Inc.		80,449		1,253
	First American Financial Corporation		15,030		722
	FNB Corporation		143,203		1,074
	Glacier Bancorp, Inc.		37,339		1,318
	Hancock Whitney Corporation		63,422		1,345
	Home BancShares, Inc.		97,368		1,497
	Horace Mann Educators Corporation		34,835		1,279
	National Bank Holdings Corporation		41,179		1,112
	OceanFirst Financial Corporation		59,417		1,048
	PacWest Bancorp		52,074		1,026
	Radian Group, Inc.		99,958		1,550
	Renasant Corporation		40,152		1,000
	Sandy Spring Bancorp, Inc.		41,682		1,033
*	Seacoast Banking Corporation of Florida		59,525		1,214
	Selective Insurance Group, Inc.		32,715		1,725
	The Hanover Insurance Group, Inc.		14,371		1,456
	Umpqua Holdings Corporation		100,507		1,069
	Western Alliance Bancorp		40,400		1,530
					25,206
	Industrials—16.2%
	Brady Corporation		53,892		2,523
	Curtiss-Wright Corporation		17,259		1,541
	ESCO Technologies, Inc.		18,227		1,541
	Federal Signal Corporation		33,151		986
*	FTI Consulting, Inc.		14,049		1,609
*	Gibraltar Industries, Inc.		31,650		1,519
*	Saia, Inc.		13,526		1,504
	Simpson Manufacturing Co., Inc.		17,985		1,517
	UniFirst Corporation		8,417		1,506
	Watts Water Technologies, Inc.		20,863		1,690
					15,936
	Real Estate—10.6%
	Agree Realty Corporation		20,415		1,342
	American Assets Trust, Inc.		40,306		1,122
	Americold Realty Trust		33,785		1,226
	CoreSite Realty Corporation		7,185		870
	Healthcare Realty Trust, Inc.		62,401		1,828
	Highwoods Properties, Inc.		29,549		1,103
	Life Storage, Inc.		16,050		1,524
	Terreno Realty Corporation		26,889		1,415
					10,430
	Consumer Discretionary—10.5%
*	Adtalem Global Education, Inc.		31,930		995
	Carter’s, Inc.		10,181		822
*	Cavco Industries, Inc.		7,162		1,381
*	Deckers Outdoor Corporation		6,525		1,281
	Dunkin’ Brands Group, Inc.		16,100		1,050
*	Helen of Troy, Ltd.†		6,750		1,273
*	Monarch Casino & Resort, Inc.		16,886		576
*	Murphy USA, Inc.		6,510		733
	Strategic Education, Inc.		5,585		858
*	TopBuild Corporation		11,860		1,349
					10,318



	Issuer	Shares		Value

	Common Stocks—(continued)
	Information Technology—6.5%
*	Inphi Corporation		6,148	$	722
*	j2 Global, Inc.		13,482		852
*	LiveRamp Holdings, Inc.		21,924		931
	MAXIMUS, Inc.		18,177		1,281
	Perspecta, Inc.		38,610		897
*	Semtech Corporation		14,141		739
*	Viavi Solutions, Inc.		77,817		991
					6,413
	Health Care—6.5%
	CONMED Corporation		24,021		1,729
	Encompass Health Corporation		30,309		1,877
*	Integer Holdings Corporation		23,029		1,682
*	Magellan Health, Inc.		14,876		1,086
					6,374
	Utilities—6.1%
	Black Hills Corporation		24,582		1,393
	Chesapeake Utilities Corporation		913		77
	IDACORP, Inc.		14,463		1,264
	ONE Gas, Inc.		22,805		1,757
	PNM Resources, Inc.		38,565		1,482
					5,973
	Materials—5.5%
	Carpenter Technology Corporation		36,769		893
	Minerals Technologies, Inc.		24,069		1,130
	PolyOne Corporation		38,674		1,014
	Sensient Technologies Corporation		19,022		992
	Silgan Holdings, Inc.		42,332		1,371
					5,400
	Energy—4.5%
	Archrock, Inc.		127,747		829
	Brigham Minerals, Inc. Class “A”		75,155		928
	Cactus, Inc. Class “A”		26,305		543
*	CNX Resources Corporation		57,995		502
*	Dril-Quip, Inc.		11,480		342
	HollyFrontier Corporation		24,565		717
*	PDC Energy, Inc.		45,200		562
					4,423
	Consumer Staples—4.3%
*	BJ’s Wholesale Club Holdings, Inc.		27,765		1,035
	Casey’s General Stores, Inc.		4,695		702
*	Darling Ingredients, Inc.		59,876		1,474
	J&J Snack Foods Corporation		7,670		975
					4,186
	Communication Services—1.1%
	The Interpublic Group of Cos., Inc.		26,795		460
*	Zynga, Inc.		60,995		582
					1,042
	Total Common Stocks—97.5% (cost $83,626)				95,701

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Small Cap Value Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)


	Principal
Issuer	Amount		Value

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $2,128, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $2,170		$2,128	$	2,128
Total Repurchase Agreement—2.2% (cost $2,128)				2,128
Total Investments—99.7% (cost $85,754)				97,829
Cash and other assets, less liabilities—0.3%				285
Net assets—100.0%			$	98,114

* = Non-income producing security

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Global Markets Review and Outlook

Global equities rebounded strongly and market volatility moderated in the second quarter as the MSCI ACWI IMI advanced 19.83% - recovering a significant portion of the pandemic-induced selloff during March. While concerns over the economic impact of the coronavirus remain, investors were encouraged by the massive stimulus measures from governments and central banks. Significant monetary and fiscal responses coupled with the gradual resumption of business activity led to a broad equity rally across both developed and emerging markets.

U.S. equities strengthened during the second quarter (MSCI USA IMI +22.10%) despite the precipitous decline in economic activity, which included a significant rise in unemployment claims. The U.S. unemployment rate reached a record high in April of 14.7% before falling back to 11.1% as of June 30 amid the gradual reopening of businesses across the country. Despite the extraordinary amount of tools used by the Federal Reserve (Fed), Chairman Powell maintained his commitment not to follow the path of other central banks and introduce negative policy rates.

European equities advanced during the quarter (MSCI Europe ex-UK IMI +18.45%) with major countries indicating progress towards lowering the rate of new coronavirus infections. German equities surged (+26.75%) on the announcement from Chancellor Angela Merkel that efforts were being made to inject a second stimulus package into the economy. Autos and other manufacturers rallied on the news. Across other primary developed markets, the UK (+8.77%) and Japan (+11.82%) were notable laggards during the quarter.

Emerging markets rebounded in the second quarter (MSCI EM IMI +18.93%), driven by strength in South Africa (+26.78%), Brazil (+23.83%) and Taiwan (+23.38%). After depreciating significantly in the first quarter, emerging market currencies such as the South African Rand and the Mexican Peso stabilized in the second quarter. China underperformed on a relative basis (+15.22%) amid a reescalation of political tensions with the U.S., as the Senate passed legislation that would potentially ban Chinese companies from listing on American exchanges.

Following the peak of the pandemic and related lock-down, economic activity accelerated strongly in June in China, Europe and the U.S., including both manufacturing and services. Our preferred supply side indicator - orders in excess of inventories-registered double-digit improvement in the Euro Area and is already back to positive territory in the U.S. Crucially, a rebound in new orders drove the improvement. Unprecedented fiscal support efforts, combined with healthy corporate and household balance sheets at the start of the pandemic-induced recession, point to a continued strong sequential recovery, although we do not expect either GDP or corporate profits to recover to pre-pandemic levels this year.

China, Europe and the U.S. followed somewhat different approaches to containing the spread of the virus. These differences may impact the recovery trajectory and speed in each of these major global demand centers, with the U.S. lagging and likely to continue to fall behind given the resurgence of cases.

The market recovery we have seen has been driven by liquidity. Major central banks acted early and decisively, such that periods of funding stress typical in acute and sudden recession were fleeting. Domestic financial conditions are normalizing rapidly and both the U.S. Fed and Europe’s ECB have assured the markets that they will remain committed to eliminating pockets of funding stress wherever necessary. In China, the People’s Bank of China has aggressively increased liquidity provisions, such that the total credit impulse in the economy is now among the strongest we have seen in a decade. Importantly, funding conditions remain adequate for the vast majority of Emerging Market economies, supported by ample dollar liquidity and lower oil prices.

From a corporate performance perspective, new economy digital business models proved more defensive and more resilient amid the pandemic-induced collapse in economic activity. While the majority of S&P 500 companies saw year-on-year revenue declines in excess of 10%, the fastest growers clocked in double digit gains. This widening performance differential is particularly interesting to us as investors in industry leading growth companies.

While valuation multiples appear inflated due to depressed earnings, this is largely consistent with historical recovery environments. Looking forward, however, successful containment of the virus, combined with improving prospects for an effective vaccine, are likely to pave the way for a broadening of market leadership to include more traditional cyclical companies as their earnings begin to stabilize and reaccelerate. This will be the ultimate catalyst to see a style reversal in the market, where the valuation differentials of high growth companies relative to all others will likely compress. We are monitoring this closely.

June 30, 2020

William Blair Funds

Global Markets Review and Outlook (continued)

Given that backdrop and this period of high uncertainty, we are focused on understanding the durability of the competitive advantage of those “digital winners”, trying to understand the nature of the acceleration of their growth; and how much of that future success is priced into the stocks. Electronic payments are a key focus area in that context.

On the other hand, we are also interested in some of the more compelling structural growth companies in cyclical industries who have been particularly impacted by the economic slowdown. While there may be limited visibility in sight, many of these stocks remain quite depressed and may represent a significant valuation as well as growth opportunity when activity normalizes. We believe that air travel and aerospace manufacturing companies are good examples.

Semiannual Report

June 30, 2020

	Global Leaders Fund

	The Global Leaders Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Andrew G. Flynn Kenneth J. McAtamney	The William Blair Global Leaders Fund (Class N shares) posted a 2.21% increase, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the MSCI All Country World IMI Index (net) (the “Index”), decreased 7.06%. Six-month outperformance versus the Index was primarily driven by positive stock selection across most sectors. The Industrials, Financials and Health Care sectors were the most significant contributors to relative return. Within Industrials, Nihon M&A Center propelled relative performance as the company’s pipeline of deals and capacity to manage them has continued to expand. Nihon M&A Center is a high-quality Japanese growth company that provides advisory services to small and medium sized businesses facing succession-oriented challenges, which is common given Japan’s aging demographics. It is led by an entrepreneurial management team that has built an attractive network of national relationships aimed at identifying buyers and sellers and sourcing transactions, and the growth outlook remains robust. BlackRock, the asset management industry leader within the Financials sector, was an additional source of outperformance. Its first quarter results were resilient, reflecting the company’s diverse business model, scale, tech-enabled platform and broad product offering. These factors underpin its ability to generate strong net flows, a key value driver. The business has low capital intensity with high cash generation that is returned to shareholders via dividends and share buybacks. Within the Health Care, Lonza Group helped relative performance. Lonza is a leader in custom manufacturing of biopharmaceuticals and specialty ingredients. Business trends remain strong, particularly in its pharma biotech segment amid the COVID-19 pandemic. Lonza offers highly visible growth, and given the strong market demand for outsourced biopharma production and related services, we remain confident they can deliver on growth in the future. Partially offsetting these effects was an overweight to Industrials, coupled with below average stock selection within the Consumer Discretionary sector. Within Consumer Discretionary, Compass Group and Fevertree Drinks weighed on relative returns. Compass is the global leader in outsourced foodservice and other support services to private businesses, schools and colleges, hospitals, and in remote environments. It is benefiting from the ongoing trend toward outsourcing foodservice and hospitality services globally. Given the COVID-19 pandemic, the narrative around contract caterers is fairly negative due to work from home dynamics, social distancing, and a challenging macro backdrop. However, as volumes recover and people gain comfort that the business model remains intact, we expect the stock will reflect the long-term earnings power of the business. We believe that current estimates do not account for an acceleration of market share gains as business may shift away from competitors with weaker offerings, the demand for outsourcing likely increasing due to health and safety concerns, or any upside from M&A, which we anticipate the company will take an active role in. Fevertree Drinks produced in-line results in the first quarter but suffered a decline in its stock price due to the COVID-19 pandemic. Fevertree produces premium mixers, including tonic water, ginger beer, cola and lemonade. We believe that the company should experience rapid growth due its expanding geographic presence, increased product mix, and the trend towards premium spirits. Please refer to the Global Markets Review and Outlook relating to the Fund beginning on page 31.

June 30, 2020

William Blair Funds

Global Leaders Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year			Since Inception
Class N		2.21	%		11.45	%		12.16	%		9.61	%		11.65	%		—
Class I		2.34			11.68			12.46			9.93			11.94			—
MSCI ACW IMI (net)		(7.06	)		1.17			5.55			6.11			9.10			—
Class R6(a)		2.41			11.81			12.55			10.00			—			10.56	%
MSCI ACW IMI (net)(a)		(7.06	)		1.17			5.55			6.11			—			7.90

(a)	Since inception is for the period from December 19, 2012 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in smaller and medium capitalization companies involves special risks, including higher volatility and lower liquidity. Smaller and medium capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. International investing involves special risk considerations, including currency fluctuations, lower liquidity, economic and political risk. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Morgan Stanley Capital International (MSCI) All Country World (ACW) Investable Market Index (IMI) (net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market of developed and emerging markets. This index approximates the minimum possible dividend reinvestment by deducting for the highest possible withholding tax rates of those markets.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

Global Leaders Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks

	Western Hemisphere—51.4%
	Canada—2.8%
	Brookfield Asset Management, Inc. Class “A” (Capital markets)†		34,147	$	1,123
*	Lululemon Athletica, Inc. (Textiles, apparel & luxury goods)		5,040		1,573
					2,696
	United States—48.6%
*	Adobe, Inc. (Software)		4,875		2,122
*	Alphabet, Inc. Class “A” (Interactive Media & Services)		2,265		3,212
*	Amazon.com, Inc. (Internet & direct marketing retail)		1,571		4,334
	BlackRock, Inc. (Capital markets)		2,656		1,445
*	CoStar Group, Inc. (Professional services) .		1,510		1,073
*	Edwards Lifesciences Corporation (Health care equipment & supplies)		15,452		1,068
*	Facebook, Inc. Class “A” (Interactive Media & Services)		11,608		2,636
	Fidelity National Information Services, Inc. (IT services)		12,211		1,637
*	IDEXX Laboratories, Inc. (Health care equipment & supplies)		3,741		1,235
*	Illumina, Inc. (Life sciences tools & services)		1,777		658
	Intercontinental Exchange, Inc. (Capital markets)		14,998		1,374
*	Intuitive Surgical, Inc. (Health care equipment & supplies)		1,663		948
	JPMorgan Chase & Co. (Banks)		13,558		1,275
	Lockheed Martin Corporation (Aerospace & defense)		3,399		1,240
	Mastercard, Inc. Class “A” (IT services)		8,763		2,591
	NextEra Energy, Inc. (Electric utilities)		3,705		890
	NIKE, Inc. Class “B” (Textiles, apparel & luxury goods)		14,365		1,408
*	PayPal Holdings, Inc. (IT services)		11,742		2,046
	Prologis, Inc. (Equity REIT)		11,205		1,046
	Roper Technologies, Inc. (Industrial conglomerates)		4,002		1,554
*	salesforce.com, Inc. (Software)		12,624		2,365
	The Estee Lauder Cos., Inc. Class “A” (Personal products)		7,146		1,348
	Thermo Fisher Scientific, Inc. (Life sciences tools & services)		3,914		1,418
*	Ulta Beauty, Inc. (Specialty retail)		5,673		1,154
	Union Pacific Corporation (Road & rail)		8,622		1,458
	UnitedHealth Group, Inc. (Health care providers & services)		6,430		1,897
*	Veeva Systems, Inc. Class “A” (Health care technology)		3,046		714
*	Workday, Inc. (Software)		8,628		1,617
	Zoetis, Inc. (Pharmaceuticals)		10,000		1,370
					47,133



	Issuer	Shares		Value

	Common Stocks—(continued)

	Europe—21.5%
	Denmark—4.0%
	Chr Hansen Holding A/S (Chemicals)		10,421	$	1,075
	DSV PANALPINA A/S (Air freight & logistics)		11,497		1,404
	Novo Nordisk A/S Class “B” (Pharmaceuticals)		21,388		1,384
					3,863
	France—3.2%
*	Airbus SE (Aerospace & defense)		21,092		1,505
	LVMH Moet Hennessy Louis Vuitton SE (Textiles, apparel & luxury goods)		3,734		1,638
					3,143
	Germany—3.8%
	Infineon Technologies AG (Semiconductors & semiconductor equipment)		83,090		1,949
*	MTU Aero Engines AG (Aerospace & defense)		6,855		1,187
	Rational AG (Machinery)		897		502
					3,638
	Ireland—2.3%
	Allegion plc (Building products)†		7,737		791
	Aptiv plc (Auto components)†		18,491		1,441
					2,232
	Netherlands—1.0%
*	Adyen N.V. (IT services)		670		975

	Sweden—4.1%
	Atlas Copco AB Class “A” (Machinery)		40,691		1,723
*	Hexagon AB Class “B” (Electronic equipment, instruments & components)		29,517		1,723
*	Indutrade AB (Trading companies & distributors)		14,042		555
					4,001
	Switzerland—3.1%
	Lonza Group AG (Life sciences tools & services)		2,820		1,489
	Partners Group Holding AG (Capital markets)		1,722		1,562
					3,051

	Emerging Asia—9.5%
	China—6.1%
*	Alibaba Group Holding, Ltd. (Internet & direct marketing retail)		98,344		2,659
	Shenzhou International Group Holdings, Ltd. (Textiles, apparel & luxury goods)		49,300		594
	Tencent Holdings, Ltd. (Interactive Media & Services)		41,000		2,638
					5,891

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Global Leaders Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	India—1.0%
	HDFC Bank, Ltd.—ADR (Banks)		21,493	$	977

	Taiwan—2.4%
	Taiwan Semiconductor Manufacturing Co., Ltd.—ADR (Semiconductors & semiconductor equipment)		41,252		2,342

	Japan—6.4%
	Daikin Industries, Ltd. (Building products)		9,700		1,558
	Keyence Corporation (Electronic equipment, instruments & components)		4,300		1,793
	Nihon M&A Center, Inc. (Professional services)		35,900		1,619
	SMC Corporation (Machinery)		2,500		1,278
					6,248

	Asia—5.4%
	Australia—3.2%
	Aristocrat Leisure, Ltd. (Hotels, restaurants & leisure)		54,343		956
*	Atlassian Corporation plc Class “A” (Software)†		5,001		902
	CSL, Ltd. (Biotechnology)		6,450		1,277
					3,135
	Hong Kong—1.6%
	AIA Group, Ltd. (Insurance)		170,200		1,588

	New Zealand—0.6%
	Fisher & Paykel Healthcare Corp., Ltd. (Health care equipment & supplies)		24,254		557

	United Kingdom—3.4%
	Compass Group plc (Hotels, restaurants & leisure)		81,449		1,122
	Experian plc (Professional services)		27,603		964
	Halma plc (Electronic equipment, instruments & components)		15,731		449
	Rentokil Initial plc (Commercial services & supplies)		116,783		738
					3,273

	Emerging Latin America—1.7%
	Argentina—1.7%
*	Globant S.A. (Software)†		5,785		867
*	MercadoLibre, Inc. (Internet & direct marketing retail)		753		742
					1,609
	Total Common Stocks—99.3% (cost $63,702)				96,352


Issuer	Principal Amount		Value

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $658, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $671	$	658	$	658
Total Repurchase Agreement—0.7% (cost $658)				658
Total Investments—100.0% (cost $64,360)				97,010
Cash and other assets, less liabilities—0.0%				25
Net assets—100.0%			$	97,035

ADR = American Depository Receipt

REIT = Real Estate Investment Trust

† = U.S. listed foreign security

* = Non-income producing security

For securities primarily traded on exchanges or markets that close before the close of regular trading on the New York Stock Exchange, the Fund may use an independent pricing service to fair value price the securities pursuant to Valuation Procedures approved by the Board of Trustees.

At June 30, 2020, the Fund’s Portfolio of Investments includes the following industry categories (as a percentage of long-term investments):

Information Technology	24.3	%
Industrials	19.9	%
Consumer Discretionary	18.3	%
Health Care	14.5	%
Financials	9.7	%
Communication Services	8.8	%
Consumer Staples	1.4	%
Materials	1.1	%
Real Estate	1.1	%
Utilities	0.9	%
Total	100.0	%

At June 30, 2020, the Fund’s Portfolio of Investments includes the following currency categories (as a percentage of long-term investments):

U.S. Dollar	60.1	%
Euro	8.0	%
Hong Kong Dollar	7.8	%
Japanese Yen	6.5	%
Swedish Krona	4.1	%
Danish Krone	4.0	%
British Pound Sterling	3.4	%
Swiss Franc	3.2	%
Australian Dollar	2.3	%
All Other Currencies	0.6	%
Total	100.0	%

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	International Leaders Fund

	The International Leaders Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Simon Fennell Kenneth J. McAtamney	The William Blair International Leaders Fund (Class N shares) posted a 1.27% decrease, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the MSCI All Country World ex-U.S. IMI (net) (the “Index”), decreased 11.24%. Six-month outperformance versus the Index was primarily driven by positive stock selection across most sectors. The Financials, Consumer Discretionary and Communication Services sectors were the most notable sources of relative return. Within Financials, London Stock Exchange Group (LSE) aided relative returns as the company’s share price appreciated on the back of strong operating results. LSE stands out with approximately 65% of revenue from more durable non-transaction driven businesses with exposure to secular growth trends including passive investing and OTC clearing. Integration planning for the Refinitiv transaction is progressing well and LSE has committed to achieving completion in 2020. We believe the company should deliver mid-teens earnings growth over the next few years driven by high single-digit revenue growth and margin expansion. Within Consumer Discretionary, TAL Education Group, a leading tutoring services provider in China with a strong brand and significant growth opportunities, was an additional source of outperformance. With brands known for improving student performance, TAL should continue to be a consolidator in the highly fragmented industry due to strong execution and scalable technology. Within the Communication Services sector, Chinese online companies NetEase and Tencent were additional sources of outperformance. Both companies reported better-than-expected results and have benefited from positive investor sentiment related to the slowing of the pandemic within China as well as the resilient nature of their business models. Partially offsetting these effects was an overweight allocation to the U.K. and below average stock selection within the Consumer Staples sector. Within Consumer Staples, Nestle and Diageo hurt relative performance. The relative underperformance from Nestle was a result of it not being owned in the Fund during the COVID-19 pandemic. The defensive nature of the business often leads it to perform well during periods of significant economic disruption, as was the case in the first half of 2020. Diageo, a global leader in spirits, has seen significant disruption in Greater China due to the pandemic. The share price decline rebounded since bottoming in the first quarter, but did not keep up with broad market. Please refer to the Global Markets Review and Outlook relating to the Fund beginning on page 31.

June 30, 2020

William Blair Funds

International Leaders Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			Since Inception
Class N(a)		(1.27	)%		7.64	%		8.43	%		7.85	%		8.95	%
Class I(a)		(1.16	)		7.93			8.72			8.12			9.22
MSCI ACW Ex-U.S. IMI (net)(a)		(11.24	)		(4.74	)		0.96			2.30			4.54
Class R6(b)		(1.10	)		7.97			8.79			8.21			9.26
MSCI ACW Ex-U.S. IMI (net)(b)		(11.24	)		(4.74	)		0.96			2.30			4.15

(a)	Since inception is for the period from August 16, 2012 (Commencement of Operations) to June 30, 2020.
(b)	Since inception is for the period from November 2, 2012 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in smaller and medium capitalization companies involves special risks, including higher volatility and lower liquidity. Smaller and medium capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. International investing involves special risk considerations, including currency fluctuations, lower liquidity, economic and political risk. From time to time the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Morgan Stanley Capital International (MSCI) All Country World (ACW) Ex-U.S. Investable Market Index (IMI) (net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of developed and emerging markets, excluding the United States. This index approximates the minimum possible dividend reinvestment by deducting for the highest possible withholding tax rates of those markets.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

International Leaders Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks

	Europe—43.4%
	Denmark—6.9%
	Chr Hansen Holding A/S (Chemicals)		32,359	$	3,337
	Coloplast A/S Class “B” (Health care equipment & supplies)		80,191		12,429
	DSV PANALPINA A/S (Air freight & logistics)		57,433		7,012
	Novo Nordisk A/S Class “B” (Pharmaceuticals)		192,526		12,465
	Orsted A/S (Electric utilities)		92,038		10,621
					45,864
	Finland—1.1%
	Neste Oyj (Oil, gas & consumable fuels)		191,662		7,496
	France—9.7%
*	Airbus SE (Aerospace & defense)		105,603		7,536
	Capgemini SE (IT services)		92,447		10,589
*	L’Oreal S.A. (Personal products)		33,438		10,733
	LVMH Moet Hennessy Louis Vuitton SE (Textiles, apparel & luxury goods)		44,000		19,304
*	Safran S.A. (Aerospace & defense)		99,997		10,024
	Teleperformance (Professional services)		24,692		6,267
					64,453
	Germany—5.9%
	Infineon Technologies AG (Semiconductors & semiconductor equipment)		597,745		14,019
	Rational AG (Machinery)		12,617		7,065
	SAP SE (Software)		102,595		14,330
*	TeamViewer AG (Software)		64,325		3,512
					38,926
	Ireland—2.0%
	Kingspan Group plc (Building products)		200,288		12,905
	Luxembourg—0.4%
	Tenaris S.A. (Energy equipment & services)		353,977		2,286
	Netherlands—2.9%
*	Adyen N.V. (IT services)		9,655		14,053
	ASML Holding N.V. (Semiconductors & semiconductor equipment)		14,637		5,375
					19,428
	Spain—1.2%
	Amadeus IT Group S.A. (IT services)		150,093		7,821
	Sweden—4.4%
	Atlas Copco AB Class “A” (Machinery)		352,008		14,906
*	Hexagon AB Class “B” (Electronic equipment, instruments & components)		246,367		14,383
					29,289



	Issuer	Shares		Value

	Common Stocks—(continued)

	Europe—(continued)
	Switzerland—8.9%
	Lonza Group AG (Life sciences tools & services)		29,482	$	15,565
	Partners Group Holding AG (Capital markets)		12,161		11,031
	Sika AG (Chemicals)		52,856		10,173
	Straumann Holding AG (Health care equipment & supplies)		12,999		11,168
	Temenos AG (Software)		71,540		11,111
					59,048

	Emerging Asia—18.3%
	China—12.9%
*	Alibaba Group Holding, Ltd. (Internet & direct marketing retail)		871,256		23,562
	China Merchants Bank Co., Ltd. Class “H” (Banks)		2,169,000		9,977
	NetEase, Inc.—ADR (Entertainment)		29,744		12,771
*	TAL Education Group—ADR (Diversified consumer services)		219,637		15,019
	Tencent Holdings, Ltd. (Interactive Media & Services)		375,800		24,176
					85,505
	India—2.9%
	Housing Development Finance Corporation, Ltd. (Thrifts & mortgage finance)		309,844		7,227
	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		511,664		11,571
*	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		36,741		389
					19,187
	Taiwan—2.5%
	Taiwan Semiconductor Manufacturing Co., Ltd. (Semiconductors & semiconductor equipment)		1,576,000		16,719

	United Kingdom—14.7%
	Abcam plc (Biotechnology)		171,279		2,829
	Ashtead Group plc (Trading companies & distributors)		254,292		8,567
	Compass Group plc (Hotels, restaurants & leisure)		516,663		7,119
	Diageo plc (Beverages)		255,283		8,482
	Experian plc (Professional services)		429,331		14,997
	Halma plc (Electronic equipment, instruments & components)		240,237		6,855
	London Stock Exchange Group plc (Capital markets)		119,799		12,407
	RELX plc (Professional services)		498,796		11,558
	Rentokil Initial plc (Commercial services & supplies)		1,273,841		8,044
	Segro plc (Equity REIT)		858,547		9,521
	Spirax-Sarco Engineering plc (Machinery)		57,872		7,154
					97,533

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

International Leaders Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

		Shares or
		Principal
	Issuer	Amount		Value

	Common Stocks—(continued)

	Japan—10.3%
	Asahi Intecc Co., Ltd. (Health care equipment & supplies)		175,900	$	4,993
	Daikin Industries, Ltd. (Building products)		76,400		12,266
	Hoya Corporation (Health care equipment & supplies)		113,300		10,766
	Keyence Corporation (Electronic equipment, instruments & components)		43,400		18,100
	Shiseido Co., Ltd. (Personal products)		146,600		9,280
	SMC Corporation (Machinery)		24,400		12,469
					67,874
	Canada—5.8%
	Brookfield Asset Management, Inc. Class “A” (Capital markets)†		296,716		9,762
	Canadian National Railway Co. (Road & rail)		146,479		12,959
	Dollarama, Inc. (Multiline retail)		204,757		6,811
*	Lululemon Athletica, Inc. (Textiles, apparel & luxury goods)		29,402		9,174
					38,706
	Asia—5.5%
	Australia—3.6%
	Aristocrat Leisure, Ltd. (Hotels, restaurants & leisure)		350,186		6,162
*	Atlassian Corporation plc Class “A” (Software)†		32,006		5,770
	CSL, Ltd. (Biotechnology)		58,717		11,629
					23,561
	Hong Kong—1.9%
	AIA Group, Ltd. (Insurance)		1,345,200		12,549
	Emerging Latin America—1.5%
	Argentina—1.5%
*	MercadoLibre, Inc. (Internet & direct marketing retail)		10,122		9,978
	Total Common Stocks—99.5% (cost $512,419)				659,128
	Repurchase Agreement
	Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $2,863, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $2,920	$	2,863		2,863
	Total Repurchase Agreement—0.4% (cost $2,863)				2,863
	Total Investments—99.9% (cost $515,282)				661,991
	Cash and other assets, less liabilities—0.1%				470
	Net assets—100.0%			$	662,461

ADR = American Depository Receipt

REIT = Real Estate Investment Trust

* = Non-income producing security

† = U.S. listed foreign security

At June 30, 2020, the Fund’s Portfolio of Investments includes the following industry categories (as a percentage of long-term investments):

Industrials	23.5	%
Information Technology	21.6	%
Consumer Discretionary	14.7	%
Health Care	12.4	%
Financials	9.6	%
Communication Services	5.6	%
Consumer Staples	4.3	%
Energy	3.3	%
Materials	2.0	%
Utilities	1.6	%
Real Estate	1.4	%
Total	100.0	%

At June 30, 2020, the Fund’s Portfolio of Investments includes the following currency categories (as a percentage of long-term investments):

Euro	23.3	%
British Pound Sterling	14.8	%
Hong Kong Dollar	10.7	%
Japanese Yen	10.3	%
U.S. Dollar	9.5	%
Swiss Franc	9.0	%
Danish Krone	6.9	%
Swedish Krona	4.4	%
Canadian Dollar	3.0	%
Indian Rupee	2.9	%
Australian Dollar	2.7	%
New Taiwan Dollar	2.5	%
Total	100.0	%

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

International Growth Fund

The International Growth Fund seeks long-term capital appreciation.

AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Simon Fennell

Kenneth J. McAtamney

The William Blair International Growth Fund (Class N shares) posted a 0.27% increase, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the MSCI All Country World ex-U.S. IMI (net) (the “Index”), decreased 11.24%.

Six-month outperformance versus the Index was primarily driven by positive stock selection across most sectors. The Information Technology, Communication Services and Industrials sectors were the most notable sources of relative return. Within Information Technology, Adyen enhanced relative returns as the company posted second quarter results that reassured investors during a time of high uncertainty given the global COVID-19 pandemic. An innovative global payment service provider with a focus on large merchant online payments, we believe that Adyen is well positioned to benefit from an accelerated shift to online payments due to its best-in-class technology and product differentiation. Sea Ltd, a South East Asian mobile gaming and e-commerce company within Communication Services, was an additional source of outperformance. SEA primarily operates in seven South East Asian markets, including Indonesia, Malaysia, the Philippines, Singapore, Thailand, Taiwan and Vietnam. More recently, it has expanded its gaming operations to include India, Russia and Latin America. The company is the market leader in both gaming revenues and e-commerce, and current game success and a robust pipeline are driving higher revenue growth and profitability expectations, while e-commerce operating metrics continue to be strong. Within the Industrials sector, SMC Corp and Atlas Copco aided relative performance as the rebound in investor sentiment help propel high quality companies in cyclical sectors higher.

Partially offsetting these effects was an overweight allocation to the U.K., an underweight allocation to Communication Services and an overweight to the Industrials sector. Additionally, companies with exposure to travel-related activities underperformed as activity remained depressed, including Airbus, Safran, MTU Aero and Amadeus.

Please refer to the Global Markets Review and Outlook relating to the Fund beginning on page 31.

June 30, 2020

William Blair Funds

International Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year															Since
	to Date			1 Year			3 Year			5 Year			10 Year			Inception(a)
Class N		0.27	%		9.49	%		6.54	%		4.78	%		7.38	%		—
Class I		0.40			9.82			6.88			5.10			7.70			—
Class R6		0.46			9.92			—			—			—			10.42	%
MSCI ACW Ex-U.S. IMI (net)		(11.24	)		(4.74	)		0.96			2.30			5.11			(4.08	)

(a)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. Investing in smaller and medium capitalization companies involves special risks, including higher volatility and lower liquidity. Smaller and medium capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. International investing involves special risk considerations, including currency fluctuations, lower liquidity, economic and political risk. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

International Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks

	Europe, Mid-East—42.7%
	Belgium—0.3%
	Melexis N.V. (Semiconductors & semiconductor equipment)		31,256	$	2,370
	Warehouses De Pauw CVA (Equity REIT)		137,691		3,759
					6,129
	Denmark—5.3%
	Chr Hansen Holding A/S (Chemicals)		77,429		7,985
	Coloplast A/S Class “B” (Health care equipment & supplies)		67,454		10,455
	DSV PANALPINA A/S (Air freight & logistics)		226,302		27,631
*	Genmab A/S (Biotechnology)		42,596		14,258
*	Netcompany Group A/S (Software)		59,114		3,877
	Novo Nordisk A/S Class “B” (Pharmaceuticals)		289,613		18,750
	Orsted A/S (Electric utilities)		97,391		11,239
*	Royal Unibrew A/S (Beverages)		44,799		3,727
	Tryg A/S (Insurance)		84,989		2,460
					100,382
	Faroe Islands—0.1%
*	Bakkafrost P/F (Food products)		41,151		2,589
	Finland—0.9%
	Neste Oyj (Oil, gas & consumable fuels)		406,763		15,908
	France—9.8%
*	Airbus SE (Aerospace & defense)		301,988		21,551
	Capgemini SE (IT services)		143,715		16,461
	Dassault Systemes SE (Software)		89,066		15,370
	Hermes International (Textiles, apparel & luxury goods)		9,306		7,777
	Kering S.A. (Textiles, apparel & luxury goods)		27,782		15,115
*	L’Oreal S.A. (Personal products)		62,299		19,997
	LVMH Moet Hennessy Louis Vuitton SE (Textiles, apparel & luxury goods)		57,336		25,155
	Orpea (Health care providers & services)		40,297		4,659
	Rubis SCA (Gas utilities)		55,609		2,673
*	Safran S.A. (Aerospace & defense)		218,258		21,878
	Sartorius Stedim Biotech (Life sciences tools & services)		26,095		6,596
	Teleperformance (Professional services)		54,748		13,895
*	Worldline S.A. (IT services)		157,698		13,656
					184,783
	Germany—5.8%
*	Carl Zeiss Meditec AG (Health care equipment & supplies)		42,958		4,189
*	HelloFresh SE (Internet & direct marketing retail)		56,632		3,016
	Infineon Technologies AG (Semiconductors & semiconductor equipment)		936,734		21,969
	KION Group AG (Machinery)		88,293		5,436
*	MTU Aero Engines AG (Aerospace & defense)		119,832		20,753



	Issuer	Shares		Value

	Common Stocks—(continued)

	Europe, Mid-East—(continued)
	Germany—(continued)
*	Puma SE (Textiles, apparel & luxury goods)		131,041	$	10,132
	SAP SE (Software)		139,779		19,524
*	TeamViewer AG (Software)		184,818		10,092
	Vonovia SE (Real estate management & development)		214,641		13,162
					108,273
	Ireland—2.0%
*	ICON plc (Life sciences tools & services)†		75,184		12,666
	Kerry Group plc Class “A” (Food products)		86,138		10,674
	Kingspan Group plc (Building products)		204,396		13,170
					36,510
	Israel—0.7%
*	CyberArk Software, Ltd. (Software)†		39,970		3,968
*	Wix.com, Ltd. (IT services)†		37,499		9,608
					13,576
	Italy—0.5%
*	Amplifon SpA (Health care providers & services)		145,089		3,865
*	Brunello Cucinelli SpA (Textiles, apparel & luxury goods)		85,305		2,534
*	Moncler SpA (Textiles, apparel & luxury goods)		77,745		2,973
					9,372
	Luxembourg—0.4%
*	Eurofins Scientific SE (Life sciences tools & services)		11,289		7,085
	Netherlands—3.7%
*	Adyen N.V. (IT services)		14,517		21,129
	ASML Holding N.V. (Semiconductors & semiconductor equipment)		100,505		36,913
	BE Semiconductor Industries N.V. (Semiconductors & semiconductor equipment)		87,856		3,914
	Euronext N.V. (Capital markets)		45,353		4,548
	IMCD N.V. (Trading companies & distributors)		39,128		3,678
					70,182
	Norway—0.4%
	TOMRA Systems ASA (Commercial services & supplies)		205,020		7,521
	Spain—1.0%
	Amadeus IT Group S.A. (IT services)		352,495		18,368
	Sweden—4.8%
*	AAK AB (Food products)		129,414		2,224
	Atlas Copco AB Class “A” (Machinery)		752,486		31,866
	Evolution Gaming Group AB (Hotels, restaurants & leisure)		180,998		10,792
	Fabege AB (Real estate management & development)		232,864		2,721

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

International Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Europe, Mid-East—(continued)
	Sweden—(continued)
*	Hexagon AB Class “B” (Electronic equipment, instruments & components)		367,043	$	21,428
*	Indutrade AB (Trading companies & distributors)		136,280		5,382
	Lifco AB Class “B” (Industrial conglomerates)		63,727		4,035
*	Nibe Industrier AB Class “B” (Building products)		251,458		5,556
*	Nolato AB Class “B” (Industrial conglomerates)		56,363		3,799
*	Vitrolife AB (Biotechnology)		104,462		2,336
					90,139
	Switzerland—7.0%
	Belimo Holding AG (Building products)		536		3,943
	Logitech International S.A. (Technology hardware, storage & peripherals)		136,783		8,931
	Lonza Group AG (Life sciences tools & services)		47,060		24,845
	Partners Group Holding AG (Capital markets)		17,929		16,263
*	SIG Combibloc Group AG (Containers & packaging)		186,919		3,024
	Sika AG (Chemicals)		116,788		22,478
*	Softwareone Holding AG (Electronic equipment, instruments & components)		157,921		3,900
	STMicroelectronics N.V. (Semiconductors & semiconductor equipment)		550,146		14,970
	Straumann Holding AG (Health care equipment & supplies)		14,637		12,575
	Tecan Group AG (Life sciences tools & services)		14,674		5,198
	Temenos AG (Software)		70,158		10,896
	VAT Group AG (Machinery)		27,047		4,939
					131,962

	Emerging Asia—21.9%
	China—14.4%
	A-Living Services Co., Ltd. Class “H” (Commercial services & supplies)		739,750		3,727
	Aier Eye Hospital Group Co., Ltd. Class “A” (Health care providers & services)		1,038,916		6,381
	AK Medical Holdings, Ltd. (Health care equipment & supplies)		860,000		2,735
*	Alibaba Group Holding, Ltd. (Internet & direct marketing retail)		1,473,384		39,845
	Centre Testing International Group Co., Ltd. Class “A” (Professional services)		2,318,700		6,477
	Country Garden Services Holdings Co., Ltd. (Commercial services & supplies)		1,732,000		8,045
	Foshan Haitian Flavouring & Food Co., Ltd. Class “A” (Food products)		339,459		5,970
	Hangzhou Tigermed Consulting Co., Ltd. Class “A” (Life sciences tools & services)		505,870		7,285



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	China—(continued)
	Kweichow Moutai Co., Ltd. Class “A” (Beverages)		54,053	$	11,178
	Li Ning Co., Ltd. (Textiles, apparel & luxury goods)		3,015,500		9,571
*	Meituan Dianping Class “B” (Internet & direct marketing retail)		497,900		11,043
	NAURA Technology Group Co., Ltd. Class “A” (Electronic equipment, instruments & components)		182,913		4,419
	NetEase, Inc.—ADR (Entertainment)		39,608		17,007
	Offcn Education Technology Co., Ltd. Class “A” (Diversified consumer services)		974,421		3,822
	Ping An Insurance Group Co. of China, Ltd. Class “H” (Insurance)		2,075,000		20,749
	Shenzhen Mindray Bio-Medical Electronics Co., Ltd. Class “A” (Health care equipment & supplies)		102,350		4,423
	Shenzhou International Group Holdings, Ltd. (Textiles, apparel & luxury goods)		468,000		5,640
	Silergy Corporation (Semiconductors & semiconductor equipment)		156,000		10,152
*	TAL Education Group—ADR (Diversified consumer services)		311,308		21,287
	Tencent Holdings, Ltd. (Interactive Media & Services)		738,900		47,534
*	Tencent Music Entertainment Group—ADR (Entertainment)		210,681		2,836
*	Topchoice Medical Corporation Class “A” (Health care providers & services)		210,339		4,959
	Vitasoy International Holdings, Ltd. (Food products)		480,000		1,836
	Will Semiconductor, Ltd. Class “A” (Semiconductors & semiconductor equipment)		85,077		2,429
	WuXi AppTec Co., Ltd. Class “A” (Life sciences tools & services)		299,414		4,089
*	Wuxi Biologics Cayman, Inc. (Life sciences tools & services)		423,500		7,748
					271,187
	India—1.5%
	HDFC Bank, Ltd. (Banks)		497,394		7,025
	Ipca Laboratories, Ltd. (Pharmaceuticals)		123,136		2,727
	Pidilite Industries, Ltd. (Chemicals)		164,478		2,991
	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		669,916		15,150
*	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		51,309		544
					28,437
	Indonesia—1.0%
	PT Bank Central Asia Tbk (Banks)		9,066,500		18,073
	South Korea—0.9%
	Kakao Corporation (Interactive Media & Services)		37,761		8,398

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

International Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	South Korea—(continued)
	Samsung SDI Co., Ltd. (Electronic equipment, instruments & components)		31,119	$	9,404
					17,802
	Taiwan—3.1%
	Globalwafers Co., Ltd. (Semiconductors & semiconductor equipment)		267,000		3,647
	MediaTek, Inc. (Semiconductors & semiconductor equipment)		1,206,000		23,667
	Taiwan Semiconductor Manufacturing Co., Ltd.—ADR (Semiconductors & semiconductor equipment)		534,335		30,334
					57,648
	Thailand—1.0%
	Airports of Thailand PCL (Transportation infrastructure)		1,456,200		2,850
*	Sea, Ltd.—ADR (Entertainment)		145,050		15,555
					18,405

	Japan—12.5%
	Asahi Intecc Co., Ltd. (Health care equipment & supplies)		293,500		8,331
	Daikin Industries, Ltd. (Building products)		127,400		20,454
	Disco Corporation (Semiconductors & semiconductor equipment)		45,200		10,922
	GMO Payment Gateway, Inc. (IT services)		50,800		5,288
	Harmonic Drive Systems, Inc. (Machinery)		84,200		4,609
	Hoya Corporation (Health care equipment & supplies)		140,400		13,341
	Keyence Corporation (Electronic equipment, instruments & components)		85,900		35,824
	Meitec Corporation (Professional services)		44,800		2,153
	MISUMI Group, Inc. (Machinery)		216,000		5,389
	MonotaRO Co., Ltd. (Trading companies & distributors)		193,000		7,722
	Nihon M&A Center, Inc. (Professional services)		219,800		9,914
	Nomura Research Institute, Ltd. (IT services)		381,300		10,336
	NS Solutions Corporation (IT services)		77,700		2,119
	Omron Corporation (Electronic equipment, instruments & components)		299,300		20,013
	Persol Holdings Co., Ltd. (Professional services)		320,900		4,399
	Shimadzu Corporation (Electronic equipment, instruments & components)		211,500		5,618
	Shiseido Co., Ltd. (Personal products)		230,400		14,585
	SMC Corporation (Machinery)		52,600		26,881
	Sushiro Global Holdings, Ltd. (Hotels, restaurants & leisure)		151,400		3,327
	TechnoPro Holdings, Inc. (Professional services)		73,800		4,203
	Terumo Corporation (Health care equipment & supplies)		308,900		11,675
	TIS, Inc. (IT services)		360,200		7,586
					234,689



	Issuer	Shares		Value

	Common Stocks—(continued)

	United Kingdom—11.7%
	3i Group plc (Capital markets)		548,813	$	5,662
	Abcam plc (Biotechnology)		139,772		2,309
	Ashtead Group plc (Trading companies & distributors)		337,716		11,378
	Avast plc (Software)		939,144		6,150
	AVEVA Group plc (Software)		107,435		5,447
	Big Yellow Group plc (Equity REIT)		294,907		3,669
*	boohoo Group plc (Internet & direct marketing retail)		995,778		5,084
	Compass Group plc (Hotels, restaurants & leisure)		1,115,229		15,367
	Croda International plc (Chemicals)		111,816		7,282
	Diageo plc (Beverages)		503,297		16,723
	Experian plc (Professional services)		647,178		22,606
	Greggs plc (Hotels, restaurants & leisure)		248,553		4,989
	Halma plc (Electronic equipment, instruments & components)		532,723		15,202
	Intermediate Capital Group plc (Capital markets)		424,689		6,783
	Intertek Group plc (Professional services)		127,746		8,611
	London Stock Exchange Group plc (Capital markets)		182,519		18,902
	RELX plc (Professional services)		574,967		13,323
	Renishaw plc (Electronic equipment, instruments & components)		62,947		3,139
	Rentokil Initial plc (Commercial services & supplies)		2,116,883		13,367
	Rotork plc (Machinery)		1,494,541		5,185
	Segro plc (Equity REIT)		1,075,169		11,924
	Softcat plc (IT services)		214,869		2,902
	Spirax-Sarco Engineering plc (Machinery)		96,237		11,896
*	Trainline plc (Internet & direct marketing retail)		456,720		2,458
					220,358

	Western Hemisphere—4.5%
	Canada—4.3%
	Alimentation Couche-Tard, Inc. Class “B” (Food & staples retailing)		423,831		13,290
	Brookfield Asset Management, Inc. Class “A” (Capital markets)†		406,457		13,372
	Canadian National Railway Co. (Road & rail)		285,524		25,261
	Enghouse Systems, Ltd. (Software)		68,632		3,665
*	Kinaxis, Inc. (Software)		35,719		5,106
*	Lululemon Athletica, Inc. (Textiles, apparel & luxury goods)		57,549		17,956
	Toromont Industries, Ltd. (Trading companies & distributors)		51,968		2,579
					81,229
	United States—0.2%
	Benefit One, Inc. (Professional services)		198,600		3,982

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

International Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Asia—3.8%
	Australia—2.2%
	Aristocrat Leisure, Ltd. (Hotels, restaurants & leisure)		570,336	$	10,036
*	Atlassian Corporation plc Class “A” (Software)†		66,556		11,998
	CSL, Ltd. (Biotechnology)		65,439		12,961
	Goodman Group (Equity REIT)		675,829		6,926
					41,921
	Hong Kong—1.6%
	AIA Group, Ltd. (Insurance)		3,095,800		28,879

	Emerging Latin America—2.1%
	Argentina—0.8%
*	Globant S.A. (Software)†		32,168		4,820
*	MercadoLibre, Inc. (Internet & direct marketing retail)		10,336		10,189
					15,009
	Brazil—1.2%
	B3 S.A.—Brasil Bolsa Balcao (Capital markets)		894,100		9,058
	Lojas Renner S.A. (Multiline retail)		289,000		2,221
	Magazine Luiza S.A. (Multiline retail)		497,500		6,555
	Notre Dame Intermedica Participacoes S.A. (Health care providers & services)		380,300		4,756
					22,590
	Mexico—0.1%
*	Grupo Aeroportuario del Sureste S.A.B. de C.V.—ADR (Transportation infrastructure)		26,655		2,993

	Emerging Europe—0.5%
	Russia—0.5%
*	Yandex N.V. Class “A” (Interactive Media & Services)†		189,126		9,460
	Total Common Stocks—99.7% (cost $1,357,985)				1,875,441


	Principal
Issuer	Amount		Value

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $7,359, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $7,507	$	7,359	$	7,359
Total Repurchase Agreement—0.4% (cost $7,359)				7,359
Total Investments—100.1% (cost $1,365,344)				1,882,800
Liabilities, plus cash and other assets—(0.1)%				(1,592	)
Net assets—100.0%			$	1,881,208

ADR = American Depository Receipt

REIT = Real Estate Investment Trust

* = Non-income producing security

† = U.S. listed foreign security

At June 30, 2020, the Fund’s Portfolio of Investments includes the following industry categories (as a percentage of long-term investments):

Information Technology	26.5	%
Industrials	22.6	%
Consumer Discretionary	13.2	%
Health Care	11.8	%
Financials	8.1	%
Consumer Staples	5.5	%
Communication Services	5.4	%
Materials	2.3	%
Real Estate	2.2	%
Energy	1.7	%
Utilities	0.7	%
Total	100.0	%

At June 30, 2020, the Fund’s Portfolio of Investments includes the following currency categories (as a percentage of long-term investments):

Euro	24.5	%
Japanese Yen	12.7	%
British Pound Sterling	11.7	%
Hong Kong Dollar	10.0	%
U.S. Dollar	9.8	%
Swiss Franc	6.2	%
Danish Krone	5.4	%
Swedish Krona	4.8	%
Chinese Yuan Renminbi	3.3	%
Canadian Dollar	2.7	%
New Taiwan Dollar	2.0	%
Australian Dollar	1.6	%
Indian Rupee	1.5	%
Brazilian Real	1.2	%
All Other Currencies	2.6	%
Total	100.0	%

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	Institutional International Growth Fund

	The Institutional International Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Simon Fennell Kenneth J. McAtamney	The William Blair Institutional International Growth Fund posted a 0.69% increase, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the MSCI All Country World ex-U.S. IMI (net) (the “Index”), decreased 11.24%. Six-month outperformance versus the Index was primarily driven by positive stock selection across most sectors. The Information Technology, Communication Services and Industrials sectors were the most notable sources of relative return. Within Information Technology, Adyen enhanced relative returns as the company posted second quarter results that reassured investors during a time of high uncertainty given the global COVID-19 pandemic. An innovative global payment service provider with a focus on large merchant online payments, we believe that Adyen is well positioned to benefit from an accelerated shift to online payments due to its best-in-class technology and product differentiation. Sea Ltd, a South East Asian mobile gaming and e-commerce company within Communication Services, was an additional source of outperformance. SEA primarily operates in seven South East Asian markets, including Indonesia, Malaysia, the Philippines, Singapore, Thailand, Taiwan and Vietnam. More recently, it has expanded its gaming operations to include India, Russia and Latin America. The company is the market leader in both gaming revenues and e-commerce, and current game success and a robust pipeline are driving higher revenue growth and profitability expectations, while e-commerce operating metrics continue to be strong. Within the Industrials sector, SMC Corp and Atlas Copco aided relative performance as the rebound in investor sentiment help propel high quality companies in cyclical sectors higher. Partially offsetting these effects was an overweight allocation to the U.K., an underweight allocation to Communication Services, and an overweight to the Industrials sector. Additionally, companies with exposure to travel-related activities underperformed as activity remained depressed, including Airbus, Safran, MTU Aero, and Amadeus. Please refer to the Global Markets Review and Outlook relating to the Fund beginning on page 31.

June 30, 2020

William Blair Funds

Institutional International Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year
Institutional International Growth Fund		0.69	%		10.26	%		7.11	%		5.30	%		7.90	%
MSCI ACW Ex-U.S. IMI (net)		(11.24	)		(4.74	)		0.96			2.30			5.11

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Investing in smaller and medium capitalization companies involves special risks, including higher volatility and lower liquidity. Smaller and medium capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. International investing involves special risk considerations, including currency fluctuations, lower liquidity, economic and political risk. Shares of the Fund are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

Institutional International Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks

	Europe, Mid-East—42.7%
	Belgium—0.3%
	Melexis N.V. (Semiconductors & semiconductor equipment)		25,680	$	1,947
	Warehouses De Pauw CVA (Equity REIT)		113,128		3,089
					5,036
	Denmark—5.3%
	Chr Hansen Holding A/S (Chemicals)		63,616		6,561
	Coloplast A/S Class “B” (Health care equipment & supplies)		55,421		8,590
	DSV PANALPINA A/S (Air freight & logistics)		185,931		22,701
*	Genmab A/S (Biotechnology)		34,997		11,714
*	Netcompany Group A/S (Software)		48,568		3,186
	Novo Nordisk A/S Class “B” (Pharmaceuticals)		237,947		15,405
	Orsted A/S (Electric utilities)		80,017		9,234
*	Royal Unibrew A/S (Beverages)		36,807		3,062
	Tryg A/S (Insurance)		69,827		2,021
					82,474
	Faroe Islands—0.1%
*	Bakkafrost P/F (Food products)		33,810		2,127
	Finland—0.9%
	Neste Oyj (Oil, gas & consumable fuels)		334,199		13,070
	France—9.8%
*	Airbus SE (Aerospace & defense)		248,115		17,707
	Capgemini SE (IT services)		118,077		13,525
	Dassault Systemes SE (Software)		73,177		12,628
	Hermes International (Textiles, apparel & luxury goods)		7,646		6,389
	Kering S.A. (Textiles, apparel & luxury goods)		22,825		12,418
*	L’Oreal S.A. (Personal products)		51,186		16,430
	LVMH Moet Hennessy Louis Vuitton SE (Textiles, apparel & luxury goods)		47,107		20,667
	Orpea (Health care providers & services)		33,108		3,828
	Rubis SCA (Gas utilities)		45,688		2,196
*	Safran S.A. (Aerospace & defense)		179,322		17,975
	Sartorius Stedim Biotech (Life sciences tools & services)		21,440		5,420
	Teleperformance (Professional services)		44,981		11,416
*	Worldline S.A. (IT services)		129,565		11,220
					151,819
	Germany—5.8%
*	Carl Zeiss Meditec AG (Health care equipment & supplies)		35,294		3,442
*	HelloFresh SE (Internet & direct marketing retail)		46,529		2,478
	Infineon Technologies AG (Semiconductors & semiconductor equipment)		769,624		18,050
	KION Group AG (Machinery)		72,542		4,466
*	MTU Aero Engines AG (Aerospace & defense)		98,454		17,051
*	Puma SE (Textiles, apparel & luxury goods)		107,664		8,324



	Issuer	Shares		Value

	Common Stocks—(continued)

	Europe, Mid-East—(continued)
	Germany—(continued)
	SAP SE (Software)		114,843	$	16,041
*	TeamViewer AG (Software)		151,847		8,291
	Vonovia SE (Real estate management & development)		176,350		10,814
					88,957
	Ireland—2.0%
*	ICON plc (Life sciences tools & services)†		61,771		10,406
	Kerry Group plc Class “A” (Food products)		70,771		8,770
	Kingspan Group plc (Building products)		167,933		10,820
					29,996
	Israel—0.7%
*	CyberArk Software, Ltd. (Software)†		32,840		3,260
*	Wix.com, Ltd. (IT services)†		30,809		7,894
					11,154
	Italy—0.5%
*	Amplifon SpA (Health care providers & services)		119,206		3,175
*	Brunello Cucinelli SpA (Textiles, apparel & luxury goods)		70,087		2,082
*	Moncler SpA (Textiles, apparel & luxury goods)		63,876		2,443
					7,700
	Luxembourg—0.4%
*	Eurofins Scientific SE (Life sciences tools & services)		9,275		5,821
	Netherlands—3.7%
*	Adyen N.V. (IT services)		11,927		17,360
	ASML Holding N.V. (Semiconductors & semiconductor equipment)		82,576		30,328
	BE Semiconductor Industries N.V. (Semiconductors & semiconductor equipment)		72,183		3,216
	Euronext N.V. (Capital markets)		37,263		3,736
	IMCD N.V. (Trading companies & distributors)		32,148		3,022
					57,662
	Norway—0.4%
	TOMRA Systems ASA (Commercial services & supplies)		168,445		6,179
	Spain—1.0%
	Amadeus IT Group S.A. (IT services)		289,611		15,091
	Sweden—4.8%
*	AAK AB (Food products)		106,327		1,827
	Atlas Copco AB Class “A” (Machinery)		618,246		26,181
	Evolution Gaming Group AB (Hotels, restaurants & leisure)		148,708		8,867
	Fabege AB (Real estate management & development)		191,322		2,236
*	Hexagon AB Class “B” (Electronic equipment, instruments & components)		301,564		17,605

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Institutional International Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Europe, Mid-East—(continued)
	Sweden—(continued)
*	Indutrade AB (Trading companies & distributors)		111,968	$	4,422
	Lifco AB Class “B” (Industrial conglomerates)		52,359		3,315
*	Nibe Industrier AB Class “B” (Building products)		206,599		4,565
*	Nolato AB Class “B” (Industrial conglomerates)		46,308		3,121
*	Vitrolife AB (Biotechnology)		85,827		1,920
					74,059
	Switzerland—7.0%
	Belimo Holding AG (Building products)		441		3,244
	Logitech International S.A. (Technology hardware, storage & peripherals)		112,381		7,337
	Lonza Group AG (Life sciences tools & services)		38,665		20,413
	Partners Group Holding AG (Capital markets)		14,730		13,361
*	SIG Combibloc Group AG (Containers & packaging)		153,573		2,485
	Sika AG (Chemicals)		95,954		18,468
*	Softwareone Holding AG (Electronic equipment, instruments & components)		129,748		3,205
	STMicroelectronics N.V. (Semiconductors & semiconductor equipment)		452,002		12,300
	Straumann Holding AG (Health care equipment & supplies)		12,026		10,332
	Tecan Group AG (Life sciences tools & services)		12,056		4,270
	Temenos AG (Software)		57,642		8,952
	VAT Group AG (Machinery)		22,222		4,058
					108,425

	Emerging Asia—22.4%
	China—14.9%
	A-Living Services Co., Ltd. Class “H” (Commercial services & supplies)		607,750		3,062
	Aier Eye Hospital Group Co., Ltd. Class “A” (Health care providers & services)		985,230		6,051
	AK Medical Holdings, Ltd. (Health care equipment & supplies)		706,000		2,245
*	Alibaba Group Holding, Ltd. (Internet & direct marketing retail)		1,202,500		32,520
	Centre Testing International Group Co., Ltd. Class “A” (Professional services)		2,198,900		6,142
	Country Garden Services Holdings Co., Ltd. (Commercial services & supplies)		1,423,000		6,610
	Foshan Haitian Flavouring & Food Co., Ltd. Class “A” (Food products)		321,940		5,661
	Hangzhou Tigermed Consulting Co., Ltd. Class “A” (Life sciences tools & services)		479,700		6,909
	Kweichow Moutai Co., Ltd. Class “A” (Beverages)		51,217		10,591



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	China—(continued)
	Li Ning Co., Ltd. (Textiles, apparel & luxury goods)		2,477,500	$	7,864
*	Meituan Dianping Class “B” (Internet & direct marketing retail)		409,100		9,073
	NAURA Technology Group Co., Ltd. Class “A” (Electronic equipment, instruments & components)		173,400		4,189
	NetEase, Inc.—ADR (Entertainment)		32,542		13,973
	Offcn Education Technology Co., Ltd. Class “A” (Diversified consumer services)		924,100		3,625
	Ping An Insurance Group Co. of China, Ltd. Class “H” (Insurance)		1,704,500		17,044
	Shenzhen Mindray Bio-Medical Electronics Co., Ltd. Class “A” (Health care equipment & supplies)		97,100		4,196
	Shenzhou International Group Holdings, Ltd. (Textiles, apparel & luxury goods)		384,400		4,632
	Silergy Corporation (Semiconductors & semiconductor equipment)		128,000		8,330
*	TAL Education Group—ADR (Diversified consumer services)		255,772		17,490
	Tencent Holdings, Ltd. (Interactive Media & Services)		607,100		39,056
*	Tencent Music Entertainment Group—ADR (Entertainment)		173,096		2,330
*	Topchoice Medical Corporation Class “A” (Health care providers & services)		199,400		4,701
	Vitasoy International Holdings, Ltd. (Food products)		392,000		1,500
	Will Semiconductor, Ltd. Class “A” (Semiconductors & semiconductor equipment)		80,670		2,303
	WuXi AppTec Co., Ltd. Class “A” (Life sciences tools & services)		283,864		3,876
*	Wuxi Biologics Cayman, Inc. (Life sciences tools & services)		348,000		6,367
					230,340
	India—1.5%
	HDFC Bank, Ltd. (Banks)		408,661		5,772
	Ipca Laboratories, Ltd. (Pharmaceuticals)		101,169		2,241
	Pidilite Industries, Ltd. (Chemicals)		135,136		2,457
*	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		39,923		423
	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		550,406		12,447
					23,340
	Indonesia—1.0%
	PT Bank Central Asia Tbk (Banks)		7,449,006		14,849
	South Korea—0.9%
	Kakao Corporation (Interactive Media & Services)		31,025		6,899
	Samsung SDI Co., Ltd. (Electronic equipment, instruments & components)		25,568		7,727
					14,626

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Institutional International Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	Taiwan—3.1%
	Globalwafers Co., Ltd. (Semiconductors & semiconductor equipment)		220,000	$	3,005
	MediaTek, Inc. (Semiconductors & semiconductor equipment)		991,000		19,447
	Taiwan Semiconductor Manufacturing Co., Ltd.—ADR (Semiconductors & semiconductor equipment)		439,012		24,923
					47,375
	Thailand—1.0%
	Airports of Thailand PCL (Transportation infrastructure)		1,196,500		2,342
*	Sea, Ltd.—ADR (Entertainment)		119,174		12,780
					15,122

	Japan—12.5%
	Asahi Intecc Co., Ltd. (Health care equipment & supplies)		241,200		6,847
	Daikin Industries, Ltd. (Building products)		104,700		16,809
	Disco Corporation (Semiconductors & semiconductor equipment)		37,100		8,964
	GMO Payment Gateway, Inc. (IT services)		41,700		4,341
	Harmonic Drive Systems, Inc. (Machinery)		69,200		3,788
	Hoya Corporation (Health care equipment & supplies)		115,400		10,965
	Keyence Corporation (Electronic equipment, instruments & components)		70,600		29,443
	Meitec Corporation (Professional services)		36,800		1,769
	MISUMI Group, Inc. (Machinery)		177,500		4,429
	MonotaRO Co., Ltd. (Trading companies & distributors)		158,600		6,345
	Nihon M&A Center, Inc. (Professional services)		180,600		8,146
	Nomura Research Institute, Ltd. (IT services)		313,300		8,493
	NS Solutions Corporation (IT services)		63,800		1,740
	Omron Corporation (Electronic equipment, instruments & components)		245,900		16,443
	Persol Holdings Co., Ltd. (Professional services)		263,700		3,614
	Shimadzu Corporation (Electronic equipment, instruments & components)		173,700		4,614
	Shiseido Co., Ltd. (Personal products)		189,300		11,983
	SMC Corporation (Machinery)		43,200		22,077
	Sushiro Global Holdings, Ltd. (Hotels, restaurants & leisure)		124,400		2,734
	TechnoPro Holdings, Inc. (Professional services)		60,600		3,452
	Terumo Corporation (Health care equipment & supplies)		253,800		9,592
	TIS, Inc. (IT services)		295,900		6,232
					192,820



	Issuer	Shares		Value

	Common Stocks—(continued)

	United Kingdom—11.7%
	3i Group plc (Capital markets)		450,907	$	4,652
	Abcam plc (Biotechnology)		114,837		1,897
	Ashtead Group plc (Trading companies & distributors)		277,469		9,348
	Avast plc (Software)		771,605		5,053
	AVEVA Group plc (Software)		88,269		4,476
	Big Yellow Group plc (Equity REIT)		242,297		3,014
*	boohoo Group plc (Internet & direct marketing retail)		818,136		4,177
	Compass Group plc (Hotels, restaurants & leisure)		916,277		12,625
	Croda International plc (Chemicals)		91,869		5,983
	Diageo plc (Beverages)		413,511		13,740
	Experian plc (Professional services)		531,724		18,573
	Greggs plc (Hotels, restaurants & leisure)		204,212		4,099
	Halma plc (Electronic equipment, instruments & components)		437,687		12,490
	Intermediate Capital Group plc (Capital markets)		348,926		5,573
	Intertek Group plc (Professional services)		104,956		7,075
	London Stock Exchange Group plc (Capital markets)		149,958		15,530
	RELX plc (Professional services)		472,395		10,946
	Renishaw plc (Electronic equipment, instruments & components)		51,718		2,579
	Rentokil Initial plc (Commercial services & supplies)		1,739,240		10,982
	Rotork plc (Machinery)		1,227,921		4,260
	Segro plc (Equity REIT)		883,364		9,797
	Softcat plc (IT services)		176,538		2,384
	Spirax-Sarco Engineering plc (Machinery)		79,069		9,774
*	Trainline plc (Internet & direct marketing retail)		375,243		2,020
					181,047

	Western Hemisphere—4.5%
	Canada—4.3%
	Alimentation Couche-Tard, Inc. Class “B” (Food & staples retailing)		348,222		10,919
	Brookfield Asset Management, Inc. Class “A” (Capital markets)†		333,947		10,987
	Canadian National Railway Co. (Road & rail)		234,588		20,755
	Enghouse Systems, Ltd. (Software)		56,388		3,011
*	Kinaxis, Inc. (Software)		29,347		4,195
*	Lululemon Athletica, Inc. (Textiles, apparel & luxury goods)		47,283		14,753
	Toromont Industries, Ltd. (Trading companies & distributors)		42,697		2,119
					66,739
	United States—0.2%
	Benefit One, Inc. (Professional services)		163,200		3,272

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Institutional International Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Asia—3.8%
	Australia—2.2%
	Aristocrat Leisure, Ltd. (Hotels, restaurants & leisure)		468,591	$	8,246
*	Atlassian Corporation plc Class “A” (Software)†		54,683		9,858
	CSL, Ltd. (Biotechnology)		53,765		10,649
	Goodman Group (Equity REIT)		555,264		5,690
					34,443
	Hong Kong—1.6%
	AIA Group, Ltd. (Insurance)		2,543,663		23,728

	Emerging Latin America—2.1%
	Argentina—0.8%
*	Globant S.A. (Software)†		26,429		3,961
*	MercadoLibre, Inc. (Internet & direct marketing retail)		8,492		8,371
					12,332
	Brazil—1.2%
	B3 S.A.—Brasil Bolsa Balcao (Capital markets)		734,600		7,442
	Lojas Renner S.A. (Multiline retail)		237,460		1,825
	Magazine Luiza S.A. (Multiline retail)		408,800		5,386
	Notre Dame Intermedica Participacoes S.A. (Health care providers & services)		312,500		3,908
					18,561
	Mexico—0.1%
	Grupo Aeroportuario del Sureste S.A.B. de C.V.—ADR (Transportation infrastructure)		21,900		2,459

	Emerging Europe—0.5%
	Russia—0.5%
*	Yandex N.V. Class “A” (Interactive Media & Services)†		155,387		7,772
	Total Common Stocks—100.2% (cost $1,128,494)				1,548,395


	Principal
Issuer	Amount		Value

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $4,201, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $4,285	$	4,201	$	4,201
Total Repurchase Agreement—0.3% (cost $4,201)				4,201
Total Investments—100.5% (cost $1,132,695)				1,552,596
Liabilities, plus cash and other assets—(0.5)%				(7,214	)
Net assets—100.0%			$	1,545,382

ADR = American Depository Receipt

REIT = Real Estate Investment Trust

* = Non-income producing security

† = U.S. listed foreign security

At June 30, 2020, the Fund’s Portfolio of Investments includes the following industry categories (as a percentage of long-term investments):

Information Technology	26.5	%
Industrials	22.5	%
Consumer Discretionary	13.1	%
Health Care	12.0	%
Financials	8.1	%
Consumer Staples	5.6	%
Communication Services	5.3	%
Materials	2.3	%
Real Estate	2.2	%
Energy	1.7	%
Utilities	0.7	%
Total	100.0	%

At June 30, 2020, the Fund’s Portfolio of Investments includes the following currency categories (as a percentage of long-term investments):

Euro	24.3	%
Japanese Yen	12.7	%
British Pound Sterling	11.7	%
Hong Kong Dollar	9.9	%
U.S. Dollar	9.8	%
Swiss Franc	6.2	%
Danish Krone	5.3	%
Swedish Krona	4.8	%
Chinese Yuan Renminbi	3.8	%
Canadian Dollar	2.6	%
New Taiwan Dollar	2.0	%
Australian Dollar	1.6	%
Indian Rupee	1.5	%
Brazilian Real	1.2	%
All Other Currencies	2.6	%
Total	100.0	%

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	International Small Cap Growth Fund

	The International Small Cap Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Simon Fennell Andrew G. Flynn	The William Blair International Small Cap Growth Fund (Class N shares) posted a 3.10% decrease, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the MSCI All Country World ex-U.S. Small Cap Index (net) (the “Index”), decreased 12.80%. Six month outperformance was driven by positive stock selection effects across most sectors, led by Industrials. Notable contributors within Industrials were Japanese holdings Nihon M&A Center and MonotaRO. Nihon M&A Center is a high-quality Japanese growth company that provides advisory services to small and medium-sized enterprises facing succession-oriented challenges. It is led by an entrepreneurial management team that has built an attractive network of national relationships aimed at identifying buyers and sellers and sourcing transactions. Maintenance, repair and operations company MonotaRO offers over 10 million products across 7 industrial categories using a single transparent price for each product and overnight delivery. The company leverages its extensive customer data base to predict client order trends, apply targeted promotions and manage inventory. Partially offsetting these positive effects were negative stock selection in the Consumer Staples and Healthcare sectors. Within Consumer Staples, South African holding Clicks Group underperformed. Clicks is a drugstore retailer with a leading market position and high returns business model, and a management team with a long track record of valuation creation. The stock weakened during the second quarter amid investor concerns over management’s cautious outlook and a challenging economic backdrop in South Africa. Within Healthcare, Germany-based Carl Zeiss Meditec underperformed. The company is one of the leading suppliers of surgical tools and equipment for the diagnosis and treatment of ophthalmic conditions. Its share price was negatively impacted by COVID-19 lockdowns and weak patient volumes during the period. Please refer to the Global Markets Review and Outlook relating to the Fund beginning on page 31.

June 30, 2020

William Blair Funds

International Small Cap Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020

	Year to Date			1 Year			3 Year			5 Year			10 Year
Class N		(3.10	)%		9.21	%		3.53	%		4.83	%		7.86	%
Class I		(2.93	)		9.53			3.85			5.16			8.19
Class R6		(2.85	)		9.70			3.94			5.25			8.35
MSCI ACW Ex-U.S. Small Cap Index (net)		(12.80	)		(4.34	)		(0.17	)		2.50			6.05

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Investing in smaller companies involves special risks, including higher volatility and lower liquidity. Smaller capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. International investing involves special risk considerations, including currency fluctuations, lower liquidity, economic and political risk. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Morgan Stanley Capital International (MSCI) All Country World (ACW) Ex-U.S. Small Cap Index (net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of small capitalization developed and emerging markets, excluding the United States. This index approximates the minimum possible dividend reinvestment by deducting for the highest possible withholding tax rates of those markets.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

Semiannual Report

June 30, 2020

International Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks

	Europe, Mid-East—43.4%
	Belgium—1.8%
	Melexis N.V. (Semiconductors & semiconductor equipment)		34,349	$	2,605
	Warehouses De Pauw CVA (Equity REIT)		79,098		2,159
					4,764
	Denmark—4.3%
*	Netcompany Group A/S (Software)		69,562		4,562
*	Royal Unibrew A/S (Beverages)		36,509		3,037
	SimCorp A/S (Software)		19,087		2,058
	Tryg A/S (Insurance)		52,708		1,526
					11,183
	Faroe Islands—1.2%
*	Bakkafrost P/F (Food products)		48,118		3,027
	Germany—6.4%
*	Carl Zeiss Meditec AG (Health care equipment & supplies)		37,962		3,702
*	HelloFresh SE (Internet & direct marketing retail)		71,694		3,818
	Siltronic AG (Semiconductors & semiconductor equipment)		41,451		4,228
*	TeamViewer AG (Software)		93,522		5,106
					16,854
	Israel—2.4%
*	CyberArk Software, Ltd. (Software)†		28,652		2,844
	Elbit Systems, Ltd. (Aerospace & defense)		12,070		1,652
	Strauss Group, Ltd. (Food products)		61,483		1,703
					6,199
	Italy—2.2%
*	Amplifon SpA (Health care providers & services)		99,851		2,660
*	Brunello Cucinelli SpA (Textiles, apparel & luxury goods)		38,986		1,158
*	Nexi SpA (IT services)		117,320		2,030
					5,848
	Jersey—0.7%
	Sanne Group plc (Capital markets)		230,559		1,800
	Netherlands—2.7%
	BE Semiconductor Industries N.V. (Semiconductors & semiconductor equipment)		45,672		2,035
	Euronext N.V. (Capital markets)		28,012		2,809
	IMCD N.V. (Trading companies & distributors)		23,413		2,201
					7,045
	Norway—1.3%
	TOMRA Systems ASA (Commercial services & supplies)		91,378		3,352
	Spain—0.9%
	EDP Renovaveis S.A. (Independent power & renewable electricity producers)		173,479		2,397



	Issuer	Shares		Value

	Common Stocks—(continued)

	*Europe, Mid-East—(continued)*
	Sweden—12.5%
	AddTech AB Class “B” (Trading companies & distributors)		61,642	$	2,477
	Arjo AB Class “B” (Health care equipment & supplies)		302,432		1,681
	Beijer Ref AB (Trading companies & distributors)		107,740		3,254
*	Biotage AB (Life sciences tools & services)		53,433		799
	Evolution Gaming Group AB (Hotels, restaurants & leisure)		62,784		3,743
*	Indutrade AB (Trading companies & distributors)		148,784		5,876
	Investment AB Latour Class “B” (Industrial conglomerates)		81,577		1,479
	Lifco AB Class “B” (Industrial conglomerates)		59,746		3,783
	MIPS AB (Leisure products)		84,376		2,910
*	Nolato AB Class “B” (Industrial conglomerates)		41,436		2,793
	Sweco AB Class “B” (Construction & engineering)		49,345		2,216
*	Vitrolife AB (Biotechnology)		81,153		1,815
					32,826
	Switzerland—7.0%
	Belimo Holding AG (Building products)		235		1,729
	Galenica AG (Health care providers & services)		23,093		1,653
	Kardex AG (Machinery)		15,748		2,872
*	Siegfried Holding AG (Life sciences tools & services)		2,468		1,120
*	SIG Combibloc Group AG (Containers & packaging)		97,823		1,583
*	Softwareone Holding AG (Electronic equipment, instruments & components)		149,670		3,696
	Tecan Group AG (Life sciences tools & services)		6,851		2,427
	VAT Group AG (Machinery)		18,634		3,402
					18,482

	*United Kingdom—16.4%*
	Abcam plc (Biotechnology)		113,334		1,872
	Avast plc (Software)		447,937		2,933
	AVEVA Group plc (Software)		89,882		4,557
	Beazley plc (Insurance)		545,490		2,771
	Big Yellow Group plc (Equity REIT)		143,386		1,784
*	boohoo Group plc (Internet & direct marketing retail)		881,742		4,501
	Burford Capital, Ltd. (Capital markets)		78,411		452
	Diploma plc (Trading companies & distributors)		173,078		3,850
	Hill & Smith Holdings plc (Metals & mining)		88,960		1,371
	Intermediate Capital Group plc (Capital markets)		267,978		4,280

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

International Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	*Common Stocks—(continued)*

	*United Kingdom—(continued)*
	Renishaw plc (Electronic equipment, instruments & components)		92,351	$	4,605
	Rotork plc (Machinery)		700,677		2,431
	Safestore Holdings plc (Equity REIT)		250,099		2,250
	Softcat plc (IT services)		151,908		2,052
*	Trainline plc (Internet & direct marketing retail)		417,580		2,248
	Workspace Group plc (Equity REIT)		124,535		1,008
					42,965

	*Emerging Asia—12.9%*
	Cambodia—0.7%
	NagaCorp, Ltd. (Hotels, restaurants & leisure)		1,748,000		2,023
	China—5.0%
	A-Living Services Co., Ltd. Class “H” (Commercial services & supplies)		480,750		2,422
	AK Medical Holdings, Ltd. (Health care equipment & supplies)		542,000		1,724
	Country Garden Services Holdings Co., Ltd. (Commercial services & supplies)		513,000		2,383
*	GSX Techedu, Inc.—ADR (Diversified consumer services)		34,826		2,089
	Silergy Corporation (Semiconductors & semiconductor equipment)		48,000		3,123
	Travelsky Technology, Ltd. Class “H” (IT services)		746,000		1,313
					13,054
	India—1.1%
	AU Small Finance Bank, Ltd. (Banks)		66,984		480
	Ipca Laboratories, Ltd. (Pharmaceuticals)		56,600		1,253
	Motherson Sumi Systems, Ltd. (Auto components)		956,732		1,198
					2,931
	South Korea—0.5%
	Koh Young Technology, Inc. (Semiconductors & semiconductor equipment)		15,275		1,270
	Taiwan—5.6%
	ASPEED Technology, Inc. (Semiconductors & semiconductor equipment)		36,000		1,513
	Chailease Holding Co., Ltd. (Diversified financial services)		633,085		2,682
	Feng TAY Enterprise Co., Ltd. (Textiles, apparel & luxury goods)		605,400		3,416
	Globalwafers Co., Ltd. (Semiconductors & semiconductor equipment)		270,000		3,688
	Tripod Technology Corporation (Electronic equipment, instruments & components)		322,000		1,430
	Voltronic Power Technology Corporation (Electrical equipment)		68,000		1,950
					14,679



	Issuer	Shares		Value

	*Common Stocks—(continued)*

	*Japan—12.6%*
	Asahi Intecc Co., Ltd. (Health care equipment & supplies)		47,400	$	1,345
	GMO Payment Gateway, Inc. (IT services)		21,300		2,217
	Harmonic Drive Systems, Inc. (Machinery)		70,100		3,837
	JINS Holdings, Inc. (Specialty retail)		24,000		1,456
	MonotaRO Co., Ltd. (Trading companies & distributors)		60,900		2,436
	Nihon M&A Center, Inc. (Professional services)		158,300		7,140
	Nihon Unisys, Ltd. (IT services)		126,800		3,952
	SMS Co., Ltd. (Professional services)		50,200		1,124
	Sushiro Global Holdings, Ltd. (Hotels, restaurants & leisure)		109,500		2,406
	TechnoPro Holdings, Inc. (Professional services)		52,700		3,002
	TIS, Inc. (IT services)		190,400		4,010
					32,925

	*Western Hemisphere—5.5%*
	Canada—4.4%
	Enghouse Systems, Ltd. (Software)		41,892		2,237
*	Kinaxis, Inc. (Software)		21,345		3,051
	Parkland Corporation (Oil, gas & consumable fuels)		113,168		2,810
	Toromont Industries, Ltd. (Trading companies & distributors)		68,517		3,400
					11,498
	United States—1.1%
	Benefit One, Inc. (Professional services)		151,500		3,038

	*Emerging Latin America—2.8%*
	Argentina—1.6%
*	Globant S.A. (Software)†		27,999		4,196
	Brazil—0.4%
	Arezzo Industria e Comercio S.A. (Textiles, apparel & luxury goods)		113,000		995
	Mexico—0.8%
*	Grupo Aeroportuario del Centro Norte S.A.B. de C.V. (Transportation infrastructure)		479,900		2,231

	*Emerging Europe, Mid-East, Africa—2.8%*
	Greece—0.9%
	OPAP S.A. (Hotels, restaurants & leisure)		258,029		2,448
	South Africa—0.7%
	Clicks Group, Ltd. (Food & staples retailing)		154,526		1,874
	United Arab Emirates—1.2%
*	Network International Holdings plc (IT services)		552,514		3,019

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

International Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

	Shares or
	Principal
Issuer	Amount		Value

Common Stocks—(continued)

Asia—1.4%
New Zealand—1.4%
Ryman Healthcare, Ltd. (Health care providers & services)		267,319	$	2,256
Spark New Zealand, Ltd. (Diversified telecommunication services)		447,074		1,316
				3,572
Total Common Stocks—97.8% (cost $208,186)				256,495

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $4,786, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $4,882		$4,786		4,786
Total Repurchase Agreement—1.8% (cost $4,786)				4,786
Total Investments—99.6% (cost $212,972)				261,281
Cash and other assets, less liabilities—0.4%				1,060
Net assets—100.0%			$	262,341

ADR = American Depository Receipt

REIT = Real Estate Investment Trust

* = Non-income producing security

† = U.S. listed foreign security

At June 30, 2020, the Fund’s Portfolio of Investments includes the following industry categories (as a percentage of long-term investments):

Information Technology	30.5	%
Industrials	29.8	%
Consumer Discretionary	13.4	%
Health Care	9.5	%
Financials	6.5	%
Consumer Staples	3.8	%
Real Estate	2.8	%
Materials	1.2	%
Energy	1.1	%
Utilities	0.9	%
Communication Services	0.5	%
Total	100.0	%

At June 30, 2020, the Fund’s Portfolio of Investments includes the following currency categories (as a percentage of long-term investments):

British Pound Sterling	18.6	%
Euro	15.3	%
Japanese Yen	14.0	%
Swedish Krona	12.8	%
Swiss Franc	7.2	%
New Taiwan Dollar	6.9	%
Canadian Dollar	4.5	%
Danish Krone	4.4	%
Hong Kong Dollar	3.9	%
U.S. Dollar	3.6	%
Norwegian Krone	2.5	%
New Zealand Dollar	1.4	%
Israeli Shekel	1.3	%
Indian Rupee	1.1	%
All Other Currencies	2.5	%
Total	100.0	%

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

	Emerging Markets Leaders Fund

	The Emerging Markets Leaders Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Todd M. McClone John C. Murphy	The William Blair Emerging Markets Leaders Fund (Class N shares) posted a 4.47% decrease, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the MSCI Emerging Markets Index (net) (the “Index”) decreased 9.78%. Six-month outperformance versus the Index was primarily driven by strong relative results during the second quarter. Positive stock selection effects within Communication Services, Consumer Discretionary and Information Technology were the main drivers of relative performance. Within Communication Services, NetEase, a leading developer of self-developed PC and mobile games in China, helped relative returns. The company’s operating performance remained solid amid increased online customer engagement in gaming and rapid growth in its online education business. China Tourism Group Duty Free drove the outperformance within Consumer Discretionary. The strong rally in the second quarter more than offset weakness in the first quarter, which was mainly driven by the impact of travel restrictions on duty free sales. Stock selection in Information Technology was bolstered by strong performance by Taiwan-based semiconductor company MediaTek in the second quarter. Partially offsetting these positive effects was negative stock selection within the Financials and Industrials sectors. IRB Brasil Resseguros, the dominant reinsurance company in Brazil, weighed on performance as the stock fell amid a short seller report and corporate governance issues. We decided to sell the position due to ongoing governance concerns coupled with a challenging operating backdrop and growth outlook. Capitec is a high quality South African financial company with a strong brand and expanding product offering. The stock underperformed amid concerns about the bank’s unsecure credit business and weak macroeconomic conditions. Industrials performance was hampered by COVID-19 concerns impacting travel-related holdings—Airports of Thailand and Grupo Aeroportuario del Pacifico. Bidvest, the South African diversified services company, weakened on the deteriorating macro backdrop and investor sentiment amid South Africa’s credit rating downgrade. Please refer to the Global Markets Review and Outlook relating to the Fund beginning on page 31.

Semiannual Report

June 30, 2020

Emerging Markets Leaders Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year
Class N		(4.47	)%		4.76	%		5.85	%		4.10	%		4.34	%
Class I		(4.28	)		5.08			6.15			4.41			4.63
Class R6		(4.28	)		5.13			6.19			4.48			4.73
MSCI Emerging Markets Index (net)		(9.78	)		(3.39	)		1.90			2.86			3.27

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. International investing involves special risk considerations, including currency fluctuations, lower liquidity, economic and political risk. These risks may be magnified when investing in emerging markets. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Morgan Stanley Capital International (MSCI) Emerging Markets Index (net) is a free float-adjusted market-capitalization-weighted index that is designed to measure equity market performance of emerging markets. This index approximates the minimum possible dividend reinvestment by deducting for the highest possible withholding tax rates of those markets.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

June 30, 2020

William Blair Funds

Emerging Markets Leaders Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks

	Emerging Asia—76.3%
	China—37.3%
*	Alibaba Group Holding, Ltd. (Internet & direct marketing retail)		542,428	$	14,669
	China International Travel Service Corporation, Ltd. Class “A” (Specialty retail)		356,656		7,766
	Jiangsu Hengrui Medicine Co., Ltd. Class “A” (Pharmaceuticals)		158,270		2,065
	Kweichow Moutai Co., Ltd. Class “A” (Beverages)		18,059		3,734
	Midea Group Co., Ltd. Class “A” (Household durables)		519,000		4,387
	NetEase, Inc.—ADR (Entertainment)		18,831		8,086
	Ping An Insurance Group Co. of China, Ltd. Class “H” (Insurance)		785,000		7,849
	Shenzhou International Group Holdings, Ltd. (Textiles, apparel & luxury goods)		341,200		4,112
*	TAL Education Group—ADR (Diversified consumer services)		53,341		3,647
	Tencent Holdings, Ltd. (Interactive Media & Services)		258,900		16,655
*	Tencent Music Entertainment Group—ADR (Entertainment)		361,189		4,862
	Travelsky Technology, Ltd. Class “H” (IT services)		1,393,000		2,451
	Zhangzhou Pientzehuang Pharmaceutical Co., Ltd. Class “A” (Pharmaceuticals)		125,100		3,011
					83,294
	India—14.9%
	Asian Paints, Ltd. (Chemicals)		117,098		2,616
	Bajaj Finance, Ltd. (Consumer finance)		39,055		1,463
	Britannia Industries, Ltd. (Food products)		39,256		1,874
	HDFC Bank, Ltd.—ADR (Banks)		3,809		173
	HDFC Bank, Ltd. (Banks)		313,166		4,423
	Housing Development Finance Corporation, Ltd. (Thrifts & mortgage finance)		128,735		3,003
	Infosys, Ltd. (IT services)		381,900		3,711
	Maruti Suzuki India, Ltd. (Automobiles)		23,390		1,806
	Motherson Sumi Systems, Ltd. (Auto components)		2,411,154		3,018
	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		319,030		7,215
*	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		23,562		250
	UPL, Ltd. (Chemicals)		661,156		3,737
					33,289
	Indonesia—2.8%
	PT Bank Rakyat Indonesia Persero Tbk (Banks)		11,839,800		2,511
	PT Telekomunikasi Indonesia Persero Tbk (Diversified telecommunication services)		17,284,800		3,691
					6,202
	South Korea—6.5%
	Douzone Bizon Co., Ltd. (Software)		28,937		2,454
	Kakao Corporation (Interactive Media & Services)		8,345		1,856



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	South Korea—(continued)
	LG Household & Health Care, Ltd. (Personal products)		4,603	$	5,151
	NAVER Corporation (Interactive Media & Services)		22,420		4,976
					14,437
	Taiwan—13.3%
	E.Sun Financial Holding Co., Ltd. (Banks)		2,860,648		2,696
	MediaTek, Inc. (Semiconductors & semiconductor equipment)		329,000		6,456
	Taiwan Semiconductor Manufacturing Co., Ltd.—ADR (Semiconductors & semiconductor equipment)		274,603		15,589
	Uni-President Enterprises Corporation (Food products)		2,091,000		5,053
					29,794
	Thailand—1.5%
	Airports of Thailand PCL (Transportation infrastructure)		1,764,000		3,453

	Emerging Latin America—14.1%
	Argentina—3.4%
*	Globant S.A. (Software)†		19,825		2,971
*	MercadoLibre, Inc. (Internet & direct marketing retail)		4,627		4,561
					7,532
	Brazil—7.0%
	B3 S.A.—Brasil Bolsa Balcao (Capital markets)		476,700		4,829
	Odontoprev S.A. (Health care providers & services)		652,653		1,708
	Raia Drogasil S.A. (Food & staples retailing)		86,500		1,759
*	Rumo S.A. (Road & rail)		831,500		3,439
	TOTVS S.A. (Software)		507,600		2,161
	WEG S.A. (Electrical equipment)		191,900		1,786
					15,682
	Mexico—2.5%
	Grupo Aeroportuario del Pacifico S.A.B. de C.V. Class “B” (Transportation infrastructure)		420,200		3,033
	Wal-Mart de Mexico S.A.B. de C.V. (Food & staples retailing)		1,066,700		2,551
					5,584
	Peru—1.2%
	Credicorp, Ltd. (Banks)†		19,642		2,626

	Emerging Europe, Africa—6.0%
	Russia—2.5%
*	Yandex N.V. Class “A” (Interactive Media & Services)†		112,072		5,606

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Emerging Markets Leaders Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

	Shares or
	Principal
Issuer	Amount		Value

Common Stocks—(continued)

Emerging Europe, Africa—(continued)
South Africa—3.5%
Bid Corporation, Ltd. (Food & staples retailing)		116,571	$	1,904
Bidvest Group, Ltd. (Industrial conglomerates)		234,426		1,919
Capitec Bank Holdings, Ltd. (Banks)		44,196		2,187
Clicks Group, Ltd. (Food & staples retailing)		154,827		1,877
				7,887
Total Common Stocks—96.4% (cost $171,200)				215,386

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $6,920, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $7,058	$	6,920		6,920
Total Repurchase Agreement—3.1% (cost $6,920)				6,920
Total Investments—99.5% (cost $178,120)				222,306
Cash and other assets, less liabilities—0.5%				1,161
Net assets—100.0%			$	223,467

ADR = American Depository Receipt

* = Non-income producing security

† = U.S. listed foreign security

At June 30, 2020, the Fund’s Portfolio of Investments includes the following industry categories (as a percentage of long-term investments):

Communication Services	21.2	%
Consumer Discretionary	20.6	%
Information Technology	16.6	%
Financials	14.7	%
Consumer Staples	11.1	%
Industrials	6.3	%
Energy	3.5	%
Health Care	3.1	%
Materials	2.9	%
Total	100.0	%

At June 30, 2020, the Fund’s Portfolio of Investments includes the following currency categories (as a percentage of long-term investments):

U.S. Dollar	22.3	%
Hong Kong Dollar	21.2	%
Indian Rupee	15.4	%
Chinese Yuan Renminbi	9.7	%
Brazilian Real	7.3	%
South Korean Won	6.7	%
New Taiwan Dollar	6.6	%
South African Rand	3.7	%
Indonesian Rupiah	2.9	%
Mexican Peso	2.6	%
Thai Baht	1.6	%
Total	100.0	%

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

	Emerging Markets Growth Fund

	The Emerging Markets Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Todd M. McClone Casey K. Preyss	The William Blair Emerging Markets Growth Fund (Class N shares) posted a 3.22% increase, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the MSCI Emerging Markets IMI (net) (the “Index”), decreased 10.09%. Six-month outperformance versus the Index was primarily driven by positive stock selection across most sectors. The Communication Services, Information Technology and Consumer Staples sectors were the largest sources of relative return. Within Communication Services, Sea Ltd contributed to relative returns amid significant growth in gaming and acceleration of e-commerce penetration and market share gains. MediaTek Inc, within Information Technology, was an additional source of outperformance on the back of strong operating momentum and a positive growth outlook supported by a strong product cycle and favorable competitive dynamics. Within the Consumer Staples sector, Wuliangye Yibin Co Ltd, the second-largest premium baijiu player in China, helped relative results. The company continues to deliver on our investment thesis, predicated on management’s reform efforts to increase the focus on high-end products, improve brand support and strengthen sales and channel management infrastructure. Partially offsetting these effects were the overweight allocation to Brazil and an underweight allocation to the Communication Services sector, coupled with below average stock selection within the Financials sector. Indian financials, especially non-bank financial companies, came under pressure amid increased stress in the financial system. In this context, Bajaj Finance weighed on relative results on the back of investor concerns over increased funding costs and deteriorating asset quality amid economic disruption in India. Brazilian financials also detracted from relative performance. Banco BTG Pactual, a leading investment bank and wealth/asset manager in Brazil and Latin America, weakened due to deteriorated business sentiment amid COVID-19’s disruption of the economic recovery. Please refer to the Global Markets Review and Outlook relating to the Fund beginning on page 31.

Semiannual Report

June 30, 2020

Emerging Markets Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year
Class N		3.22	%		14.00	%		7.41	%		5.30	%		5.95	%
Class I		3.33			14.36			7.69			5.58			6.23
Class R6		3.37			14.37			7.76			5.65			6.37
MSCI Emerging Markets IMI (net)		(10.09	)		(3.97	)		1.35			2.35			3.11

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. International investing involves special risk considerations, including currency fluctuations, lower liquidity, economic and political risk. These risks may be magnified when investing in emerging markets. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Morgan Stanley Capital International (MSCI) Emerging Markets Investable Market Index (IMI) (net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of emerging markets. This index approximates the minimum possible dividend reinvestment by deducting for the highest possible withholding tax rates of those markets.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

June 30, 2020

William Blair Funds

Emerging Markets Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks

	Emerging Asia—87.1%
	China—45.5%
	A-Living Services Co., Ltd. Class “H” (Commercial services & supplies)		989,500	$	4,986
	Aier Eye Hospital Group Co., Ltd. Class “A” (Health care providers & services)		633,114		3,889
*	Alibaba Group Holding, Ltd. (Internet & direct marketing retail)		2,112,032		57,117
*	Alibaba Health Information Technology, Ltd. (Health care technology)		2,044,000		5,960
	Beijing Oriental Yuhong Waterproof Technology Co., Ltd. Class “A” (Construction materials)		428,800		2,463
	Centre Testing International Group Co., Ltd. Class “A” (Professional services)		1,495,000		4,176
	Chacha Food Co., Ltd. Class “A” (Food products)		371,068		2,843
	Chengdu Hongqi Chain Co., Ltd. Class “A” (Food & staples retailing)		1,509,000		2,329
	China Education Group Holdings, Ltd. (Diversified consumer services)		1,026,000		1,649
	China Meidong Auto Holdings, Ltd. (Specialty retail)		850,000		2,084
	China Merchants Bank Co., Ltd. Class “H” (Banks)		859,500		3,953
	Chongqing Zhifei Biological Products Co., Ltd. Class “A” (Biotechnology)		222,400		3,149
	Country Garden Services Holdings Co., Ltd. (Commercial services & supplies)		1,292,000		6,001
	Double Medical Technology, Inc. Class “A” (Health care equipment & supplies)		137,400		2,317
	Foshan Haitian Flavouring & Food Co., Ltd. Class “A” (Food products)		363,844		6,398
	Gigadevice Semiconductor Beijing, Inc. Class “A” (Semiconductors & semiconductor equipment)		88,800		2,961
	Guangdong Haid Group Co., Ltd. Class “A” (Food products)		393,200		2,645
	Hangzhou Tigermed Consulting Co., Ltd. Class “A” (Life sciences tools & services)		290,466		4,183
	Hefei Meiya Optoelectronic Technology, Inc. Class “A” (Machinery)		295,200		2,195
	Hualan Biological Engineering, Inc. Class “A” (Biotechnology)		372,500		2,639
	Hundsun Technologies, Inc. Class “A” (Software)		294,604		4,485
	Jiajiayue Group Co., Ltd. Class “A” (Food & staples retailing)		429,204		2,989
	Jiangsu Hengli Hydraulic Co., Ltd. Class “A” (Machinery)		597,146		6,770
	Jiangsu Hengrui Medicine Co., Ltd. Class “A” (Pharmaceuticals)		416,806		5,438
*	Kingdee International Software Group Co., Ltd. (Software)		1,696,000		3,943
	Kweichow Moutai Co., Ltd. Class “A” (Beverages)		39,242		8,115
	Li Ning Co., Ltd. (Textiles, apparel & luxury goods)		1,220,500		3,874



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	China—(continued)
	Luxshare Precision Industry Co., Ltd. Class “A” (Electronic equipment, instruments & components)		1,379,529	$	10,014
*	Meituan Dianping Class “B” (Internet & direct marketing retail)		766,800		17,007
	NAURA Technology Group Co., Ltd. Class “A” (Electronic equipment, instruments & components)		112,600		2,720
	NetEase, Inc.—ADR (Entertainment)		36,286		15,581
	Offcn Education Technology Co., Ltd. Class “A” (Diversified consumer services)		1,326,800		5,205
*	Ping An Healthcare and Technology Co., Ltd. (Health care technology)		390,100		5,934
	Ping An Insurance Group Co. of China, Ltd. Class “H” (Insurance)		393,300		3,933
	Proya Cosmetics Co., Ltd. Class “A” (Personal products)		133,000		3,385
	Sangfor Technologies, Inc. Class “A” (Software)		82,400		2,399
	SG Micro Corporation Class “A” (Semiconductors & semiconductor equipment)		87,800		3,786
	Shandong Weigao Group Medical Polymer Co., Ltd. Class “H” (Health care equipment & supplies)		1,616,000		3,595
	Shanghai M&G Stationery, Inc. Class “A” (Commercial services & supplies)		266,800		2,059
	Shennan Circuits Co., Ltd. Class “A” (Electronic equipment, instruments & components)		109,084		2,583
	Shenzhen Mindray Bio-Medical Electronics Co., Ltd. Class “A” (Health care equipment & supplies)		153,500		6,633
	Silergy Corporation (Semiconductors & semiconductor equipment)		156,000		10,152
	Skshu Paint Co., Ltd. Class “A” (Chemicals)		181,300		2,363
	Sunny Optical Technology Group Co., Ltd. (Electronic equipment, instruments & components)		210,200		3,363
	Tencent Holdings, Ltd. (Interactive Media & Services)		914,260		58,816
*	Topchoice Medical Corporation Class “A” (Health care providers & services)		128,200		3,022
	Topsports International Holdings Ltd. (Specialty retail)		1,908,000		2,437
	Will Semiconductor, Ltd. Class “A” (Semiconductors & semiconductor equipment)		95,600		2,729
	Wuliangye Yibin Co., Ltd. Class “A” (Beverages)		359,994		8,708
	WuXi AppTec Co., Ltd. Class “H” (Life sciences tools & services)		528,600		6,868
*	Wuxi Biologics Cayman, Inc. (Life sciences tools & services)		514,500		9,413

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Emerging Markets Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	China—(continued)
	Yifeng Pharmacy Chain Co., Ltd. Class “A” (Food & staples retailing)		257,060	$	3,307
*	Yihai International Holding, Ltd. (Food products)		577,000		5,915
	Zhangzhou Pientzehuang Pharmaceutical Co., Ltd. Class “A” (Pharmaceuticals)		260,900		6,279
	Zhejiang Dingli Machinery Co., Ltd. Class “A” (Machinery)		397,860		4,261
	Zhongsheng Group Holdings, Ltd. (Specialty retail)		772,500		4,276
					376,294
	India—7.8%
	Asian Paints, Ltd. (Chemicals)		122,283		2,732
	Dabur India, Ltd. (Personal products)		335,010		2,072
	HDFC Asset Management Co., Ltd. (Capital markets)		51,536		1,695
	HDFC Bank, Ltd. (Banks)		863,409		12,195
*	HDFC Life Insurance Co. Ltd. (Insurance)		279,005		2,033
	Hindustan Unilever, Ltd. (Household products)		149,275		4,304
	Housing Development Finance Corporation, Ltd. (Thrifts & mortgage finance)		307,182		7,165
*	Indraprastha Gas, Ltd. (Gas utilities)		372,449		2,186
	Nestle India, Ltd. (Food products)		20,967		4,762
	Pidilite Industries, Ltd. (Chemicals)		118,278		2,151
	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		705,948		15,965
*	Reliance Industries, Ltd. (Oil, gas & consumable fuels)		45,229		479
	SRF, Ltd. (Chemicals)		33,590		1,605
	Tata Consultancy Services, Ltd. (IT services)		133,548		3,688
	Varun Beverages, Ltd. (Beverages)		182,654		1,645
					64,677
	Indonesia—1.0%
	PT Bank Central Asia Tbk (Banks)		4,296,900		8,565
	Malaysia—1.1%
	Hartalega Holdings Bhd (Health care equipment & supplies)		1,023,600		3,105
	Top Glove Corporation Bhd (Health care equipment & supplies)		1,674,900		6,293
					9,398
	South Korea—11.1%
	Kakao Corporation (Interactive Media & Services)		73,410		16,325
	LEENO Industrial, Inc. (Semiconductors & semiconductor equipment)		23,334		2,192
	LG Household & Health Care, Ltd. (Personal products)		6,102		6,828
	Macquarie Korea Infrastructure Fund (Capital markets)		194,940		1,847
	NAVER Corporation (Interactive Media & Services)		66,127		14,678



Issuer	Shares		Value

Common Stocks—(continued)

Emerging Asia—(continued)
South Korea—(continued)
NCSoft Corporation (Entertainment)		12,201	$	9,038
NHN KCP Corporation (IT services)		45,261		1,857
NICE Information Service Co., Ltd. (Professional services)		100,559		1,526
RFHIC Corporation (Semiconductors & semiconductor equipment)		39,928		1,205
Samsung Electronics Co., Ltd. (Technology hardware, storage & peripherals)		774,393		33,993
Seegene, Inc. (Biotechnology)		21,004		1,970
				91,459
Taiwan—19.1%
Accton Technology Corporation (Communications equipment)		470,000		3,632
Advantech Co., Ltd. (Technology hardware, storage & peripherals)		266,000		2,664
Airtac International Group (Machinery)		372,000		6,506
Alchip Technologies, Ltd. (Semiconductors & semiconductor equipment)		119,000		2,017
ASMedia Technology, Inc. (Semiconductors & semiconductor equipment)		156,000		7,587
ASPEED Technology, Inc. (Semiconductors & semiconductor equipment)		141,000		5,926
E.Sun Financial Holding Co., Ltd. (Banks)		7,884,007		7,428
Elite Material Co., Ltd. (Electronic equipment, instruments & components)		643,000		3,476
ITEQ Corporation (Electronic equipment, instruments & components)		462,000		2,310
King Yuan Electronics Co., Ltd. (Semiconductors & semiconductor equipment)		2,051,000		2,388
Lotes Co., Ltd. (Electronic equipment, instruments & components)		212,000		2,720
MediaTek, Inc. (Semiconductors & semiconductor equipment)		1,064,000		20,880
momo.com, Inc. (Internet & direct marketing retail)		81,000		1,966
Parade Technologies, Ltd. (Semiconductors & semiconductor equipment)		144,000		4,793
Powertech Technology, Inc. (Semiconductors & semiconductor equipment)		1,131,000		4,102
Poya International Co., Ltd. (Multiline retail)		100,000		1,973
Realtek Semiconductor Corporation (Semiconductors & semiconductor equipment)		303,000		3,071
Sinbon Electronics Co., Ltd. (Electronic equipment, instruments & components)		550,000		2,777
Taiwan Semiconductor Manufacturing Co., Ltd.—ADR (Semiconductors & semiconductor equipment)		674,637		38,299
Taiwan Semiconductor Manufacturing Co., Ltd. (Semiconductors & semiconductor equipment)		1,644,000		17,440

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Emerging Markets Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	Taiwan—(continued)
	Taiwan Union Technology Corporation (Electronic equipment, instruments & components)		592,000	$	2,879
	Tripod Technology Corporation (Electronic equipment, instruments & components)		510,000		2,264
	Voltronic Power Technology Corporation (Electrical equipment)		114,700		3,289
	Win Semiconductors Corporation (Semiconductors & semiconductor equipment)		402,000		4,074
	Wiwynn Corporation (Technology hardware, storage & peripherals)		129,000		3,506
					157,967
	Thailand—1.5%
*	Sea, Ltd.—ADR (Entertainment)		115,606		12,398

	Emerging Latin America—6.4%
	Argentina—2.2%
*	Globant S.A. (Software)†		29,482		4,418
*	MercadoLibre, Inc. (Internet & direct marketing retail)		13,805		13,608
					18,026
	Brazil—3.8%
*	Arco Platform, Ltd. Class “A” (Diversified consumer services)†		37,898		1,648
*	B2W Cia Digital (Internet & direct marketing retail)		142,600		2,807
	B3 S.A.—Brasil Bolsa Balcao (Capital markets)		759,300		7,692
*	Locaweb Servicos de Internet S.A. (IT services)		167,600		1,331
	Magazine Luiza S.A. (Multiline retail)		606,800		7,995
*	StoneCo, Ltd. Class “A” (IT services)†		80,067		3,103
	TOTVS S.A. (Software)		561,100		2,389
	WEG S.A. (Electrical equipment)		508,020		4,728
					31,693
	Mexico—0.4%
	Wal-Mart de Mexico S.A.B. de C.V. (Food & staples retailing)		1,483,800		3,549

	Emerging Europe, Africa—6.1%
	Greece—0.3%
	JUMBO S.A. (Specialty retail)		151,171		2,718
	Kenya—0.3%
	Safaricom plc (Wireless telecommunication services)		8,934,854		2,415
	Poland—1.4%
	CD Projekt S.A. (Entertainment)		54,808		5,471
*	Dino Polska S.A. (Food & staples retailing)		118,147		5,990
					11,461

		Shares or
		Principal
	Issuer	Amount		Value

	Common Stocks—(continued)

	Emerging Europe, Africa—(continued)
	Russia—1.6%
*	Yandex N.V. Class “A” (Interactive Media & Services)†		258,536	$	12,932
	South Africa—2.5%
	Clicks Group, Ltd. (Food & staples retailing)		230,813		2,798
	Naspers, Ltd. (Internet & direct marketing retail)		97,359		17,747
					20,545
	Total Common Stocks—99.6% (cost $594,088)				824,097

	Repurchase Agreement
	Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $5,980, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $6,099		$5,980		5,980
	Total Repurchase Agreement—0.7% (cost $5,980)				5,980
	Total Investments—100.3% (cost $600,068)				830,077
	Liabilities, plus cash and other assets—(0.3)%				(2,122	)
	Net assets—100.0%			$	827,955

ADR = American Depository Receipt

* = Non-income producing security

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Emerging Markets Growth Fund

Portfolio of Investments, June 30, 2020 (unaudited)

At June 30, 2020, the Fund’s Portfolio of Investments includes the following industry categories (as a percentage of long-term investments):

Information Technology	29.1	%
Communication Services	17.9	%
Consumer Discretionary	17.5	%
Health Care	9.8	%
Consumer Staples	9.5	%
Financials	6.9	%
Industrials	5.6	%
Energy	2.0	%
Materials	1.4	%
Utilities	0.3	%
Total	100.0	%

At June 30, 2020, the Fund’s Portfolio of Investments includes the following currency categories (as a percentage of long-term investments):

Hong Kong Dollar	25.6	%
Chinese Yuan Renminbi	16.9	%
New Taiwan Dollar	15.8	%
U.S. Dollar	12.4	%
South Korean Won	11.1	%
Indian Rupee	7.8	%
Brazilian Real	3.3	%
South African Rand	2.5	%
Polish Zloty	1.4	%
Malaysian Ringgit	1.1	%
Indonesian Rupiah	1.0	%
All Other Currencies	1.1	%
Total	100.0	%

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

	Emerging Markets Small Cap Growth Fund

	The Emerging Markets Small Cap Growth Fund seeks long-term capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Todd M. McClone Casey K. Preyss	The William Blair Emerging Markets Small Cap Growth Fund (Class N shares) posted a 1.01% increase, net of fees, for the six months ended June 30, 2020. By comparison, the Fund’s benchmark index, the MSCI Emerging Markets Small Cap Index (net) (the “Index”), decreased 12.74%. Six-month outperformance versus the Index was primarily driven by positive stock selection across most sectors. The Industrials and Information Technology sectors were the most notable sources of relative return. Within Industrials, A-Living Services Co Ltd and Country Garden Services Holdings helped relative returns over the period due to strong results in the first quarter. The property management companies’ share price acceleration in the first quarter was underpinned by robust growth in the gross floor area under management and increased revenue from value added services. Both companies benefited from heightened demand for extra services and local governments subsidies on the back of the COVID-19 outbreak. Within Information Technology, Parade Technologies Ltd, the Taiwanese fabless semiconductor company focused on high-speed video interfacing and processing, was an additional source of outperformance. The company continues to benefit from market share and content gains amid improving display technology across devices and increasing demand for faster data transmission capabilities within datacenters. Partially offsetting these effects were the overweight allocation to Brazil and an underweight allocation to South Korea, coupled with below average stock selection within the Financials sector. Within Financials, Capitec Bank Holdings Ltd and Bank BTPN Syariah Tbk (BTPS) hurt relative results. Capitec is a high quality South African financial company with strong brand, execution and expanding product offering. BTPS is a highly-profitable Shariah bank in Indonesia with a leading position in the ultra-micro segment. Both stocks were hit by investor concerns over the banks’ unsecure credit business coupled with weaker outlooks for growth and credit quality. Please refer to the Global Markets Review and Outlook relating to the Fund beginning on page 31.

Semiannual Report

June 30, 2020

Emerging Markets Small Cap Growth Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			Since Inception
Class N(a)		1.01	%		11.64	%		2.93	%		1.78	%		8.35	%
Class I(a)		1.12			11.89			3.19			2.07			8.65
MSCI Emerging Markets Small Cap Index (net)(a)		(12.74	)		(8.82	)		(2.95	)		(1.38	)		1.93
Class R6(b)		1.12			11.93			3.26			2.15			6.47
MSCI Emerging Markets Small Cap Index (net)(b)		(12.74	)		(8.82	)		(2.95	)		(1.38	)		0.59

(a)	Since inception is for the period from October 24, 2011 (Commencement of Operations) to June 30, 2020.
(b)	Since inception is for the period from December 20, 2012 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. International investing involves special risk considerations, including currency fluctuations, lower liquidity, economic and political risk. These risks may be magnified when investing in emerging markets. Smaller capitalization stocks are also more sensitive to purchase/sale transactions and changes in the issuer’s financial condition. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Morgan Stanley Capital International (MSCI) Emerging Markets Small Cap Index (net) is a free float-adjusted market capitalization index that is designed to measure the equity market performance of emerging markets. This index approximates the minimum possible dividend reinvestment by deducting for the highest possible withholding tax rates of those markets.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total long-term securities.

June 30, 2020

William Blair Funds

Emerging Markets Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks

	Emerging Asia—79.8%
	Cambodia—0.8%
	NagaCorp, Ltd. (Hotels, restaurants & leisure)		1,922,000	$	2,224
	China—31.8%
	A-Living Services Co., Ltd. Class “H” (Commercial services & supplies)		685,000		3,451
	Airtac International Group (Machinery)		337,000		5,894
	AK Medical Holdings, Ltd. (Health care equipment & supplies)		342,000		1,088
*	Aoyuan Healthy Life Group Co., Ltd. (Real estate management & development)		1,200,000		1,228
	Centre Testing International Group Co., Ltd.Class “A” (Professional services)		1,473,305		4,115
	Chacha Food Co., Ltd. Class “A” (Food products)		129,573		993
	Changzhou Xingyu Automotive Lighting Systems Co., Ltd. Class “A” (Auto components)		99,147		1,780
	Chengdu Hongqi Chain Co., Ltd. Class “A” (Food & staples retailing)		716,380		1,106
	China Feihe, Ltd. (Food products)		366,000		733
	China Lesso Group Holdings, Ltd. (Building products)		1,188,000		1,545
	China Meidong Auto Holdings, Ltd. (Specialty retail)		768,000		1,883
	China Overseas Property Holdings, Ltd. (Real estate management & development)		595,000		629
	Country Garden Services Holdings Co., Ltd. (Commercial services & supplies)		748,000		3,474
	Double Medical Technology, Inc. Class “A” (Health care equipment & supplies)		88,700		1,496
	Ever Sunshine Lifestyle Services Group, Ltd. (Commercial services & supplies)		2,056,000		3,178
	Hangzhou Tigermed Consulting Co., Ltd. Class “A” (Life sciences tools & services)		219,317		3,159
	Hefei Meiya Optoelectronic Technology, Inc. Class “A” (Machinery)		193,295		1,437
	Jiajiayue Group Co., Ltd. Class “A” (Food & staples retailing)		360,352		2,509
	Jiangsu Hengli Hydraulic Co., Ltd. Class “A” (Machinery)		365,009		4,138
	Jonjee Hi-Tech Industrial and Commercial Holding Co., Ltd. Class “A” (Food products)		349,591		2,892
*	Kingdee International Software Group Co., Ltd. (Software)		1,364,000		3,171
*	Kingsoft Cloud Holdings, Ltd.—ADR (IT services)		49,398		1,557
*	KWG Group Holdings, Ltd. (Real estate management & development)		1,667,500		2,801
	Offcn Education Technology Co., Ltd. Class “A” (Diversified consumer services)		384,000		1,506
	Ovctek China, Inc. Class “A” (Health care equipment & supplies)		156,977		1,539
*	Ping An Healthcare and Technology Co., Ltd. (Health care technology)		182,300		2,773



	Issuer	Shares		Value

	*Common Stocks—(continued)*

	*Emerging Asia—(continued)*
	China—(continued)
	Poly Property Development Co., Ltd. Class “H” (Real estate management & development)		112,200	$	1,129
	Proya Cosmetics Co., Ltd. Class “A” (Personal products)		129,124		3,286
	Shandong Weigao Group Medical Polymer Co., Ltd. Class “H” (Health care equipment & supplies)		900,000		2,002
	Shanghai M&G Stationery, Inc. Class “A” (Commercial services & supplies)		64,219		496
	Silergy Corporation (Semiconductors & semiconductor equipment)		81,000		5,271
*	Topchoice Medical Corporation Class “A” (Health care providers & services)		97,000		2,287
	Topsports International Holdings, Ltd. (Specialty retail)		551,000		704
	Yifeng Pharmacy Chain Co., Ltd. Class “A” (Food & staples retailing)		61,000		785
*	Yihai International Holding, Ltd. (Food products)		224,000		2,296
	Zhejiang Dingli Machinery Co., Ltd. Class “A” (Machinery)		281,471		3,015
	Zhongsheng Group Holdings, Ltd. (Specialty retail)		277,500		1,536
					82,882
	India—13.3%
	Aarti Industries, Ltd. (Chemicals)		151,187		1,874
	Apollo Hospitals Enterprise, Ltd. (Health care providers & services)		33,462		600
*	Arti Surfactants, Ltd. (Chemicals)**		13,896		2
	Astral Poly Technik, Ltd. (Building products)		166,404		2,116
	Balkrishna Industries, Ltd. (Auto components)		88,412		1,485
	Bandhan Bank, Ltd. (Banks)		632,154		2,685
	Bata India, Ltd. (Textiles, apparel & luxury goods)		30,783		532
	Berger Paints India, Ltd. (Chemicals)		308,007		2,015
	Divi’s Laboratories, Ltd. (Life sciences tools & services)		35,960		1,084
	Dr. Lal PathLabs, Ltd. (Health care providers & services)		30,406		630
*	Godrej Properties, Ltd. (Real estate management & development)		99,018		1,131
	HDFC Asset Management Co., Ltd. (Capital markets)		32,601		1,072
*	Indraprastha Gas, Ltd. (Gas utilities)		302,991		1,779
	Info Edge India, Ltd. (Interactive Media & Services)		29,824		1,090
	Ipca Laboratories, Ltd. (Pharmaceuticals)		86,394		1,913
	PI Industries, Ltd. (Chemicals)		125,023		2,492
	Pidilite Industries, Ltd. (Chemicals)		34,632		630
	Relaxo Footwears, Ltd. (Textiles, apparel & luxury goods)		134,039		1,122

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Emerging Markets Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	India—(continued)
	SRF, Ltd. (Chemicals)		62,721	$	2,996
	Tata Consumer Products, Ltd. (Food products)		313,530		1,611
	The Phoenix Mills, Ltd. (Real estate management & development)		108,942		839
	Titan Co., Ltd. (Textiles, apparel & luxury goods)		21,050		265
	Torrent Pharmaceuticals, Ltd. (Pharmaceuticals)		24,874		781
	Trent, Ltd. (Multiline retail)		143,853		1,185
	Varun Beverages, Ltd. (Beverages)		289,565		2,608
					34,537
	Indonesia—1.9%
	PT Bank Tabungan Pensiunan Nasional Syariah Tbk (Banks)		8,848,800		1,970
	PT Jasa Marga Persero Tbk (Transportation infrastructure)		4,684,700		1,443
	PT Pakuwon Jati Tbk (Real estate management & development)		55,403,000		1,613
					5,026
	Malaysia—0.9%
	Hartalega Holdings Bhd (Health care equipment & supplies)		238,500		724
	Top Glove Corporation Bhd (Health care equipment & supplies)		437,400		1,643
					2,367
	Philippines—1.2%
	Bloomberry Resorts Corporation (Hotels, restaurants & leisure)		8,344,600		1,244
	Wilcon Depot, Inc. (Specialty retail)		6,127,300		1,904
					3,148
	South Korea—8.6%
	Douzone Bizon Co., Ltd. (Software)		67,330		5,710
	Hite Jinro Co., Ltd. (Beverages)		51,064		1,859
	JYP Entertainment Corporation (Entertainment)		39,867		703
	Koh Young Technology, Inc. (Semiconductors & semiconductor equipment)		49,448		4,111
	LEENO Industrial, Inc. (Semiconductors & semiconductor equipment)		20,305		1,908
	NHN KCP Corporation (IT services)		40,902		1,678
	NICE Information Service Co., Ltd. (Professional services)		109,595		1,663
	RFHIC Corporation (Semiconductors & semiconductor equipment)		35,035		1,057
	Seegene, Inc. (Biotechnology)		14,666		1,375
*	WONIK IPS Co., Ltd. (Semiconductors & semiconductor equipment)		80,941		2,399
					22,463



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Asia—(continued)
	Taiwan—19.2%
	Accton Technology Corporation (Communications equipment)		251,000	$	1,940
	Alchip Technologies, Ltd. (Semiconductors & semiconductor equipment)		80,000		1,356
	ASMedia Technology, Inc. (Semiconductors & semiconductor equipment)		43,000		2,091
	ASPEED Technology, Inc. (Semiconductors & semiconductor equipment)		69,000		2,900
	Elite Material Co., Ltd. (Electronic equipment, instruments & components)		413,000		2,233
	Globalwafers Co., Ltd. (Semiconductors & semiconductor equipment)		30,000		410
	Hiwin Technologies Corporation (Machinery)		355,000		3,531
	ITEQ Corporation (Electronic equipment, instruments & components)		515,000		2,575
	Lotes Co., Ltd. (Electronic equipment, instruments & components)		219,000		2,809
	momo.com, Inc. (Internet & direct marketing retail)		38,000		922
	Parade Technologies, Ltd. (Semiconductors & semiconductor equipment)		129,000		4,294
	Powertech Technology, Inc. (Semiconductors & semiconductor equipment)		783,000		2,840
	Poya International Co., Ltd. (Multiline retail)		111,000		2,190
	Realtek Semiconductor Corporation (Semiconductors & semiconductor equipment)		242,000		2,452
	RichWave Technology Corporation (Semiconductors & semiconductor equipment)		168,000		1,073
	Sinbon Electronics Co., Ltd. (Electronic equipment, instruments & components)		886,000		4,474
	Sporton International, Inc. (Professional services)		318,000		2,587
	Taiwan Union Technology Corporation (Electronic equipment, instruments & components)		635,000		3,088
	Tripod Technology Corporation (Electronic equipment, instruments & components)		67,000		297
	Voltronic Power Technology Corporation (Electrical equipment)		116,100		3,329
	Wiwynn Corporation (Technology hardware, storage & peripherals)		96,000		2,610
					50,001
	Thailand—1.3%
	Carabao Group PCL Class “F” (Beverages)		542,000		1,824
	Com7 PCL Class “F” (Specialty retail)		1,609,000		1,470
					3,294
	Vietnam—0.8%
*	Hoa Phat Group JSC (Metals & mining)		1,805,930		2,086

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Emerging Markets Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)



	Issuer	Shares		Value

	Common Stocks—(continued)

	Emerging Latin America—12.3%
	Argentina—1.2%
*	Globant S.A. (Software)†		21,393	$	3,206
	Brazil—10.4%
*	Arco Platform, Ltd. Class “A” (Diversified consumer services)†		44,076		1,916
*	B2W Cia Digital (Internet & direct marketing retail)		175,200		3,449
	Banco BTG Pactual S.A. (Capital markets)		218,300		3,071
	Construtora Tenda S.A. (Household durables)		388,900		2,218
	Cyrela Brazil Realty S.A. Empreendimentos e Participacoes (Household durables)		544,700		2,289
	Ez Tec Empreendimentos e Participacoes S.A. (Household durables)		115,200		845
*	Grupo SBF S.A. (Specialty retail)		512,092		3,080
	Hapvida Participacoes e Investimentos S.A. (Health care providers & services)		92,700		1,060
*	Locaweb Servicos de Internet S.A. (IT services)		330,900		2,629
	Tegma Gestao Logistica S.A. (Road & rail)		512,700		2,195
	TOTVS S.A. (Software)		1,057,900		4,503
					27,255
	Mexico—0.7%
*	Grupo Aeroportuario del Centro Norte S.A.B. de C.V. (Transportation infrastructure)		372,500		1,731

	Emerging Europe, Africa—6.2%
	Greece—1.9%
	JUMBO S.A. (Specialty retail)		99,031		1,780
	OPAP S.A. (Hotels, restaurants & leisure)		195,530		1,855
	Terna Energy S.A. (Independent power & renewable electricity producers)		114,274		1,234
					4,869
	Kenya—0.6%
	Safaricom plc (Wireless telecommunication services)		5,828,700		1,575
	Poland—2.5%
	CD Projekt S.A. (Entertainment)		12,344		1,232
*	Dino Polska S.A. (Food & staples retailing)		103,373		5,242
					6,474
	Russia—0.4%
	HeadHunter Group plc—ADR (Professional services)		41,301		966
	South Africa—0.8%
	Clicks Group, Ltd. (Food & staples retailing)		86,957		1,054
	Transaction Capital, Ltd. (Consumer finance)		1,010,447		1,083
					2,137

	Shares or
	Principal
Issuer	Amount		Value

Common Stocks—(continued)
Total Common Stocks—98.3% (cost $200,924)			$	256,241

Preferred Stock
Brazil—0.7%
Randon S.A. Implementos e Participacoes (Machinery)		943,250		1,667
Total Preferred Stock—0.7% (cost $1,942)				1,667

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $1,789, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $1,825	$	1,789		1,789
Total Repurchase Agreement—0.7% (cost $1,789)				1,789
Total Investments—99.7% (cost $204,655)				259,697
Cash and other assets, less liabilities—0.3%				871
Net assets—100.0%			$	260,568

ADR = American Depository Receipt

* = Non-income producing security

** = Fair valued pursuant to Valuation Procedures approved by the Board of Trustees. This holding represents 0.00% of the Fund’s net assets at June 30, 2020.

† = U.S. listed foreign security

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Emerging Markets Small Cap Growth Fund

Portfolio of Investments, June 30, 2020 (unaudited)

At June 30, 2020, the Fund’s Portfolio of Investments includes the following industry categories (as a percentage of long-term investments):

Information Technology	28.8	%
Industrials	20.2	%
Consumer Discretionary	15.3	%
Consumer Staples	11.2	%
Health Care	9.4	%
Materials	4.7	%
Financials	3.8	%
Real Estate	3.6	%
Communication Services	1.8	%
Utilities	1.2	%
Total	100.0	%

At June 30, 2020, the Fund’s Portfolio of Investments includes the following currency categories (as a percentage of long-term investments):

New Taiwan Dollar	23.7	%
Chinese Yuan Renminbi	14.2	%
Hong Kong Dollar	13.9	%
Indian Rupee	13.4	%
Brazilian Real	10.5	%
South Korean Won	8.7	%
U.S. Dollar	3.0	%
Polish Zloty	2.5	%
Indonesian Rupiah	1.9	%
Euro	1.9	%
Thai Baht	1.3	%
Philippine Peso	1.2	%
All Other Currencies	3.8	%
Total	100.0	%

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Fixed Income Market Review and Outlook

The Bloomberg Barclays U.S. Aggregate Index returned +2.90% during the second quarter of 2020 and +6.14% for the year-to-date period ending June 30, 2020. It has been a favorable environment for treasuries and higher quality credit, especially longer duration profiles. Interest rates declined, with the majority of the move happening in the first quarter of 2020 as the Federal Reserve (Fed) responded to the COVID-19 pandemic and subsequent lockdowns. Year-to-date, the 10 Year U.S. Treasury note and 30 Year U.S. Treasury bond’s yields declined by roughly 1.26% and 0.98%, respectively. Corporate credit spreads widened 1.79% in first quarter 2020 as economic activity slowed due to the COVID-19 pandemic. As fiscal and monetary stimulus was injected into the economy in late March/early April of 2020, corporate credit spreads tightened 1.22%, ending the second quarter of 2020 at +1.50%, wider for the year by 0.57%.

Due to COVID-19 pandemic, the Federal Open Market Committee (FOMC) made an emergency cut of 0.50% to the Fed Funds rate on March 3, 2020. This was followed by another cut on Sunday March 15, 2020. The target rate is now 0-0.25%. The curve experienced a parallel shift downward as the Fed hit the ZLB (Zero Lower Bound). The 3-month T-bill was briefly negative intra-month in March. In addition to rate cuts, in March 2020, the Fed also boosted funding markets by creating the Commercial Paper Funding Facility (CPFF), which was designed to support the flow of liquidity within commercial paper market, and the Money Market Liquidity Facility (MMLF), which was re-launched to assist in meeting the demands for possible redemptions. Finally, the Fed also focused on stabilizing credit markets, and in late March 2020, announced the Primary & Secondary Market Corporate Credit Facility (PMCFF & SMCCF), which were new facilities created to support highly rated US corporate bonds, and the Term Asset-Backed Loan Facility (TALF), which was created to support flow of credit to US consumers.

The Fed also expanded their balance sheet ~63% year-to-date through open market purchases, targeting U.S. Treasury bills & notes as well as Agency Mortgage-Backed Securities. All told, we believe that these actions coupled with rate cuts and targeted lending programs by the Fed helped stabilize markets, which led to the significant tightening of spread sectors in the second quarter of 2020.

U.S. Treasury Inflation-Protected Securities (TIPS) performed in-line with the overall Aggregate index year-to-date (+6.01%) and outperformed in the second quarter (+4.24%). Market-implied break-even inflation rates dropped materially year-to-date, moving from 1.78% to 1.34%, using the U.S. 10 year break-even levels. That being said, in March of 2020 break-evens reached 0.55%, their lowest levels in the last five years.

Agency mortgage-backed securities (+3.50%) underperformed the Aggregate Index year-to-date. Per the index, the best-performing segments of the market for the quarter were higher-coupon 30-year pools (coupons of 5.5% and higher) and the lowest coupon pools (coupons of 3.0%) that were supported as part of the Fed’s MBS purchasing program. Many lower-coupon pools (3.5–4.5%) experienced higher prepayment activity in light of the decline in interest rates during the year.

Corporate bonds of all tenors, credit qualities, and sectors underperformed similar-maturity Treasury instruments during the year. Higher quality Investment Grade bonds (AAA-A) outperformed lower rated corporate bonds (BBB’s). Longer maturity corporate bonds outperformed shorter maturity corporate bonds. BB- and B-rated high yield corporate bonds underperformed investment-grade corporate bonds as the Bloomberg Barclays US Corporate High Yield Bond Index returned -3.8% year-to-date.

U.S. economic growth projections at the end of June 2020 were negative, but have rebounded from dire projections seen at the end of first quarter 2020. We believe that inflationary pressures are benign, and inflation projections are below the FOMC’s longer-term objective of 2.0%-2.5%.

We believe that the FOMC will be very patient in moving away from the ZLB, with Chair Powell stating at the end of June 2020, “We are committed to using our full range of tools to support the economy and to help assure that the recovery from this difficult period will be as robust as possible.”

TIPS have market-implied breakeven inflation rates that are below the FOMC’s stated target range of 2.0%-2.5%. We believe TIPS are an attractive alternative to fixed-rate Treasuries to mitigate the effects of rising rates driven by accelerating inflationary pressures.

We believe that spread sectors remain relatively attractive to Treasuries over the intermediate-to-long term. Corporate risk premiums are near their longer-term averages, and we believe the tailwinds exist as their remains explicit support from the Fed for pockets of the credit markets. That being said, we believe security selection will be key as certain business models may not be sustainable in the post-pandemic environment.

Semiannual Report

June 30, 2020

Fixed Income Market Review and Outlook (continued)

We believe that higher-coupon segments (30-year mortgage-backed securities (MBS) coupon rates of 5.0% and above) of the agency MBS market offer compelling value. These segments of the agency MBS market offer attractive spreads and a defensive duration profile. Prepayment protection is critical in this lower interest rate environment. We continue to mitigate this risk by focusing on specified pools comprised of borrowers that do not have the economic incentive to refinance their loans: seasoned low-loan balance pools.

June 30, 2020

William Blair Funds

Bond Fund

The Bond Fund seeks to outperform the Bloomberg Barclays U.S. Aggregate Index by maximizing total return through a combination of income and capital appreciation.

AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Paul J. Sularz

Ruta Ziverte

The William Blair Bond Fund (Class N shares) returned 4.29%, net of fees, for the six month period ended June 30, 2020. By comparison, the Fund’s benchmark, the Bloomberg Barclays U.S. Aggregate Index (the “Index”), returned 6.14%.

A couple of factors detracted from the Fund’s performance relative to the Index year-to-date. The Fund’s significant underweight and shorter duration positioning in Treasuries detracted from performance as Treasuries continue to be the best performing sector year-to-date. In addition, modest allocations to higher beta sectors such as high yield corporates and emerging markets detracted from attribution, however security selection offset the majority of the detraction.

Positive attribution came from the Fund’s overweight and security selection of higher coupon segments within the mortgage-backed securities (MBS) space, hedging credit exposure in first quarter 2020 with credit default swap positions, and security selection within Investment Grade corporate securities, offset only slightly by the Fund’s overweight.

Please refer to the Fixed Income Market Review and Outlook relating to the Fund beginning on page 74.

Semiannual Report

June 30, 2020

Bond Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year
	to Date			1 Year			3 Year			5 Year			10 Year
Class N		4.29	%		7.23	%		4.76	%		4.03	%		4.22	%
Class I		4.30			7.32			4.91			4.21			4.39
Class R6		4.32			7.48			5.01			4.29			4.50
Bloomberg Barclays U.S. Aggregate Index		6.14			8.74			5.32			4.30			3.82

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Bloomberg Barclays U.S. Aggregate Index indicates broad intermediate government/corporate bond market performance.

This report identifies the Fund’s investments on June 30, 2020. These holdings are subject to change. Not all investments in the Fund performed the same, nor is there any guarantee that these investments will perform as well in the future. Market forecasts provided in this report may not necessarily come to pass.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total investments.

June 30, 2020

William Blair Funds

Bond Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)


	Principal
Issuer	Amount			Value

U.S. Government and U.S. Government Agency—56.1%
U.S. Treasury Inflation Indexed Notes/Bonds—3.4%
U.S. Treasury Inflation Indexed Bond, 3.875%, due 4/15/29	$	6,708	$	9,484
U.S. Treasury—2.1%
U.S. Treasury Strip Principal, 0.000%, due 8/15/27		4,000		3,877
U.S. Treasury Bond, 2.375%, due 11/15/49		1,530		1,890
Total U.S. Treasury Obligations				5,767
Federal Home Loan Mortgage Corp. (FHLMC)—13.4%
#J02986, 6.500%, due 7/1/21		1		1
#G02210, 7.000%, due 12/1/28		34		39
#G02183, 6.500%, due 3/1/30		3		4
#G01400, 7.000%, due 4/1/32		361		423
#G01728, 7.500%, due 7/1/32		62		75
#C01385, 6.500%, due 8/1/32		47		54
#C01623, 5.500%, due 9/1/33		54		62
#A15039, 5.500%, due 10/1/33		2		2
#A17603, 5.500%, due 1/1/34		1,317		1,525
#G01843, 6.000%, due 6/1/35		11		13
#A62858, 6.500%, due 7/1/37		63		73
#G03170, 6.500%, due 8/1/37		115		134
#A78138, 5.500%, due 6/1/38		161		185
#G04466, 5.500%, due 7/1/38		9,713		11,370
#G60366, 6.000%, due 10/1/39		9,471		11,081
#G61450, 6.000%, due 4/1/40		9,782		11,615
#C03665, 9.000%, due 4/1/41		227		277
Total FHLMC Mortgage Obligations				36,933
Federal National Mortgage Association (FNMA)—37.2%
#900725, 6.000%, due 8/1/21		3		3
#893325, 7.000%, due 9/1/21		2		2
#255956, 5.500%, due 10/1/25		6		7
#AL2853, 4.500%, due 6/1/26		2,615		2,787
#AL9857, 4.000%, due 2/1/29		1,351		1,434
#252925, 7.500%, due 12/1/29		1		1
#AD0729, 7.500%, due 12/1/30		2,560		3,009
#535977, 6.500%, due 4/1/31		4		5
#253907, 7.000%, due 7/1/31		1		1
#587849, 6.500%, due 11/1/31		4		5
#545437, 7.000%, due 2/1/32		28		33
#545759, 6.500%, due 7/1/32		236		278
#545869, 6.500%, due 7/1/32		780		911
#670385, 6.500%, due 9/1/32		356		421
#254548, 5.500%, due 12/1/32		23		26
#AD0725, 7.000%, due 12/1/32		1,183		1,406
#555340, 5.500%, due 4/1/33		179		208
#741850, 5.500%, due 9/1/33		274		315
#555800, 5.500%, due 10/1/33		26		30
#CA2754, 4.500%, due 11/1/33		701		756
#756153, 5.500%, due 11/1/33		279		320
#AL3455, 5.500%, due 11/1/33		3,820		4,428
#AL3401, 5.500%, due 2/1/34		768		891
#763798, 5.500%, due 3/1/34		49		57

	NRSRO
	Rating	Principal
Issuer	(unaudited)	Amount			Value

U.S. Government and U.S. Government Agency—(continued)
Federal National Mortgage Association (FNMA)—(continued)
#725611, 5.500%, due 6/1/34		$	59	$	68
#745563, 5.500%, due 8/1/34			336		386
#AL6413, 8.000%, due 8/1/34			346		398
#794474, 6.000%, due 10/1/34			29		34
#745092, 6.500%, due 7/1/35			187		219
#357944, 6.000%, due 9/1/35			7		8
#AL6412, 7.500%, due 9/1/35			556		641
#AD0979, 7.500%, due 10/1/35			37		44
#888305, 7.000%, due 3/1/36			6		7
#895637, 6.500%, due 5/1/36			33		39
#831540, 6.000%, due 6/1/36			15		17
#893318, 6.500%, due 8/1/36			7		9
#831926, 6.000%, due 12/1/36			395		460
#902974, 6.000%, due 12/1/36			98		114
#AB0265, 6.000%, due 2/1/37			7,595		8,886
#938440, 6.000%, due 7/1/37			59		69
#948689, 6.000%, due 8/1/37			88		101
#AL6411, 7.000%, due 12/1/37			1,321		1,517
#AL0904, 5.500%, due 1/1/38			69		79
#986856, 6.500%, due 9/1/38			75		89
#FM1735, 6.500%, due 10/1/38			4,425		5,387
#991911, 7.000%, due 11/1/38			73		84
#FM2467, 6.000%, due 1/1/39			4,273		5,076
#AD0752, 7.000%, due 1/1/39			372		469
#AC1619, 5.500%, due 8/1/39			229		262
#FM1736, 6.500%, due 10/1/39			7,210		8,683
#AD7137, 5.500%, due 7/1/40			2,743		3,223
#BM1689, 5.500%, due 8/1/40			2,224		2,557
#AL5815, 5.500%, due 4/1/41			2,651		3,112
#BM3525, 6.000%, due 4/1/41			9,327		10,934
#AL9226, 5.500%, due 12/1/41			11,099		12,979
#AL9225, 6.000%, due 1/1/42			4,983		5,848
#BM5121, 5.500%, due 12/1/48			11,649		13,678
Total FNMA Mortgage Obligations					102,811

U.S. Government Agency—1.8%
TBA—1.8%
FNCL 2 7/20, 2.000%, due 7/1/50			5,000		5,117

Asset-Backed Securities—1.5%
Centre Point Funding LLC—144A, 2012-2A, Tranche 1, 2.610%, 8/20/21	A1		24		24
Tesla Auto Lease Trust—144A, 2019-A, Tranche E, 5.480%, 5/22/23	Ba3		1,000		1,024
GM Financial Automobile Leasing Trust, 2020-1, Tranche D, 2.280%, 6/20/24	A		3,050		3,018
Total Asset-Backed Securities					4,066

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Bond Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

	NRSRO
	Rating	Principal
Issuer	(unaudited)	Amount			Value

Corporate Obligations—41.4%
Fresenius Medical Care US Finance II, Inc.—144A, 5.875%, due 1/31/22	BBB	$	2,000	$	2,110
Toyota Motor Credit Corporation, 1.150%, due 5/26/22	A+		1,000		1,012
Jones Lang LaSalle, Inc., 4.400%, due 11/15/22	BBB+		2,500		2,623
Toll Brothers Finance Corporation, 4.375%, due 4/15/23	BBB-		2,750		2,863
CNH Industrial Capital LLC, 1.950%, due 7/2/23	BBB		1,600		1,611
Wells Fargo & Co., 4.480%, due 1/16/24	A3		1,500		1,666
Lennar Corporation, 4.500%, due 4/30/24	BBB-		2,450		2,554
Banco Inbursa S.A. Institucion de Banca Multiple—144A, 4.125%, due 6/6/24	BBB		2,000		2,057
Grupo Bimbo S.A.B. de C.V.—144A, 3.875%, due 6/27/24	BBB		2,000		2,143
JPMorgan Chase & Co., SOFRRATE + 3.125%, 4.600%, due 2/1/25, VRN	BBB+		3,000		2,681
Ford Motor Co., 9.000%, due 4/22/25	BB+		700		759
Booz Allen Hamilton, Inc.—144A, 5.125%, due 5/1/25	Ba2		1,400		1,426
DaVita, Inc., 5.000%, due 5/1/25	Ba3		1,400		1,433
Simon Property Group L.P., 3.300%, due 1/15/26	A		2,750		2,953
Xylem, Inc., 3.250%, due 11/1/26	BBB		2,225		2,459
Netflix, Inc., 4.375%, due 11/15/26	BB-		1,400		1,460
Fibria Overseas Finance, Ltd., 5.500%, due 1/17/27	BBB-		2,000		2,155
Sirius XM Radio, Inc.—144A, 5.000%, due 8/1/27	BB		1,400		1,433
Motorola Solutions, Inc., 4.600%, due 2/23/28	BBB-		2,750		3,130
Winnebago Industries, Inc.—144A, 6.250%, due 7/15/28	BB		250		250
Roper Technologies, Inc., 4.200%, due 9/15/28	BBB+		2,500		2,934
The Kroger Co., 8.000%, due 9/15/29	Baa1		2,250		3,249
United Rentals North America, Inc., 5.250%, due 1/15/30	BB-		1,250		1,294
Sysco Corporation, 2.400%, due 2/15/30	Baa1		3,200		3,170
Omnicom Group, Inc., 2.450%, due 4/30/30	BBB+		2,800		2,863
Abbott Laboratories, 1.400%, due 6/30/30	A-		1,350		1,345
Intuit, Inc., 1.650%, due 7/15/30	A-		1,200		1,199

	NRSRO
	Rating	Principal
Issuer	(unaudited)	Amount			Value

Corporate Obligations—(continued)
Costco Wholesale Corporation, 1.750%, due 4/20/32	Aa3	$	2,500	$	2,542
Owens Corning, 7.000%, due 12/1/36	BBB		2,250		2,881
Yum! Brands, Inc., 6.875%, due 11/15/37	B+		1,250		1,349
ConocoPhillips, 6.500%, due 2/1/39	A		2,000		2,916
Citigroup, Inc., 5.875%, due 1/30/42	A		2,000		2,917
Bank of America Corporation, 5.875%, due 2/7/42	A+		2,000		2,988
Cox Communications, Inc.—144A, 4.700%, due 12/15/42	BBB+		2,500		3,096
Orbia Advance Corp S.A.B. de C.V.—144A, 5.875%, due 9/17/44	BBB		2,250		2,474
AbbVie, Inc., 4.700%, due 5/14/45	BBB+		2,500		3,147
ERP Operating L.P., 4.500%, due 6/1/45	A		2,500		3,293
Apple, Inc., 4.650%, due 2/23/46	AA+		2,250		3,104
PepsiCo, Inc., 4.450%, due 4/14/46	A+		2,250		3,016
Brookfield Finance, Inc., 4.700%, due 9/20/47	A-		2,750		3,127
Union Pacific Corporation, 4.300%, due 3/1/49	A-		2,500		3,202
Microsoft Corporation, 4.750%, due 11/3/55	AAA		2,250		3,277
AT&T, Inc., 5.700%, due 3/1/57	A-		2,250		3,089
Comcast Corporation, 4.950%, due 10/15/58	A-		2,000		2,853
Altria Group, Inc., 6.200%, due 2/14/59	A3		2,250		3,011
The Boeing Co., 5.930%, due 5/1/60	Baa2		1,400		1,667
Amazon.com, Inc., 2.700%, due 6/3/60	AA-		1,250		1,279
Corning, Inc., 5.850%, due 11/15/68	BBB+		2,400		3,052
Petrobras Global Finance BV, 6.850%, due 6/5/15	Ba2		1,250		1,236
Total Corporate Obligations					114,348
Total Long-Term Investments—100.8% (cost $259,476)					278,526

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Bond Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)


	Principal
Issuer	Amount			Value

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $2,159, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $2,202	$	2,159	$	2,159
Total Repurchase Agreement—0.8% (cost $2,159)				2,159
Total Investments—101.6% (cost $261,635)				280,685
Liabilities, plus cash and other assets—(1.6)%				(4,530	)
Net assets—100.0%			$	276,155

The obligations of certain U.S. Government-sponsored securities are neither issued nor guaranteed by the U.S. Treasury.

144A = Security exempt from registration under Rule 144A of the Securities Act of 1933. These securities may be resold in transactions exempt from registration, normally to qualified institutional buyers.

NRSRO = Nationally Recognized Statistical Rating Organization—The credit quality ratings of the securities in the Fund reflect the highest category rating by any of Fitch Ratings, Moody’s Investors Service Inc., or Standard & Poor’s, a division of the McGraw-Hill Companies, Inc.

TBA = To Be Announced—TBAs are mortgage-backed securities traded under delayed delivery commitments, settling after June 30, 2020. The term TBA comes from the fact that the specific mortgage-backed security that will be delivered to fulfill a TBA trade is not designated at the time the trade is made.

VRN = Variable Rate Note

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	Income Fund

	The Income Fund seeks a high level of current income with relative stability of principal.

	AN OVERVIEW FROM THE PORTFOLIO MANAGER

Ruta Ziverte	The William Blair Income Fund (Class N shares) returned 3.14%, net of fees, for the six month period ended June 30, 2020. By comparison, the Fund’s benchmark, the Bloomberg Barclays Intermediate Government/Credit Bond Index (the “Index”), returned 5.28%. A couple of factors detracted from the Fund’s performance relative to the Index year-to-date. The Fund’s significant underweight and shorter duration positioning in Treasuries detracted from performance as Treasuries continue to be the best performing sector year-to-date. Additionally, security selection within treasuries detracted from performance as U.S. Treasury Inflation-Protected Securities (TIPS) underperformed nominal treasuries. Security selection in Investment Grade Credit detracted from attribution, primarily from owning shorter duration exposure as 7-10 year credit outperformed 3-5 year credit. Finally, the Fund has a shorter duration profile versus the benchmark, which detracted from performance. Positive attribution came from the Fund’s security selection of higher coupon segments within the mortgage-backed securities (MBS) space, which contributed to performance as these securities outperformed current coupon MBS. In addition, the Fund’s overweight to select asset-backed securities (ABS) was a contributor to performance as spreads continued to tighten. Finally, the structural bias to up-in quality Investment Grade Credit contributed to attribution as the Fund limits its BBB exposure to 10% of the portfolio. Please refer to the Fixed Income Market Review and Outlook relating to the Fund beginning on page 74.

June 30, 2020

William Blair Funds

Income Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year			Since Inception(a)
Class N		3.14	%		4.70	%		2.87	%		2.34	%		2.69	%		—
Class I		3.22			4.87			3.10			2.60			2.93			—
Class R6		3.25			4.92			—			—			—			5.58	%
Bloomberg Barclays Intermediate Government/ Credit Bond Index		5.28			7.12			4.43			3.46			3.13			8.29

(a)	Since inception is for the period from May 2, 2019 (Commencement of Operations) to June 30, 2020.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The Bloomberg Barclays Intermediate Government/Credit Bond Index indicates broad intermediate government/corporate bond market performance.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total investments.

Semiannual Report

June 30, 2020

Income Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)


	Principal
Issuer	Amount		Value

U.S. Government and U.S. Government Agency—65.8%
U.S. Treasury Inflation Indexed Notes/Bonds—3.1%
U.S. Treasury Inflation Indexed Bond, 3.875%, due 4/15/29	$	1,170	$	1,654
U.S. Treasury—3.8%
U.S. Treasury Strip Principal, 0.000%, due 5/15/22		1,000		997
U.S. Treasury Strip Principal, 0.000%, due 8/15/27		775		751
U.S. Treasury Bill, 0.175%, due 09/17/2020		240		240
Total U.S. Treasury Obligations				1,988
Federal Home Loan Mortgage Corp. (FHLMC)—8.8%
#E02490, 6.000%, due 4/1/23		20		21
#J13022, 4.000%, due 9/1/25		195		206
#G14150, 4.500%, due 4/1/26		59		63
#J16051, 4.500%, due 7/1/26		440		472
#G15030, 4.000%, due 3/1/29		143		154
#A17603, 5.500%, due 1/1/34		381		442
#G01705, 5.500%, due 6/1/34		693		804
#A45790, 7.500%, due 5/1/35		65		75
#G04126, 6.000%, due 6/1/37		166		195
#G04564, 6.000%, due 12/1/37		133		155
#G05566, 5.500%, due 12/1/38		94		108
#G05875, 5.500%, due 2/1/40		69		81
#G61450, 6.000%, due 4/1/40		1,466		1,741
#C03665, 9.000%, due 4/1/41		110		134
Total FHLMC Mortgage Obligations				4,651
Federal National Mortgage Association (FNMA)—50.1%
#735574, 8.000%, due 3/1/22		10		11
FNR G93-19 SH, 1M USD LIBOR + 56.169%, 11.234%, due 4/25/23, VRN		10		10
#982885, 5.000%, due 5/1/23		103		109
#933985, 5.500%, due 8/1/23		51		53
#255956, 5.500%, due 10/1/25		19		21
#AH0971, 4.000%, due 12/1/25		219		232
#AL2853, 4.500%, due 6/1/26		338		360
#AJ6954, 4.000%, due 11/1/26		98		104
#256639, 5.000%, due 2/1/27		4		5
#AL9730, 4.500%, due 2/1/27		675		721
#806458, 8.000%, due 6/1/28		62		71
#AL9857, 4.000%, due 2/1/29		4,100		4,351
#880155, 8.500%, due 7/1/29		93		107
#797846, 7.000%, due 3/1/32		23		23
#745519, 8.500%, due 5/1/32		44		50
#654674, 6.500%, due 9/1/32		32		36
#AD0725, 7.000%, due 12/1/32		505		600
#254693, 5.500%, due 4/1/33		4		5
#555531, 5.500%, due 6/1/33		38		43
#711736, 5.500%, due 6/1/33		58		66
#555591, 5.500%, due 7/1/33		6		7
#AL3455, 5.500%, due 11/1/33		1,122		1,301
#CA2754, 4.500%, due 11/1/33		384		413
#725424, 5.500%, due 4/1/34		40		46

	NRSRO
	Rating	Principal
Issuer	(unaudited)	Amount		Value

U.S. Government and U.S. Government Agency—(continued)
Federal National Mortgage Association (FNMA)—(continued)
#AL6413, 8.000%, due 8/1/34		$	169	$	194
#AL6412, 7.500%, due 9/1/35			417		481
#888884, 5.500%, due 12/1/35			93		106
#991911, 7.000%, due 11/1/38			47		54
#928658, 6.500%, due 9/1/37			15		17
#889371, 6.000%, due 1/1/38			1,723		2,025
#FM1735, 6.500%, due 10/1/38			1,252		1,524
#FM2467, 6.000%, due 1/1/39			475		564
#FM1736, 6.500%, due 10/1/39			1,193		1,436
#BM1689, 5.500%, due 8/1/40			301		346
#BM3525, 6.000%, due 4/1/41			828		970
#AL5815, 5.500%, due 4/1/41			379		445
#AL9226, 5.500%, due 12/1/41			3,508		4,102
#AL9225, 6.000%, due 1/1/42			1,370		1,608
#BM1328, 6.000%, due 1/1/42			1,426		1,671
#BM5121, 5.500%, due 12/1/48			1,915		2,249
Total FNMA Mortgage Obligations					26,537

Asset-Backed Securities—2.6%
GM Financial Automobile Leasing Trust, 2020-1, Tranche C, 2.040%, 12/20/23	A+		950		944
Verizon Owner Trust, 2020-A, Tranche C, 2.060%, 7/22/24	Aa3		425		426
Total Asset-Backed Securities					1,370

Corporate Obligations—30.9%
HSBC Holdings plc, 3M USD LIBOR + 2.240%, 2.558%, due 3/8/21, VRN	A+		500		506
Toyota Motor Credit Corporation, 1.150%, due 5/26/22	A+		500		506
Jones Lang LaSalle, Inc., 4.400%, due 11/15/22	BBB+		500		525
Toll Brothers Finance Corporation, 4.375%, due 4/15/23	BBB-		500		521
CNH Industrial Capital LLC, 1.950%, due 7/2/23	BBB		350		352
Wells Fargo & Co., 4.480%, due 1/16/24	A3		550		611
The Goldman Sachs Group, Inc., 4.000%, due 3/3/24	A		550		608
Bank of America Corporation, 3M USD LIBOR + 0.780%, 3.550%, due 3/5/24, VRN	A+		650		695
Mitsubishi UFJ Financial Group, Inc., 3.407%, due 3/7/24	A1		550		594
Citigroup, Inc., SOFR + 1.667%, 1.678%, due 5/15/24, VRN	A		500		510
Grupo Bimbo S.A.B. de C.V.—144A, 3.875%, due 6/27/24	BBB		500		536
ERP Operating L.P., 3.375%, due 6/1/25	A		550		605

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Income Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

	NRSRO
	Rating	Principal
Issuer	(unaudited)	Amount		Value

Corporate Obligations—(continued)
Intuit, Inc., 0.950%, due 7/15/25	A-	$	450	$	452
The Hershey Co., 0.900%, due 6/1/25	A1		525		528
Comcast Corporation, 3.950%, due 10/15/25	A-		500		573
Capital One Financial Corporation, 4.200%, due 10/29/25	Baa1		500		556
Intercontinental Exchange, Inc., 3.750%, due 12/1/25	A		550		627
Simon Property Group L.P., 3.300%, due 1/15/26	A		550		591
AT&T, Inc., 4.125%, due 2/17/26	A-		550		627
Merck & Co., Inc., 0.750%, due 2/24/26	AA-		700		699
ConocoPhillips Co., 4.950%, due 3/15/26	A		500		600
Brookfield Finance, Inc., 4.250%, due 6/2/26	A-		550		622
Costco Wholesale Corporation, 1.375%, due 6/20/27	Aa3		500		512
Abbott Laboratories, 1.150%, due 1/30/28	A-		450		452
Motorola Solutions, Inc., 4.600%, due 2/23/28	BBB-		450		512
Roper Technologies, Inc., 4.200%, due 9/15/28	BBB+		375		440
The Kroger Co., 8.000%, due 9/15/29	Baa1		350		505
Sysco Corporation, 2.400%, due 2/15/30	Baa1		525		520
Omnicom Group, Inc., 2.450%, due 4/30/30	BBB+		500		511
Amazon.com, Inc., 1.500%, due 6/3/30	AA-		450		456
Total Corporate Obligations					16,352
Total Long-Term Investments—99.3% (cost $50,975)					52,552


	Principal
Issuer	Amount		Value

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $119, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $122	$	119	$	119
Total Repurchase Agreement—0.2% (cost $119)				119

Commercial Paper
Societe Generale, 0.101%, due 7/1/20		350		350
Total Commercial Paper—0.7% (cost $350)				350
Total Investments—100.2% (cost $51,444)				53,021
Liabilities, plus cash and other assets—(0.2)%				(88	)
Net assets—100.0%			$	52,933

The obligations of certain U.S. Government-sponsored securities are neither issued nor guaranteed by the U.S. Treasury.

VRN = Variable Rate Note

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	Low Duration Fund

	The Low Duration Fund seeks to maximize total return. Total return includes both income and capital appreciation.

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Kathleen M. Lynch Paul J. Sularz	The William Blair Low Duration Fund (Class N shares) returned 1.85%, net of fees, for the six month period ended June 30, 2020. By comparison, the Fund’s benchmark index, the ICE BofAML 1-Year US Treasury Note Index (the “Index”), returned 1.69%. A couple of factors contributed to the Fund’s performance relative to the Index year-to-date. The Fund’s allocation to and security selection within higher coupon segments within the mortgage-backed securities (MBS) space contributed the most to performance. In addition, allocation to and security selection within Investment Grade Credit also contributed to performance as credit spreads continued to tighten. Finally, exposure to asset-backed securities (ABS) also contributed to performance as spreads tightened. While all sectors contributed positive returns to the Fund over the period, Investment Grade Credit and ABS exposure contributed the least to the Fund’s performance. Please refer to the Fixed Income Market Review and Outlook relating to the Fund beginning on page 74.

June 30, 2020

William Blair Funds

Low Duration Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			10 Year
Class N		1.85	%		2.87	%		2.23	%		1.61	%		1.36	%
Class I		1.93			2.91			2.39			1.78			1.52
Class R6		1.84			2.96			2.40			1.82			1.61
ICE BofAML 1-Year US Treasury Note Index		1.69			2.86			2.25			1.54			0.93

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The ICE BofAML 1-Year US Treasury Note Index is comprised of a single U.S. Treasury Note issue purchased at the beginning of the month and held for a full month. Each month the index is rebalanced and the issue selected is the outstanding U.S. Treasury Note that matures closest to, but not beyond one year from the rebalancing date.

Sector Diversification (Unaudited)

The sector diversification shown is based on the total investments.

Semiannual Report

June 30, 2020

Low Duration Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)


	Principal
Issuer	Amount		Value

U.S. Government and U.S. Government Agency—65.6%
U.S. Treasury—13.5%
U.S. Treasury Bill, 0.094%, due 7/14/20		$1,220	$	1,220
U.S. Treasury Bill, 0.194%, due 7/16/20		1,625		1,625
U.S. Treasury Bill, 0.122%, due 8/13/20		1,650		1,650
U.S. Treasury Bill, 0.125%, due 8/25/20		1,650		1,649
U.S. Treasury Bill, 0.175%, due 9/17/20		1,000		999
U.S. Treasury Bill, 0.150%, due 9/24/20		3,900		3,899
U.S. Treasury Strip Principal, 0.000%, due 8/15/21		3,990		3,985
Total U.S. Treasury Obligations				15,027
Federal Home Loan Mortgage Corp. (FHLMC)—14.2%
#E02322, 5.500%, due 5/1/22		5		5
#G12725, 6.000%, due 6/1/22		26		27
#J08450, 5.500%, due 7/1/23		9		9
#J08703, 5.500%, due 9/1/23		13		14
#C00351, 8.000%, due 7/1/24		20		22
#J11208, 5.000%, due 11/1/24		24		26
#G00363, 8.000%, due 6/1/25		32		35
#C80329, 8.000%, due 8/1/25		7		7
#G14550, 4.500%, due 9/1/26		606		647
#G15360, 4.500%, due 11/1/26		205		218
#G14402, 4.000%, due 2/1/27		146		155
#G04821, 8.500%, due 7/1/31		1,269		1,543
#A81372, 6.000%, due 8/1/38		140		159
#G04687, 6.000%, due 9/1/38		43		50
#G04745, 6.000%, due 9/1/38		169		193
#G06085, 6.500%, due 9/1/38		39		45
#G60681, 7.000%, due 2/1/39		5,268		6,635
#G60680, 6.500%, due 9/1/39		652		781
#G61450, 6.000%, due 4/1/40		4,399		5,223
Total FHLMC Mortgage Obligations				15,794
Federal National Mortgage Association (FNMA)—37.9%
#831497, 6.000%, due 4/1/21		13		14
#879607, 5.500%, due 4/1/21		2		2
#831525, 5.500%, due 6/1/21		4		4
#880993, 6.000%, due 1/1/22		1		1
#888982, 6.000%, due 12/1/22		33		34
#972934, 5.500%, due 2/1/23		41		42
#889670, 5.500%, due 6/1/23		8		8
#AE0011, 5.500%, due 9/1/23		6		7
#995253, 5.500%, due 12/1/23		391		403
#995395, 6.000%, due 12/1/23		20		20
#190988, 9.000%, due 6/1/24		3		3
#AL8529, 6.000%, due 11/1/24		3,415		3,580
#AL2853, 4.500%, due 6/1/26		1,072		1,143
#AL9730, 4.500%, due 2/1/27		1,688		1,803
#AL3388, 4.000%, due 9/1/27		353		379

	NRSRO
	Rating	Principal
Issuer	(unaudited)	Amount		Value

U.S. Government Agency—(continued)
Federal National Mortgage Association (FNMA)—(continued)
#AL9870, 6.500%, due 2/1/28			$ 987	$	1,099
#AL4502, 4.000%, due 11/1/28			420		453
#AL9857, 4.000%, due 2/1/29			3,475		3,687
#323933, 7.000%, due 9/1/29			239		275
#555933, 7.000%, due 6/1/32			331		385
#555866, 7.500%, due 3/1/33			204		239
#CA2754, 4.500%, due 11/1/33			115		124
#AL6413, 8.000%, due 8/1/34			196		226
#AD0720, 5.500%, due 12/1/34			228		262
#AL6412, 7.500%, due 9/1/35			694		802
#886762, 7.000%, due 9/1/36			186		226
#888530, 7.500%, due 8/1/37			1,446		1,832
#AL6411, 7.000%, due 12/1/37			1,321		1,517
#FM1735, 6.500%, due 10/1/38			2,235		2,721
#AD0100, 7.000%, due 12/1/38			459		552
#FM2467, 6.000%, due 1/1/39			1,899		2,256
#FM1736, 6.500%, due 10/1/39			2,880		3,469
#AL0515, 6.000%, due 7/1/40			561		664
#BM3525, 6.000%, due 4/1/41			2,649		3,105
#AL9226, 5.500%, due 12/1/41			2,461		2,877
#AL9225, 6.000%, due 1/1/42			2,242		2,632
#BM1328, 6.000%, due 1/1/42			1,371		1,607
#AL6276, 5.500%, due 10/1/43			181		211
#BM5121, 5.500%, due 12/1/48			1,264		1,484
#CA5837, 6.000%, due 7/1/49			1,723		2,049
Total FNMA Mortgage Obligations					42,197

Asset-Backed Securities—8.9%
Tesla Auto Lease Trust 2018-B—144A, 2018-B, Tranche A, 3.710%, 8/20/21	Aaa		597		606
Honda Auto Receivables Owner Trust, 2019-3, Tranche A2, 1.900%, 4/15/22	AAA		904		910
CNH Equipment Trust 2019-A, 2019-A, Tranche A2, 2.960%, 5/16/22	AAA		392		394
Toyota Auto Receivables 2020-B Owner Trust, 2020-B, Tranche A2, 1.380%, 12/15/22	AAA		1,250		1,261
Tesla Auto Lease Trust—144A, 2019-A, Tranche C, 2.680%, 1/20/23	A2		675		679
American Express Credit Account Master Trust, 2017-6, Tranche A, 2.040%, 5/15/23	AAA		1,000		1,005
BA Credit Card Trust, 2018-A2, Tranche A2, 3.000%, 9/15/23	AAA		1,000		1,020
GM Financial Automobile Leasing Trust, 2020-1, Tranche C, 2.040%, 12/20/23	A+		1,400		1,391
Verizon Owner Trust, 2020-A, Tranche C, 2.060%, 7/22/24	Aa3		1,250		1,253

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Low Duration Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

	NRSRO
	Rating	Principal
Issuer	(unaudited)	Amount		Value

Asset-Backed Securities—(continued)
CNH Equipment Trust 2020-A, 2020-A, Tranche A3, 1.160%, 6/16/25	AAA		$ 300	$	303
Canadian Pacer Auto Receivables Trust—144A, 2020-1A, Tranche B, 2.000%, 7/21/25	AA+		500		503
CarMax Auto Owner Trust, 2020-1, Tranche C, 2.340%, 11/17/25	A		600		597
Total Asset-Backed Securities					9,922

Corporate Obligations—22.3%
The Bank of Nova Scotia, 2.150%, due 7/14/20	Aa2		2,097		2,098
Apple, Inc., 3M USD LIBOR + 1.130%, 1.490%, due 2/23/21, VRN	AA+		550		554
JPMorgan Chase & Co., 3M USD LIBOR + 1.480%, 1.830%, due 3/1/21, VRN	AA-		1,500		1,511
Wells Fargo & Co., 3M USD LIBOR + 1.340%, 1.671%, due 3/4/21, VRN	A+		1,500		1,511
HSBC Holdings plc, 3M USD LIBOR + 2.240%, 2.558%, due 3/8/21, VRN	A+		1,500		1,519
Bank of America Corporation, 3M USD LIBOR + 1.420%, 2.555%, due 4/19/21, VRN	A+		1,000		1,011
The Goldman Sachs Group, Inc., 3M USD LIBOR + 1.360%, 2.351%, due 4/23/21, VRN	A		1,000		1,008
Bristol-Myers Squibb Co.—144A, 2.600%, due 5/16/22	A+		1,000		1,040
Toyota Motor Credit Corporation, 1.150%, due 5/26/22	A+		1,600		1,619
AT&T, Inc., 3.000%, due 6/30/22	A-		1,500		1,567
John Deere Capital Corporation, 0.550%, due 7/5/22	A		1,200		1,204
Mitsubishi UFJ Financial Group, Inc., 2.623%, due 7/18/22	A1		2,000		2,074
Philip Morris International, Inc., 2.375%, due 8/17/22	A		1,500		1,558
Capital One Bank USA NA, SOFRRATE + 0.616%, 2.014%, due 1/27/23, VRN	A-		1,400		1,420
Morgan Stanley, 3.750%, due 2/25/23	A		2,003		2,162
Caterpillar Financial Services Corporation, 2.625%, due 3/1/23	A		1,579		1,669
Intuit, Inc., 0.650%, due 7/15/23	A-		1,300		1,303
Total Corporate Obligations					24,828
Total Long-Term Investments—96.8% (cost $106,870)					107,768


	Principal
Issuer	Amount		Value

Repurchase Agreement
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $1,111, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $1,134		$ 1,111	$	1,111
Total Repurchase Agreement—1.0% (cost $1,111)				1,111

Commercial Paper
American Transmission, 0.132%, due 7/1/20		1,600		1,600
Cargill GBL Funding, 0.101%, due 7/1/20		1,600		1,600
Societe Generale, 0.101%, due 7/1/20		1,600		1,600
Total Commercial Paper—4.3% (cost $4,800)				4,800
Total Investments—102.1% (cost $112,781)				113,679
Liabilities, plus cash and other assets—(2.1)%				(2,317	)
Net assets—100.0%			$	111,362

The obligations of certain U.S. Government-sponsored securities are neither issued nor guaranteed by the U.S. Treasury.

VRN = Variable Rate Note

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

	Macro Allocation Fund

	AN OVERVIEW FROM THE PORTFOLIO MANAGERS

Thomas Clarke Brian D. Singer	The William Blair Macro Allocation Fund (Class N shares) posted a 7.08% decrease, net of fees, for the six month period ended June 30, 2020. By comparison, the Fund’s benchmark index, the ICE BofAML US 3-Month Treasury Bill Index (the “Index”), increased 0.60%. The first six months of 2020 had significant volatility across assets and currencies, triggered by the onset of the COVID-19 pandemic and subsequent “lockdowns” and restrictions on people’s freedoms and movements. These lockdowns have put the global economy into its first recession in over a decade, with GDP forecasts collapsing and unemployment ballooning. This led to a material decline in global equities in the first quarter. But since then, equity markets have rebounded as governments eased their restrictions and optimism about economic prospects have emerged. However, the rebound in equity markets has not been uniform across countries and sectors, such that, on a year-to-date basis, there is significant dispersion. The S&P 500 finished the first six months of the year down 3.0%, while MSCI UK (hedged) was down 17.5% and MSCI EMU (hedged) was down 11.4%. Broad emerging market equities were down 5.0%, but again with wide dispersion: MSCI China (hedged) was up 3.3% while MSCI Brazil (hedged) was down 17.4%, for example. The significant volatility and economic slowdown brought response from central banks, including rate cuts and liquidity injections. This brought bond yields down and bond prices up. Within currencies, the “risk-off” nature of the first quarter caused a sell-off in emerging currencies and a rally in safe haven currencies. This trend was only mildly reversed in the second quarter. The Fund’s market and currency strategies were both negative during the period. Within markets, the negative performance was driven by long exposure to equities, most notably UK, Spain, Greece and Brazil. Partially offsetting this was short exposure to Mexico, Netherlands and South Africa equities. The Fund maintained long exposure to U.S. government bonds, which contributed positively to performance. Within currencies, the largest detractors were long exposure to the Mexican peso, Colombian peso, Norwegian krone and Russian ruble. Contributing positively to performance were short exposure to the Indonesian rupiah, New Zealand dollar and Thai baht. We significantly de-risked our equity and currency exposures through the first quarter of the year. Our long equity exposure entering 2020 was already somewhat scaled back and we scaled back further through the quarter as well as fully neutralizing many of our long emerging currency exposures. Our interpretation and analysis of developments since then is such that we have only modestly re-established long equity market exposure that we had de-risked in the first quarter. We remain slightly long of government bonds, despite their long-standing and significant over-valuation based on our fundamental analysis, which taken alone would warrant short exposure. We have made a more significant re-engagement with respect to currency risk exposures (compared to our activity in equities). In short, we believe there are significant long-term valuation opportunities in all three domains (equities attractive, bonds very unattractive, most emerging currencies attractive relative to safe havens), but we are most inclined to seek to exploit the currency opportunity at this point, remaining cautious with respect to the equity opportunity, and, as mentioned previously, we are going slightly against the expensive sovereign bond signal. The primary impact of the pandemic on financial markets comes through curtailment of economic activity, which was a policy enacted worldwide as countries went into varying degrees of “lockdown.” With no vaccine nor effective treatment for the virus, which is fatal in some cases, the effort to limit its spread focused on keeping people distant from each other and shuttering most forms of non-essential economic activity. This focus exerted a powerfully depressive influence on spending and earnings. While one or two quarters of lost revenue to a business might not reduce the fundamental value to a very large extent, we believe that many firms are likely to be operating well below former capacity for a considerable time, and some will not survive in their present form. Almost all central banks have ramped up their provision of ultra-easy monetary conditions (low, zero or negative policy interest rates; accelerated asset purchases; and significant increases to provisions of guaranteed liquidity and credit). Governments, too, have aggressively responded through relaxed fiscal policies with increased investment and spending, including outright cash transfers to businesses and individuals, unemployment insurance payments, and, in some countries, direct wage support to employees

June 30, 2020

William Blair Funds

and self-employed people who have been prevented from working by government-imposed lockdowns. A side effect of these policy responses has been to preserve a large number of firms under the premise that they can eventually restart their prior trading patterns. But since this will not be universally the case, these “zombies” (businesses that will scarcely be viable in a post-pandemic world) will unwittingly have been financed to a greater extent than before, which we believe represents an enormous misallocation of resources. We believe this will have an enduring contractionary side effect on fundamental values in relevant areas. In addition, ballooning government debt as a result of this may ultimately require tax increases that impair future corporate earnings flowing to investors. Equity price rises have been surprisingly robust since late March given that the spread of the virus has only been slowed down by the deliberate squashing of growth, but we believe market rallies are significantly influenced by the aggressive central bank action, which is not a long-term substitute for valuation support. For these reasons, we are disinclined to materially chase equities upward from generally prevailing levels.

With respect to bonds, in some contrast, the effect of ever-more-powerful quantitative easing on sovereign fixed income yields, along with communicated interest rate expectations of “even-lower-for-even-longer,” can have a much more enduring impact on the suppression of yields well below what equilibrium conditions would indicate was fair value. In short, if ultra-easy policy is maintained through to the maturity date of government bonds, such debt can effectively be held above fundamental value for the remainder of its life. Monetary authorities thus have more ability to persistently counter the prospect of negative returns that bond markets would otherwise generate in many cases. We believe fundamental valuation accordingly exerts its weakest pull on fixed income in the present environment (compared to other assets) and we are not following valuation signals.

Conversely, exchange rates have not generally been a direct policy objective of central banks. Therefore, we believe that the widening of currency opportunities that was caused by the pandemic impact has not been “artificially” suppressed/countered in the same way it has with equities and (even more so) government bonds. Indeed, deeper currency under-valuations across oil-producing economies were rather reinforced and exacerbated by ill-timed oil production increase announcements from Saudi Arabia and Russia in early March. This “price war” was later defused, but not before it had disproportionately affected oil-sensitive currencies that continued to weaken in April even after stock markets had regained some stability. As currencies moved far below value through April and beyond in some cases, we saw fit to significantly reverse the large amount of de-risking that we had undertaken in the first quarter.

Markets and currencies remain somewhat abnormally correlated and lacking in diversification in the short term but, for the reasons previously referenced, we anticipate that the fundamental investment opportunities will converge differentially, with the currency opportunities being somewhat more robust looking ahead, followed by equities, and with little likelihood of bond yields experiencing any noticeable near-term “pull” from value.

We do not think there is a high chance of a repeat of the panic conditions that manifested due to the pandemic in the first quarter. This may be the case even as secondary waves of COVID-19 transmission are likely in some places, and even as infection rates continue to climb in several emerging countries where lockdowns were not as effective as in the developed world and merely slowed accelerating infection rates rather than decelerating the spread. Importantly, market participants now know that even liberal democracies can lock down activity if they need to, and it is also known that this is effective in slowing down the disease transmission (though less effective in emerging economies than developed ones, as noted). Extra capacity in health services that was hurriedly built in many places successfully averted extreme stress on care capacity in health systems in the developed world. Unless secondary waves of infection stress this capacity, which largely did not happen the first time, we believe that stringent economic lockdowns are not likely to be repeated. Future adverse shocks to market sentiment should therefore not carry the same fear-inducing, nonlinear aspect that was dominant in the first quarter.

Although, as previously noted, several emerging countries have not been able to achieve declining virus spread rates at this point, they too have loosened their social and economic restrictions (that likely did prevent a worse outcome). While the human cost of the pandemic remains large, and in parts of the world is getting larger, populations will and have already been able to adapt and accommodate risks and adversity over time. From a dispassionate investing perspective, resuming economic activity amid an ongoing health catastrophe that is being controlled, but not yet defeated, argues for fundamental valuations in equities and currencies to ultimately re-exert their prevailing pull on prices. Our goal as investors is to position portfolios to best capture the risks and returns as they relate to price, value, and navigation influences. Previously we observed that our portfolios were well placed to step into what we believe will eventually prove to be large opportunities to take active risk, and for an eventual environment in which fundamental value is not prevented from being an effective force exerted onto prices. We believe that the pull of valuation will endure and ultimately prevail over today’s large, tragic, but temporary influences.

Semiannual Report

June 30, 2020

Macro Allocation Fund

Performance Highlights (Unaudited)

Average Annual Total Return through 6/30/2020
	Year to Date			1 Year			3 Year			5 Year			Since Inception
Class N(a)		(7.08	)%		(5.71	)%		(0.84	)%		(1.63	)%		3.13	%
Class I(a)		(6.96	)		(5.60	)		(0.58	)		(1.38	)		3.39
ICE BofAML US 3-Month Treasury Bill Index(a)		0.60			1.63			1.77			1.19			0.72
Class R6(b)		(6.87	)		(5.37	)		(0.45	)		(1.26	)		0.39
ICE BofAML US 3-Month Treasury Bill Index(b)		0.60			1.63			1.77			1.19			0.90

(a)	Since inception is for the period from November 29, 2011 (Commencement of Operations) to June 30, 2020.
(b)	Since inception is for the period from October 21, 2013 (Commencement of Operations) to June 30, 2020.

Performance cited represents past performance. Past performance does not guarantee future results and current performance may be lower or higher than the data quoted. Results shown are average annual total returns, which assume reinvestment of dividends and capital gains. Investment returns and principal will fluctuate and you may have a gain or loss when you sell shares. For the most current month-end performance information, please call 1-800-742-7272, or visit our Web site at www.williamblairfunds.com. The Fund involves a high level of risk and may not be appropriate for everyone. You could lose money by investing in the Fund. There can be no assurance that the Fund’s investment objective will be achieved or that the Fund’s investment strategies will be successful. The Fund is not a complete investment program. From time to time, the investment adviser may waive fees or reimburse expenses for the Fund. Without these waivers/reimbursements, performance would be lower. Class N shares are not subject to a sales load. Class I shares are not subject to a sales load or distribution (Rule 12b-1) fees. Class R6 shares are not subject to a sales load, distribution (Rule 12b-1) fees, or sub-transfer agent fees.

The performance highlights and graph presented above do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

The ICE BofAML US 3-Month Treasury Bill Index measures total return on cash, including price and interest income, based on short-term government Treasury Bills of about 90-day maturity. The Index is unmanaged, does not incur fees or expenses, and cannot be invested in directly.

This report identifies the Fund’s investments on June 30, 2020. These holdings are subject to change. Not all investments in the Fund performed the same, nor is there any guarantee that these investments will perform as well in the future. Market forecasts provided in this report may not necessarily come to pass.

Portfolio Allocation (Unaudited)

The table below provides the allocation of the Fund’s holdings as a percent of net assets as of June 30, 2020.

Category	% of net assets
Equity Exchange-Traded Funds		55.8	%
Fixed Income Exchange-Traded Funds		9.1
Foreign Government Bond		3.3
Repurchase Agreement		2.8
U.S. Government.		28.4
Cash and Other Assets, Less Liabilities		0.6
Net Assets		100.0	%

June 30, 2020

William Blair Funds

Macro Allocation Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

Issuer	Shares or Principal Amount		Value

Exchange-Traded Funds—64.9%
Equity Exchange-Traded Funds—55.8%
iShares Core MSCI Emerging Markets ETF		461,600	$	21,972
iShares MSCI Brazil ETF		36,800		1,058
iShares MSCI Chile ETF		210,700		5,310
SPDR S&P 500 ETF Trust		857,400		264,388
Utilities Select Sector SPDR Fund		23,900		1,349
Vietnam Enterprise Investments, Ltd. Class “C”		2,109,100		10,859
Total Equity Exchange-Traded Funds				304,936
Fixed Income Exchange-Traded Funds—9.1%
iShares iBoxx $ Investment Grade Corporate Bond ETF		123,800		16,651
iShares MBS ETF		250,000		27,675
SPDR Bloomberg Barclays High Yield Bond ETF		55,300		5,594
Total Fixed Income Exchange-Traded Funds				49,920
Total Exchange-Traded Funds—64.9% (cost $328,109)				354,856

Foreign Government Bond—3.3%
Malaysia—3.3%
Malaysia Government Bond, 4.160%, due 7/15/21	MYR 76,000			18,104
Total Foreign Government Bonds—3.3% (cost $18,525)				18,104

Repurchase Agreement—2.8%
Fixed Income Clearing Corporation, 0.000% dated 6/30/20, due 7/1/20, repurchase price $15,297, collateralized by U.S. Treasury Note, 1.625%, due 2/15/26, valued at $15,604		15,297		15,297
Total Repurchase Agreement—2.8% (cost $15,297)				15,297


Issuer	Principal Amount		Value

U.S. Government—28.4%
U.S. Treasury Bill, 1.776%, due 7/16/20(a)		17,500	$	17,499
U.S. Treasury Bill, 1.723%, due 8/13/20		17,500		17,497
U.S. Treasury Bill, 1.742%, due 9/10/20(a)		17,500		17,496
U.S. Treasury Bill, 1.542%, due 10/8/20(a)(b)		17,500		17,493
U.S. Treasury Bill, 1.558%, due 11/5/20(a)		17,500		17,491
U.S. Treasury Bill, 1.544%, due 12/3/20(a)		15,000		14,991
U.S. Treasury Bill, 0.165%, due 12/31/20		7,500		7,494
U.S. Treasury Bill, 1.424%, due 1/28/21		7,500		7,493
U.S. Treasury Bill, 1.280%, due 2/25/21(b)		7,500		7,493
U.S. Treasury Bill, 0.213%, due 3/25/21		7,500		7,491
U.S. Treasury Bill, 0.162%, due 4/22/21(a)		7,500		7,491
U.S. Treasury Bill, 0.157%, due 5/20/21		7,500		7,489
U.S. Treasury Bill, 0.192%, due 6/17/21		7,500		7,487
Total U.S. Government—28.4% (cost $154,398)				154,905
Total Investments in Securities—99.4% (cost $516,329)				543,162
Cash and other assets, less liabilities—0.6%				3,302
Net assets—100.0%			$	546,464

a) Security, or portion of security, is segregated as collateral for centrally cleared swaps and to cover initial margin requirements on open futures contracts aggregating a total value of $48,907 (in thousands).

(b) Security, or portion of security, is pledged as collateral for forward foreign currency contracts and for OTC swap contracts aggregating a total value of $7,431 (in thousands).

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Macro Allocation Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

Forward Foreign Currency Contracts
Settlement Date	Deliver/Receive	Counterparty	Local Currency (in thousands)		USD (Base) Purchased or Sold			Current Value			Net Unrealized Appreciation (Depreciation)
Purchased
7/15/20	Australian Dollar	Citibank N.A. London		4,891		$	3,370		$	3,376		$	6
7/15/20	Brazilian Real	Citibank N.A. London		138,291			27,068			25,415			(1,653	)
7/15/20	British Pound Sterling	Citibank N.A. London		25,010			31,668			30,992			(676	)
7/15/20	Chilean Peso	Citibank N.A. London		4,090,635			5,212			4,982			(230	)
7/15/20	Chinese Yuan Renminbi	Citibank N.A. London		22,564			3,191			3,189			(2	)
7/15/20	Colombian Peso	Citibank N.A. London		62,775,654			16,714			16,686			(28	)
7/15/20	Euro	Citibank N.A. London		897			1,008			1,008			—
7/15/20	Hong Kong Dollar	Citibank N.A. London		14,505			1,871			1,871			—
7/15/20	Indian Rupee	Citibank N.A. London		722,966			9,502			9,555			53
7/15/20	Indonesian Rupiah	Citibank N.A. London		11,511,384			794			792			(2	)
7/15/20	Israeli Shekel	Citibank N.A. London		11,743			3,396			3,391			(5	)
7/15/20	Japanese Yen	Citibank N.A. London		2,431,316			22,754			22,521			(233	)
7/15/20	Mexican Peso	Citibank N.A. London		756,850			33,640			32,873			(767	)
7/15/20	New Zealand Dollar	Citibank N.A. London		5,565			3,585			3,591			6
7/15/20	Norwegian Krone	Citibank N.A. London		392,407			41,524			40,770			(754	)
7/15/20	Philippine Peso	Citibank N.A. London		1,207,218			24,036			24,260			224
7/15/20	Russian Ruble	Citibank N.A. London		1,454,811			20,889			20,408			(481	)
7/15/20	Singapore Dollar	Citibank N.A. London		44,767			32,284			32,124			(160	)
7/15/20	South African Rand	Citibank N.A. London		388,756			22,839			22,371			(468	)
7/15/20	South Korean Won	Citibank N.A. London		4,800,793			4,004			4,002			(2	)
7/15/20	Swedish Krona	Citibank N.A. London		321,056			34,881			34,460			(421	)
7/15/20	Swiss Franc	Citibank N.A. London		707			746			746			—
7/15/20	Taiwan Dollar	Citibank N.A. London		59,659			2,034			2,034			—
7/15/20	Thai Baht	Citibank N.A. London		38,047			1,234			1,231			(3	)
7/16/20	New Turkish Lira	Citibank N.A. London		192,874			27,981			28,054			73
												$	(5,523	)
Sold
7/15/20	Australian Dollar	Citibank N.A. London		53,030		$	36,631		$	36,599		$	32
7/15/20	British Pound Sterling	Citibank N.A. London		537			664			665			(1	)
7/15/20	Canadian Dollar	Citibank N.A. London		11,099			8,193			8,175			18
7/15/20	Chinese Yuan Renminbi	Citibank N.A. London		338,057			47,741			47,779			(38	)
7/15/20	Colombian Peso	Citibank N.A. London		2,536,308			677			674			3
7/15/20	Czech Koruna	Citibank N.A. London		213,006			9,099			8,979			120
7/15/20	Euro	Citibank N.A. London		18,847			21,447			21,180			267
7/15/20	Hong Kong Dollar	Citibank N.A. London		144,003			18,576			18,579			(3	)
7/15/20	Indonesian Rupiah	Citibank N.A. London		172,529,287			11,907			11,863			44
7/15/20	Israeli Shekel	Citibank N.A. London		144,079			41,721			41,606			115
7/15/20	Japanese Yen	Citibank N.A. London		95,336			884			883			1
7/15/20	Mexican Peso	Citibank N.A. London		14,743			637			640			(3	)
7/15/20	New Zealand Dollar	Citibank N.A. London		69,555			45,031			44,886			145
7/15/20	Norwegian Krone	Citibank N.A. London		22,706			2,353			2,359			(6	)
7/15/20	Philippine Peso	Citibank N.A. London		122,168			2,451			2,455			(4	)
7/15/20	Russian Ruble	Citibank N.A. London		57,073			800			801			(1	)
7/15/20	Singapore Dollar	Citibank N.A. London		1,146			821			822			(1	)
7/15/20	South African Rand	Citibank N.A. London		16,953			974			976			(2	)
7/15/20	South Korean Won	Citibank N.A. London		33,427,381			27,877			27,864			13
7/15/20	Swedish Krona	Citibank N.A. London		6,848			735			735			—
7/15/20	Swiss Franc	Citibank N.A. London		32,728			34,849			34,556			293
7/15/20	Taiwan Dollar	Citibank N.A. London		854,783			28,973			29,146			(173	)
7/15/20	Thai Baht	Citibank N.A. London		926,519			29,977			29,977			—
7/16/20	New Turkish Lira	Citibank N.A. London		7,776			1,131			1,131			—
												$	819
Total net unrealized appreciation (depreciation) on forward foreign currency contracts												$	(4,704	)

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Macro Allocation Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

Futures Contracts

Number of Contracts	Description	Expiration Date	Local Currency	Notional Value (Local, in Thousands)		Notional Amount (USD)			Notional Value (USD)			Net Unrealized Appreciation (Depreciation)
Long
125	CAC 40 Index	July 2020	Euro		6,142		$	6,886		$	6,900		$	14
130	IBEX 35 Index	July 2020	Euro		9,373			10,899			10,530			(369	)
806	MSCI Singapore ETS Index	July 2020	Singapore Dollar		23,846			17,434			17,111			(323	)
2	HSCEI Index	July 2020	Hong Kong Dollar		965			127			124			(3	)
49	KOSPI 200 Index	September 2020	South Korean Won		3,439,800			2,952			2,860			(92	)
10	NIKKEI 225 Index	September 2020	Japanese Yen		111,300			1,069			1,031			(38	)
120	SPI 200 Index	September 2020	Australian Dollar		17,676			11,964			12,198			234
22	DAX Index	September 2020	Euro		6,779			7,624			7,616			(8	)
475	FTSE 100 Index	September 2020	British Pound Sterling		29,201			35,387			36,183			796
48	FTSE MIB Index	September 2020	Euro		4,629			5,185			5,201			16
													$	227
Short
12	Amsterdam Index	July 2020	Euro		1,343		$	1,519		$	1,509		$	10
53	OMXS 30 Index	July 2020	Swedish Krona		8,831			912			948			(36	)
78	HANG SENG Index	July 2020	Hong Kong Dollar		94,563			12,449			12,201			248
61	MSCI Taiwan Index	July 2020	U.S. Dollar		2,640			2,663			2,640			23
171	EURO-BTP	September 2020	Euro		24,603			27,160			27,642			(482	)
106	FTSE 40 Index	September 2020	South African Rand		53,310			2,989			3,072			(83	)
2	S&P TSX 60 Index	September 2020	Canadian Dollar		371			266			274			(8	)
994	EURO STOXX 50 Index	September 2020	Euro		32,037			34,622			35,993			(1,371	)
664	MSCI Emerging Markets Index	September 2020	U.S. Dollar		32,725			31,803			32,725			(922	)
334	MSCI Mexico Index	September 2020	U.S. Dollar		5,731			5,994			5,731			263
1,595	S&P 500 E Mini Index	September 2020	U.S. Dollar		246,444			243,266			246,444			(3,178	)
39	S&P E Mini Com Ser Index	September 2020	U.S. Dollar		2,758			2,822			2,758			64
27	XAK Technology	September 2020	U.S. Dollar		2,840			2,716			2,840			(124	)
43	XAY Cons Discret	September 2020	U.S. Dollar		5,546			5,588			5,546			42
77	10YR Can Bond	September 2020	Canadian Dollar		11,844			8,698			8,724			(26	)
													$	(5,580	)
Total net unrealized appreciation (depreciation) on futures contracts													$	(5,353	)

Centrally Cleared Interest Rate Swap

Floating
Rate
Reference

Pay/Receive
Floating
Rate

Fixed Rate

Pay/Receive
Payment
Frequency

Maturity
Date

Cleared
Exchange

Notional
Amount
(in thousands)

Upfront
Payment
Paid
(Received)

Value

Unrealized
Appreciation
(Depreciation)

China 1-Week Repo Rate

Pay

1.960%

June 2025

LCH

CNY 311,580

$(320)

$(773)

$(453)

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Macro Allocation Fund

Portfolio of Investments, June 30, 2020 (all dollar amounts in thousands) (unaudited)

Total Return Swaps

Reference Entity	Pay/Receive Floating Rate	Floating Rate	Maturity Date	Counterparty	Notional Amount (in thousands		)	Market Value			Unrealized Appreciation (Depreciation)
Swiss Market Index (Total Return)	Receive	3 Month LIBOR minus 0 bp	Sep 2020	Credit Suisse International	CHF	7,465		$	168			$	168
MSCI World Energy Sector Net Index	Pay	3 Month LIBOR minus 70 bp	Sep 2020	Credit Suisse International	$	16,826			(545	)			(545	)
MSCI Emerging Markets Indonesia Net Total Return USD	Pay	3 Month LIBOR minus 110 bp	Sep 2020	Citibank N.A.	$	5,152			(83	)			(83	)
RTS Index Future	Receive	0 bp	Sep 2020	Credit Suisse International	$	4,333			99				99
Euro-Bund Future	Receive	0 bp	Sep 2020	Credit Suisse International	EUR	2,975			(29	)			(29	)
10YR T-Note Future	Pay	0 bp	Sep 2020	Credit Suisse International	$	52,841			184				184
5YR T-Note Future	Pay	0 bp	Sep 2020	Credit Suisse International	$	22,461			47				47
												$	(159	)

Centrally Cleared Credit Default Swap

Reference
Entity

Buy/Sell
Protection

Fixed Deal
Pay Rate

Payment
Frequency

Maturity
Date

Cleared
Exchange

Notional
Amount
(in thousands

)

Upfront
Payment
Paid
(Received

)

Value

Unrealized
Appreciation
(Depreciation)

iTRAXX Europe 33

Sell

1.000%

June 2025

ICE

$10,095

$52

$194

142

Total net unrealized appreciation (depreciation) on swaps

(470)

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Statements of Assets and Liabilities

As of June 30, 2020 (dollar amounts in thousands) (unaudited)

			Large Cap		Mid Cap		Small-Mid
	Growth		Growth		Growth		Cap Core
	Fund		Fund		Fund		Fund
*Assets*
Investments in securities, at cost	$	149,946	$	407,282	$	57,158	$	212,385
Investments in securities, at value	$	249,604	$	522,073	$	70,447	$	199,437
Receivable for securities sold		1,834		2,596		1,359		1,991
Receivable for fund shares sold		47		2,467		13		2
Receivable from Adviser		1		52		21		39
Dividend and interest receivable		88		238		13		130
Total assets		251,574		527,426		71,853		201,599
*Liabilities*
Payable for securities purchased		1,835		5,836		766		1,128
Payable for fund shares redeemed		171		1,066		28		1,115
Management fee payable		151		248		53		153
Distribution fee payable		6		26		1		—
Other payables and accrued expenses		78		15		57		105
Total liabilities		2,241		7,191		905		2,501
Net assets	$	249,333	$	520,235	$	70,948	$	199,098
*Capital*
Composition of net assets
Paid in capital	$	125,147	$	387,041	$	53,747	$	224,050
Total distributable earnings (loss)		124,186		133,194		17,201		(24,952	)
Net assets	$	249,333	$	520,235	$	70,948	$	199,098

Class N shares
Net assets	$	31,139	$	131,166	$	5,003		—
Shares outstanding		3,058,143		7,834,131		461,507		—
Net asset value per share	$	10.18	$	16.74	$	10.84		—
Class I shares
Net assets	$	217,361	$	386,509	$	65,781	$	194,012
Shares outstanding		17,905,884		21,750,702		5,579,850		20,284,560
Net asset value per share	$	12.14	$	17.77	$	11.79	$	9.56
Class R6 shares
Net assets	$	833	$	2,560	$	164	$	5,086
Shares outstanding		68,542		144,181		13,911		531,649
Net asset value per share	$	12.16	$	17.76	$	11.80	$	9.57

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Statements of Operations

For the Period Ended June 30, 2020 (all amounts in thousands) (unaudited)

				Large Cap			Mid Cap			Small-Mid
	Growth			Growth			Growth			Cap Core
	Fund			Fund			Fund			Fund
*Investment income*
Dividends	$	955		$	2,018		$	192		$	1,053
Less foreign tax withheld		—			—			(1	)		(8	)
Interest		1			1			—			1
Total income		956			2,019			191			1,046
*Expenses*
Investment advisory fees		878			1,180			304			910
Distribution fees		37			110			6			—
Custodian fees		32			33			31			40
Transfer agent fees		33			31			7			10
Sub-transfer agent fees
Class N		22			49			3			—
Class I		63			108			41			130
Professional fees		24			25			20			23
Registration fees		38			32			28			19
Shareholder reporting fees		9			12			2			2
Trustee fees		10			10			3			5
Other expenses		7			9			5			6
Total expenses before expense limitation		1,153			1,599			450			1,145
Expenses waived or reimbursed by the Adviser
Class N		(12	)		(61	)		(9	)		—
Class I		—			(149	)		(113	)		(183	)
Class R6		—			(1	)		—			(2	)
Total expenses waived or reimbursed by the Adviser		(12	)		(211	)		(122	)		(185	)
Net expenses		1,141			1,388			328			960
Net investment income (loss)		(185	)		631			(137	)		86
*Realized and unrealized gain (loss)*
Net realized gain (loss) on transactions from:
Investments in securities		18,568			16,041			2,017			(12,119	)
Futures contracts		—			—			—			45
Total net realized gain (loss)		18,568			16,041			2,017			(12,074	)
Change in net unrealized appreciation (depreciation) of:
Investments in securities		(191	)		27,947			(2,832	)		(13,334	)
Change in net unrealized appreciation (depreciation)		(191	)		27,947			(2,832	)		(13,334	)
Net increase (decrease) in net assets resulting from operations	$	18,192		$	44,619		$	(952	)	$	(25,322	)

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Statements of Changes in Net Assets

For the Period Ended June 30, 2020 (unaudited) and the Year Ended December 31, 2019 (all amounts in thousands)

	Growth Fund						Large Cap Growth Fund						Mid Cap Growth Fund						Small-Mid Cap Core Fund
	2020			2019			2020			2019			2020			2019			2020			2019 (a)
*Operations*
Net investment income (loss)	$	(185	)	$	(175	)	$	631		$	475		$	(137	)	$	(171	)	$	86		$	4
Net realized gain (loss) on investments, and other assets and liabilities		18,568			24,088			16,041			17,324			2,017			7,108			(12,074	)		(16	)
Change in net unrealized appreciation (depreciation) on investments, and other assets and liabilities		(191	)		45,368			27,947			49,902			(2,832	)		13,055			(13,334	)		386
Net increase (decrease) in net assets resulting from operations		18,192			69,281			44,619			67,701			(952	)		19,992			(25,322	)		374
Distributions to shareholders from
Class N		—			(3,190	)		—			(3,981	)		—			(480	)		—			—
Class I		—			(17,880	)		—			(12,030	)		—			(5,507	)		—			(1	)
Class R6		—			(17	)		—			(97	)		—			(12	)		—			(3	)
Total distributions		—			(21,087	)		—			(16,108	)		—			(5,999	)		—			(4	)
*Capital stock transactions*
Proceeds from sale of shares		9,204			21,672			228,157			122,974			6,515			10,314			264,119			6,238
Shares issued in reinvestment of income dividends and capital gain distributions		—			20,274			—			13,134			—			5,817			—			4
Less cost of shares redeemed		(31,650	)		(62,229	)		(56,375	)		(62,827	)		(8,161	)		(12,695	)		(46,287	)		(24	)
Net increase (decrease) in net assets resulting from capital share transactions		(22,446	)		(20,283	)		171,782			73,281			(1,646	)		3,436			217,832			6,218
Increase (decrease) in net assets		(4,254	)		27,911			216,401			124,874			(2,598	)		17,429			192,510			6,588
*Net assets*
Beginning of period		253,587			225,676			303,834			178,960			73,546			56,117			6,588			—
End of period	$	249,333		$	253,587		$	520,235		$	303,834		$	70,948		$	73,546		$	199,098		$	6,588

(a) For the period from October 1, 2019 (Commencement of Operations) to December 31, 2019.

See accompanying Notes to Financial Statements.

Semiannual Report

June 30, 2020

Statements of Assets and Liabilities

As of June 30, 2020 (dollar amounts in thousands) (unaudited)

	Small-Mid Cap Growth Fund		Small-Mid Cap Value Fund					Small Cap Growth Fund		Small Cap Value Fund
Assets
Investments in securities, at cost	$	2,263,830		$	996		$	430,218	$	85,754
Investments in securities, at value	$	2,811,649		$	1,171		$	513,639	$	97,829
Cash		—			47			—		—
Receivable for securities sold		2,233			24			6,254		1,266
Receivable for fund shares sold		2,099			3			440		29
Receivable from Adviser		122			17			25		41
Dividend and interest receivable		622			1			146		79
Total assets		2,816,725			1,263			520,504		99,244
Liabilities
Payable for securities purchased		—			15			797		945
Payable for fund shares redeemed		3,032			—			892		50
Management fee payable		2,333			1			469		80
Distribution fee payable		57			—			30		1
Other payables and accrued expenses		503			43			128		54
Total liabilities		5,925			59			2,316		1,130
Net assets	$	2,810,800		$	1,204		$	518,188	$	98,114
Capital
Composition of net assets
Paid in capital	$	2,306,971		$	4,210		$	434,478	$	105,036
Total distributable earnings (loss)		503,829			(3,006	)		83,710		(6,922	)
Net assets	$	2,810,800		$	1,204		$	518,188	$	98,114

Class N shares
Net assets	$	273,268		$	161		$	141,873	$	7,027
Shares outstanding		10,683,610			18,792			5,264,016		684,696
Net asset value per share	$	25.58		$	8.54		$	26.95	$	10.26
Class I shares
Net assets	$	2,464,057		$	814		$	312,187	$	90,613
Shares outstanding		90,577,963			95,642			10,291,217		8,482,660
Net asset value per share	$	27.20		$	8.51		$	30.34	$	10.68
Class R6 shares
Net assets	$	73,475		$	229		$	64,128	$	474
Shares outstanding		2,698,296			27,019			2,112,763		44,374
Net asset value per share	$	27.23		$	8.49		$	30.35	$	10.69

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

Statements of Operations

For the Period June 30, 2020 (all amounts in thousands) (unaudited)

	Small-Mid Cap Growth Fund				Small-Mid Cap Value Fund				Small Cap Growth Fund				Small Cap Value Fund
*Investment income*
Dividends		$	6,865			$	50			$	1,482			$	1,239
Less foreign tax withheld			(65	)			—				(30	)			—
Interest			18				9				3				1
Total income			6,818				59				1,455				1,240
*Expenses*
Investment advisory fees			13,686				22				2,986				652
Distribution fees			361				—				187				12
Custodian fees			40				47				39				39
Transfer agent fees			183				1				57				24
Sub-transfer agent fees
Class N			229				—				115				9
Class I			1,409				2				196				95
Professional fees			104				19				39				33
Registration fees			82				28				52				26
Shareholder reporting fees			126				1				39				10
Trustee fees			105				—				25				16
Other expenses			51				3				8				7
Total expenses before expense limitation			16,376				123				3,743				923
Expenses waived or reimbursed by the Adviser
Class N			(158	)			(5	)			(74	)			(15	)
Class I			(817	)			(91	)			(105	)			(173	)
Class R6			(1	)			(4	)			—				(1	)
Total expenses waived or reimbursed by the Adviser			(976	)			(100	)			(179	)			(189	)
Net expenses			15,400				23				3,564				734
Net investment income (loss)			(8,582	)			36				(2,109	)			506
*Realized and unrealized gain (loss)*
Net realized gain (loss) on transactions from:
Investments in securities			(59,181	)			(3,166	)			7,655				(16,350	)
Redemptions in-kind			6,220				—				—				—
Total net realized gain (loss)			(52,961	)			(3,166	)			7,655				(16,350	)
Change in net unrealized appreciation (depreciation) of:
Investments in securities			55,293				(253	)			(42,004	)			(30,436	)
Change in net unrealized appreciation (depreciation)			55,293				(253	)			(42,004	)			(30,436	)
Net increase (decrease) in net assets resulting from operations		$	(6,250	)		$	(3,383	)		$	(36,458	)		$	(46,280	)

See accompanying Notes to Financial Statements.

100

Semiannual Report

June 30, 2020

Statements of Changes in Net Assets

For the Period Ended June 30, 2020 (unaudited) and the Year Ended December 31, 2019 (all amounts in thousands)

		Small-Mid Cap Growth Fund					Small-Mid Cap Value Fund								Small Cap Growth Fund						Small Cap Value Fund
		2020			2019		2020				2019				2020			2019			2020			2019
*Operations*
Net investment income (loss)	$	(8,582	)	$	(15,808	)		$	36			$	40		$	(2,109	)	$	(4,727	)	$	506		$	3,710
Net realized gain (loss) on investments, and other assets and liabilities		(52,961	)		293,543				(3,166	)			109			7,655			10,576			(16,350	)		73,420
Change in net unrealized appreciation (depreciation) on investments, and other assets and liabilities		55,293			439,745				(253	)			446			(42,004	)		125,876			(30,436	)		15,381
Net increase (decrease) in net assets resulting from operations		(6,250	)		717,480				(3,383	)			595			(36,458	)		131,725			(46,280	)		92,511
*Distributions to shareholders from*
Class N		—			(24,075	)			—				(6	)		—			(4,188	)		(2,077	)		(498	)
Class I		—			(172,835	)			—				(131	)		—			(8,605	)		(26,233	)		(14,700	)
Class R6		—			(2,668	)			—				(3	)		—			(1,345	)		(101	)		(16	)
Total distributions		—			(199,578	)			—				(140	)		—			(14,138	)		(28,411	)		(15,214	)
*Capital stock transactions*
Proceeds from sale of shares		420,380			835,740				3,164				7,068			56,548			265,349			10,771			49,983
Shares issued in reinvestment of income dividends and capital gain distributions		—			193,454				—				139			—			14,035			27,328			14,998
Less cost of shares redeemed		(509,144	)		(1,045,252	)			(6,105	)			(1,813	)		(172,439	)		(305,741	)		(40,572	)		(458,515	)
Net increase (decrease) in net assets resulting from capital share transactions		(88,764	)		(16,058	)			(2,941	)			5,394			(115,891	)		(26,357	)		(2,473	)		(393,534	)
Increase (decrease) in net assets		(95,014	)		501,844				(6,324	)			5,849			(152,349	)		91,230			(77,164	)		(316,237	)
*Net assets*
Beginning of period		2,905,814			2,403,970				7,528				1,679			670,537			579,307			175,278			491,515
End of period	$	2,810,800		$	2,905,814			$	1,204			$	7,528		$	518,188		$	670,537		$	98,114		$	175,278

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

101

Statements of Assets and Liabilities

As of June 30, 2020 (dollar amounts in thousands) (unaudited)

	Global Leaders Fund			International Leaders Fund			International Growth Fund			Institutional International Growth Fund
Assets
Investments in securities, at cost		$	64,360		$	515,282		$	1,365,344		$	1,132,695
Investments in securities, at value		$	97,010		$	661,991		$	1,882,800		$	1,552,596
Cash			9			84			122			117
Foreign currency, at value (cost $— ; $— ; $66; $63)			—			—			66			63
Receivable for securities sold			34			—			—			228,801
Receivable for fund shares sold			1			682			588			186
Receivable from Adviser			26			46			1			—
Dividend and interest receivable			125			821			4,878			3,339
Total assets			97,205			663,624			1,888,455			1,785,102
Liabilities
Payable for securities purchased			—			311			3,162			2,026
Payable for fund shares redeemed			—			102			1,865			236,001
Management fee payable			86			456			1,550			1,367
Distribution fee payable			2			2			47			—
Foreign capital gains tax liability			—			197			—			17
Other payables and accrued expenses			82			95			623			309
Total liabilities			170			1,163			7,247			239,720
Net assets		$	97,035		$	662,461		$	1,881,208		$	1,545,382

Capital
Composition of net assets
Paid in capital		$	44,585		$	520,933		$	1,366,029		$	1,122,363
Total distributable earnings (loss)			52,450			141,528			515,179			423,019
Net assets		$	97,035		$	662,461		$	1,881,208		$	1,545,382
Class N shares
Net assets		$	8,862		$	8,102		$	232,632			—
Shares outstanding			581,013			453,917			7,816,757			—
Net asset value per share		$	15.25		$	17.85		$	29.76			—
Class I shares
Net assets		$	86,976		$	187,634		$	1,591,582			—
Shares outstanding			5,691,626			10,472,996			52,185,622			—
Net asset value per share		$	15.28		$	17.92		$	30.50			—
Institutional/Class R6 shares
Net assets		$	1,197		$	466,725		$	56,994		$	1,545,382
Shares outstanding			78,297			26,047,546			1,868,239			88,481,200
Net asset value per share		$	15.29		$	17.92		$	30.51		$	17.47

See accompanying Notes to Financial Statements.

102

Semiannual Report

June 30, 2020

Statements of Operations

For the Period Ended June 30, 2020 (all amounts in thousands) (unaudited)

	Global Leaders Fund				International Leaders Fund				International Growth Fund				Institutional International Growth Fund
*Investment income*
Dividends		$	799			$	4,429			$	12,135			$	11,360
Less foreign tax withheld			(50	)			(482	)			(1,200	)			(1,128	)
Interest			1				4				4				5
Total income			750				3,951				10,939				10,237
Expenses
Investment advisory fees			616				2,621				9,301				8,069
Distribution fees			10				12				423				—
Custodian fees			39				61				165				132
Transfer agent fees			5				25				85				34
Sub-transfer agent fees
Class N			6				7				300				—
Class I			38				65				601				—
Professional fees			27				46				95				90
Registration fees			31				30				44				15
Shareholder reporting fees			2				9				60				8
Trustee fees			7				21				85				72
Other expenses			7				16				29				27
Total expenses before expense limitation			788				2,913				11,188				8,447
Expenses waived or reimbursed by the Adviser
Class N			(11	)			(8	)			(88	)			—
Class I			(97	)			(79	)			—				—
Institutional/Class R6			(27	)			(146	)			—				—
Total expenses waived or reimbursed by the Adviser			(135	)			(233	)			(88	)			—
Net expenses			653				2,680				11,100				8,447
Net investment income (loss)			97				1,271				(161	)			1,790
*Realized and unrealized gain (loss)*
Net realized gain (loss) on transactions from:
Investments in securities, net of foreign taxes, if applicable			12,076				(2,957	)			15,464				41,231
Redemptions in-kind			7,974				—				—				7,699
Foreign currency transactions			(16	)			(86	)			(290	)			(156	)
Total net realized gain (loss)			20,034				(3,043	)			15,174				48,774
Change in net unrealized appreciation (depreciation) of:
Investments in securities			(16,195	)			(7,610	)			(27,500	)			(52,107	)
Foreign currency translations			—				46				(65	)			(95	)
Change in net unrealized appreciation (depreciation)			(16,195	)			(7,564	)			(27,565	)			(52,202	)
Net increase (decrease) in net assets resulting from operations		$	3,936			$	(9,336	)		$	(12,552	)		$	(1,638	)

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

103

Statements of Changes in Net Assets

For the Period Ended June 30, 2020 (unaudited) and the Year Ended December 31, 2019 (all amounts in thousands)

	Global Leaders Fund						International Leaders Fund						International Growth Fund						Institutional International Growth Fund
	2020			2019			2020			2019			2020			2019			2020			2019
*Operations*
Net investment income (loss)	$	97		$	690		$	1,271		$	4,360		$	(161	)	$	12,129		$	1,790		$	14,030
Net realized gain (loss) on investments, and other assets and liabilities		20,034			21,561			(3,043	)		138			15,174			31,125			48,774			4,333
Change in net unrealized appreciation (depreciation) on investments, and other assets and liabilities		(16,195	)		27,856			(7,564	)		139,075			(27,565	)		530,581			(52,202	)		472,155
Net increase (decrease) in net assets resulting from operations		3,936			50,107			(9,336	)		143,573			(12,552	)		573,835			(1,638	)		490,518
Distributions to shareholders from
Class N		—			(99	)		—			(37	)		—			(5,328	)		—			—
Class I		—			(1,500	)		—			(981	)		—			(19,998	)		—			—
Institutional/Class R6		—			(656	)		—			(2,772	)		—			(819	)		—			(17,917	)
Total distributions		—			(2,255	)		—			(3,790	)		—			(26,145	)		—			(17,917	)
Capital stock transactions
Proceeds from sale of shares		10,540			16,564			90,159			150,318			268,419			290,402			101,823			192,878
Shares issued in reinvestment of income dividends and capital gain distributions		—			2,241			—			3,249			—			24,177			—			17,852
Less cost of shares redeemed		(89,150	)		(65,648	)		(72,266	)		(49,445	)		(483,718	)		(856,554	)		(447,714	)		(574,855	)
Net increase (decrease) in net assets resulting from capital share transactions		(78,610	)		(46,843	)		17,893			104,122			(215,299	)		(541,975	)		(345,891	)		(364,125	)
Increase (decrease) in net assets		(74,674	)		1,009			8,557			243,905			(227,851	)		5,715			(347,529	)		108,476
Net assets
Beginning of period		171,709			170,700			653,904			409,999			2,109,059			2,103,344			1,892,911			1,784,435
End of period	$	97,035		$	171,709		$	662,461		$	653,904		$	1,881,208		$	2,109,059		$	1,545,382		$	1,892,911

See accompanying Notes to Financial Statements.

104

Semiannual Report

June 30, 2020

Statements of Assets and Liabilities

As of June 30, 2020 (dollar amounts in thousands) (unaudited)

	International			Emerging		Emerging		Emerging
	Small Cap			Markets		Markets		Markets
	Growth			Leaders		Growth		Small Cap
	Fund			Fund		Fund		Growth Fund
Assets
Investments in securities, at cost		$	212,972	$	178,120	$	600,068		$	204,655
Investments in securities, at value		$	261,281	$	222,306	$	830,077		$	259,697
Foreign currency, at value (cost $195; $— ; $643; $816)			196		—		643			817
Receivable for securities sold			—		954		1,701			1,555
Receivable for fund shares sold			179		101		3,032			66
Receivable from Adviser			—		35		—			43
Dividend and interest receivable			1,137		458		1,213			396
Total assets			262,793		223,854		836,666			262,574
Liabilities
Payable for securities purchased			—		—		628			1,311
Payable for fund shares redeemed			37		3		6,499			36
Management fee payable			214		198		730			232
Distribution fee payable			1		—		2			1
Foreign capital gains tax liability			—		—		457			—
Other payables and accrued expenses			200		186		395			426
Total liabilities			452		387		8,711			2,006
Net assets		$	262,341	$	223,467	$	827,955		$	260,568
Capital
Composition of net assets
Paid in capital		$	232,357	$	188,195	$	614,106		$	249,031
Total distributable earnings (loss)			29,984		35,272		213,849			11,537
Net assets		$	262,341	$	223,467	$	827,955		$	260,568

Class N shares
Net assets		$	2,530	$	1,391	$	7,934		$	3,314
Shares outstanding			188,464		138,543		562,190			195,292
Net asset value per share		$	13.42	$	10.04	$	14.11		$	16.97
Class I shares
Net assets		$	126,889	$	43,268	$	75,381		$	122,722
Shares outstanding			9,350,127		4,298,432		5,278,540			7,179,432
Net asset value per share		$	13.57	$	10.07	$	14.28		$	17.09
Class R6 shares
Net assets		$	132,922	$	178,808	$	744,640		$	134,532
Shares outstanding			9,737,564		17,779,815		51,663,560			7,856,017
Net asset value per share		$	13.65	$	10.06	$	14.41		$	17.12

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

105

Statements of Operations

For the Period Ended June 30, 2020 (all amounts in thousands) (unaudited)

													Emerging
	International				Emerging				Emerging				Markets
	Small Cap				Markets				Markets				Small Cap
	Growth				Leaders				Growth				Growth
	Fund				Fund				Fund				Fund
Investment income
Dividends		$	2,045			$	1,836			$	4,753			$	1,377
Less foreign tax withheld			(183	)			(209	)			(562	)			(117	)
Interest			1				2				56				1
Total income			1,863				1,629				4,247				1,261
Expenses
Investment advisory fees			1,253				1,166				4,151				1,403
Distribution fees			4				2				9				4
Custodian fees			73				72				200				167
Transfer agent fees			12				6				17				29
Sub-transfer agent fees
Class N			2				1				3				3
Class I			70				14				35				59
Professional fees			40				39				82				97
Registration fees			29				31				31				29
Shareholder reporting fees			18				6				3				15
Trustee fees			14				10				32				12
Other expenses			7				7				16				8
Total expenses before expense limitation			1,522				1,354				4,579				1,826
Expenses waived or reimbursed by the Adviser
Class N			—				(2	)			—				(5	)
Class I			—				(37	)			—				(106	)
Class R6			—				(136	)			—				(83	)
Total expenses waived or reimbursed by the Adviser			—				(175	)			—				(194	)
Net expenses			1,522				1,179				4,579				1,632
Net investment income (loss)			341				450				(332	)			(371	)
Realized and unrealized gain (loss)
Net realized gain (loss) on transactions from:
Investments in securities, net of foreign taxes, if applicable			1,331				(9,096	)			(14,889	)			5,871
Foreign currency transactions			(30	)			(123	)			(951	)			(238	)
Total net realized gain (loss)			1,301				(9,219	)			(15,840	)			5,633
Change in net unrealized appreciation (depreciation) of:
Investments in securities			(12,216	)			(3,322	)			51,053				(5,436	)
Foreign currency translations			(13	)			875				1,530				(19	)
Change in net unrealized appreciation (depreciation)			(12,229	)			(2,447	)			52,583				(5,455	)
Net increase (decrease) in net assets resulting from operations		$	(10,587	)		$	(11,216	)		$	36,411			$	(193	)

See accompanying Notes to Financial Statements.

106

Semiannual Report

June 30, 2020

Statements of Changes in Net Assets

For the Period Ended June 30, 2020 (unaudited) and the Year Ended December 31, 2019 (all amounts in thousands)

	International																		Emerging Markets
	Small Cap						Emerging Markets						Emerging Markets						Small Cap
	Growth Fund						Leaders Fund						Growth Fund						Growth Fund
	2020			2019			2020			2019			2020			2019			2020			2019
Operations
Net investment income (loss)	$	341		$	2,537		$	450		$	1,416		$	(332	)	$	9,209		$	(371	)	$	848
Net realized gain (loss) on investments, and other assets and liabilities		1,301			(185	)		(9,219	)		5,825			(15,840	)		42,250			5,633			(596	)
Change in net unrealized appreciation (depreciation) on investments, and other assets and liabilities		(12,229	)		92,376			(2,447	)		48,207			52,583			143,459			(5,455	)		51,198
Net increase (decrease) in net assets resulting from operations		(10,587	)		94,728			(11,216	)		55,448			36,411			194,918			(193	)		51,450
Distributions to shareholders from
Class N		—			(3	)		—			(11	)		—			(311	)		—			—
Class I		—			(460	)		—			(393	)		—			(3,046	)		—			(236	)
Class R6		—			(597	)		—			(1,820	)		—			(28,573	)		—			(286	)
Total distributions		—			(1,060	)		—			(2,224	)		—			(31,930	)		—			(522	)
Capital stock transactions
Proceeds from sale of shares		12,079			45,917			23,357			38,679			84,384			171,633			52,171			60,868
Shares issued in reinvestment of income dividends and capital gain distributions		—			969			—			2,206			—			26,669			—			465
Less cost of shares redeemed		(48,217	)		(172,212	)		(26,957	)		(54,740	)		(83,032	)		(312,069	)		(69,031	)		(111,575	)
Net increase (decrease) in net assets resulting from capital share transactions		(36,138	)		(125,326	)		(3,600	)		(13,855	)		1,352			(113,767	)		(16,860	)		(50,242	)
Increase (decrease) in net assets		(46,725	)		(31,658	)		(14,816	)		39,369			37,763			49,221			(17,053	)		686
Net assets
Beginning of period		309,066			340,724			238,283			198,914			790,192			740,971			277,621			276,935
End of period	$	262,341		$	309,066		$	223,467		$	238,283		$	827,955		$	790,192		$	260,568		$	277,621

See accompanying Notes to Financial Statements.

June 30, 2020

William Blair Funds

107

Statements of Assets and Liabilities

As of June 30, 2020 (dollar amounts in thousands) (unaudited)

							Low			Macro
	Bond			Income			Duration			Allocation
	Fund			Fund			Fund			Fund
Assets
Investments in securities, at cost	$	261,635		$	51,444		$	112,781			$	516,329
Investments in securities, at value	$	280,685		$	53,021		$	113,679			$	543,162
Receivable for securities sold		—			—			—				15,512
Receivable for fund shares sold		1,222			166			3,290				276
Receivable from Adviser		19			7			12				10
Dividend and interest receivable		1,798			246			391				1,576
Unrealized appreciation on swap contracts		—			—			—				498
Unrealized appreciation on forward foreign currency contracts		—			—			—				1,413
Total assets		283,724			53,440			117,372				562,447
Liabilities
Payable for futures variation margin		—			—			—				3,752
Payable for securities purchased		6,888			348			5,813				4,436
Payable for fund shares redeemed		416			88			67				494
Unrealized depreciation on swap contracts		—			—			—				657
Unrealized depreciation on forward foreign currency contracts		—			—			—				6,117
Management fee payable		67			16			23				370
Distribution fee payable		4			3			1				2
Distributions payable to shareholders		134			9			51				—
Other payables and accrued expenses		60			43			55				155
Total liabilities		7,569			507			6,010				15,983
Net assets	$	276,155		$	52,933		$	111,362			$	546,464
Capital
Composition of net assets
Paid in capital	$	278,430		$	58,088		$	139,014			$	744,653
Total distributable earnings (loss)		(2,275	)		(5,155	)		(27,652	)			(198,189	)
Net assets	$	276,155		$	52,933		$	111,362			$	546,464

Class N shares
Net assets	$	30,598		$	21,204		$	7,192			$	8,519
Shares outstanding		2,871,527			2,436,104			826,898				801,351
Net asset value per share	$	10.66		$	8.70		$	8.70			$	10.63
Class I shares
Net assets	$	199,616		$	31,659		$	63,588			$	248,277
Shares outstanding		18,932,705			3,661,908			7,316,160				23,500,815
Net asset value per share	$	10.54		$	8.65		$	8.69			$	10.56
Class R6 shares
Net assets	$	45,941		$	70		$	40,582			$	289,668
Shares outstanding		4,359,352			8,073			4,667,469				27,385,803
Net asset value per share	$	10.54		$	8.65		$	8.69			$	10.58

See accompanying Notes to Financial Statements.

108

Semiannual Report

June 30, 2020

Statements of Operations

For the Period Ended June 30, 2020 (all amounts in thousands) (unaudited)

								Low				Macro
	Bond			Income				Duration				Allocation
	Fund			Fund				Fund				Fund
Investment income
Dividends	$	—			$	—			$	—			$	3,603
Interest		4,397				659				887				1,742
Total income		4,397				659				887				5,345
Expenses
Investment advisory fees		415				98				119				2,529
Distribution fees		23				15				2				13
Custodian fees		55				38				38				66
Transfer agent fees		36				5				3				127
Sub-transfer agent fees
Class N		21				14				1				8
Class I		86				7				7				142
Professional fees		27				20				18				51
Registration fees		32				28				29				26
Shareholder reporting fees		13				3				1				20
Trustee fees		14				2				4				41
Other expenses		7				5				5				70
Total expenses before expense limitation		729				235				227				3,093
Expenses waived or reimbursed by the Adviser
Class N		(17	)			(22	)			(3	)			(3	)
Class I		(66	)			(19	)			(35	)			(10	)
Class R6		(7	)			—				(37	)			—
Total expenses waived or reimbursed by the Adviser		(90	)			(41	)			(75	)			(13	)
Net expenses		639				194				152				3,080
Net investment income (loss)		3,758				465				735				2,265
Realized and unrealized gain (loss)
Net realized gain (loss) on transactions from:
Investments in securities		170				21				(364	)			(4,464	)
Options		—				—				—				(6,041	)
Futures contracts		—				—				—				9,318
Swaps		405				(34	)			(56	)			5,111
Forward foreign currency contracts		—				—				—				(9,183	)
Foreign currency transactions		—				—				—				(1,272	)
Total net realized gain (loss)		575				(13	)			(420	)			(6,531	)
Change in net unrealized appreciation (depreciation) of:
Investments in securities		6,351				1,168				1,163				(40,593	)
Futures contracts		—				—				—				(373	)
Swaps		626				—				—				(1,481	)
Forward foreign currency contracts		—				—				—				(1,892	)
Foreign currency translations		—				—				—				43
Change in net unrealized appreciation (depreciation)		6,977				1,168				1,163				(44,296	)
Net increase (decrease) in net assets resulting from operations	$	11,310			$	1,620			$	1,478			$	(48,562	)

See accompanying Notes to Financial Statements.

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Statements of Changes in Net Assets

For the Period Ended June 30, 2020 (unaudited) and the Year Ended December 31, 2019 (all amounts in thousands)

															Low Duration						Macro Allocation
	Bond Fund							Income Fund							Fund						Fund
	2020				2019			2020				2019			2020			2019			2020			2019
Operations
Net investment income (loss)		$	3,758		$	11,304			$	465		$	1,286		$	735		$	2,273		$	2,265		$	10,006
Net realized gain (loss) on investments, and other assets and liabilities			575			5,641				(13	)		98			(420	)		(575	)		(6,531	)		(33,187	)
Change in net unrealized appreciation (depreciation) on investments, and other assets and liabilities			6,977			25,603				1,168			2,291			1,163			1,875			(44,296	)		58,793
Net increase (decrease) in net assets resulting from operations			11,310			42,548				1,620			3,675			1,478			3,573			(48,562	)		35,612
Distributions to shareholders from
Class N			(572	)		(2,191	)			(313	)		(699	)		(39	)		(60	)		—			(503	)
Class I			(3,880	)		(10,482	)			(524	)		(1,385	)		(664	)		(1,999	)		—			(15,861	)
Class R6			(857	)		(2,442	)			(1	)		(1	)		(641	)		(1,674	)		—			(16,522	)
Total distributions			(5,309	)		(15,115	)			(838	)		(2,085	)		(1,344	)		(3,733	)		—			(32,886	)
Capital stock transactions
Proceeds from sale of shares			34,241			80,419				8,429			17,977			40,452			14,009			58,225			222,795
Shares issued in reinvestment of income dividends and capital gain distributions			4,477			13,243				781			1,968			1,015			2,946			—			27,731
Less cost of shares redeemed			(50,699	)		(261,506	)			(8,402	)		(27,407	)		(6,754	)		(45,646	)		(213,999	)		(424,270	)
Net increase (decrease) in net assets resulting from capital share transactions			(11,981	)		(167,844	)			808			(7,462	)		34,713			(28,691	)		(155,774	)		(173,744	)
Increase (decrease) in net assets			(5,980	)		(140,411	)			1,590			(5,872	)		34,847			(28,851	)		(204,336	)		(171,018	)
Net assets
Beginning of period			282,135			422,546				51,343			57,215			76,515			105,366			750,800			921,818
End of period		$	276,155		$	282,135			$	52,933		$	51,343		$	111,362		$	76,515		$	546,464		$	750,800

See accompanying Notes to Financial Statements.

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

(1) Organization

(a) Description of the Trust

William Blair Funds (the “Trust”) is a Delaware statutory trust registered under the Investment Company Act of 1940, as amended (the “1940 Act”), as an open-end management investment company. As of the date of this report, the Trust has the following twenty funds (the “Funds”) available for sale, each with its own investment objective and policies. For each Fund, the number of shares authorized is unlimited.

U.S. Equity Funds	Global Equity Fund	Fixed Income Funds
Growth	Global Leaders	Bond
Large Cap Growth		Income
Mid Cap Growth	International Equity Funds	Low Duration
Small-Mid Cap Core	International Leaders
Small-Mid Cap Growth	International Growth	Multi-Asset and Alternative Fund
Small-Mid Cap Value	Institutional International Growth	Macro Allocation
Small Cap Growth	International Small Cap Growth
Small Cap Value	Emerging Markets Leaders
	Emerging Markets Growth
	Emerging Markets Small Cap Growth

William Blair Investment Management, LLC (the “Adviser”) serves as the Trust’s investment adviser. William Blair & Company, L.L.C. (“WBC” or the “Distributor”), an affiliate of the Adviser, serves as the Trust’s principal underwriter and distributor.

(b) Share Classes

Each Fund is comprised of Class N, Class I and Class R6 shares, except Small-Mid Cap Core Fund, which is comprised of Class I and Class R6 shares, and Institutional International Growth Fund, which does not offer multiple classes of shares.

Class N shares are available to the general public, either directly through the Trust’s distributor or through a select number of financial intermediaries. Class N shares are sold without any sales load and carry an annual 12b-1 distribution fee at a fixed rate (0.25% for the U.S. Equity, Global Equity, International Equity and Multi-Asset and Alternative Funds and 0.15% for the Fixed Income Funds as discussed in Note 4(b) – Transactions with Affiliates – Underwriting Distribution Services and Shareholder Administration Agreements) and a sub-transfer agent fee that is not a fixed rate and varies by Fund and class, as discussed below.

Class I shares are available to certain retirement and deferred compensation plans, clients of certain financial intermediaries, and asset-based fee advisory clients of William Blair. The minimum initial investment for a Class I account is $500,000, subject to certain exceptions. Class I shares do not carry any sales load or distribution fees and generally have lower ongoing expenses than Class N shares. Class I shares have a sub-transfer agent fee that is not a fixed rate and varies by Fund and class, as discussed below.

Class R6 shares are available to certain retirement and deferred compensation plans, clients of certain financial intermediaries, asset-based fee advisory clients of William Blair, and additional types of investors, provided that neither the investor nor the financial intermediary requires the Funds to make any type of servicing or administrative payment. The minimum initial investment for a Class R6 account is $1 million, subject to certain exceptions.

Shares of the Institutional International Growth Fund require a minimum initial investment of $5 million, subject to certain exceptions.

Class R6 shares and the Institutional International Growth Fund do not carry any sales load, distribution fees or sub-transfer agents fees. Class R6 shares of a Fund generally have lower ongoing expenses than the Fund’s Class N and Class I shares.

Sub-transfer agent fees: For Class N and Class I shares, the Funds may reimburse WBC for fees paid to intermediaries such as banks, broker-dealers, financial advisers or other financial institutions for sub-administration, sub-transfer agency and other services provided to investors whose shares of record are held in omnibus, other group accounts, retirement plans or accounts

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

traded through registered securities clearing agents. These fees may vary based on, for example, the nature of services provided, but generally range up to 0.15% of the assets of the class serviced or maintained by the intermediary or up to $15 per sub-account maintained by the intermediary, depending on the method by which the intermediary charges for the services.

(c) Fund Objectives

The investment objectives of the Funds are as follows:

U.S. Equity Funds	Long-term capital appreciation.
Global Equity Fund	Long-term capital appreciation.
International Equity Funds	Long-term capital appreciation.
Bond Fund	Outperform the Bloomberg Barclays U.S. Aggregate Index by maximizing total return through a combination of income and capital appreciation.
Income Fund	High level of current income with relative stability of principal.
Low Duration Fund	Maximize total return. Total return includes both income and capital appreciation.
Macro Allocation Fund	Maximize long-term risk-adjusted total return.

(2) Significant Accounting Policies

The following is a summary of the Trust’s significant accounting policies in effect during the periods covered by the financial statements, which are in accordance with U.S. generally accepted accounting principles (“US GAAP”), which includes the accounting and reporting guidelines under Accounting Standards Topic 946, Financial Services—Investment Companies.

(a) Investment income and transactions

Investment income, realized and unrealized gains and losses, and certain Fund level expenses and expense reductions, if any, are allocated based on the relative net assets of each class, except for certain class-specific expenses, which are charged directly to the appropriate class. Differences in class expenses may result in the payment of different per share dividends by class. All share classes of the Funds have equal rights with respect to voting, subject to class specific arrangements.

Dividend income and expenses are recorded on the ex-dividend date, except for those dividends from certain foreign securities that are recorded when the information is available.

Interest income is recorded on an accrual basis, adjusted for amortization of premium or accretion of discount. Variable rate bonds and floating rate notes earn interest at coupon rates that fluctuate at specific time intervals. The interest rates shown in the Portfolio of Investments for the Bond, Income, Low Duration and Macro Allocation Funds were the rates in effect on June 30, 2020. Put bonds may be redeemed at the discretion of the holder on specified dates prior to maturity.

Premiums and discounts are amortized and accreted, respectively, on a straight-line basis for short-term investments and on an effective interest method for long-term investments.

Paydown gains and losses on mortgage-backed and asset-backed securities are treated as an adjustment to interest income. For the period ended June 30, 2020, the Bond, Income and Low Duration Funds recognized a reduction of interest income and a corresponding increase in net realized gain of $1,684, $373 and $610, respectively (in thousands). This reclassification had no effect on the net increase (decrease) in net assets resulting from operations, net asset value or the net assets of the Funds.

The Funds do not isolate the portion of operations resulting from fluctuations in foreign currency exchange rates on investments from the fluctuations arising from changes in the value of securities held. Such currency fluctuations are included with the net realized and unrealized gain or loss from investments.

Reported net realized foreign currency gains or losses arise from disposition of foreign currency, the difference in the foreign exchange rates between the trade and settlement dates on securities transactions, and the difference between the amounts of dividends, interest and foreign withholding taxes recorded on the ex-date or accrual date and the U.S. dollar equivalent of the amounts actually received or paid. Net unrealized foreign exchange gains and losses arise from changes (due to the changes in the exchange rate) in the value of foreign currency and other assets and liabilities denominated in foreign currencies held at period end.

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

For financial reporting purposes, security and shareholder transactions are recorded on trade date in accordance with US GAAP. Realized gains and losses from securities transactions are recognized on a specifically identified cost basis.

Awards from class action litigation may be recorded as a reduction of cost. If the Funds no longer own the applicable securities, the proceeds are recorded as realized gains.

(b) Share Valuation and Distributions to Shareholders

Shares are sold and redeemed on a continuous basis at net asset value. The net asset value per share is determined separately for each class by dividing the Fund’s net assets attributable to that class by the number of shares of the class outstanding as of the close of regular trading on the New York Stock Exchange (the “NYSE”), which is generally 4:00 p.m. Eastern time, on each day the NYSE is open.

Distributions from net investment income, if any, for all Equity and Multi-Asset and Alternative Funds are declared and paid at least annually. Distributions from net investment income for the Fixed Income Funds are declared daily and paid monthly. Capital gain distributions, if any, for all Funds, are declared and paid at least annually in December and/or January. The Small Cap Value Fund paid a distribution from capitals gains in March 2020. Distributions payable to shareholders are recorded on the ex-dividend date.

(c) Foreign Currency Translation

The Funds may invest in securities denominated in foreign currencies. As such, assets and liabilities denominated in foreign currencies are translated into U.S. dollar amounts at the current exchange rate on the date of valuation. The values of foreign investments, open forward foreign currency contracts, and cash denominated in foreign currencies are translated into U.S. dollars using a spot market rate of exchange as of the time of the determination of each Fund’s net asset value, typically 4:00 p.m. Eastern time on days when there is regular trading on the NYSE. Payables and receivables for securities transactions, dividends, interest income and tax reclaims are translated into U.S. dollars using a spot market rate of exchange as of 4:00 p.m. Eastern time. Settlement of purchases and sales and dividend and interest receipts are translated into U.S. dollars using a spot market rate of exchange as of 11:00 a.m. Eastern time.

(d) Income Taxes

Each Fund intends to comply with the provisions of Subchapter M of the Internal Revenue Code of 1986, as amended (the “Code”), in order to qualify as regulated investment companies. Each Fund intends to make the requisite distributions of income and capital gains to its shareholders sufficient to relieve it from all, or substantially all, federal income and excise taxes. No provision for federal income and excise taxes has been made.

Certain Funds may be subject to foreign income taxes imposed on realized gains on securities of issuers from certain foreign countries. Such taxes, if applicable, are included within net realized gain (loss) on transactions from investments in securities in the Statement of Operations.

Management evaluates tax positions taken or expected to be taken in the course of preparing the Funds’ tax returns to determine whether it is “more likely than not” that each tax position would be sustained upon examination by a taxing authority based on the technical merits of the positions. Tax positions not deemed to meet the “more likely than not” threshold would be recorded as a tax benefit or expense in the current year. Management has evaluated all of the uncertain tax positions of the Funds and has determined that no liability is required to be recorded in the financial statements.

The statute of limitations on the Funds’ tax returns for the prior three years remains open and the returns are subject to examination.

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

Adjustments to the cost of investments for tax purposes may be due to the deferred loss associated with current and prior year wash sales, income recognition from investments in real estate investment trusts and partnerships, and the Funds’ election to mark-to-market their investments in Passive Foreign Investment Companies (“PFICs”). The cost of investments, including derivatives, for federal income tax purposes and related gross unrealized appreciation (depreciation) and net unrealized appreciation/(depreciation) at June 30, 2020, were as follows (in thousands):

								Net
			Gross			Gross		Unrealized
	Cost of		Unrealized			Unrealized		Appreciation/
Fund	Investments		Appreciation			Depreciation		(Depreciation)
Growth	$	150,788	$	102,027		$	3,211	$	98,816
Large Cap Growth		409,230		116,638			3,795		112,843
Mid Cap Growth		57,409		14,708			1,670		13,038
Small-Mid Cap Core		213,211		15,644			29,418		(13,774	)
Small-Mid Cap Growth		2,279,923		594,822			63,096		531,726
Small-Mid Cap Value		1,297		(122	)		4		(126	)
Small Cap Growth		444,152		97,875			28,388		69,487
Small Cap Value		87,994		16,746			6,911		9,835
Global Leaders		65,145		32,800			935		31,865
International Leaders		519,860		160,926			18,795		142,131
International Growth		1,383,291		527,960			28,451		499,509
Institutional International Growth		1,152,408		422,652			22,464		400,188
International Small Cap Growth		216,688		54,244			9,651		44,593
Emerging Markets Leaders		181,107		51,651			10,452		41,199
Emerging Markets Growth		608,520		224,418			2,861		221,557
Emerging Markets Small Cap Growth		208,353		55,451			4,107		51,344
Bond		261,703		19,505			523		18,982
Income		51,453		1,614			46		1,568
Low Duration		112,781		1,254			356		898
Macro Allocation		512,815		33,305			3,700		29,605

As of December 31, 2019, the Funds may have unused capital loss carryforwards available for federal income tax purposes to be applied against future capital gains, if any. Under current law, the Funds may carry forward net capital losses indefinitely to use to offset capital gains realized in future years. The following table details the Funds’ available capital loss carryforwards as of December 31, 2019, and the capital loss carryforwards utilized by the Funds in 2019:

	Available Capital Loss Carryforwards						Capital Loss Carryforwards
Fund	Short Term		Long Term		Total		Utilized in 2019
Small-Mid Cap Core	$	14	$	—	$	14	$	—
International Growth		8,604		—		8,604		—
Institutional International Growth		33,252		—		33,252		—
International Small Cap Growth		15,355		—		15,355		—
Emerging Markets Small Cap Growth		46,476		—		46,476		—
Bond		10,477		9,850		20,327		1,720
Income		2,323		4,026		6,349		—
Low Duration		12,502		15,028		27,530		—
Macro Allocation		195,996		25,044		221,040		—

In order to meet certain excise tax distribution requirements, the Funds are required to measure and distribute annually, net capital gains realized during a twelve month period ending October 31 and net investment income earned during a twelve month period ending December 31. In connection with this, the Funds are permitted for tax purposes to defer into their next fiscal year qualified late year losses. Qualified late year capital losses are any short term or long term capital losses incurred between November 1 and the end of their fiscal year, December 31, 2019. Qualified late year ordinary losses are comprised of losses related to swaps, foreign currency and PFICs incurred between November 1 and the end of their fiscal year, December 31, 2019.

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

As of December 31, 2019, the following Funds deferred, on a tax basis, qualified late year losses of (in thousands):

	Qualified Late Year Losses
	Ordinary		Net
Fund	Income		Capital
Small Cap Growth	$	—	$	600
Bond		432		—

(e) Repurchase Agreements

In a repurchase agreement, a Fund buys a security at one price and at the time of sale, the seller agrees to repurchase the security at a mutually agreed upon time and price (usually within seven days). The repurchase agreement thereby determines the yield during the purchaser’s holding period, while the seller’s obligation to repurchase is secured by the value of the underlying collateral. The Adviser monitors, on an ongoing basis, the value of the underlying collateral to ensure that the value always equals or exceeds the repurchase price plus accrued interest. Repurchase agreements may involve certain risks in the event of a default or insolvency of the other party to the agreement, including possible delays or restrictions upon a Fund’s ability to dispose of the underlying collateral. The risk to a Fund is limited to the ability of the seller to pay the agreed upon sum on the delivery date. In the event of default, a repurchase agreement provides that a Fund is entitled to sell the underlying collateral. The loss, if any, to a Fund will be the difference between the proceeds from the sale and the repurchase price. However, if bankruptcy proceedings are commenced with respect to the seller of the security, disposition of the collateral by the Fund may be delayed or limited. The Funds have master repurchase agreements which allow the Funds to offset amounts owed to a counterparty with amounts owed from the same counterparty, including any collateral, in the event the counterparty defaults. Each Fund’s outstanding repurchase agreements, if any, and related collateral, are shown on the Fund’s Portfolio of Investments. Although no definitive creditworthiness criteria are used, the Adviser reviews the creditworthiness of the banks and non-bank dealers with which a Fund enters into repurchase agreements to evaluate those risks. A Fund may, for tax purposes, deem repurchase agreements collateralized by U.S. Government securities to be investments in U.S. Government securities.

(f) TBA Securities

The Fixed Income Funds may invest in mortgage pass-through securities eligible to be sold in the “to-be announced” market (“TBAs”). TBAs provide for the forward or delayed delivery of the underlying instrument with settlement in up to 180 days. The term TBA comes from the fact that the specific mortgage-backed security that will be delivered to fulfill a TBA trade is not designated at the time the trade is made, but rather is generally announced 48 hours before the settlement date. A Fund generally has the ability to close out a TBA obligation on or before the settlement date, rather than take delivery of the security. When a Fund sells TBAs, it incurs risks similar to those incurred in short sales. For example, when a Fund sells TBAs without owning or having the right to obtain the deliverable securities it incurs a risk of loss because it could have to purchase the securities at a price that is higher than the price at which it sold the securities.

(g) Securities Sold, Not Yet Purchased

A Fund may sell a security it does not own (known as selling a security short) in anticipation of a decline in the fair value of that security. When a Fund sells a security short, it must borrow the security sold short and deliver it to the broker through which it made the short sale. A gain, limited to the price at which the fund sold the security short, or a loss, unlimited in size, will be recognized upon the termination of the short sale. A Fund is also subject to the risk that it may be unable to acquire a security to terminate a short position except at a price substantially in excess of the price at which it sold the security short.

(h) Use of Estimates

The preparation of financial statements in conformity with US GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements. Actual results may differ from those estimates.

(i) Indemnification

In the normal course of business, the Funds have entered into contracts in which the Funds agree to indemnify the other party or parties against various potential costs or liabilities. The Funds’ maximum exposure under these arrangements is unknown. No claim has been made for indemnification pursuant to any such agreement of the Funds.

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

(j) Redemption In-Kind

In accordance with the Trust’s prospectus, the Funds may distribute portfolio securities rather than cash as payment for a redemption of Fund shares (in-kind redemption). For financial reporting purposes, the Fund recognizes a gain or loss on the transfer of securities depending on the value of those securities on the date of redemption. Gains and losses realized on in-kind redemptions may not be recognized for tax purposes and are reclassified from accumulated net realized gain (loss) to capital paid in excess of par value. During the period ended June 30, 2020, the Small-Mid Cap Growth, Global Leaders and Institutional International Growth Funds redeemed $20,321, $19,073 and $37,257 (in thousands), respectively, of Fund shares in-kind rather than with cash and recognized net realized gains of $6,220, $7,974 and $7,699 (in thousands), respectively, on the securities distributed to shareholders.

(3) Valuation

(a) Investment Valuation

The value of U.S. equity securities, including exchange-traded funds, is determined by valuing securities traded on national securities markets or in the over-the-counter markets at the last sale price or, if applicable, the official closing price or, in the absence of a recent sale on the date of determination, at the mean between the last reported bid and ask prices.

The value of foreign equity securities is generally determined based upon the last sale price on the foreign exchange or market on which it is primarily traded and in the currency of that market as of the close of the appropriate exchange or, if there have been no sales during that day, at the mean between the last reported bid and ask prices. The Board of Trustees has determined that the passage of time between when the foreign exchanges or markets close and when the Funds compute their net asset values could cause the value of foreign equity securities to no longer be representative or accurate and, as a result, may necessitate that such securities be fair valued. Accordingly, for foreign equity securities, the Funds may use an independent pricing service to fair value price the security as of the close of regular trading on the NYSE. As a result, a Fund’s value for a foreign security may be different from the last sale price (or the mean between the last reported bid and ask prices). As of June 30, 2020, fair valuation estimates for foreign equity securities were not obtained.

Fixed income securities are generally valued using evaluated prices provided by an independent pricing service. The evaluated prices are formed using various market inputs that the pricing service believes accurately represent the market value of a security at a particular point in time. The pricing service determines evaluated prices for fixed income securities using inputs including, but not limited to, recent transaction prices for such securities, dealer quotes, transaction prices for other securities with similar characteristics, collateral characteristics, credit quality, payment history, liquidity and market conditions.

Repurchase agreements are valued at cost, which approximates fair value.

Option contracts on securities, currencies and other financial instruments traded on one or more exchanges are valued at their most recent sale price on the exchange on which they are traded most extensively. Option contracts on foreign indices are valued at the settlement price. If there were no sales that day or if no settlement price is available, such option contracts are valued at the mean between the last reported bid and ask prices. Option contracts traded in the Over-the-Counter (“OTC”) market shall be valued by an independent pricing service. Futures contracts are valued at the most recent settlement price on the exchange on which they are traded most extensively, or if no settlement price is available, at the last sale price as of the close of the exchange. Forward foreign currency contracts are valued on the basis of the value of the underlying currencies at the prevailing currency exchange rate as supplied by an independent pricing service.

Swaps that are centrally cleared through an exchange are valued at the most recent settlement price provided by the exchange on which they are cleared. Total return swaps on equities, equity baskets, indices and other financial instruments are valued by an independent pricing service, or if unavailable, based on the security’s or instrument’s underlying reference asset. All other swap contracts are valued by an independent pricing service. Depending on the product and the terms of the transaction, the independent pricing service may use a series of techniques, including simulation pricing models. The pricing models use inputs that are observed from actively quoted markets such as issuer details, indices, spreads, interest rates, yield curves, dividends and exchange rates.

Securities, and other assets, for which a market price is not available or is deemed unreliable (e.g., securities affected by unusual or extraordinary events, such as natural disasters or securities affected by market or economic events, such as bankruptcy filings), or the value of which is affected by a significant valuation event, are valued at a fair value as determined in good faith by, or under the direction of, the Board of Trustees and in accordance with the Valuation Procedures approved by the Board of Trustees. The value of these fair valued securities may be different from the last sale price (or the mean between the last reported bid and ask prices), and there is no guarantee that a fair valued security will be sold at the price at which a Fund is carrying the security.

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

(b) Fair Value Measurements

Fair value is defined as the price that a Fund would receive upon selling a security in an orderly transaction to an independent buyer in the principal or most advantageous market for the investment. Various inputs are used in determining the value of a Fund’s investments. A three-tier hierarchy of inputs is used to classify fair value measurements for disclosure purposes. The three-tier hierarchy of inputs is summarized in the three broad levels listed below:

	•	Level 1—Quoted prices (unadjusted) in active markets for an identical security.

	•	Level 2—Prices determined using other significant observable inputs. Observable inputs are inputs that other market participants would use in pricing a security. These may include quoted prices for similar securities, interest rates, prepayment speeds, credit risk, and others. In addition, other observable inputs such as foreign exchange rates, benchmark securities indices and foreign futures contracts may be utilized in the valuation of certain foreign securities when significant events occur between the last sale on the foreign securities exchange and the time at which the net asset value of the Fund is calculated.

	•	Level 3—Prices determined using significant unobservable inputs. In situations where quoted prices or observable inputs are unavailable (for example, when there is little or no market activity for an investment), unobservable inputs may be used. Unobservable inputs reflect the Fund’s own assumptions about the factors market participants would use in pricing an investment, and are based on the best information available.

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

A description of the valuation methodologies applied to the Funds’ major categories of assets and liabilities measured at fair value on a recurring basis is as follows:

Exchange-Traded Securities

Securities traded on a national securities exchange (or reported on the NASDAQ national market), including exchange-traded funds, are stated at the last reported sales price on the day of valuation. Other securities traded in the over-the-counter market and listed securities for which no sale was reported on that date are stated at the mean between the last reported bid and ask prices. To the extent these securities are actively traded and valuation adjustments are not applied, they are categorized as Level 1 of the fair value hierarchy. Securities traded on inactive markets or valued by reference to similar instruments are generally categorized as Level 2 of the fair value hierarchy.

Fixed Income Securities

Fixed income securities including corporate, convertible and municipal bonds and notes, U.S. government agency obligations, U.S. treasury obligations, sovereign issues, bank loans, convertible preferred securities, asset-backed securities, non-U.S. bonds and commercial paper are generally valued using evaluated prices provided by an independent pricing service. The evaluated prices are formed using various market inputs that the pricing service believes accurately represent the fair value of a security at a particular point in time. The pricing service determines evaluated prices for fixed income securities using inputs including, but not limited to, recent transaction prices for such securities, dealer quotes, transaction prices for other securities with similar characteristics, collateral characteristics, credit quality, payment history, liquidity and market conditions. Securities that use similar valuation techniques and observable inputs as described above are categorized as Level 2 of the fair value hierarchy.

Repurchase Agreements

Repurchase agreements are valued at cost, which approximates fair value. Repurchase agreements are categorized as Level 2 of the fair value hierarchy.

Derivative Instruments

Listed derivatives, such as certain options and futures contracts, that are actively traded are valued based on quoted prices from the exchange on which they are traded most extensively and are categorized as Level 1 of the fair value hierarchy. OTC derivative contracts include forward foreign currency contracts, swap and certain option contracts related to interest rates, foreign currencies, the credit standing of reference entities, equity prices, or commodity prices. Depending on the product and the terms of the transaction, the fair value of OTC derivative products can be modeled by independent pricing services taking into account the counterparties’ creditworthiness and using a series of techniques, including simulation models. Many pricing models do not entail material subjectivity because the methodologies employed do not necessitate significant judgments and the pricing inputs are

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117

Notes to Financial Statements (information as of June 30, 2020 is unaudited)

observed from actively quoted markets, as is the case of forward foreign currency contracts and interest rate swaps. A substantial majority of OTC derivative products valued by a Fund using pricing models fall into this category and are categorized as Level 2 of the fair value hierarchy.

As of June 30, 2020, the value of investments in securities and other financial instruments, segregated by their hierarchical input levels used in determining fair value and by security class or other financial instruments, are shown below (in thousands).

			Large Cap		Mid Cap		Small-Mid
Investments in securities	Growth		Growth		Growth		Cap Core
Level 1—Quoted prices
Common Stocks	$	247,720	$	517,783	$	68,678	$	197,267
Level 2—Other significant observable inputs
Repurchase Agreements		1,884		4,290		1,769		2,170
Level 3—Significant unobservable inputs
None		—		—		—		—
Total investments in securities	$	249,604	$	522,073	$	70,447	$	199,437

	Small-Mid		Small-Mid		Small Cap		Small Cap
Investments in securities	Cap Growth		Cap Value		Growth		Value
Level 1—Quoted prices
Common Stocks	$	2,787,231	$	1,171	$	503,039	$	95,701
Level 2—Other significant observable inputs
Repurchase Agreements		24,418		—		10,600		2,128
Level 3—Significant unobservable inputs
None		—		—		—		—
Total investments in securities	$	2,811,649	$	1,171	$	513,639	$	97,829

	Global		International		International		Institutional International
Investments in securities	Leaders		Leaders		Growth		Growth
Level 1—Quoted prices
Common Stocks	$	96,352	$	659,128	$	1,872,591	$	1,546,053
Level 2—Other significant observable inputs
Common Stocks		—		—		2,850		2,342
Repurchase Agreements		658		2,863		7,359		4,201
Level 3—Significant unobservable inputs
None		—		—		—		—
Total investments in securities	$	97,010	$	661,991	$	1,882,800	$	1,552,596

							Emerging
	International		Emerging		Emerging		Markets
	Small Cap		Markets		Markets		Small Cap
Investments in securities	Growth		Leaders		Growth		Growth
Level 1—Quoted prices
Common Stocks	$	256,495	$	211,933	$	824,097	$	252,945
Preferred Stocks		—		—		—		1,667
Level 2—Other significant observable inputs
Common Stocks		—		3,453		—		3,294
Repurchase Agreements		4,786		6,920		5,980		1,789
Level 3—Significant unobservable inputs
Common Stocks		—		—		—		2
Total investments in securities	$	261,281	$	222,306	$	830,077	$	259,697

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					Low		Macro
Investments in securities	Bond		Income		Duration		Allocation
Assets
Level 1—Quoted prices
Exchange-Traded Funds	$	—	$	—	$	—	$	354,856
Level 2—Other significant observable inputs
Asset-Backed Securities		4,066		1,370		9,922		—
Commercial Paper		—		350		4,800		—
Corporate Obligations		114,348		16,352		24,828		—
Foreign Government Bonds		—		—		—		18,104
Repurchase Agreements		2,159		119		1,111		15,297
U.S. Government and U.S. Government Agency		160,112		34,830		73,018		154,905
Level 3—Significant unobservable inputs
None		—		—		—		—
Liabilities
Level 1—Quoted prices
None		—		—		—		—
Level 2—Other significant observable inputs
None		—		—		—		—
Level 3—Significant unobservable inputs
None		—		—		—		—
Total investments in securities	$	280,685	$	53,021	$	113,679	$	543,162

Other financial instruments

Assets
Level 1—Quoted prices
Futures Contracts	$	—	$	—	$	—	$	1,710
Level 2—Other significant observable inputs
Forward Foreign Currency Contracts		—		—		—		1,413
Swaps		—		—		—		640
Level 3—Significant unobservable inputs
None		—		—		—		—
Liabilities
Level 1—Quoted prices
Futures Contracts		—		—		—		(7,063	)
Level 2—Other significant observable inputs
Forward Foreign Currency Contracts		—		—		—		(6,117	)
Swaps		—		—		—		(1,110	)
Level 3—Significant unobservable inputs
None		—		—		—		—
Total other financial instruments	$	—	$	—	$	—	$	(10,527	)

Level 1 Common Stocks are exchange-traded securities with a quoted price. See Portfolio of Investments for Sector Classification.

The fair value estimate for the Level 3 security in the Emerging Markets Small Cap Growth Fund was determined in good faith by the Pricing Committee, pursuant to the Valuation Procedures approved by the Board of Trustees. There were various factors considered in reaching the fair value determination, including, but not limited to, the following: the type of security, the extent of public trading of the security, information obtained for the security, and analysis of the company’s performance and market trends that influence its performance. The Level 3 security represented 0.00% as a percentage of net assets in the Emerging Markets Small Cap Growth Fund. The change in net unrealized gain (loss) related to this security held at June 30, 2020 is included within change in net unrealized appreciation (depreciation) of investments in securities in the Statement of Operations.

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(4) Transactions with Affiliates

(a) Management and Expense Limitation Agreements

Each Fund has a management agreement with the Adviser for investment management, clerical, bookkeeping and administrative services. Each Fund pays the Adviser an annual management fee, which is accrued daily and paid monthly, based on a specified percentage of the Fund’s average daily net assets. Each Fund’s annual management fee rate is as follows:

U.S. Equity Funds
Growth	0.75	%
Large Cap Growth	0.60	%
Mid Cap Growth	0.90	%
Small-Mid Cap Core	0.90	%
Small-Mid Cap Growth	1.00	%
Small-Mid Cap Value²	0.85	%
Small Cap Growth	1.10	%
Small Cap Value³	0.95	%

Fixed Income Funds
Bond	0.30	%
Income¹:
First $250 million	0.25	%
In excess of $250 million	0.20	%
Low Duration	0.30	%

Multi-Asset and Alternative Fund
Macro Allocation	0.80	%

Global Equity Fund
Global Leaders	0.85	%

International Equity Funds
International Leaders	0.85	%
International Growth:
First $250 million	1.10	%
Next $2.25 billion	1.00	%
Next $2.5 billion	0.975	%
Next $5 billion	0.95	%
Next $5 billion	0.925	%
In excess of $15 billion	0.90	%
Institutional International Growth:
First $500 million	1.00	%
Next $500 million	0.95	%
Next $1.5 billion	0.90	%
Next $2.5 billion	0.875	%
Next $5 billion	0.85	%
Next $5 billion	0.825	%
In excess of $15 billion	0.80	%
International Small Cap Growth	1.00	%
Emerging Markets Leaders	1.10	%
Emerging Markets Growth	1.10	%
Emerging Markets Small Cap Growth	1.10	%

1	Management fee also includes a charge of 5% of gross income.
2	Prior to May 1, 2020, the Small-Mid Cap Value Fund paid a management fee at a rate of 0.95% of the Fund’s average daily net assets. Effective May 1, 2020, the management fee paid to the Adviser was reduced to 0.85%.
3	Prior to May 1, 2020, the Small Cap Value Fund paid a management fee at a rate of 1.10% of the Fund’s average daily net assets. Effective May 1, 2020, the management fee paid to the Adviser was reduced to 0.95%.

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The Funds have also entered into an Amended and Restated Expense Limitation Agreement with the Adviser. Under the terms of the agreement, the Adviser will waive its management fee and/or reimburse a Fund for certain operating expenses, subject to certain excluded expenses, in excess of the agreed upon rate through April 30, 2021. The amount the Adviser owes a Fund as of the reporting date is recorded as Receivable from Adviser in the Statements of Assets and Liabilities. The Adviser reimburses the Funds on a monthly basis. The Adviser will waive fees and/or reimburse expenses to the extent that the total operating expenses for the stated class of the Funds, subject to certain excluded expenses, exceed the following rates (as a percentage of average daily net assets):

	Class N						Class I						Institutional/Class R6
	Effective			Effective			Effective			Effective			Effective			Effective
	May 1, 2020			May 1, 2019			May 1, 2020			May 1, 2019			May 1, 2020			May 1, 2019
	through			through			through			through			through			through
	April 30,			April 30,			April 30,			April 30,			April 30,			April 30,
Fund	2021			2020			2021			2020			2021			2020
Growth		1.20	%		1.20	%		0.95	%		0.95	%		0.90	%		0.90	%
Large Cap Growth		0.90	%		0.90	%		0.65	%		0.65	%		0.60	%		0.60	%
Mid Cap Growth		1.20	%		1.20	%		0.95	%		0.95	%		0.90	%		0.90	%
Small-Mid Cap Core		N/A			N/A			0.95	%		0.95	%¹		0.90	%		0.90	%¹
Small-Mid Cap Growth		1.35	%		1.35	%		1.10	%		1.10	%		1.05	%		1.05	%
Small-Mid Cap Value		1.15	%		1.25	%		0.90	%		1.00	%		0.85	%		0.95	%
Small Cap Growth		1.50	%		1.50	%		1.25	%		1.25	%		1.20	%		1.20	%
Small Cap Value		1.25	%		1.50	%		1.00	%		1.25	%		0.95	%		1.20	%
Global Leaders		1.15	%		1.15	%		0.90	%		0.90	%		0.85	%		0.85	%
International Leaders		1.15	%		1.15	%		0.90	%		0.90	%		0.85	%		0.85	%
International Growth		1.45	%		1.45	%		1.20	%		1.20	%		1.15	%		1.15	%
Institutional International Growth		N/A			N/A			N/A			N/A			1.05	%		1.05	%
International Small Cap Growth		1.55	%		1.55	%		1.30	%		1.30	%		1.25	%		1.25	%
Emerging Markets Leaders		1.40	%		1.40	%		1.15	%		1.15	%		1.10	%		1.10	%
Emerging Markets Growth		1.60	%		1.60	%		1.35	%		1.35	%		1.30	%		1.30	%
Emerging Markets Small Cap Growth		1.55	%		1.55	%		1.30	%		1.30	%		1.25	%		1.25	%
Bond		0.60	%		0.60	%		0.45	%		0.45	%		0.40	%		0.40	%
Income		0.85	%		0.85	%		0.70	%		0.70	%		0.65	%		0.65	%
Low Duration		0.55	%		0.55	%		0.40	%		0.40	%		0.35	%		0.35	%
Macro Allocation		1.25	%		1.25	%		1.00	%		1.00	%		0.95	%		0.95	%

1 Effective October 1, 2019 (Commencement of Operations).

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

The fee waivers and/or expense reimbursements received by each class are reported in the Statements of Operations.

With respect to the Small-Mid Cap Core Fund, the Adviser is entitled to recoupment of previously waived fees and reimbursed expenses for a period of three years subsequent to October 1, 2019 (Commencement of Operations) to the extent that such recoupment does not cause the fund’s annual operating expenses (after the recoupment is taken into account) to exceed both (1) the expense limit in place when such amounts were waived or reimbursed and (2) the fund’s current expense limitation.

(b) Underwriting and Distribution Services Agreements

Pursuant to separate Underwriting and Distribution Agreements, WBC is the principal underwriter and distributor for the continuous offering of shares of the Trust and acts as agent of the Trust in the sale of its shares. The Underwriting Agreement provides that the Distributor will use its best efforts to distribute the Trust’s shares. The Distributor is not compensated under the Underwriting Agreement.

Each Fund, except the Small-Mid Cap Core and Institutional International Growth Funds, has a Distribution Agreement with WBC for distribution services to the Funds’ Class N shares. Each Fund pays WBC an annual fee, payable monthly, based on a specified percentage of its average daily net assets of Class N shares. The annual rate expressed as a percentage of average daily net assets for Class N is 0.25% for all Funds except the Bond, Income and Low Duration Funds, which is 0.15%. Pursuant to the Distribution Agreement, WBC enters into related selling group agreements with various firms at various rates for sales of the Funds’ Class N shares.

(5) Investment Transactions

Investment transactions, excluding U.S. government securities and short-term securities, for the period ended June 30, 2020, were as follows (in thousands):

Fund	Purchases		Sales
Growth	$	60,965	$	84,213
Large Cap Growth		253,800		81,944
Mid Cap Growth		17,779		20,068
Small-Mid Cap Core		299,866		83,633
Small-Mid Cap Growth		847,718		911,534
Small-Mid Cap Value		6,846		9,663
Small Cap Growth		201,878		321,735
Small Cap Value		52,891		77,946
Global Leaders		27,737		85,686
International Leaders		157,328		119,958
International Growth		375,739		571,347
Institutional International Growth		376,648		652,062
International Small Cap Growth		89,660		127,185
Emerging Markets Leaders		49,149		55,036
Emerging Markets Growth		349,450		340,919
Emerging Markets Small Cap Growth		176,416		193,372
Bond		131,044		126,324
Income		19,690		22,724
Low Duration		71,412		64,020
Macro Allocation		72,110		189,249

Investment transactions in U.S. government securities, excluding short-term securities, for the period ended June 30, 2020, were as follows (in thousands):

Fund	Purchases		Sales
Bond	$	5,834	$	5,424
Income		1,719		—
Low Duration		3,900		—
Macro Allocation		—		—

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Notes to Financial Statements (information as of June 30, 2020 is unaudited)

(6) Financial Derivative Instruments

Each Fund may use derivative instruments to maintain liquidity, to provide hedging, or in anticipation of changes in the composition of its portfolio holdings or as otherwise provided in each Fund’s prospectus. Macro Allocation Fund may also use derivative instruments to obtain investment exposures. The derivative instruments held as of June 30, 2020, as disclosed in each Fund’s Portfolios of Investments, are representative of each Fund’s derivative instrument trading activity during the period ended June 30, 2020.

Derivative transactions carry counterparty risk as they are based on contracts between a Fund and the applicable counterparty. For exchange-traded or cleared derivative contracts, such counterparty risk is limited due to the role of the exchange or clearinghouse. OTC derivative contracts, however, are exposed to counterparty risk in the amount of unrealized gains, net of collateral held, for the duration of the contract.

Macro Allocation Fund is subject to certain netting arrangements through International Swaps and Derivatives Association, Inc. Master Agreements and Credit Support Annexes (“ISDAs”). The ISDAs maintain provisions for general obligations, representations, agreements, collateral and events of default or termination. The ISDAs cover certain OTC derivative securities entered into by Macro Allocation Fund with various counterparties and allow Macro Allocation Fund to close out and net its total exposure to a counterparty in the event of a default.

Futures Contracts

A futures contract provides for the future sale by one party and purchase by another party of a specified amount of a specific financial instrument for a specified price at a designated date, time and place. An index futures contract is an agreement pursuant to which the parties agree to take or make delivery of an amount of cash equal to the difference between the value of the index at the close of the last trading day of the contract and the price at which the index futures contract was originally written. A futures contract can be closed out prior to delivery by entering into an offsetting transaction in a matching futures contract. Although the value of an index might be a function of the value of certain specified securities, no physical delivery of those securities is made. If the offsetting purchase price is less than the original sale price, a Fund realizes a gain; if it is more, a Fund realizes a loss. Conversely, if the offsetting sale price is more than the original purchase price, a Fund realizes a gain; if it is less, a Fund realizes a loss. The transaction costs must also be included in these calculations. There can be no assurance, however, that a Fund will be able to enter into an offsetting transaction with respect to a particular futures contract at a particular time. If a Fund is not able to enter into an offsetting transaction, a Fund will continue to be required to maintain the margin deposits on the futures contract.

Upon entering into a futures contract, a Fund is required to pledge to the broker an amount of cash, U.S. government securities, or other liquid assets equal to a certain percentage of the contract amount (“initial margin deposit”). Futures contracts are marked to market daily and an appropriate payable or receivable for the change in value (“variation margin”) is recorded by a Fund and a cash payment is either made to or received from the broker each day. Gains or losses on futures contracts are recognized but not considered realized until the contracts expire or are closed and are included in the Statement of Operations.

Options

The purchase or sale of an option by a Fund involves the payment or receipt of a premium by the investor and the corresponding right or obligation, as the case may be, either to purchase or sell the underlying security, commodity, or other instrument for a specific price at a certain time or during a certain period. Purchasing options involves the risk that the underlying instrument will not change price in the manner expected, so the investor loses its premium. Writing options involves potentially greater risk because the investor is exposed to the extent of the actual price movement in the underlying security rather than only the amount of the premium paid (which could result in a potentially unlimited loss). OTC options also involve counterparty credit risk. Purchased options are shown as an asset in the Statement of Assets and Liabilities and are included in Investments in securities. Premiums received for written options are shown as a liability in the Statement of Assets and Liabilities. Realized gains and losses on the sale, expiration or assignment of an option are disclosed in the Statement of Operations.

Forward Foreign Currency Contracts

The Global Equity, International Equity and Multi-Asset and Alternative Funds may enter into forward foreign currency contracts. When entering into a forward foreign currency contract, a Fund agrees to receive or deliver a fixed quantity of foreign currency for an agreed-upon price on an agreed future date. A Fund’s net equity therein, representing unrealized gain or loss on the

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contracts as measured by the difference between the forward foreign exchange rates at the dates of entry into the contracts and the forward rates at the reporting date, is included in the Statement of Assets and Liabilities as unrealized appreciation/depreciation on forward foreign currency contracts. Realized and unrealized gains and losses are included in the Statement of Operations. These instruments may involve market risk, credit risk, or both kinds of risks in excess of the amount recognized in the Statement of Assets and Liabilities. Risks arise from the possible inability of counterparties to meet the terms of their contracts and from the price movements in currencies.

Swap Contracts

Swap agreements may include total return, interest rate, securities index, commodity, security, currency exchange rate, credit default index, volatility and variance swaps. Cleared swaps are transacted through futures commission merchants that are members of central clearing houses with the clearing house serving as a central counterparty similar to transactions in futures contracts. In a standard “swap” transaction, two parties agree to exchange the returns (or differentials in rates of return) earned or realized on particular predetermined investments or instruments. The gross returns to be exchanged or “swapped” between the parties are calculated with respect to a “notional amount” (i.e., the change in the value of a particular dollar amount invested, for example, at a particular interest rate, in a particular foreign currency, or in a “basket” of securities representing a particular index). Swap agreements are subject to the risk that the counterparty to the swap will default on its obligation to pay a Fund and the risk that a Fund will not be able to meet its obligations to pay the counterparty to the swap. Swap agreements may also involve fees, commissions or other costs that may reduce a Fund’s gains from a swap agreement or may cause a Fund to lose money. To the extent permitted by its investment policies and restrictions, a Fund may invest in the following types of swaps:

Credit Default Swaps—A Fund may invest in credit default swaps as a means of “buying” credit protection (i.e., attempting to mitigate the risk of default or credit quality deterioration in some portion of a Fund’s holdings) or “selling” credit protection (i.e., attempting to gain exposure to an underlying issuer’s credit quality characteristics without directly investing in that issuer). A credit default swap is a contract between a buyer and a seller of protection against a pre-defined credit event (e.g., a ratings downgrade or default) on an underlying reference obligation, which may be a single debt instrument or baskets or indices of securities. A Fund may be a buyer or seller of a credit default swap. As a seller of protection on credit default swap agreements, a Fund will generally receive from the buyer of protection a fixed rate of income throughout the term of the swap provided that there is no credit event. A Fund adds leverage to its portfolio because the Fund is subject to investment exposure on the notional amount of the swap. The maximum potential amount of future payments that a Fund as a seller of protection could be required to make under a credit default swap agreement equals the notional amount of the agreement. Notional amounts of each individual credit default swap agreement outstanding as of the period end for which a Fund is the seller of protection are disclosed in the Fund’s Portfolio of Investments. These potential amounts would be partially offset by any recovery values of the respective referenced obligations, upfront payments received upon entering into the agreement, or net amounts received from the settlement of buy protection credit default swap agreements entered into by the same Fund for the same referenced entity or entities. For credit default swap contracts on credit indices, the quoted market prices and resulting values serve as an indicator of the payment performance risk. Increasing market values, in absolute terms when compared to the notional amount of the swap, typically represent deterioration of the referenced entities’ credit soundness and a greater likelihood or risk of default or other credit event occurring as defined under the terms of the swap.

Interest Rate Swap—A Fund may invest in interest rate swaps to gain or mitigate exposure to changes in interest rates. Interest rate swap agreements involve a commitment between parties to pay either a fixed interest rate or a floating interest rate based on a notional amount of principal. The parties make payments at predetermined intervals throughout the life of the swap. As a payer, a Fund would make the fixed payment and receive the floating payment. As a receiver, a Fund would make the floating payment and receive the fixed payment.

Total Return Swap—A Fund may invest in total return swaps to gain or mitigate exposure to an underlying security, or securities. Total return swap agreements may involve commitments to pay interest in exchange for the return on the underlying security, or securities. At maturity, a net cash flow is exchanged between the parties based on the total return of the underlying security, or securities, less a financing rate. As a receiver in the transaction, a Fund would receive a payment for a positive return and would make a payment for a negative return. As a payer in the transaction, a Fund would make a payment for a positive return and would receive a payment for a negative return.

Variance Swap—A Fund may invest in variance swaps in order to gain or mitigate its exposure to an underlying reference entity such as a broad based index. A variance swap is an agreement between two parties to exchange cash flows based on the measured

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variance of a reference entity. The payer agrees to exchange the fixed rate, which is the variance strike price of the reference entity, to the receiver for the floating rate, which is the realized variance price of the reference entity. At the time the trade is originated, the agreed upon variance strike price is generally set so that the fair value of the swap is near zero. At maturity, a net cash flow is exchanged between the parties based on the difference between the final realized variance price of the swap and the variance strike price multiplied by the notional, or vega amount. As a receiver of the floating rate, a Fund would receive a payment if the final realized variance price is greater than the variance strike price and would make a payment if the final realized variance price is less than the variance strike price. As a payer of the floating rate, a Fund would receive a payment if the final realized variance price is less than the variance strike price and would make a payment if the final realized variance price is greater than the variance strike price.

The following table presents the value of financial derivative instruments, by Fund and primary risk exposure, as of June 30, 2020, and their respective location in the Statements of Assets and Liabilities (in thousands):

Assets

Liabilities

Fund and
Primary Risk Exposure

Statements of Assets
and Liabilities

Value

Statements of Assets
and Liabilities

Value

Macro Allocation

Credit

Receivable for variation margin on centrally cleared swaps⁽¹⁾

142

Payable for variation margin on centrally cleared swaps⁽¹⁾

—

Currency

Unrealized appreciation on forward currency contracts

1,413

Unrealized depreciation on forward currency contracts

6,117

Equity

Receivable for variation margin on futures⁽¹⁾

1,710

Payable for variation margin on futures⁽¹⁾

6,555

Equity

Unrealized appreciation on swap contracts

267

Unrealized depreciation on swap contracts

628

Interest rate

Unrealized appreciation on swap contracts

231

Unrealized depreciation on swap contracts

Interest rate

Receivable for variation margin on futures⁽¹⁾

—

Payable for variation margin on futures⁽¹⁾

508

Interest rate

Receivable for variation margin on centrally cleared swaps⁽¹⁾

—

Payable for variation margin on centrally cleared swaps⁽¹⁾

453

⁽¹⁾

The table above includes cumulative appreciation/(depreciation) on futures contracts and centrally cleared swaps as reported in the applicable Fund’s Portfolio of Investments. Receivable/payable for variation margin on futures contracts and centrally cleared swaps as reported in the applicable Fund’s Statement of Assets and Liabilities represents the current day’s variation margin.

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The following table indicates the effect of derivatives, by Fund and primary risk exposure, in the Statements of Operations for the period ended June 30, 2020 (in thousands):

	Realized Gain (Loss)					Change in Net Unrealized Appreciation (Depreciation)
Fund and Primary Risk Exposure	Statements of Operations		Value			Statements of Operations	Value
Small-Mid Cap Core
Equity	Futures contracts		$	45		Futures contracts	$	—
Bond
Credit	Swaps			405		Swaps		626
Income
Credit	Swaps			(34	)	Swaps		—
Low Duration
Credit	Swaps			(56	)	Swaps		—
Macro Allocation		��
Credit	Swaps			(175	)	Swaps		32
Currency	Forward foreign currency contracts			(9,183	)	Forward foreign currency contracts		(1,892	)
Equity	Futures contracts			5,648		Futures contracts		(657	)
Equity	Options			(6,041	)	Options		—
Equity	Swaps			1,246		Swaps		(1,409	)
Interest rate	Futures contracts			3,670		Futures contracts		284
Interest rate	Swaps			4,040		Swaps		(104	)

The following table is a summary by counterparty of the derivative instruments and collateral pledged/(received) included in the Macro Allocation Fund’s Statement of Assets and Liabilities at June 30, 2020 (in thousands):

	Financial Derivative Assets						Financial Derivative Liabilities
Counterparty	Forward Foreign Currency Contracts		Swaps		Total		Forward Foreign Currency Contracts			Swaps			Total			Net Market Value			Collateral Pledged (Received)		Net Exposure
Citibank N.A.	$	1,413	$	—	$	1,413	$	(6,117	)	$	(83	)	$	(6,200	)	$	(4,787	)	$	4,765	$	(22	)
Credit Suisse		—		498		498		—			(574	)		(574	)		(76	)		76		—
	$	1,413	$	498	$	1,911	$	(6,117	)	$	(657	)	$	(6,774	)

The net exposure represents the amount due from/(due to) the counterparty in the event of default. Any net exposure is generally due to changes in market value of the underlying derivative instruments on the last day of the period as timing of collateral movement occurs the following day. For Credit Suisse, the table does not include collateral pledged in the amount of $2,590 (in thousands) that is necessary to cover initial margin requirements on OTC swap contracts.

126

Semiannual Report

June 30, 2020

Notes to Financial Statements (information as of June 30, 2020 is unaudited)

(7) Fund Share Transactions

The following tables summarize the activity in capital shares of each Fund for the period ended June 30, 2020 (in thousands):

																Class N
							Dollars									Shares
Fund	Sales		Reinvest		Redemptions		Total			Sales		Reinvest		Redemptions		Total
Growth	$	872	$	—	$	4,529	$	(3,657	)		95		—		499		(404	)
Large Cap Growth		80,476		—		26,094		54,382			5,309		—		1,751		3,558
Mid Cap Growth		332		—		733		(401	)		38		—		73		(35	)
Small-Mid Cap Growth		33,030		—		89,626		(56,596	)		1,433		—		3,894		(2,461	)
Small-Mid Cap Value		34		—		120		(86	)		5		—		14		(9	)
Small Cap Growth		20,100		—		49,558		(29,458	)		840		—		2,088		(1,248	)
Small Cap Value		788		2,060		3,241		(393	)		75		172		287		(40	)
Global Leaders		384		—		586		(202	)		27		—		43		(16	)
International Leaders		2,513		—		5,224		(2,711	)		142		—		305		(163	)
International Growth		29,264		—		250,059		(220,795	)		1,248		—		10,100		(8,852	)
International Small Cap Growth		139		—		923		(784	)		9		—		85		(76	)
Emerging Markets Leaders		2,603		—		2,955		(352	)		273		—		311		(38	)
Emerging Markets Growth		1,348		—		1,395		(47	)		113		—		122		(9	)
Emerging Markets Small Cap Growth		45		—		654		(609	)		2		—		47		(45	)
Bond		6,106		566		8,777		(2,105	)		586		54		859		(219	)
Income		4,347		307		3,427		1,227			505		36		398		143
Low Duration		6,270		36		631		5,675			721		4		72		653
Macro Allocation		452		—		4,815		(4,363	)		40		—		439		(399	)

																Class I
							Dollars									Shares
Fund	Sales		Reinvest		Redemptions		Total			Sales		Reinvest		Redemptions		Total
Growth	$	7,796	$	—	$	27,121	$	(19,325	)		716		—		2,427		(1,711	)
Large Cap Growth		146,890		—		30,251		116,639			9,030		—		1,913		7,117
Mid Cap Growth		6,160		—		7,428		(1,268	)		555		—		668		(113	)
Small-Mid Cap Core		263,449		—		46,248		217,201			24,720		—		4,590		20,130
Small-Mid Cap Growth		353,299		—		417,873		(64,574	)		13,865		—		17,088		(3,223	)
Small-Mid Cap Value		3,013		—		5,985		(2,972	)		291		—		828		(537	)
Small Cap Growth		30,327		—		117,026		(86,699	)		1,112		—		4,409		(3,297	)
Small Cap Value		9,850		25,167		37,316		(2,299	)		851		2,013		3,375		(511	)
Global Leaders		7,698		—		37,865		(30,167	)		606		—		2,595		(1,989	)
International Leaders		44,397		—		36,738		7,659			2,699		—		2,246		453
International Growth		237,171		—		227,590		9,581			9,408		—		8,322		1,086
International Small Cap Growth		11,033		—		20,625		(9,592	)		899		—		1,775		(876	)
Emerging Markets Leaders		7,977		—		7,217		760			815		—		801		14
Emerging Markets Growth		6,439		—		6,810		(371	)		521		—		561		(40	)
Emerging Markets Small Cap Growth		11,520		—		30,534		(19,014	)		751		—		2,026		(1,275	)
Bond		26,138		3,054		40,308		(11,116	)		2,522		294		3,910		(1,094	)
Income		4,066		473		4,975		(436	)		475		55		582		(52	)
Low Duration		27,603		650		2,877		25,376			3,175		75		332		2,918
Macro Allocation		32,429		—		120,741		(88,312	)		2,953		—		11,075		(8,122	)

June 30, 2020

William Blair Funds

127

Notes to Financial Statements (information as of June 30, 2020 is unaudited)

	Institutional/Class R6
									Dollars									Shares
Fund		Sales			Reinvest		Redemptions		Total			Sales		Reinvest		Redemptions		Total
Growth		$	536		$	—	$	—	$	536			50		—		—		50
Large Cap Growth			791			—		30		761			48		—		2		46
Mid Cap Growth			23			—		—		23			2		—		—		2
Small-Mid Cap Core			670			—		39		631			75		—		5		70
Small-Mid Cap Growth			34,051			—		1,645		32,406			1,285		—		67		1,218
Small-Mid Cap Value			117			—		—		117			12		—		—		12
Small Cap Growth			6,121			—		5,855		266			209		—		210		(1	)
Small Cap Value			133			101		15		219			10		8		2		16
Global Leaders			2,458			—		50,699		(48,241	)		190		—		3,335		(3,145	)
International Leaders			43,249			—		30,304		12,945			2,554		—		1,949		605
International Growth			1,984			—		6,069		(4,085	)		69		—		239		(170	)
Institutional International Growth			101,823			—		447,714		(345,891	)		6,520		—		27,169		(20,649	)
International Small Cap Growth			907			—		26,669		(25,762	)		76		—		1,900		(1,824	)
Emerging Markets Leaders			12,777			—		16,785		(4,008	)		1,337		—		1,758		(421	)
Emerging Markets Growth			76,597			—		74,827		1,770			6,461		—		5,659		802
Emerging Markets Small Cap Growth			40,606			—		37,843		2,763			2,562		—		2,428		134
Bond			1,997			857		1,614		1,240			193		82		156		119
Income			16			1		—		17			2		—		—		2
Low Duration			6,579			329		3,246		3,662			757		38		373		422
Macro Allocation			25,344			—		88,443		(63,099	)		2,259		—		8,165		(5,906	)

				Net Change in Net Assets Relating to Fund Share Activity
									Dollars									Shares
Fund		Sales			Reinvest		Redemptions		Total			Sales		Reinvest		Redemptions		Total
Growth		$	9,204		$	—	$	31,650	$	(22,446	)		861		—		2,926		(2,065	)
Large Cap Growth			228,157			—		56,375		171,782			14,387		—		3,666		10,721
Mid Cap Growth			6,515			—		8,161		(1,646	)		595		—		741		(146	)
Small-Mid Cap Core			264,119			—		46,287		217,832			24,795		—		4,595		20,200
Small-Mid Cap Growth			420,380			—		509,144		(88,764	)		16,583		—		21,049		(4,466	)
Small-Mid Cap Value			3,164			—		6,105		(2,941	)		308		—		842		(534	)
Small Cap Growth			56,548			—		172,439		(115,891	)		2,161		—		6,707		(4,546	)
Small Cap Value			10,771			27,328		40,572		(2,473	)		936		2,193		3,664		(535	)
Global Leaders			10,540			—		89,150		(78,610	)		823		—		5,973		(5,150	)
International Leaders			90,159			—		72,266		17,893			5,395		—		4,500		895
International Growth			268,419			—		483,718		(215,299	)		10,725		—		18,661		(7,936	)
Institutional International Growth			101,823			—		447,714		(345,891	)		6,520		—		27,169		(20,649	)
International Small Cap Growth			12,079			—		48,217		(36,138	)		984		—		3,760		(2,776	)
Emerging Markets Leaders			23,357			—		26,957		(3,600	)		2,425		—		2,870		(445	)
Emerging Markets Growth			84,384			—		83,032		1,352			7,095		—		6,342		753
Emerging Markets Small Cap Growth			52,171			—		69,031		(16,860	)		3,315		—		4,501		(1,186	)
Bond			34,241			4,477		50,699		(11,981	)		3,301		430		4,925		(1,194	)
Income			8,429			781		8,402		808			982		91		980		93
Low Duration			40,452			1,015		6,754		34,713			4,653		117		777		3,993
Macro Allocation			58,225			—		213,999		(155,774	)		5,252		—		19,679		(14,427	)

128

Semiannual Report

June 30, 2020

Notes to Financial Statements (information as of June 30, 2020 is unaudited)

The following tables summarize the activity in capital shares of each Fund for the year ended December 31, 2019 (in thousands):

																Class N
							Dollars									Shares
Fund	Sales		Reinvest		Redemptions		Total			Sales		Reinvest		Redemptions		Total
Growth	$	4,699	$	3,142	$	21,051	$	(13,210	)		512		339		2,242		(1,391	)
Large Cap Growth		33,843		3,913		25,920		11,836			2,320		263		1,756		827
Mid Cap Growth		476		431		1,578		(671	)		43		40		143		(60	)
Small-Mid Cap Growth		74,019		23,898		268,742		(170,825	)		2,970		946		11,034		(7,118	)
Small-Mid Cap Value		102		6		76		32			10		—		7		3
Small Cap Growth		57,125		4,113		83,288		(22,050	)		2,151		150		3,066		(765	)
Small Cap Value		2,377		495		9,131		(6,259	)		138		29		531		(364	)
Global Leaders		953		98		1,463		(412	)		72		7		112		(33	)
International Leaders		2,342		37		2,610		(231	)		145		2		161		(14	)
International Growth		44,662		5,263		133,868		(83,943	)		1,723		183		5,050		(3,144	)
International Small Cap Growth		76		3		908		(829	)		7		—		75		(68	)
Emerging Markets Leaders		3,645		11		4,555		(899	)		388		1		483		(94	)
Emerging Markets Growth		1,739		300		2,909		(870	)		142		23		231		(66	)
Emerging Markets Small Cap Growth		561		—		6,536		(5,975	)		37		—		440		(403	)
Bond		13,853		2,166		58,587		(42,568	)		1,355		212		5,682		(4,115	)
Income		2,090		686		6,085		(3,309	)		245		80		714		(389	)
Low Duration		613		53		809		(143	)		70		6		93		(17	)
Macro Allocation		6,932		489		37,706		(30,285	)		607		43		3,261		(2,611	)

																Class I
							Dollars									Shares
Fund	Sales		Reinvest		Redemptions		Total			Sales		Reinvest		Redemptions		Total
Growth	$	16,720	$	17,115	$	41,128	$	(7,293	)		1,519		1,552		3,712		(641	)
Large Cap Growth		87,517		9,125		36,804		59,838			5,611		578		2,424		3,765
Mid Cap Growth		9,653		5,374		11,067		3,960			818		460		945		333
Small-Mid Cap Core (a)		1,600		1		1		1,600			155		—		—		155
Small-Mid Cap Growth		722,356		166,901		775,495		113,762			27,182		6,225		29,057		4,350
Small-Mid Cap Value		6,397		130		1,342		5,185			589		12		125		476
Small Cap Growth		137,860		8,577		216,223		(69,786	)		4,617		278		7,091		(2,196	)
Small Cap Value		47,012		14,487		449,289		(387,790	)		2,655		811		25,120		(21,654	)
Global Leaders		13,378		1,486		9,732		5,132			983		102		710		375
International Leaders		93,939		938		21,157		73,720			5,758		53		1,312		4,499
International Growth		187,914		18,095		720,429		(514,420	)		7,104		614		26,516		(18,798	)
International Small Cap Growth		37,548		370		104,497		(66,579	)		3,181		27		8,815		(5,607	)
Emerging Markets Leaders		11,138		376		10,689		825			1,144		37		1,102		79
Emerging Markets Growth		6,749		2,839		31,465		(21,877	)		529		211		2,480		(1,740	)
Emerging Markets Small Cap Growth		34,235		217		89,550		(55,098	)		2,330		13		5,987		(3,644	)
Bond		63,530		8,645		165,844		(93,669	)		6,285		855		16,289		(9,149	)
Income		15,837		1,281		21,322		(4,204	)		1,889		151		2,517		(477	)
Low Duration		5,864		1,972		25,726		(17,890	)		673		226		2,953		(2,054	)
Macro Allocation		95,661		13,901		238,819		(129,257	)		8,287		1,233		20,648		(11,128	)

June 30, 2020

William Blair Funds

129

Notes to Financial Statements (information as of June 30, 2020 is unaudited)

													Institutional/Class R6
								Dollars										Shares
Fund	Sales			Reinvest		Redemptions		Total			Sales			Reinvest		Redemptions		Total
Growth (b)	$	253		$	17	$	50	$	220			21			2		4		19
Large Cap Growth (b)		1,614			96		103		1,607			98			6		6		98
Mid Cap Growth		185			12		50		147			15			1		4		12
Small-Mid Cap Core (a)		4,638			3		23		4,618			464			—		2		462
Small-Mid Cap Growth (b)		39,365			2,655		1,015		41,005			1,417			99		36		1,480
Small-Mid Cap Value (b)		569			3		395		177			52			—		37		15
Small Cap Growth (b)		70,364			1,345		6,230		65,479			2,272			44		202		2,114
Small Cap Value (b)		594			16		95		515			32			1		5		28
Global Leaders		2,233			657		54,453		(51,563	)		167			45		3,935		(3,723	)
International Leaders		54,037			2,274		25,678		30,633			3,363			129		1,540		1,952
International Growth (b)		57,826			819		2,257		56,388			2,087			28		77		2,038
Institutional International Growth		192,878			17,852		574,855		(364,125	)		12,482			1,060		37,590		(24,048	)
International Small Cap Growth		8,293			596		66,807		(57,918	)		690			44		5,534		(4,800	)
Emerging Markets Leaders		23,896			1,819		39,496		(13,781	)		2,519			179		4,094		(1,396	)
Emerging Markets Growth		163,145			23,530		277,695		(91,020	)		12,739			1,737		21,289		(6,813	)
Emerging Markets Small Cap Growth		26,072			248		15,489		10,831			1,756			15		1,035		736
Bond		3,036			2,432		37,075		(31,607	)		304			241		3,654		(3,109	)
Income (b)		50			1		—		51			6			—		—		6
Low Duration		7,532			921		19,111		(10,658	)		863			106		2,191		(1,222	)
Macro Allocation		120,202			13,341		147,745		(14,202	)		10,415			1,183		12,734		(1,136	)

			Net Change in Net Assets Relating to Fund Share Activity
								Dollars										Shares
Fund	Sales			Reinvest		Redemptions		Total			Sales			Reinvest		Redemptions		Total
Growth	$	21,672		$	20,274	$	62,229	$	(20,283	)		2,052			1,893		5,958		(2,013	)
Large Cap Growth		122,974			13,134		62,827		73,281			8,029			847		4,186		4,690
Mid Cap Growth		10,314			5,817		12,695		3,436			876			501		1,092		285
Small-Mid Cap Core (a)		6,238			4		24		6,218			619			—		2		617
Small-Mid Cap Growth		835,740			193,454		1,045,252		(16,058	)		31,569			7,270		40,127		(1,288	)
Small-Mid Cap Value		7,068			139		1,813		5,394			651			12		169		494
Small Cap Growth		265,349			14,035		305,741		(26,357	)		9,040			472		10,359		(847	)
Small Cap Value		49,983			14,998		458,515		(393,534	)		2,825			841		25,656		(21,990	)
Global Leaders		16,564			2,241		65,648		(46,843	)		1,222			154		4,757		(3,381	)
International Leaders		150,318			3,249		49,445		104,122			9,266			184		3,013		6,437
International Growth		290,402			24,177		856,554		(541,975	)		10,914			825		31,643		(19,904	)
Institutional International Growth		192,878			17,852		574,855		(364,125	)		12,482			1,060		37,590		(24,048	)
International Small Cap Growth		45,917			969		172,212		(125,326	)		3,878			71		14,424		(10,475	)
Emerging Markets Leaders		38,679			2,206		54,740		(13,855	)		4,051			217		5,679		(1,411	)
Emerging Markets Growth		171,633			26,669		312,069		(113,767	)		13,410			1,971		24,000		(8,619	)
Emerging Markets Small Cap Growth		60,868			465		111,575		(50,242	)		4,123			28		7,462		(3,311	)
Bond		80,419			13,243		261,506		(167,844	)		7,944			1,308		25,625		(16,373	)
Income		17,977			1,968		27,407		(7,462	)		2,140			231		3,231		(860	)
Low Duration		14,009			2,946		45,646		(28,691	)		1,606			338		5,237		(3,293	)
Macro Allocation		222,795			27,731		424,270		(173,744	)		19,309			2,459		36,643		(14,875	)

(a)	For the period from October 1, 2019 (Commencement of Operations) to December 31, 2019.
(b)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.

(8) Subsequent Events

The Funds have evaluated subsequent events through the date of issuance of the Funds’ financial statements and have determined there is no impact to the Funds’ financial statements.

130

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Growth Fund

	Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	9.45		$	7.91		$	10.27		$	11.41		$	12.52		$	13.55
Income (loss) from investment operations:
Net investment income (loss)			(0.02	)		(0.03	)		(0.04	)		(0.02	)		(0.02	)		(0.04	)
Net realized and unrealized gain (loss) on investments			0.75			2.54			0.75			2.78			(0.08	)		0.75
Total from investment operations			0.73			2.51			0.71			2.76			(0.10	)		0.71
Less distributions from:
Net investment income			—			—			—			—			—			—
Net realized gain			—			0.97			3.07			3.90			1.01			1.74
Total distributions			—			0.97			3.07			3.90			1.01			1.74
Net asset value, end of year		$	10.18		$	9.45		$	7.91		$	10.27		$	11.41		$	12.52
Total return (%)*			7.72			31.97			5.10			24.35			(0.98	)		5.31
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.28			1.24			1.22			1.20			1.21			1.19
Expenses, net of waivers and reimbursements			1.20			1.20			1.20			1.20			1.21			1.19
Net investment income (loss), before waivers and reimbursements			(0.46	)		(0.35	)		(0.36	)		(0.14	)		(0.15	)		(0.29	)
Net investment income (loss), net of waivers and reimbursements			(0.38	)		(0.31	)		(0.34	)		(0.14	)		(0.15	)		(0.29	)
Class N net assets at the end of the year (in thousands)		$	31,139		$	32,710		$	38,370		$	34,886		$	62,936		$	149,754
Portfolio turnover rate (%)*			26			39			46			38			79			78

	Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	11.25		$	9.25		$	11.51		$	12.39		$	13.50		$	14.43
Income (loss) from investment operations:
Net investment income (loss)			(0.01	)		(0.00	)^		(0.01	)		0.02			0.03			0.01
Net realized and unrealized gain (loss) on investments			0.90			2.97			0.82			3.02			(0.10	)		0.80
Total from investment operations			0.89			2.97			0.81			3.04			(0.07	)		0.81
Less distributions from:
Net investment income			—			—			0.00	^		0.02			0.03			—
Net realized gain			—			0.97			3.07			3.90			1.01			1.74
Total distributions			—			0.97			3.07			3.92			1.04			1.74
Net asset value, end of year			12.14		$	11.25		$	9.25		$	11.51		$	12.39		$	13.50
Total return (%)*			7.91			32.32			5.42			24.64			(0.69	)		5.69
Ratios to average daily net assets (%)**:
Expenses			0.94			0.92			0.91			0.92			0.90			0.89
Net investment income (loss)			(0.13	)		(0.03	)		(0.06	)		0.12			0.20			0.06
Class I net assets at the end of the year (in thousands)		$	217,361		$	220,660		$	187,306		$	318,848		$	514,870		$	696,744
Portfolio turnover rate (%)*			26			39			46			38			79			78

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

131

Financial Highlights — For a share outstanding throughout each period

Growth Fund

	Class R6
	Period Ended June 30,				Period Ended December 31,
	2020				2019(a)
Net asset value, beginning of year		$	11.26			$	11.06
Income (loss) from investment operations:
Net investment income (loss)			(0.00	)^			(0.00	)^
Net realized and unrealized gain (loss) on investments			0.90				1.17
Total from investment operations			0.90				1.17
Less distributions from:
Net investment income			—				—
Net realized gain			—				0.97
Total distributions			—				0.97
Net asset value, end of year		$	12.16			$	11.26
Total return (%)*			7.99				10.75
Ratios to average daily net assets (%)**:
Expenses			0.88				0.88
Net investment income (loss)			(0.06	)			(0.06	)
Class R6 net assets at the end of the year (in thousands)		$	833			$	217
Portfolio turnover rate (%)*			26				39

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

132

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Large Cap Growth Fund

	Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	15.27		$	11.99		$	13.35		$	10.26		$	10.15		$	10.46
Income (loss) from investment operations:
Net investment income (loss)			0.01			0.00	^		(0.02	)		(0.02	)		0.02			(0.02	)
Net realized and unrealized gain (loss) on investments			1.46			4.29			0.81			3.19			0.18			0.75
Total from investment operations			1.47			4.29			0.79			3.17			0.20			0.73
Less distributions from:
Net investment income			—			0.01			—			—			0.01			—
Net realized gain			—			1.00			2.15			0.08			0.08			1.04
Total distributions			—			1.01			2.15			0.08			0.09			1.04
Net asset value, end of year		$	16.74		$	15.27		$	11.99		$	13.35		$	10.26		$	10.15
Total return (%)*			9.63			36.00			4.96			30.88			1.97			7.04
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.04			1.12			1.21			1.19			1.23			1.28
Expenses, net of waivers and reimbursements			0.90			0.95			1.05			1.05			1.05			1.07
Net investment income (loss), before waivers and reimbursements			(0.02	)		(0.14	)		(0.33	)		(0.27	)		(0.01	)		(0.43	)
Net investment income (loss), net of waivers and reimbursements			0.12			0.03			(0.17	)		(0.13	)		0.17			(0.22	)
Class N net assets at the end of the year (in thousands)		$	131,166		$	65,314		$	41,361		$	25,604		$	11,860		$	10,443
Portfolio turnover rate (%)*			21			37			47			29			44			38

	Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	16.19		$	12.66		$	13.97		$	10.70		$	10.58		$	10.84
Income (loss) from investment operations:
Net investment income (loss)			0.03			0.04			0.01			0.02			0.04			(0.00	)^
Net realized and unrealized gain (loss) on investments			1.55			4.54			0.85			3.33			0.19			0.78
Total from investment operations			1.58			4.58			0.86			3.35			0.23			0.78
Less distributions from:
Net investment income			—			0.05			0.02			—			0.03			—
Net realized gain			—			1.00			2.15			0.08			0.08			1.04
Total distributions			—			1.05			2.17			0.08			0.11			1.04
Net asset value, end of year		$	17.77		$	16.19		$	12.66		$	13.97		$	10.70		$	10.58
Total return (%)*			9.76			36.35			5.21			31.29			2.22			7.26
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.75			0.81			0.90			0.90			0.91			0.95
Expenses, net of waivers and reimbursements			0.65			0.70			0.80			0.80			0.80			0.82
Net investment income (loss), before waivers and reimbursements			0.28			0.16			(0.01	)		0.03			0.30			(0.10	)
Net investment income (loss), net of waivers and reimbursements			0.38			0.27			0.09			0.13			0.41			0.03
Class I net assets at the end of the year (in thousands)		$	386,509		$	236,930		$	137,599		$	177,959		$	110,475		$	59,038
Portfolio turnover rate (%)*			21			37			47			29			44			38

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

133

Financial Highlights — For a share outstanding throughout each period

Large Cap Growth Fund

	Class R6
	(unaudited) Period Ended June 30,			Period Ended December 31,
	2020			2019(a)
Net asset value, beginning of year		$	16.17		$	15.12
Income (loss) from investment operations:
Net investment income (loss)			0.03			0.04
Net realized and unrealized gain (loss) on investments			1.56			2.07
Total from investment operations			1.59			2.11
Less distributions from:
Net investment income			—			0.06
Net realized gain			—			1.00
Total distributions			—			1.06
Net asset value, end of year		$	17.76		$	16.17
Total return (%)*			9.83			14.13
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.68			0.71
Expenses, net of waivers and reimbursements			0.60			0.60
Net investment income (loss), before waivers and reimbursements			0.34			0.22
Net investment income (loss), net of waivers and reimbursements			0.42			0.33
Class R6 net assets at the end of the year (in thousands)		$	2,560		$	1,590
Portfolio turnover rate (%)*			21			37

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

134

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Mid Cap Growth Fund

	Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	10.99		$	8.87		$	10.92		$	10.69		$	11.28		$	14.20
Income (loss) from investment operations:
Net investment income (loss)			(0.03	)		(0.05	)		(0.06	)		(0.08	)		(0.06	)		(0.09	)
Net realized and unrealized gain (loss) on investments			(0.12	)		3.22			0.03			2.29			0.09			0.04
Total from investment operations			(0.15	)		3.17			(0.03	)		2.21			0.03			(0.05	)
Less distributions from:
Net investment income			—			—			—			—			—			—
Net realized gain			—			1.05			2.02			1.98			0.62			2.87
Total distributions			—			1.05			2.02			1.98			0.62			2.87
Net asset value, end of year		$	10.84		$	10.99		$	8.87		$	10.92		$	10.69		$	11.28
Total return (%)*			(1.36	)		36.02			(1.20	)		20.88			0.23			(0.20	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.55			1.51			1.57			1.49			1.45			1.43
Expenses, net of waivers and reimbursements			1.20			1.20			1.23			1.30			1.30			1.32
Net investment income (loss), before waivers and reimbursements			(0.99	)		(0.79	)		(0.85	)		(0.84	)		(0.68	)		(0.76	)
Net investment income (loss), net of waivers and reimbursements			(0.64	)		(0.48	)		(0.51	)		(0.65	)		(0.53	)		(0.65	)
Class N net assets at the end of the year (in thousands)		$	5,003		$	5,465		$	4,944		$	6,166		$	16,234		$	25,105
Portfolio turnover rate (%)*			27			43			58			59			60			65

	Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	11.93		$	9.55		$	11.57		$	11.20		$	11.76		$	14.65
Income (loss) from investment operations:
Net investment income (loss)			(0.02	)		(0.03	)		(0.03	)		(0.05	)		(0.03	)		(0.06	)
Net realized and unrealized gain (loss) on investments			(0.12	)		3.46			0.03			2.40			0.09			0.04
Total from investment operations			(0.14	)		3.43			—			2.35			0.06			(0.02	)
Less distributions from:
Net investment income			—			—			—			—			—			—
Net realized gain			—			1.05			2.02			1.98			0.62			2.87
Total distributions			—			1.05			2.02			1.98			0.62			2.87
Net asset value, end of year		$	11.79		$	11.93		$	9.55		$	11.57		$	11.20		$	11.76
Total return (%)*			(1.17	)		36.17			(0.86	)		21.18			0.48			0.00
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.31			1.28			1.31			1.23			1.18			1.14
Expenses, net of waivers and reimbursements			0.95			0.95			0.98			1.05			1.05			1.07
Net investment income (loss), before waivers and reimbursements			(0.74	)		(0.56	)		(0.58	)		(0.58	)		(0.39	)		(0.48	)
Net investment income (loss), net of waivers and reimbursements			(0.38	)		(0.23	)		(0.25	)		(0.40	)		(0.26	)		(0.41	)
Class I net assets at the end of the year (in thousands)		$	65,781		$	67,936		$	51,173		$	71,369		$	119,424		$	174,617
Portfolio turnover rate (%)*			27			43			58			59			60			65

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

135

Financial Highlights — For a share outstanding throughout each period

Mid Cap Growth Fund

	Class R6
	(unaudited)
	Period Ended				Period Ended
	June 30,				December 31,
	2020				2019(a)
Net asset value, beginning of year		$	11.94			$	11.93
Income (loss) from investment operations:
Net investment income (loss)			(0.02	)			(0.01	)
Net realized and unrealized gain (loss) on investments			(0.12	)			1.07
Total from investment operations			(0.14	)			1.06
Less distributions from:
Net investment income			—				—
Net realized gain			—				1.05
Total distributions			—				1.05
Net asset value, end of year		$	11.80			$	11.94
Total return (%)*			(1.17	)			9.10
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.18				1.14
Expenses, net of waivers and reimbursements			0.90				0.90
Net investment income (loss), before waivers and reimbursements			(0.60	)			(0.41	)
Net investment income (loss), net of waivers and reimbursements			(0.32	)			(0.17	)
Class R6 net assets at the end of the year (in thousands)		$	164			$	145
Portfolio turnover rate (%)*			27				43

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

136

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Small-Mid Cap Core Fund

	Class I
	(unaudited)
	Period Ended				Period Ended
	June 30,				December 31,
	2020				2019(a)
Net asset value, beginning of year		$	10.68			$	10.00
Income (loss) from investment operations:
Net investment income (loss)			0.00	^			0.02
Net realized and unrealized gain (loss) on investments			(1.12	)			0.67
Total from investment operations			(1.12	)			0.69
Less distributions from:
Net investment income			—				0.01
Net realized gain			—				—
Total distributions			—				0.01
Net asset value, end of year		$	9.56			$	10.68
Total return (%)*			(10.49	)			6.87
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.14				3.92
Expenses, net of waivers and reimbursements			0.95				0.95
Net investment income (loss), before waivers and reimbursements			(0.11	)			(2.23	)
Net investment income (loss), net of waivers and reimbursements			0.08				0.74
Class N net assets at the end of the year (in thousands)		$	194,012			$	1,655
Portfolio turnover rate (%)*			48				12

	Class R6
	(unaudited)
	Period Ended				Period Ended
	June 30,				December 31,
	2020				2019(a)
Net asset value, beginning of year		$	10.68			$	10.00
Income (loss) from investment operations:
Net investment income (loss)			0.01				0.01
Net realized and unrealized gain (loss) on investments			(1.12	)			0.68
Total from investment operations			(1.11	)			0.69
Less distributions from:
Net investment income			—				0.01
Net realized gain			—				—
Total distributions			—				0.01
Net asset value, end of year		$	9.57			$	10.68
Total return (%)*			(10.39	)			6.88
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.01				3.92
Expenses, net of waivers and reimbursements			0.90				0.90
Net investment income (loss), before waivers and reimbursements			0.04				(2.71	)
Net investment income (loss), net of waivers and reimbursements			0.15				0.31
Class I net assets at the end of the year (in thousands)		$	5,086			$	4,933
Portfolio turnover rate (%)*			48				12

(a)	For the period from October 1, 2019 (commencement of operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

137

Financial Highlights — For a share outstanding throughout each period

Small-Mid Cap Growth Fund

		Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	25.41		$	20.97		$	23.36		$	19.20		$	18.53		$	18.72
Income (loss) from investment operations:
Net investment income (loss)			(0.10	)		(0.20	)		(0.18	)		(0.16	)		(0.09	)		(0.10	)
Net realized and unrealized gain (loss) on investments			0.27			6.56			(0.25	)		5.62			1.29			0.93
Total from investment operations			0.17			6.36			(0.43	)		5.46			1.20			0.83
Less distributions from:
Net investment income			—			—			—			—			—			—
Net realized gain			—			1.92			1.96			1.30			0.53			1.02
Total distributions			—			1.92			1.96			1.30			0.53			1.02
Net asset value, end of year		$	25.58		$	25.41		$	20.97		$	23.36		$	19.20		$	18.53
Total return (%)*			0.67			30.41			(2.29	)		28.57			6.45			4.47
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.46			1.43			1.44			1.43			1.43			1.42
Expenses, net of waivers and reimbursements			1.35			1.35			1.35			1.35			1.35			1.35
Net investment income (loss), before waivers and reimbursements			(0.97	)		(0.88	)		(0.81	)		(0.82	)		(0.59	)		(0.58	)
Net investment income (loss), net of waivers and reimbursements			(0.86	)		(0.80	)		(0.72	)		(0.74	)		(0.51	)		(0.51	)
Class N net assets at the end of the year (in thousands)		$	273,268		$	334,017		$	424,865		$	228,828		$	171,638		$	169,595
Portfolio turnover rate (%)*			31			56			46			64			66			44

		Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	26.99		$	22.12		$	24.48		$	20.02		$	19.25		$	19.36
Income (loss) from investment operations:
Net investment income (loss)			(0.08	)		(0.14	)		(0.12	)		(0.11	)		(0.05	)		(0.06	)
Net realized and unrealized gain (loss) on investments			0.29			6.93			(0.28	)		5.87			1.35			0.97
Total from investment operations			0.21			6.79			(0.40	)		5.76			1.30			0.91
Less distributions from:
Net investment income			—			—			—			—			—			—
Net realized gain			—			1.92			1.96			1.30			0.53			1.02
Total distributions			—			1.92			1.96			1.30			0.53			1.02
Net asset value, end of year		$	27.20		$	26.99		$	22.12		$	24.48		$	20.02		$	19.25
Total return (%)*			0.78			30.77			(2.06	)		28.90			6.72			4.74
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.17			1.16			1.16			1.16			1.16			1.15
Expenses, net of waivers and reimbursements			1.10			1.10			1.10			1.10			1.10			1.10
Net investment income (loss), before waivers and reimbursements			(0.67	)		(0.59	)		(0.53	)		(0.55	)		(0.34	)		(0.33	)
Net investment income (loss), net of waivers and reimbursements			(0.60	)		(0.53	)		(0.47	)		(0.49	)		(0.28	)		(0.28	)
Class I net assets at the end of the year (in thousands)		$	2,464,057		$	2,531,823		$	1,979,105		$	1,576,180		$	1,090,939		$	1,019,544
Portfolio turnover rate (%)*			31			56			46			64			66			44

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

138

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Small-Mid Cap Growth Fund

	Class R6
	(unaudited)
	Period Ended				Period Ended
	June 30,				December 31,
	2020				2019(a)
Net asset value, beginning of year		$	27.01			$	26.76
Income (loss) from investment operations:
Net investment income (loss)			(0.07	)			(0.09	)
Net realized and unrealized gain (loss) on investments			0.29				2.26
Total from investment operations			0.22				2.17
Less distributions from:
Net investment income			—				—
Net realized gain			—				1.92
Total distributions			—				1.92
Net asset value, end of year		$	27.23			$	27.01
Total return (%)*			0.81				8.17
Ratios to average daily net assets (%)**:
Expenses			1.05				1.05
Net investment income (loss)			(0.53	)			(0.46	)
Class R6 net assets at the end of the year (in thousands)		$	73,475			$	39,974
Portfolio turnover rate (%)*			31				56

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

139

Financial Highlights — For a share outstanding throughout each period

Small-Mid Cap Value Fund

																	Class N
	(unaudited) Period Ended June 30,										Years Ended December 31,
		2020			2019			2018			2017			2016				2015
Net asset value, beginning of year		$	11.22		$	9.31		$	14.31		$	14.53		$	12.54			$	13.63
Income (loss) from investment operations:
Net investment income (loss)			0.06			0.10			0.09			0.04			0.04				0.04
Net realized and unrealized gain (loss) on investments			(2.74	)		2.00			(2.08	)		1.33			2.55				(0.47	)
Total from investment operations			(2.68	)		2.10			(1.99	)		1.37			2.59				(0.43	)
Less distributions from:
Net investment income			—			0.03			0.03			0.02			0.01				0.01
Net realized gain			—			0.16			2.98			1.57			0.59				0.65
Total distributions			—			0.19			3.01			1.59			0.60				0.66
Net asset value, end of year		$	8.54		$	11.22		$	9.31		$	14.31		$	14.53			$	12.54
Total return (%)*			(23.89	)		22.77			(15.32	)		9.59			20.69				(3.13	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			5.52			6.76			6.88			4.83			4.15				3.93
Expenses, net of waivers and reimbursements			1.22			1.25			1.28			1.35			1.35				1.37
Net investment income (loss), before waivers and reimbursements			(2.89	)		(4.59	)		(4.97	)		(3.21	)		(2.51	)			(2.29	)
Net investment income (loss), net of waivers and reimbursements			1.41			0.92			0.63			0.27			0.29				0.27
Class N net assets at the end of the year (in thousands)		$	161		$	315		$	234		$	284		$	267			$	855
Portfolio turnover rate (%)*			142			107			104			70			45				35

																		Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020				2019			2018			2017			2016				2015
Net asset value, beginning of year		$	11.13		$	9.23		$	14.24		$	14.47		$	12.54			$	13.63
Income (loss) from investment operations:
Net investment income (loss)			0.07			0.14			0.11			0.07			0.08				0.07
Net realized and unrealized gain (loss) on investments			(2.69	)		1.98			(2.06	)		1.33			2.55				(0.47	)
Total from investment operations			(2.62	)		2.12			(1.95	)		1.40			2.63				(0.40	)
Less distributions from:
Net investment income			—			0.06			0.08			0.06			0.11				0.04
Net realized gain			—			0.16			2.98			1.57			0.59				0.65
Total distributions			—			0.22			3.06			1.63			0.70				0.69
Net asset value, end of year		$	8.51		$	11.13		$	9.23		$	14.24		$	14.47			$	12.54
Total return (%)*			(23.63	)		23.00			(15.03	)		9.84			21.00				(2.86	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			5.21			6.45			6.54			4.55			3.92				3.72
Expenses, net of waivers and reimbursements			0.97			1.00			1.03			1.10			1.10				1.12
Net investment income (loss), before waivers and reimbursements			(2.74	)		(4.13	)		(4.69	)		(2.94	)		(2.20	)			(2.08	)
Net investment income (loss), net of waivers and reimbursements			1.50			1.32			0.82			0.51			0.62				0.52
Class I net assets at the end of the year (in thousands)		$	814		$	7,042		$	1,445		$	3,359		$	3,186			$	3,220
Portfolio turnover rate (%)*			142			107			104			70			45				35

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

140

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Small-Mid Cap Value Fund

	Class R6
	(unaudited) Period Ended June 30,				Period Ended December 31,
	2020				2019(a)
Net asset value, beginning of year		$	11.13			$	10.93
Income (loss) from investment operations:
Net investment income (loss)			0.08				0.11
Net realized and unrealized gain (loss) on investments			(2.72	)			0.31
Total from investment operations			(2.64	)			0.42
Less distributions from:
Net investment income			—				0.06
Net realized gain			—				0.16
Total distributions			—				0.22
Net asset value, end of year		$	8.49			$	11.13
Total Return (%)*			(23.81	)			3.89
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			5.11				4.85
Expenses, net of waivers and reimbursements			0.92				0.95
Net investment income (loss), before waivers and reimbursements			(2.34	)			(2.41	)
Net investment income (loss), net of waivers and reimbursements			1.85				1.49
Class R6 net assets at the end of the year (in thousands)		$	229			$	171
Portfolio turnover rate (%)*			142				107

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

141

Financial Highlights — For a share outstanding throughout each period

Small Cap Growth Fund

																	Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	27.75		$	23.23		$	26.87		$	25.24		$	22.47		$	25.61
Income (loss) from investment operations:
Net investment income (loss)			(0.12	)		(0.24	)		(0.27	)		(0.25	)		(0.18	)		(0.22	)
Net realized and unrealized gain (loss) on investments			(0.68	)		5.40			(0.10	)		6.88			4.43			(0.93	)
Total from investment operations			(0.80	)		5.16			(0.37	)		6.63			4.25			(1.15	)
Less distributions from:
Net investment income			—			—			—			—			—			—
Net realized gain			—			0.64			3.27			5.00			1.48			1.99
Total distributions			—			0.64			3.27			5.00			1.48			1.99
Net asset value, end of year		$	26.95		$	27.75		$	23.23		$	26.87		$	25.24		$	22.47
Total return (%)*			(2.88	)		22.26			(2.14	)		26.70			18.89			(4.44	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.60			1.54			1.55			1.54			1.55			1.59
Expenses, net of waivers and reimbursements			1.50			1.50			1.50			1.50			1.50			1.50
Net investment income (loss), before waivers and reimbursements			(1.06	)		(0.92	)		(0.94	)		(0.93	)		(0.84	)		(0.94	)
Net investment income (loss), net of waivers and reimbursements			(0.96	)		(0.88	)		(0.89	)		(0.89	)		(0.79	)		(0.85	)
Class N net assets at the end of the year (in thousands)		$	141,873		$	180,706		$	169,074		$	146,291		$	117,068		$	111,944
Portfolio turnover rate (%)*			37			51			74			81			90			91

																		Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	31.19		$	25.99		$	29.61		$	27.34		$	24.17		$	27.32
Income (loss) from investment operations:
Net investment income (loss)			(0.10	)		(0.19	)		(0.21	)		(0.20	)		(0.13	)		(0.17	)
Net realized and unrealized gain (loss) on investments			(0.75	)		6.03			(0.14	)		7.47			4.78			(0.99	)
Total from investment operations			(0.85	)		5.84			(0.35	)		7.27			4.65			(1.16	)
Less distributions from:
Net investment income			—			—			—			—			—			—
Net realized gain			—			0.64			3.27			5.00			1.48			1.99
Total distributions			—			0.64			3.27			5.00			1.48			1.99
Net asset value, end of year		$	30.34		$	31.19		$	25.99		$	29.61		$	27.34		$	24.17
Total return (%)*			(2.73	)		22.51			(1.88	)		26.99			19.22			(4.20	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.31			1.27			1.25			1.25			1.27			1.30
Expenses, net of waivers and reimbursements			1.25			1.25			1.25			1.25			1.25			1.25
Net investment income (loss), before waivers and reimbursements			(0.78	)		(0.65	)		(0.65	)		(0.64	)		(0.56	)		(0.66	)
Net investment income (loss), net of waivers and reimbursements			(0.72	)		(0.63	)		(0.65	)		(0.64	)		(0.54	)		(0.61	)
Class I net assets at the end of the year (in thousands)		$	312,187		$	423,881		$	410,233		$	343,119		$	271,830		$	261,269
Portfolio turnover rate (%)*			37			51			74			81			90			91

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

142

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Small Cap Growth Fund

	Class R6
	(unaudited) Period Ended June 30,				Period Ended December 31,
	2020				2019(a)
Net asset value, beginning of year		$	31.20			$	31.00
Income (loss) from investment operations:
Net investment income (loss)			(0.09	)			(0.11	)
Net realized and unrealized gain (loss) on investments			(0.76	)			0.95
Total from investment operations			(0.85	)			0.84
Less distributions from:
Net investment income			—				—
Net realized gain			—				0.64
Total distributions			—				0.64
Net asset value, end of year		$	30.35			$	31.20
Total Return (%)*			(2.72	)			2.75
Ratios to average daily net assets (%)**:
Expenses			1.20				1.18
Net investment income (loss)			(0.65	)			(0.51	)
Class R6 net assets at the end of the year (in thousands)		$	64,128			$	65,950
Portfolio turnover rate (%)*			37				51

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

143

Financial Highlights — For a share outstanding throughout each period

Small Cap Value Fund

		Class N
	(unaudited)
	Period Ended
	June 30,				Years Ended December 31,
		2020			2019		2018			2017			2016		2015
Net asset value, beginning of year		$	17.47		$	15.04	$	20.15		$	20.18		$	16.68	$	17.76
Income (loss) from investment operations:
Net investment income (loss)			0.04			0.09		0.03			0.01			0.04		0.02
Net realized and unrealized gain (loss) on investments			(4.21	)		2.92		(3.12	)		1.50			4.34		(1.05	)
Total from investment operations			(4.17	)		3.01		(3.09	)		1.51			4.38		(1.03	)
Less distributions from:
Net investment income			—			0.09		—			—			0.04		—
Net realized gain			3.04			0.49		2.02			1.54			0.84		0.05
Total distributions			3.04			0.58		2.02			1.54			0.88		0.05
Net asset value, end of year		$	10.26		$	17.47	$	15.04		$	20.15		$	20.18	$	16.68
Total return (%)*			(26.37	)		20.09		(15.93	)		7.57			26.19		(5.77	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.75			1.55		1.56			1.55			1.53		1.54
Expenses, net of waivers and reimbursements			1.42			1.50		1.50			1.50			1.50		1.50
Net investment income (loss), before waivers and reimbursements			0.27			0.49		0.08			(0.01	)		0.19		0.10
Net investment income (loss), net of waivers and reimbursements			0.60			0.54		0.14			0.04			0.22		0.14
Class N net assets at the end of the year (in thousands)		$	7,027		$	12,672	$	16,381		$	29,271		$	33,359	$	33,351
Portfolio turnover rate (%)*			43			116		56			38			33		30

			Class I
	(unaudited)
		Period Ended
		June 30,				Years Ended December 31,
			2020			2019		2018			2017		2016		2015
Net asset value, beginning of year			$	18.02		$	15.50	$	20.70		$	20.68	$	17.08	$	18.17
Income (loss) from investment operations:
Net investment income (loss)				0.05			0.14		0.08			0.06		0.09		0.08
Net realized and unrealized gain (loss) on investments				(4.35	)		3.01		(3.21	)		1.54		4.44		(1.08	)
Total from investment operations				(4.30	)		3.15		(3.13	)		1.60		4.53		(1.00	)
Less distributions from:
Net investment income				—			0.14		0.05			0.04		0.09		0.04
Net realized gain				3.04			0.49		2.02			1.54		0.84		0.05
Total distributions				3.04			0.63		2.07			1.58		0.93		0.09
Net asset value, end of year			$	10.68		$	18.02	$	15.50		$	20.70	$	20.68	$	17.08
Total return (%)*				(26.34	)		20.45		(15.74	)		7.85		26.46		(5.47	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements				1.47			1.31		1.30			1.29		1.29		1.24
Expenses, net of waivers and reimbursements				1.17			1.25		1.25			1.25		1.25		1.24
Net investment income (loss), before waivers and reimbursements				0.54			0.74		0.36			0.25		0.43		0.43
Net investment income (loss), net of waivers and reimbursements				0.84			0.80		0.41			0.29		0.47		0.43
Class I net assets at the end of the year (in thousands)			$	90,613		$	162,093	$	475,134		$	644,749	$	675,272	$	579,010
Portfolio turnover rate (%)*				43			116		56			38		33		30

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

144

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Small Cap Value Fund

					Class R6
	(unaudited)
	Period Ended				Period Ended
	June 30,				December 31,
	2020				2019(a)
Net asset value, beginning of year		$	18.03			$	18.19
Income (loss) from investment operations:
Net investment income (loss)			0.06				0.16
Net realized and unrealized gain (loss) on investments			(4.36	)			0.32
Total from investment operations			(4.30	)			0.48
Less distributions from:
Net investment income			—				0.15
Net realized gain			3.04				0.49
Total distributions			3.04				0.64
Net asset value, end of year		$	10.69			$	18.03
Total Return (%)*			(26.27	)			2.69
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.30				1.17
Expenses, net of waivers and reimbursements			1.12				1.17
Net investment income (loss), before waivers and reimbursements			0.76				1.28
Net investment income (loss), net of waivers and reimbursements			0.94				1.28
Class R6 net assets at the end of the year (in thousands)		$	474			$	513
Portfolio turnover rate (%)*			43				116

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

145

Financial Highlights — For a share outstanding throughout each period

Global Leaders Fund

			Class N
	(unaudited)
		Period Ended
		June 30,				Years Ended December 31,
			2020			2019			2018			2017		2016			2015
Net asset value, beginning of year			$	14.92		$	11.47		$	14.53		$	11.60	$	11.58		$	11.84
Income (loss) from investment operations:
Net investment income (loss)				(0.01	)		0.01			0.02			0.05		0.03			0.02
Net realized and unrealized gain (loss) on investments				0.34			3.61			(1.12	)		3.46		0.04			0.27
Total from investment operations				0.33			3.62			(1.10	)		3.51		0.07			0.29
Less distributions from:
Net investment income				—			0.03			—			0.10		—			0.01
Net realized gain				—			0.14			1.96			0.48		0.05			0.54
Total distributions				—			0.17			1.96			0.58		0.05			0.55
Net asset value, end of year			$	15.25		$	14.92		$	11.47		$	14.53	$	11.60		$	11.58
Total return (%)*				2.21			31.57			(8.23	)		30.31		0.62			2.49
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements				1.40			1.39			1.47			1.63		1.62			1.61
Expenses, net of waivers and reimbursements				1.15			1.20			1.33			1.37		1.36			1.39
Net investment income (loss), before waivers and reimbursements				(0.35	)		(0.10	)		(0.01	)		0.09		(0.03	)		(0.10	)
Net investment income (loss), net of waivers and reimbursements				(0.10	)		0.09			0.13			0.35		0.23			0.12
Class N net assets at the end of the year (in thousands)			$	8,862		$	8,910		$	7,225		$	7,761	$	5,760		$	5,588
Portfolio turnover rate (%)*				20			27			49			41		75			55

			Class I
	(unaudited)
		Period Ended
		June 30,				Years Ended December 31,
			2020			2019		2018			2017		2016		2015
Net asset value, beginning of year			$	14.93		$	11.47	$	14.56		$	11.62	$	11.59	$	11.85
Income (loss) from investment operations:
Net investment income (loss)				0.01			0.05		0.06			0.09		0.06		0.06
Net realized and unrealized gain (loss) on investments				0.34			3.61		(1.13	)		3.47		0.05		0.26
Total from investment operations				0.35			3.66		(1.07	)		3.56		0.11		0.32
Less distributions from:
Net investment income				—			0.06		0.06			0.14		0.03		0.04
Net realized gain				—			0.14		1.96			0.48		0.05		0.54
Total distributions				—			0.20		2.02			0.62		0.08		0.58
Net asset value, end of year			$	15.28		$	14.93	$	11.47		$	14.56	$	11.62	$	11.59
Total return (%)*				2.34			31.96		(8.06	)		30.69		0.98		2.77
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements				1.09			1.07		1.15			1.33		1.31		1.32
Expenses, net of waivers and reimbursements				0.90			0.95		1.07			1.07		1.05		1.10
Net investment income (loss), before waivers and reimbursements				(0.04	)		0.22		0.31			0.39		0.28		0.23
Net investment income (loss), net of waivers and reimbursements				0.15			0.34		0.39			0.65		0.54		0.45
Class I net assets at the end of the year (in thousands)			$	86,976		$	114,666	$	83,790		$	60,067	$	45,772	$	45,853
Portfolio turnover rate (%)*				20			27		49			41		75		55

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

146

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Global Leaders Fund

			Class R6
	(unaudited)
		Period Ended
		June 30,				Years Ended December 31,
			2020			2019		2018			2017		2016		2015
Net asset value, beginning of year			$	14.93		$	11.47	$	14.56		$	11.62	$	11.59	$	11.85
Income (loss) from investment operations:
Net investment income (loss)				0.01			0.06		0.07			0.10		0.07		0.06
Net realized and unrealized gain (loss) on investments				0.35			3.61		(1.13	)		3.47		0.05		0.27
Total from investment operations				0.36			3.67		(1.06	)		3.57		0.12		0.33
Less distributions from:
Net investment income				—			0.07		0.07			0.15		0.04		0.05
Net realized gain				—			0.14		1.96			0.48		0.05		0.54
Total distributions				—			0.21		2.03			0.63		0.09		0.59
Net asset value, end of year			$	15.29		$	14.93	$	11.47		$	14.56	$	11.62	$	11.59
Total return (%)*				2.41			32.02		(7.99	)		30.78		1.03		2.85
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements				1.01			1.01		1.08			1.10		1.11		1.11
Expenses, net of waivers and reimbursements				0.85			0.90		1.00			1.00		1.00		1.03
Net investment income (loss), before waivers and reimbursements				(0.03	)		0.32		0.39			0.65		0.48		0.39
Net investment income (loss), net of waivers and reimbursements				0.13			0.43		0.47			0.75		0.59		0.47
Class R6 net assets at the end of the year (in thousands)			$	1,197		$	48,133	$	79,685		$	143,521	$	125,199	$	137,527
Portfolio turnover rate (%)*				20			27		49			41		75		55

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

147

Financial Highlights — For a share outstanding throughout each period

International Leaders Fund

	Class N
	(unaudited) Period Ended June 30,			Years Ended December 31,
	2020			2019		2018			2017		2016			2015
Net asset value, beginning of year	$	18.08		$	13.80	$	16.37		$	12.88	$	12.89		$	12.25
Income (loss) from investment operations:
Net investment income (loss)		0.01			0.09		0.13			0.11		0.03			0.07
Net realized and unrealized gain (loss) on investments		(0.24	)		4.25		(2.19	)		3.70		0.08			0.66
Total from investment operations		(0.23	)		4.34		(2.06	)		3.81		0.11			0.73
Less distributions from:
Net investment income		—			0.06		0.06			0.20		0.12			0.02
Net realized gain		—			—		0.45			0.12		—			0.07
Total distributions		—			0.06		0.51			0.32		0.12			0.09
Net asset value, end of year	$	17.85		$	18.08	$	13.80		$	16.37	$	12.88		$	12.89
Total return (%)*		(1.27	)		31.46		(12.70	)		29.65		0.88			6.01
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements		1.31			1.32		1.39			1.59		1.56			1.56
Expenses, net of waivers and reimbursements		1.15			1.18		1.28			1.35		1.30			1.24
Net investment income (loss), before waivers and reimbursements		(0.03	)		0.44		0.70			0.48		(0.02	)		0.19
Net investment income (loss), net of waivers and reimbursements		0.13			0.58		0.81			0.72		0.24			0.51
Class N net assets at the end of the year (in thousands)	$	8,102		$	11,163	$	8,715		$	9,651	$	2,922		$	377
Portfolio turnover rate (%)*		20			20		33			41		59			29

	Class I
		(unaudited) Period Ended June 30,		Years Ended December 31,
		2020			2019		2018			2017		2016			2015
Net asset value, beginning of year	$	18.13		$	13.84	$	16.44		$	12.92	$	12.91		$	12.25
Income (loss) from investment operations:
Net investment income (loss)		0.03			0.12		0.17			0.16		0.10			0.10
Net realized and unrealized gain (loss) on investments		(0.24	)		4.27		(2.19	)		3.71		0.04			0.65
Total from investment operations		(0.21	)		4.39		(2.02	)		3.87		0.14			0.75
Less distributions from:
Net investment income		—			0.10		0.13			0.23		0.13			0.02
Net realized gain		—			—		0.45			0.12		—			0.07
Total distributions		—			0.10		0.58			0.35		0.13			0.09
Net asset value, end of year	$	17.92		$	18.13	$	13.84		$	16.44	$	12.92		$	12.91
Total return (%)*		(1.16	)		31.76		(12.45	)		30.05		1.10			6.18
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements.		0.99			1.01		1.07			1.28		1.30			1.46
Expenses, net of waivers and reimbursements		0.90			0.93		1.03			1.05		1.04			1.13
Net investment income (loss), before waivers and reimbursements		0.29			0.64		1.02			0.86		0.48			0.42
Net investment income (loss), net of waivers and reimbursements		0.38			0.72		1.06			1.09		0.74			0.75
Class I net assets at the end of the year (in thousands)	$	187,634		$	181,617	$	76,382		$	60,279	$	30,944		$	13,474
Portfolio turnover rate (%)*		20			20		33			41		59			29

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

148

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

International Leaders Fund

	Class R6
	(unaudited) Period Ended June 30,			Years Ended December 31,
	2020			2019		2018			2017		2016			2015
Net asset value, beginning of year	$	18.12		$	13.83	$	16.43		$	12.92	$	12.90		$	12.24
Income (loss) from investment operations:
Net investment income (loss)		0.04			0.14		0.18			0.18		0.12			0.11
Net realized and unrealized gain (loss) on investments		(0.24	)		4.26		(2.19	)		3.70		0.04			0.66
Total from investment operations		(0.20	)		4.40		(2.01	)		3.88		0.16	��		0.77
Less distributions from:
Net investment income		—			0.11		0.14			0.25		0.14			0.04
Net realized gain		—			—		0.45			0.12		—			0.07
Total distributions		—			0.11		0.59			0.37		0.14			0.11
Net asset value, end of year	$	17.92		$	18.12	$	13.83		$	16.43	$	12.92		$	12.90
Total return (%)*		(1.10	)		31.83		(12.38	)		30.08		1.25			6.33
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements		0.92			0.93		0.99			1.03		1.06			1.15
Expenses, net of waivers and reimbursements		0.85			0.88		0.95			0.95		0.95			0.98
Net investment income (loss), before waivers and reimbursements		0.36			0.80		1.07			1.10		0.81			0.71
Net investment income (loss), net of waivers and reimbursements		0.43			0.85		1.11			1.18		0.92			0.88
Class R6 net assets at the end of the year (in thousands)	$	466,725		$	461,124	$	324,902		$	308,898	$	221,356		$	102,227
Portfolio turnover rate (%)*		20			20		33			41		59			29

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

149

Financial Highlights — For a share outstanding throughout each period

International Growth Fund

	Class N
	(unaudited) Period Ended June 30,			Years Ended December 31,
	2020			2019		2018			2017		2016			2015
Net asset value, beginning of year	$	29.68		$	23.04	$	30.41		$	23.86	$	24.94		$	25.24
Income (loss) from investment operations:
Net investment income (loss)		(0.05	)		0.09		0.16			0.21		0.20			0.18
Net realized and unrealized gain (loss) on investments		0.13			6.87		(5.56	)		6.73		(0.92	)		(0.25	)
Total from investment operations		0.08			6.96		(5.40	)		6.94		(0.72	)		(0.07	)
Less distributions from:
Net investment income		—			0.32		0.12			0.39		0.36			0.23
Net realized gain		—			—		1.85			—		—			—
Total distributions		—			0.32		1.97			0.39		0.36			0.23
Net asset value, end of year	$	29.76		$	29.68	$	23.04		$	30.41	$	23.86		$	24.94
Total return (%)*		0.27			30.24		(18.00	)		29.11		(2.88	)		(0.27	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements		1.50			1.45		1.46			1.47		1.43			1.42
Expenses, net of waivers and reimbursements		1.45			1.45		1.45			1.45		1.43			1.42
Net investment income (loss), before waivers and reimbursements		(0.41	)		0.34		0.54			0.76		0.84			0.71
Net investment income (loss), net of waivers and reimbursements		(0.36	)		0.34		0.55			0.78		0.84			0.71
Class N net assets at the end of the year (in thousands)	$	232,632		$	494,788	$	456,533		$	763,740	$	729,544		$	1,023,588
Portfolio turnover rate (%)*		20			34		78			82		101			70

	Class I
	(unaudited) Period Ended June 30,			Years Ended December 31,
		2020			2019		2018			2017		2016			2015
Net asset value, beginning of year	$	30.38		$	23.56	$	31.13		$	24.42	$	25.51		$	25.82
Income (loss) from investment operations:
Net investment income (loss)		0.01			0.18		0.26			0.30		0.29			0.27
Net realized and unrealized gain (loss) on investments		0.11			7.03		(5.70	)		6.89		(0.94	)		(0.28	)
Total from investment operations		0.12			7.21		(5.44	)		7.19		(0.65	)		(0.01	)
Less distributions from:
Net investment income		—			0.39		0.28			0.48		0.44			0.30
Net realized gain		—			—		1.85			—		—			—
Total distributions		—			0.39		2.13			0.48		0.44			0.30
Net asset value, end of year	$	30.50		$	30.38	$	23.56		$	31.13	$	24.42		$	25.51
Total return (%)*		0.40			30.66		(17.73	)		29.49		(2.54	)		(0.03	)
Ratios to average daily net assets (%)**:
Expenses		1.16			1.14		1.13			1.14		1.13			1.14
Net investment income (loss)		0.06			0.65		0.86			1.08		1.16			1.02
Class I net assets at the end of the year (in thousands)	$	1,591,582		$	1,552,355	$	1,646,811		$	2,375,326	$	2,251,701		$	2,655,156
Portfolio turnover rate (%)*		20			34		78			82		101			70

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

150

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

International Growth Fund

		Class R6
	(unaudited) Period Ended June 30,			Period Ended December 31,
		2020			2019(a)
Net asset value, beginning of year		$	30.37		$	27.56
Income (loss) from investment operations:
Net investment income (loss)			0.02			(0.05	)
Net realized and unrealized gain (loss) on investments			0.12			3.27
Total from investment operations			0.14			3.22
Less distributions from:
Net investment income			—			0.41
Net realized gain			—			—
Total distributions			—			0.41
Net asset value, end of year		$	30.51		$	30.37
Total Return (%)*			0.46			11.71
Ratios to average daily net assets (%)**:
Expenses			1.07			1.06
Net investment income (loss)			0.11			(0.26	)
Class R6 net assets at end of year (in thousands)		$	56,994		$	61,916
Portfolio turnover rate (%)*			20			34

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

151

Financial Highlights — For a share outstanding throughout each period

Institutional International Growth Fund

	Institutional
	(unaudited) Period Ended June 30,			Years Ended December 31,
		2020		2019		2018			2017		2016			2015
Net asset value, beginning of year		$	17.35	$	13.40	$	18.08		$	14.55	$	15.08		$	15.26
Income (loss) from investment operations:
Net investment income (loss)			0.02		0.12		0.18			0.21		0.18			0.19
Net realized and unrealized gain (loss) on investments			0.10		4.00		(3.29	)		4.07		(0.54	)		(0.18	)
Total from investment operations			0.12		4.12		(3.11	)		4.28		(0.36	)		0.01
Less distributions from:
Net investment income			—		0.17		0.17			0.44		0.17			0.09
Net realized gain			—		—		1.40			0.31		—			0.10
Total distributions			—		0.17		1.57			0.75		0.17			0.19
Net asset value, end of year		$	17.47	$	17.35	$	13.40		$	18.08	$	14.55		$	15.08
Total return (%)*			0.69		30.75		(17.50	)		29.53		(2.40	)		0.09
Ratios to average daily net assets (%)**:
Expenses			0.99		0.99		0.97			0.97		0.98			0.96
Net investment income (loss),			0.21		0.77		1.01			1.22		1.25			1.18
Net assets at the end of the year (in thousands)		$	1,545,382	$	1,892,911	$	1,784,435		$	2,330,299	$	2,093,971		$	2,335,632
Portfolio turnover rate (%)*			22		35		82			84		105			70

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

152

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

International Small Cap Growth Fund

	Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019		2018			2017		2016			2015
Net asset value, beginning of year		$	13.85		$	10.36	$	15.49		$	12.87	$	13.50		$	12.56
Income (loss) from investment operations:
Net investment income (loss)			(0.01	)		0.05		0.04			0.12		0.10			0.05
Net realized and unrealized gain (loss) on investments			(0.42	)		3.45		(3.78	)		3.98		(0.72	)		1.16
Total from investment operations			(0.43	)		3.50		(3.74	)		4.10		(0.62	)		1.21
Less distributions from:
Net investment income			—			0.01		0.08			0.32		0.01			0.24
Net realized gain			—			—		1.31			1.16		0.00^			0.03
Total distributions			—			0.01		1.39			1.48		0.01			0.27
Net asset value, end of year		$	13.42		$	13.85	$	10.36		$	15.49	$	12.87		$	13.50
Total return (%)*			(3.10	)		33.81		(24.48	)		32.17		(4.60	)		9.67
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.54			1.48		1.48			1.62		1.59			1.62
Expenses, net of waivers and reimbursements			1.54			1.48		1.48			1.47		1.44			1.47
Net investment income (loss), before waivers and reimbursements			(0.15	)		0.45		0.29			0.70		0.62			0.19
Net investment income (loss), net of waivers and reimbursements			(0.15	)		0.45		0.29			0.85		0.77			0.34
Class N net assets at the end of the year (in thousands)		$	2,530		$	3,650	$	3,440		$	6,275	$	10,361		$	11,350
Portfolio turnover rate (%)*			35			38		88			64		73			90

	Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019		2018			2017		2016			2015
Net asset value, beginning of year		$	13.98		$	10.45	$	15.65		$	13.00	$	13.65		$	12.70
Income (loss) from investment operations:
Net investment income (loss)			0.01			0.09		0.09			0.14		0.14			0.09
Net realized and unrealized gain (loss) on investments			(0.42	)		3.48		(3.84	)		4.07		(0.75	)		1.18
Total from investment operations			(0.41	)		3.57		(3.75	)		4.21		(0.61	)		1.27
Less distributions from:
Net investment income			—			0.04		0.14			0.40		0.04			0.29
Net realized gain			—			—		1.31			1.16		0.00^			0.03
Total distributions			—			0.04		1.45			1.56		0.04			0.32
Net asset value, end of year		$	13.57		$	13.98	$	10.45		$	15.65	$	13.00		$	13.65
Total return (%)*			(2.93	)		34.22		(24.29	)		32.70		(4.41	)		10.00
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.27			1.21		1.18			1.31		1.30			1.31
Expenses, net of waivers and reimbursements			1.27			1.21		1.18			1.16		1.15			1.16
Net investment income (loss), before waivers and reimbursements			0.21			0.75		0.60			0.77		0.91			0.51
Net investment income (loss), net of waivers and reimbursements			0.21			0.75		0.60			0.92		1.06			0.66
Class I net assets at the end of the year (in thousands)		$	126,889		$	142,951	$	165,451		$	338,920	$	306,526		$	342,232
Portfolio turnover rate (%)*			35			38		88			64		73			90

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

153

Financial Highlights — For a share outstanding throughout each period

International Small Cap Growth Fund

	Class R6
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019		2018			2017		2016			2015
Net asset value, beginning of year		$	14.05		$	10.50	$	15.73		$	13.07	$	13.72		$	12.77
Income (loss) from investment operations:
Net investment income (loss)			0.02			0.11		0.10			0.15		0.15			0.10
Net realized and unrealized gain (loss) on investments			(0.42	)		3.49		(3.85	)		4.08		(0.74	)		1.18
Total from investment operations			(0.40	)		3.60		(3.75	)		4.23		(0.59	)		1.28
Less distributions from:
Net investment income			—			0.05		0.17			0.41		0.06			0.30
Net realized gain			—			—		1.31			1.16		0.00^			0.03
Total distributions			—			0.05		1.48			1.57		0.06			0.33
Net asset value, end of year		$	13.65		$	14.05	$	10.50		$	15.73	$	13.07		$	13.72
Total return (%)*			(2.85	)		34.32		(24.19	)		32.70		(4.31	)		10.03
Ratios to average daily net assets (%)**:
Expenses			1.15			1.12		1.08			1.08		1.07			1.08
Net investment income (loss)			0.34			0.86		0.67			0.99		1.13			0.76
Class R6 net assets at the end of the year (in thousands)		$	132,922		$	162,465	$	171,833		$	256,558	$	199,746		$	221,018
Portfolio turnover rate (%)*			35			38		88			64		73			90

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

154

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Emerging Markets Leaders Fund

	Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019		2018			2017			2016		2015
Net asset value, beginning of year		$	10.51		$	8.26	$	11.06		$	7.84		$	7.73	$	9.06
Income (loss) from investment operations:
Net investment income (loss)			0.01			0.03		0.03			0.01			0.02		0.02
Net realized and unrealized gain (loss) on investments			(0.48	)		2.28		(1.97	)		3.26			0.09		(1.34	)
Total from investment operations			(0.47	)		2.31		(1.94	)		3.27			0.11		(1.32	)
Less distributions from:
Net investment income			—			0.04		0.07			0.05			—		—
Net realized gain			—			0.02		0.79			—			—		0.01
Total distributions			—			0.06		0.86			0.05			—		0.01
Net asset value, end of year		$	10.04		$	10.51	$	8.26		$	11.06		$	7.84	$	7.73
Total return (%)*			(4.47	)		27.98		(17.73	)		41.68			1.42		(14.56	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.66			1.62		1.60			1.62			1.81		1.89
Expenses, net of waivers and reimbursements			1.40			1.45		1.58			1.47			1.57		1.64
Net investment income (loss), before waivers and reimbursements			(0.13	)		0.17		0.27			(0.01	)		0.05		(0.07	)
Net investment income (loss), net of waivers and reimbursements			0.13			0.34		0.29			0.14			0.29		0.18
Class N net assets at the end of the year (in thousands)		$	1,391		$	1,856	$	2,239		$	2,766		$	2,479	$	1,599
Portfolio turnover rate (%)*			24			33		52			59			135		110

	Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019		2018			2017			2016		2015
Net asset value, beginning of year		$	10.52		$	8.27	$	11.09		$	7.87		$	7.74	$	9.08
Income (loss) from investment operations:
Net investment income (loss)			0.02			0.06		0.06			0.02			0.04		0.05
Net realized and unrealized gain (loss) on investments			(0.47	)		2.29		(1.97	)		3.27			0.10		(1.36	)
Total from investment operations			(0.45	)		2.35		(1.91	)		3.29			0.14		(1.31	)
Less distributions from:
Net investment income			—			0.08		0.12			0.07			0.01		0.02
Net realized gain			—			0.02		0.79			—			—		0.01
Total distributions			—			0.10		0.91			0.07			0.01		0.03
Net asset value, end of year		$	10.07		$	10.52	$	8.27		$	11.09		$	7.87	$	7.74
Total return (%)*			(4.28	)		28.36		(17.45	)		41.89			1.82		(14.37	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.33			1.29		1.27			1.40			1.54		1.54
Expenses, net of waivers and reimbursements			1.15			1.20		1.27			1.25			1.30		1.29
Net investment income (loss), before waivers and reimbursements			0.20			0.53		0.58			0.09			0.28		0.28
Net investment income (loss), net of waivers and reimbursements			0.38			0.62		0.58			0.24			0.52		0.53
Class I net assets at the end of the year (in thousands)		$	43,268		$	45,090	$	34,786		$	47,666		$	30,346	$	32,862
Portfolio turnover rate (%)*			24			33		52			59			135		110

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

155

Financial Highlights — For a share outstanding throughout each period

Emerging Markets Leaders Fund

	Class R6
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019		2018			2017		2016		2015
Net asset value, beginning of year		$	10.51		$	8.26	$	11.09		$	7.86	$	7.74	$	9.07
Income (loss) from investment operations:
Net investment income (loss)			0.02			0.06		0.07			0.03		0.03		0.04
Net realized and unrealized gain (loss) on investments			(0.47	)		2.29		(1.98	)		3.28		0.10		(1.33	)
Total from investment operations			(0.45	)		2.35		(1.91	)		3.31		0.13		(1.29	)
Less distributions from:
Net investment income			—			0.08		0.13			0.08		0.01		0.03
Net realized gain			—			0.02		0.79			—		—		0.01
Total distributions			—			0.10		0.92			0.08		0.01		0.04
Net asset value, end of year		$	10.06		$	10.51	$	8.26		$	11.09	$	7.86	$	7.74
Total return (%)*			(4.28	)		28.45		(17.46	)		42.15		1.74		(14.24	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.26			1.23		1.20			1.19		1.34		1.35
Expenses, net of waivers and reimbursements			1.10			1.15		1.20			1.19		1.25		1.25
Net investment income (loss), before waivers and reimbursements			0.28			0.57		0.71			0.33		0.30		0.39
Net investment income (loss), net of waivers and reimbursements			0.44			0.65		0.71			0.33		0.39		0.49
Class R6 net assets at the end of the year (in thousands)		$	178,808		$	191,337	$	161,889		$	427,480	$	272,678	$	93,217
Portfolio turnover rate (%)*			24			33		52			59		135		110

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

156

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Emerging Markets Growth Fund

		Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019		2018			2017			2016		2015
Net asset value, beginning of year		$	13.67		$	11.14	$	16.20		$	10.99		$	10.85	$	12.91
Income (loss) from investment operations:
Net investment income (loss)			(0.03	)		0.11		0.01			(0.02	)		0.03		0.04
Net realized and unrealized gain (loss) on investments			0.47			2.98		(3.49	)		5.35			0.13		(1.98	)
Total from investment operations			0.44			3.09		(3.48	)		5.33			0.16		(1.94	)
Less distributions from:
Net investment income			—			0.16		0.11			0.12			0.02		—
Net realized gain			—			0.40		1.47			—			—		0.12
Total distributions			—			0.56		1.58			0.12			0.02		0.12
Net asset value, end of year		$	14.11		$	13.67	$	11.14		$	16.20		$	10.99	$	10.85
Total return (%)*			3.22			27.89		(21.61	)		48.53			1.49		(15.03	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.54			1.51		1.52			1.65			1.65		1.65
Expenses, net of waivers and reimbursements			1.54			1.51		1.52			1.50			1.50		1.50
Net investment income (loss), before waivers and reimbursements			(0.43	)		0.84		0.09			(0.29	)		0.13		0.18
Net investment income (loss), net of waivers and reimbursements			(0.43	)		0.84		0.09			(0.14	)		0.28		0.33
Class N net assets at the end of the year (in thousands)		$	7,934		$	7,804	$	7,103		$	10,479		$	8,488	$	9,367
Portfolio turnover rate (%)*			46			79		113			91			105		121

		Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019		2018			2017			2016		2015
Net asset value, beginning of year		$	13.82		$	11.25	$	16.36		$	11.10		$	10.96	$	13.01
Income (loss) from investment operations:
Net investment income (loss)			(0.01	)		0.14		0.05			0.01			0.06		0.07
Net realized and unrealized gain (loss) on investments			0.47			3.02		(3.52	)		5.40			0.13		(2.00	)
Total from investment operations			0.46			3.16		(3.47	)		5.41			0.19		(1.93	)
Less distributions from:
Net investment income			—			0.19		0.17			0.15			0.05		—
Net realized gain			—			0.40		1.47			—			—		0.12
Total distributions			—			0.59		1.64			0.15			0.05		0.12
Net asset value, end of year		$	14.28		$	13.82	$	11.25		$	16.36		$	11.10	$	10.96
Total return (%)*			3.33			28.29		(21.37	)		48.83			1.73		(14.83	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements.			1.30			1.26		1.27			1.42			1.41		1.40
Expenses, net of waivers and reimbursements			1.30			1.26		1.27			1.27			1.26		1.25
Net investment income (loss), before waivers and reimbursements			(0.19	)		1.06		0.34			(0.07	)		0.38		0.43
Net investment income (loss), net of waivers and reimbursements			(0.19	)		1.06		0.34			0.08			0.53		0.58
Class I net assets at the end of the year (in thousands)		$	75,381		$	73,496	$	79,427		$	129,481		$	93,668	$	130,491
Portfolio turnover rate (%)*			46			79		113			91			105		121

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

157

Financial Highlights — For a share outstanding throughout each period

Emerging Markets Growth Fund

		Class R6
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019		2018			2017		2016		2015
Net asset value, beginning of year		$	13.94		$	11.35	$	16.49		$	11.18	$	11.05	$	13.09
Income (loss) from investment operations:
Net investment income (loss)			(0.00	)^		0.15		0.07			0.02		0.07		0.08
Net realized and unrealized gain (loss) on investments			0.47			3.04		(3.56	)		5.46		0.12		(2.00	)
Total from investment operations			0.47			3.19		(3.49	)		5.48		0.19		(1.92	)
Less distributions from:
Net investment income			—			0.20		0.18			0.17		0.06		—
Net realized gain			—			0.40		1.47			—		—		0.12
Total distributions			—			0.60		1.65			0.17		0.06		0.12
Net asset value, end of year		$	14.41		$	13.94	$	11.35		$	16.49	$	11.18	$	11.05
Total return (%)*			3.37			28.28		(21.29	)		49.06		1.71		(14.67	)
Ratios to average daily net assets (%)**:
Expenses			1.20			1.19		1.19			1.17		1.19		1.17
Net investment income (loss)			(0.07	)		1.17		0.46			0.17		0.60		0.61
Class R6 net assets at the end of the year (in thousands)		$	744,640		$	708,892	$	654,441		$	1,178,853	$	831,587	$	739,253
Portfolio turnover rate (%)*			46			79		113			91		105		121

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

158

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Emerging Markets Small Cap Growth Fund

		Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	16.80		$	13.96		$	18.66		$	13.73		$	14.84		$	16.52
Income (loss) from investment operations:
Net investment income (loss)			(0.05	)		0.00	^		(0.02	)		0.01			0.09			(0.01	)
Net realized and unrealized gain (loss) on investments			0.22			2.84			(4.38	)		5.46			(0.88	)		(1.05	)
Total from investment operations			0.17			2.84			(4.40	)		5.47			(0.79	)		(1.06	)
Less distributions from:
Net investment income			—			—			—			0.50			0.32			—
Net realized gain			—			—			0.30			0.04			—			0.62
Total distributions			—			—			0.30			0.54			0.32			0.62
Net asset value, end of year		$	16.97		$	16.80		$	13.96		$	18.66		$	13.73		$	14.84
Total return (%)*			1.01			20.34			(23.57	)		40.09			(5.33	)		(6.40	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.80			1.71			1.70			1.83			1.82			1.94
Expenses, net of waivers and reimbursements			1.55			1.55			1.58			1.64			1.61			1.65
Net investment income (loss), before waivers and reimbursements			(0.83	)		(0.14	)		(0.22	)		(0.11	)		0.41			(0.35	)
Net investment income (loss), net of waivers and reimbursements			(0.58	)		0.02	��		(0.10	)		0.08			0.62			(0.06	)
Class N net assets at the end of the year (in thousands)		$	3,314		$	4,025		$	8,977		$	15,082		$	9,263		$	11,306
Portfolio turnover rate (%)*			69			142			187			183			157			167

		Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019			2018			2017			2016			2015
Net asset value, beginning of year		$	16.90		$	14.03		$	18.73		$	13.77		$	14.90		$	16.52
Income (loss) from investment operations:
Net investment income (loss)			(0.03	)		0.04			0.03			0.08			0.13			0.05
Net realized and unrealized gain (loss) on investments			0.22			2.86			(4.41	)		5.47			(0.89	)		(1.05	)
Total from investment operations			0.19			2.90			(4.38	)		5.55			(0.76	)		(1.00	)
Less distributions from:
Net investment income			—			0.03			0.02			0.55			0.37			—
Net realized gain			—			—			0.30			0.04			—			0.62
Total distributions			—			0.03			0.32			0.59			0.37			0.62
Net asset value, end of year		$	17.09		$	16.90		$	14.03		$	18.73		$	13.77		$	14.90
Total return (%)*			1.12			20.58			(23.31	)		40.53			(5.11	)		(6.03	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.47			1.40			1.38			1.50			1.51			1.52
Expenses, net of waivers and reimbursements			1.30			1.30			1.33			1.31			1.30			1.31
Net investment income (loss), before waivers and reimbursements			(0.49	)		0.18			0.13			0.30			0.66			0.09
Net investment income (loss), net of waivers and reimbursements			(0.32	)		0.28			0.18			0.49			0.87			0.30
Class I net assets at the end of the year (in thousands)		$	122,722		$	142,885		$	169,770		$	282,620		$	147,949		$	162,375
Portfolio turnover rate (%)*			69			142			187			183			157			167

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

159

Financial Highlights — For a share outstanding throughout each period

Emerging Markets Small Cap Growth Fund

		Class R6
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019		2018			2017		2016			2015
Net asset value, beginning of year		$	16.93		$	14.06	$	18.76		$	13.79	$	14.92		$	16.53
Income (loss) from investment operations:
Net investment income (loss)			(0.02	)		0.05		0.05			0.10		0.14			0.06
Net realized and unrealized gain (loss) on investments			0.21			2.86		(4.41	)		5.47		(0.89	)		(1.05	)
Total from investment operations			0.19			2.91		(4.36	)		5.57		(0.75	)		(0.99	)
Less distributions from:
Net investment income			—			0.04		0.04			0.56		0.38			0.00^
Net realized gain			—			—		0.30			0.04		—			0.62
Total distributions			—			0.04		0.34			0.60		0.38			0.62
Net asset value, end of year		$	17.12		$	16.93	$	14.06		$	18.76	$	13.79		$	14.92
Total return (%)*			1.12			20.69		(23.24	)		40.62		(5.05	)		(5.97	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.38			1.33		1.30			1.29		1.31			1.31
Expenses, net of waivers and reimbursements			1.25			1.25		1.25			1.25		1.25			1.25
Net investment income (loss), before waivers and reimbursements			(0.39	)		0.27		0.22			0.53		0.88			0.28
Net investment income (loss), net of waivers and reimbursements			(0.26	)		0.35		0.27			0.57		0.94			0.34
Class R6 net assets at the end of the year (in thousands)		$	134,532		$	130,711	$	98,188		$	166,927	$	125,650		$	123,160
Portfolio turnover rate (%)*			69			142		187			183		157			167

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.
^	Amount is less than $0.005 per share.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

160

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Bond Fund

	Class N
	(unaudited) Period Ended June 30,			Years Ended December 31,
	2020			2019		2018			2017		2016		2015
Net asset value, beginning of year		$	10.41	$	9.75	$	10.41		$	10.41	$	10.34	$	10.74
Income (loss) from investment operations:
Net investment income (loss)			0.13		0.30		0.31			0.27		0.27		0.27
Net realized and unrealized gain (loss) on investments			0.31		0.77		(0.56	)		0.12		0.18		(0.29	)
Total from investment operations			0.44		1.07		(0.25	)		0.39		0.45		(0.02	)
Less distributions from:
Net investment income			0.19		0.41		0.41			0.39		0.38		0.38
Net realized gain			—		—		—			—		—		—
Total distributions			0.19		0.41		0.41			0.39		0.38		0.38
Net asset value, end of year		$	10.66	$	10.41	$	9.75		$	10.41	$	10.41	$	10.34
Total return (%)*			4.29		11.09		(2.42	)		3.83		4.40		(0.23	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.71		0.69		0.69			0.82		0.82		0.79
Expenses, net of waivers and reimbursements			0.60		0.60		0.62			0.65		0.65		0.61
Net investment income (loss), before waivers and reimbursements			2.44		2.90		3.01			2.40		2.43		2.42
Net investment income (loss), net of waivers and reimbursements			2.55		2.99		3.08			2.57		2.60		2.60
Class N net assets at the end of the year (in thousands)		$	30,598	$	32,176	$	70,253		$	83,662	$	125,866	$	139,303
Portfolio turnover rate (%)*			47		58		40			17		17		32

	Class I
	(unaudited) Period Ended June 30,			Years Ended December 31,
	2020			2019		2018			2017		2016		2015
Net asset value, beginning of year		$	10.30	$	9.65	$	10.31		$	10.30	$	10.24	$	10.64
Income (loss) from investment operations:
Net investment income (loss)			0.14		0.31		0.32			0.29		0.30		0.31
Net realized and unrealized gain (loss) on investments			0.30		0.76		(0.56	)		0.13		0.16		(0.31	)
Total from investment operations			0.44		1.07		(0.24	)		0.42		0.46		—
Less distributions from:
Net investment income			0.20		0.42		0.42			0.41		0.40		0.40
Net realized gain			—		—		—			—		—		—
Total distributions			0.20		0.42		0.42			0.41		0.40		0.40
Net asset value, end of year		$	10.54	$	10.30	$	9.65		$	10.31	$	10.30	$	10.24
Total return (%)*			4.30		11.22		(2.31	)		4.16		4.55		(0.05	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.51		0.47		0.46			0.60		0.58		0.59
Expenses, net of waivers and reimbursements			0.45		0.45		0.46			0.43		0.41		0.41
Net investment income (loss), before waivers and reimbursements			2.65		3.10		3.24			2.62		2.66		2.75
Net investment income (loss), net of waivers and reimbursements			2.71		3.12		3.24			2.79		2.83		2.93
Class I net assets at the end of the year (in thousands)		$	199,616	$	206,304	$	281,442		$	384,464	$	322,174	$	237,587
Portfolio turnover rate (%)*			47		58		40			17		17		32

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

161

Financial Highlights — For a share outstanding throughout each period

Bond Fund

	Class R6
	(unaudited) Period Ended June 30,			Years Ended December 31,
	2020			2019		2018			2017		2016		2015
Net asset value, beginning of year		$	10.30	$	9.64	$	10.30		$	10.29	$	10.23	$	10.63
Income (loss) from investment operations:
Net investment income (loss)			0.14		0.32		0.33			0.30		0.30		0.32
Net realized and unrealized gain (loss) on investments			0.30		0.76		(0.56	)		0.13		0.17		(0.31	)
Total from investment operations			0.44		1.08		(0.23	)		0.43		0.47		0.01
Less distributions from:
Net investment income			0.20		0.42		0.43			0.42		0.41		0.41
Net realized gain			—		—		—			—		—		—
Total distributions			0.20		0.42		0.43			0.42		0.41		0.41
Net asset value, end of year		$	10.54	$	10.30	$	9.64		$	10.30	$	10.29	$	10.23
Total return (%)*			4.32		11.39		(2.26	)		4.24		4.61		0.01
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.43		0.41		0.38			0.37		0.37		0.38
Expenses, net of waivers and reimbursements			0.40		0.40		0.38			0.35		0.35		0.35
Net investment income (loss), before waivers and reimbursements			2.73		3.17		3.32			2.85		2.88		2.98
Net investment income (loss), net of waivers and reimbursements			2.76		3.18		3.32			2.87		2.90		3.01
Class R6 net assets at the end of the year (in thousands)		$	45,941	$	43,655	$	70,851		$	91,629	$	95,216	$	103,904
Portfolio turnover rate (%)*			47		58		40			17		17		32

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

162

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Income Fund

	Class N
	(unaudited) Period Ended June 30,			Years Ended December 31,
	2020			2019		2018			2017			2016		2015
Net asset value, beginning of year		$	8.57	$	8.36	$	8.72		$	8.86		$	8.90	$	9.12
Income (loss) from investment operations:
Net investment income (loss)			0.07		0.17		0.17			0.16			0.16		0.15
Net realized and unrealized gain (loss) on investments			0.20		0.32		(0.25	)		(0.03	)		0.06		(0.11	)
Total from investment operations			0.27		0.49		(0.08	)		0.13			0.22		0.04
Less distributions from:
Net investment income			0.14		0.28		0.28			0.27			0.26		0.26
Net realized gain			—		—		—			—			—		—
Total distributions			0.14		0.28		0.28			0.27			0.26		0.26
Net asset value, end of year		$	8.70	$	8.57	$	8.36		$	8.72		$	8.86	$	8.90
Total return (%)*			3.14		5.92		(0.86	)		1.46			2.44		0.39
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.07		0.98		0.91			0.88			0.79		0.81
Expenses, net of waivers and reimbursements			0.85		0.85		0.85			0.85			0.79		0.81
Net investment income (loss), before waivers and reimbursements			1.49		1.85		1.96			1.77			1.80		1.71
Net investment income (loss), net of waivers and reimbursements			1.71		1.98		2.02			1.80			1.80		1.71
Class N net assets at the end of the year (in thousands)		$	21,204	$	19,662	$	22,422		$	39,625		$	52,710	$	32,942
Portfolio turnover rate (%)*			40		114		97			37			22		21

	Class I
	(unaudited) Period Ended June 30,			Years Ended December 31,
	2020			2019		2018			2017			2016		2015
Net asset value, beginning of year		$	8.52	$	8.30	$	8.66		$	8.80		$	8.83	$	9.05
Income (loss) from investment operations:
Net investment income (loss)			0.08		0.18		0.19			0.18			0.18		0.18
Net realized and unrealized gain (loss) on investments			0.19		0.33		(0.25	)		(0.03	)		0.06		(0.12	)
Total from investment operations			0.27		0.51		(0.06	)		0.15			0.24		0.06
Less distributions from:
Net investment income			0.14		0.29		0.30			0.29			0.27		0.28
Net realized gain			—		—		—			—			—		—
Total distributions			0.14		0.29		0.30			0.29			0.27		0.28
Net asset value, end of year		$	8.65	$	8.52	$	8.30		$	8.66		$	8.80	$	8.83
Total return (%)*			3.22		6.24		(0.69	)		1.68			2.78		0.63
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.82		0.74		0.65			0.62			0.57		0.55
Expenses, net of waivers and reimbursements			0.70		0.70		0.65			0.62			0.57		0.55
Net investment income (loss), before waivers and reimbursements			1.75		2.10		2.22			2.03			2.05		1.97
Net investment income (loss), net of waivers and reimbursements			1.87		2.14		2.22			2.03			2.05		1.97
Class I net assets at the end of the year (in thousands)		$	31,659	$	31,629	$	34,793		$	51,153		$	58,160	$	62,722
Portfolio turnover rate (%)*			40		114		97			37			22		21

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

163

Financial Highlights — For a share outstanding throughout each period

Income Fund

	Class R6
	(unaudited) Period Ended June 30,			Period Ended December 31,
	2020			2019(a)
Net asset value, beginning of year		$	8.52		$	8.45
Income (loss) from investment operations:
Net investment income (loss)			0.08			0.09
Net realized and unrealized gain (loss) on investments			0.19			0.18
Total from investment operations			0.27			0.27
Less distributions from:
Net investment income			0.14			0.20
Net realized gain			—			—
Total distributions			0.14			0.20
Net asset value, end of year		$	8.65		$	8.52
Total Return (%)*			3.25			3.18
Ratios to average daily net assets (%)**:
Expenses, before of waivers and reimbursements			0.78			0.71
Expenses, net waivers and reimbursements			0.65			0.65
Net investment income (loss), before of waivers and reimbursements			1.78			1.46
Net investment income (loss), net waivers and reimbursements			1.91			1.52
Class R6 net assets at end of year (in thousands)		$	70		$	52
Portfolio turnover rate (%)*			40			114

(a)	For the period from May 2, 2019 (Commencement of Operations) to December 31, 2019.
*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

164

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Low Duration Fund

	Class N
	(unaudited) Period Ended June 30,			Years Ended December 31,
		2020		2019		2018			2017			2016		2015
Net asset value, beginning of year		$	8.68	$	8.70	$	8.92		$	9.07		$	9.16	$	9.38
Income (loss) from investment operations:
Net investment income (loss)			0.06		0.19		0.17			0.11			0.09		0.07
Net realized and unrealized gain (loss) on investments			0.10		0.11		(0.10	)		(0.04	)		0.02		(0.07	)
Total from investment operations			0.16		0.30		0.07			0.07			0.11		—
Less distributions from:
Net investment income			0.14		0.32		0.29			0.22			0.20		0.22
Net realized gain			—		—		—			—			—		—
Total distributions			0.14		0.32		0.29			0.22			0.20		0.22
Net asset value, end of year		$	8.70	$	8.68	$	8.70		$	8.92		$	9.07	$	9.16
Total return (%)*			1.85		3.48		0.80			0.84			1.16		0.01
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.77		0.75		0.72			0.79			0.83		0.77
Expenses, net of waivers and reimbursements			0.55		0.55		0.58			0.61			0.68		0.60
Net investment income (loss), before waivers and reimbursements			1.22		1.96		1.83			1.04			0.83		0.54
Net investment income (loss), net of waivers and reimbursements			1.44		2.16		1.97			1.22			0.98		0.71
Class N net assets at the end of the year (in thousands)		$	7,192	$	1,513	$	1,661		$	1,979		$	7,237	$	2,712
Portfolio turnover rate (%)*			76		183		122			109			81		106

	Class I
	(unaudited) Period Ended June 30,			Years Ended December 31,
			2020		2019		2018			2017			2016		2015
Net asset value, beginning of year		$	8.67	$	8.70	$	8.91		$	9.07		$	9.16	$	9.37
Income (loss) from investment operations:
Net investment income (loss)			0.08		0.20		0.19			0.13			0.11		0.08
Net realized and unrealized gain (loss) on investments			0.09		0.10		(0.09	)		(0.05	)		0.02		(0.05	)
Total from investment operations			0.17		0.30		0.10			0.08			0.13		0.03
Less distributions from:
Net investment income			0.15		0.33		0.31			0.24			0.22		0.24
Net realized gain			—		—		—			—			—		—
Total distributions			0.15		0.33		0.31			0.24			0.22		0.24
Net asset value, end of year		$	8.69	$	8.67	$	8.70		$	8.91		$	9.07	$	9.16
Total return (%)*			1.93		3.52		1.12			0.91			1.40		0.30
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.58		0.53		0.46			0.59			0.59		0.59
Expenses, net of waivers and reimbursements			0.40		0.40		0.39			0.41			0.44		0.42
Net investment income (loss), before waivers and reimbursements			1.63		2.19		2.05			1.27			1.05		0.70
Net investment income (loss), net of waivers and reimbursements			1.81		2.32		2.12			1.45			1.20		0.87
Class I net assets at the end of the year (in thousands)		$	63,588	$	38,156	$	56,120		$	131,186		$	219,714	$	107,137
Portfolio turnover rate (%)*			76		183		122			109			81		106

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

165

Financial Highlights — For a share outstanding throughout each period

Low Duration Fund

	Class R6
	(unaudited) Period Ended June 30,			Years Ended December 31,
		2020		2019		2018			2017			2016		2015
Net asset value, beginning of year		$	8.68	$	8.70	$	8.91		$	9.07		$	9.16	$	9.38
Income (loss) from investment operations:
Net investment income (loss)			0.08		0.21		0.19			0.14			0.11		0.09
Net realized and unrealized gain (loss) on investments			0.08		0.11		(0.09	)		(0.05	)		0.02		(0.07	)
Total from investment operations			0.16		0.32		0.10			0.09			0.13		0.02
Less distributions from:
Net investment income			0.15		0.34		0.31			0.25			0.22		0.24
Net realized gain			—		—		—			—			—		—
Total distributions			0.15		0.34		0.31			0.25			0.22		0.24
Net asset value, end of year		$	8.69	$	8.68	$	8.70		$	8.91		$	9.07	$	9.16
Total return (%)*			1.84		3.69		1.15			0.96			1.43		0.22
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.54		0.50		0.42			0.40			0.40		0.42
Expenses, net of waivers and reimbursements			0.35		0.35		0.35			0.37			0.40		0.40
Net investment income (loss), before waivers and reimbursements			1.70		2.22		2.10			1.48			1.25		0.92
Net investment income (loss), net of waivers and reimbursements			1.89		2.37		2.17			1.51			1.25		0.94
Class R6 net assets at the end of the year (in thousands)		$	40,582	$	36,846	$	47,585		$	99,912		$	53,122	$	21,863
Portfolio turnover rate (%)*			76		183		122			109			81		106

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

166

Semiannual Report

June 30, 2020

Financial Highlights — For a share outstanding throughout each period

Macro Allocation Fund

	Class N
	(unaudited) Period Ended June 30,				Years Ended December 31,
		2020			2019		2018			2017		2016		2015
Net asset value, beginning of year		$	11.44		$	11.41	$	11.84		$	11.34	$	11.32	$	12.14
Income (loss) from investment operations:
Net investment income (loss)			0.02			0.08		0.08			0.06		0.04		0.04
Net realized and unrealized gain (loss) on investments			(0.83	)		0.37		(0.24	)		0.51		0.19		(0.80	)
Total from investment operations			(0.81	)		0.45		(0.16	)		0.57		0.23		(0.76	)
Less distributions from:
Net investment income			—			0.42		0.27			0.07		0.21		0.06
Net realized gain			—			—		—			—		—		—
Total distributions			—			0.42		0.27			0.07		0.21		0.06
Net asset value, end of year		$	10.63		$	11.44	$	11.41		$	11.84	$	11.34	$	11.32
Total return (%)*			(7.08	)		3.97		(1.30	)		5.06		2.01		(6.24	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.33			1.22		1.30			1.52		1.38		1.42
Expenses, net of waivers and reimbursements			1.26			1.22		1.30			1.37		1.23		1.27
Expenses (excluding interest or short dividend expense), net of waivers and reimbursements			1.25			1.21		1.28			1.31		1.23		1.27
Net investment income (loss), before waivers and reimbursements			0.33			0.70		0.66			0.35		0.17		0.17
Net investment income (loss), net of waivers and reimbursements			0.40			0.70		0.66			0.50		0.32		0.32
Class N net assets at the end of the year (in thousands)		$	8,519		$	13,717	$	43,463		$	41,483	$	61,376	$	150,606
Portfolio turnover rate (%)*			16			31		36			43		50		34

	Class I
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019		2018			2017		2016		2015
Net asset value, beginning of year		$	11.35		$	11.38	$	11.88		$	11.38	$	11.38	$	12.22
Income (loss) from investment operations:
Net investment income (loss)			0.04			0.13		0.11			0.11		0.08		0.09
Net realized and unrealized gain (loss) on investments			(0.83	)		0.34		(0.24	)		0.51		0.18		(0.82	)
Total from investment operations			(0.79	)		0.47		(0.13	)		0.62		0.26		(0.73	)
Less distributions from:
Net investment income			—			0.50		0.37			0.12		0.26		0.11
Net realized gain			—			—		—			—		—		—
Total distributions			—			0.50		0.37			0.12		0.26		0.11
Net asset value, end of year		$	10.56		$	11.35	$	11.38		$	11.88	$	11.38	$	11.38
Total return (%)*			(6.96	)		4.14		(1.08	)		5.50		2.26		(6.00	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			1.01			0.97		0.99			1.17		1.12		1.14
Expenses, net of waivers and reimbursements			1.01			0.97		0.99			1.02		0.97		0.99
Expenses (excluding interest or short dividend expense), net of waivers and reimbursements			1.00			0.96		0.97			0.96		0.97		0.98
Net investment income (loss), before waivers and reimbursements			0.65			1.09		0.95			0.75		0.52		0.58
Net investment income (loss), net of waivers and reimbursements			0.65			1.09		0.95			0.90		0.67		0.73
Class I net assets at the end of the year (in thousands)		$	248,277		$	358,935	$	486,543		$	780,075	$	937,244	$	1,155,051
Portfolio turnover rate (%)*			16			31		36			43		50		34

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

June 30, 2020

William Blair Funds

167

Financial Highlights — For a share outstanding throughout each period

Macro Allocation Fund

	Class R6
	(unaudited) Period Ended June 30,				Years Ended December 31,
			2020			2019		2018			2017		2016		2015
Net asset value, beginning of year		$	11.36		$	11.38	$	11.89		$	11.40	$	11.39	$	12.23
Income (loss) from investment operations:
Net investment income (loss)			0.04			0.14		0.13			0.12		0.09		0.12
Net realized and unrealized gain (loss) on investments			(0.82	)		0.34		(0.24	)		0.51		0.19		(0.84	)
Total from investment operations			(0.78	)		0.48		(0.11	)		0.63		0.28		(0.72	)
Less distributions from:
Net investment income			—			0.50		0.40			0.14		0.27		0.12
Net realized gain			—			—		—			—		—		—
Total distributions			—			0.50		0.40			0.14		0.27		0.12
Net asset value, end of year		$	10.58		$	11.36	$	11.38		$	11.89	$	11.40	$	11.39
Total return (%)*			(6.87	)		4.29		(0.94	)		5.51		2.44		(5.92	)
Ratios to average daily net assets (%)**:
Expenses, before waivers and reimbursements			0.92			0.89		0.91			0.92		0.89		0.90
Expenses, net of waivers and reimbursements			0.92			0.89		0.91			0.92		0.89		0.90
Expenses (excluding interest or short dividend expense), net of waivers and reimbursements			0.91			0.88		0.89			0.86		0.89		0.90
Net investment income (loss), before waivers and reimbursements			0.79			1.23		1.10			1.04		0.81		0.95
Net investment income (loss), net of waivers and reimbursements			0.79			1.23		1.10			1.04		0.81		0.95
Class R6 net assets at the end of the year (in thousands)		$	289,668		$	378,148	$	391,812		$	487,082	$	582,298	$	426,230
Portfolio turnover rate (%)*			16			31		36			43		50		34

*	Rates are not annualized for periods less than a year.
**	Rates are annualized for periods less than a year.

Note: Net investment income (loss) per share is based on the average shares outstanding during the year.

168

Semiannual Report

June 30, 2020

Renewal of the Management Agreement

On April 29, 2020, the Board of Trustees (the “Board”) of the William Blair Funds (the “Trust”), including the Trustees who are not “interested persons” of the Trust as defined by the Investment Company Act of 1940, as amended (the “Independent Trustees”), approved the renewal for an additional one-year term of the Trust’s Management Agreement with William Blair Investment Management, LLC (the “Adviser”) on behalf of each of the William Blair Funds (each, a “Fund” and collectively, the “Funds”), with the exception of the Small-Mid Cap Core Fund, for which the Management Agreement was approved for an initial two-year term by the Board on July 31, 2019. In deciding to approve the renewal of the Management Agreement, the Board did not identify any single factor or group of factors as all important or controlling and considered all factors together. The Board did not allot a particular weight to any one factor or group of factors.

The information in this summary outlines the Board’s considerations associated with its renewal of the Management Agreement. In connection with its deliberations regarding the continuation of the Management Agreement, the Board considered such information and factors as it believed to be necessary to evaluate the terms of the Management Agreement. As described below, the Board considered the nature, quality and extent of the services performed by the Adviser under the Management Agreement; the investment performance of each Fund and the Adviser; comparative management fees and expense ratios as prepared by an independent provider (Broadridge); the estimated profitability realized by the Adviser; the extent to which the Adviser realizes economies of scale as a Fund grows; and whether fall-out benefits are being realized by the Adviser. In addition, the Independent Trustees discussed the renewal of the Management Agreement with Trust management and in private sessions with independent legal counsel at which no representatives of the Adviser were present.

The Board, including the Independent Trustees, considered the renewal of the Management Agreement pursuant to a process that concluded at the Board’s April 29, 2020 meeting. In preparation for the review process, the Independent Trustees considered the type and nature of information to be requested, and independent legal counsel sent a formal request for information to the Adviser. The Adviser provided extensive information in response to the request. After reviewing the information received, the Independent Trustees requested supplemental information, which the Adviser provided. The Independent Trustees also received a memorandum from legal counsel advising them of their duties and responsibilities in connection with the consideration of the Management Agreement. The Independent Trustees reviewed comparative performance for a performance peer universe and peer group of funds and comparative management fees and expense ratios for an expense peer group and an expense peer universe of funds provided by Broadridge for each Fund. In addition, the Independent Trustees considered: (1) the nature, quality and extent of services provided by the Adviser; (2) information comparing the performance of each Fund to one or more relevant securities indexes; (3) information comparing management fees of each Fund to fees charged by the Adviser to other funds and client accounts with similar investment strategies; (4) the estimated allocated direct or indirect costs of services provided and estimated profits realized by the Adviser for both the Trust as a whole and each Fund individually; and (5) information describing other benefits to the Adviser and its affiliate, William Blair & Company, L.L.C. (the “Distributor,” and collectively with the Adviser, “William Blair”), resulting from their relationship with the Funds. The Independent Trustees also noted that they receive information from the Adviser regarding the Funds throughout the year in connection with regular Board meetings, including presentations from portfolio managers. In addition, the Adviser made a presentation to the Board regarding the contract review information, including addressing the supplemental information requests, and answered questions from the Independent Trustees. The Board, including the Independent Trustees, determined that, given the totality of the information provided with respect to the Management Agreement, the Board had received sufficient information to renew the Management Agreement. The Independent Trustees noted that in evaluating the Management Agreement, they were taking into account their accumulated experience as Board members in working with the Adviser on matters relating to the Funds. Based on their review, the Independent Trustees concluded that it was in the best interest of each Fund to renew the Management Agreement and, accordingly, recommended to the Board of the Trust the renewal of the Management Agreement for each Fund. The Board considered the recommendation of the Independent Trustees along with other factors that the Board deemed relevant.

Nature, Quality and Extent of Services. In evaluating the nature, quality and extent of the services provided by the Adviser to the Funds, the Board noted that the Adviser is a quality firm with a reputation for integrity and honesty that employs high-quality people and has a long association with the Funds, in each case other than the Growth Fund, since the inception of the Funds. The Board believes that a long-term relationship with a capable, conscientious adviser is in the best interests of shareholders and that shareholders have invested in the Funds knowing that the Adviser manages the Funds and knowing the management fees. The Board considered the Adviser’s fundamental research approach in actively managed, process oriented investing. The Board considered biographical information about the Trust’s officers, other Adviser personnel and the Funds’ portfolio managers, including information on the portfolio managers’ personal investments in the Fund(s) they manage. The Board also considered the administrative services performed by the Adviser, financial information regarding the Adviser, the Adviser’s execution quality and use of soft dollars, risk management oversight, compliance program and the expense limitations proposed for each of the Funds’ share classes. The Board also considered the nature, quality and extent of services that the

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Adviser provides to the Funds compared to the services that the Adviser provides to other clients. The Board noted that the Adviser pays the compensation of all of the officers of the Trust. Based upon all relevant factors, the Board concluded that the nature, quality and extent of the services provided by the Adviser to each Fund were appropriate.

Performance. The Board reviewed information on the annualized total returns of each share class of the Funds for the one-, three-, five- and ten-year periods ended December 31, 2019, as applicable, along with annualized total return information for a Morningstar performance peer universe of funds and one or more benchmark securities indexes. The Morningstar performance peer universe for each Fund included all funds in the same Morningstar category as the Fund. For purposes of this report, Class I shares were used for comparison purposes as the Board noted that Class I shares represent the largest percentage of assets in the Trust. In evaluating performance, the Board recognized that the performance data reflects a snapshot of a period as of a particular date and that selecting a different performance period could produce different results.

The Board considered that the Adviser seeks to provide superior performance over the long term and was committed to managing each Fund consistently with the Fund’s stated investment strategies and that at times relative performance will be affected by whether the market environment favors or disfavors particular investments, styles and/or market capitalizations. The Board concluded that the Adviser had managed the equity Funds in the U.S., Global/International and Emerging Markets growth strategies consistent with its disciplined quality growth philosophy. Based on the information provided, the Board considered the following with respect to the total returns of each Fund.

Growth Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe for the one-, three- and five-year periods ended December 31, 2019. The Board also considered that the Fund underperformed the benchmark (Russell 3000^®Growth Index) for the one- and five-year periods and outperformed the benchmark for the three-year period ended December 31, 2019.

Large Cap Growth Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe for the one-, three- and five-year periods ended December 31, 2019. The Board also considered that the Fund was within range of the benchmark (Russell 1000^®Growth Index) for the one-year period and outperformed the benchmark for the three- and five-year periods ended December 31, 2019.

Mid Cap Growth Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe and the benchmark (Russell Midcap^®Growth Index) for the one- and three-year periods and below the average of its Morningstar performance peer universe and the benchmark for the five-year period ended December 31, 2019.

Small-Mid Cap Growth Fund. The Board considered that the Fund’s total return was below the average of its Morningstar performance peer universe and the benchmark (Russell 2500^TMGrowth Index) for the one-year period and above the average of its Morningstar performance peer universe and the benchmark for the three- and five-year periods ended December 31, 2019.

Small-Mid Cap Value Fund. The Board considered that the Fund’s total return was below the average of its Morningstar performance peer universe and the benchmark (Russell 2500^TMValue Index) for the one-, three- and five-year periods ended December 31, 2019. The Board considered the Adviser’s view that while better stock selection would have lessened underperformance over the three- and five- year periods, that the rally in deeper value stocks and the outperformance of smaller cap and lower quality stocks contributed to underperformance.

Small Cap Growth Fund. The Board considered that the Fund’s total return was below the average of its Morningstar performance peer universe and the benchmark (Russell 2000^®Growth Index) for the one-year period and above the average of its Morningstar performance peer universe and the benchmark for the three- and five-year periods ended December 31, 2019.

Small Cap Value Fund. The Board considered that the Fund’s total return was below the average of its Morningstar performance peer universe and the benchmark (Russell 2000^®Value Index) for the one-, three- and five-year periods ended December 31, 2019. The Board considered the Adviser’s view that while better stock selection would have lessened underperformance over the three- and five- year periods, that the rally in deeper value stocks and the outperformance of smaller cap and lower quality stocks contributed to underperformance.

Global Leaders Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe and the benchmark (MSCI All Country World IMI (net) Index) for the one-, three- and five-year periods ended December 31, 2019.

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International Leaders Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe and the benchmark (MSCI All Country World Ex-U.S. IMI (net) Index) for the one-, three- and five-year periods ended December 31, 2019.

International Growth Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe for the one-year period and below the average of its Morningstar performance peer universe for the three- and five-year periods ended December 31, 2019. The Board also considered that the Fund outperformed the benchmark (MSCI All Country World Ex-U.S. IMI (net) Index) for the one-, three- and five-year periods ended December 31, 2019.

Institutional International Growth Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe for the one-year period and below the average of its Morningstar performance peer universe for the three- and five-year periods ended December 31, 2019. The Board also considered that the Fund outperformed the benchmark (MSCI All Country World Ex-U.S. IMI (net) Index) for the one-, three- and five-year periods ended December 31, 2019.

International Small Cap Growth Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe for the one-year period and below the average of its Morningstar performance peer universe for the three- and five-year periods ended December 31, 2019. The Board also considered that the Fund outperformed the benchmark (MSCI All Country World Ex-U.S. Small Cap (net) Index) for the one-, three- and five-year periods ended December 31, 2019.

Emerging Markets Leaders Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe for the one-, three- and five-year periods ended December 31, 2019. The Board also considered that the Fund outperformed the benchmark (MSCI Emerging Markets (net) Index) for the one- and three-year periods and was within range of the benchmark for the five-year period ended December 31, 2019.

Emerging Markets Growth Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe and the benchmark (MSCI Emerging Markets IMI (net) Index) for the one-, three- and five-year periods ended December 31, 2019.

Emerging Markets Small Cap Growth Fund. The Board considered that the Fund’s total return was within range of the average of its Morningstar performance peer universe for the one-year period and below the average of its Morningstar performance peer universe for the three- and five-year periods ended December 31, 2019. The Board also considered that the Fund outperformed the benchmark (MSCI Emerging Markets Small Cap (net) Index) for the one- and three-year periods and was within range of the benchmark for the five-year period ended December 31, 2019.

Bond Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe and the benchmark (Bloomberg Barclays U.S. Aggregate Bond Index) for the one-, three- and five-year periods ended December 31, 2019.

Income Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe for the one- and five-year periods and within range of its Morningstar performance peer universe for the three-year period ended December 31, 2019. The Board also considered that the Fund underperformed the benchmark (Bloomberg Barclays Intermediate Government/Credit Bond Index) for the one-, three- and five-year periods ended December 31, 2019.

Low Duration Fund. The Board considered that the Fund’s total return was above the average of its Morningstar performance peer universe for the one-year period and below the average of its Morningstar performance peer universe for the three- and five-year periods ended December 31, 2019. The Board also considered that the Fund outperformed the benchmark (ICE BofAML 1-Year US Treasury Note Index) for the one-, three- and five-year periods ended December 31, 2019.

Macro Allocation Fund. The Board considered that the Fund’s total return was below the average of its Morningstar performance peer universe for the one- and five-year periods and above the average of its Morningstar performance peer universe for the three-year period ended December 31, 2019. The Board also considered that the Fund outperformed the benchmark (ICE BofAML 3-Month US Treasury Bill Index) for the one- and three-year periods and underperformed the benchmark for the five-year period ended December 31, 2019. The Board considered the Adviser’s view that many of the strategies in the Morningstar peer group were of the type that had a much higher correlation to the global and U.S. equity market than the Fund, and/or realized greater levels of volatility during these time periods, which may have helped contribute to higher returns compared to the Fund as equity markets were generally positively performing, with the U.S. equity market among the strongest segment.

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Management Fees. The Board reviewed each Fund’s management fee and reviewed information comparing the management fee to those of an expense peer group and an expense peer universe of funds provided by Broadridge for each share class of the Funds. The Broadridge expense peer group for Class N shares of each Fund (“Class N Broadridge Expense Group”) consisted of a group of retail no-load funds with a similar investment strategy and asset size, as classified by Broadridge. The Broadridge expense peer group for Class I (the “Class I Broadridge Expense Group”) and Class R6 of each Fund consisted of a group of institutional funds with a similar investment strategy and asset size, as classified by Broadridge. The Broadridge expense peer universe for each share class of each Fund consisted of the Fund’s Broadridge expense peer group and all other no-load funds with an investment strategy as classified by Broadridge similar to the Fund’s. In considering the Broadridge information and giving effect to the contractual management fee reductions proposed by the Adviser, the Board noted that the contractual management fees for the Growth Fund, the Large Cap Growth Fund, the Small-Mid Cap Value Fund, the International Small Cap Growth Fund, the Emerging Markets Small Cap Growth Fund and the Bond Fund were below the average contractual management fee of their Class I Broadridge Expense Group. The Board also noted that the contractual management fees for the Mid Cap Growth Fund, the Small-Mid Cap Growth Fund, the Small Cap Growth Fund, the Small Cap Value Fund, the Global Leaders Fund, the International Leaders Fund, the International Growth Fund, the Emerging Markets Leaders Fund, the Emerging Markets Growth Fund, the Income Fund, the Low Duration Fund and the Macro Allocation Fund were above the average contractual management fee of their Class I Broadridge Expense Group. The Board also considered the Adviser’s proposal to reduce the contractual management fee for the Small-Mid Cap Value Fund and the Small Cap Value Fund.

In considering the management fee for the Institutional International Growth Fund, which does not have share classes, the Board noted that the contractual management fee for the Fund was above the average contractual management fee of its Broadridge expense peer group.

The Board noted the current and proposed contractual expense limitations for the Funds and further noted that the Adviser proposed reducing the contractual limit on operating expenses for the Small-Mid Cap Value Fund and the Small Cap Value Fund. The Board considered that the Adviser proposed to contractually limit operating expenses until April 30, 2021 for each share class of the Funds. The Board considered the amount of management fees waived and other expenses reimbursed by the Adviser on behalf of the Funds in 2019, noting that the Adviser waived its entire management fee for and reimbursed other expenses to the Small-Mid Cap Value Fund.

For each Fund, the Board also reviewed amounts charged by the Adviser to other pooled investment vehicles, including other registered funds for which the Adviser acts as a sub-adviser, and the Adviser’s fee schedule for institutional accounts. With respect to other pooled investment vehicles and institutional accounts, the Board considered the Adviser’s statements to the effect that the level of services provided to the Funds and the regulatory responsibilities associated with sponsoring registered investment companies were greater as compared to the work involved for other pooled investment vehicles, including other registered funds for which the Adviser acts as a sub-adviser, and institutional accounts. In addition, the Board considered the Adviser’s statements to the effect that institutional accounts are distributed differently, operate under different investment and regulatory structures and have different business risks as compared to the Funds and that there are responsibilities and duties involved in sponsoring a registered fund that are not present in sub-advising a registered fund.

On the basis of all the information provided, the Board concluded that each Fund’s management fee, coupled with the applicable expense limitations, was reasonable.

Profitability. With respect to the profitability of the Management Agreement to the Adviser, the Board considered the overall fees paid under the Management Agreement, including the estimated allocated costs of the services provided, management fees waived and other expenses reimbursed, if any, and profits realized by the Adviser from its relationship with the Trust as a whole and each Fund individually. The Board concluded that the estimated profits realized by the Adviser were not unreasonable.

Economies of Scale. The Board considered the extent to which economies of scale would be realized as the Funds grow and whether fee levels reflect these economies of scale for the benefit of investors. The Board noted the Adviser’s statements to the effect that the resources required for the Adviser’s fundamental investment process typically increase as a Fund increases in size. The Board also considered that certain of the Funds were part of investment strategies that were capacity constrained by the Adviser so that opportunities for economies of scale were limited. The Board further considered that of the Funds that are subject to capacity constraints, the International Growth Fund, Institutional International Growth Fund, International Small Cap Growth Fund and Emerging Markets Small Cap Growth Fund are closed to investors, except as noted in each Fund’s prospectus.

In considering whether fee levels reflect economies of scale for the benefit of Fund investors, the Board considered each Fund’s asset size, management fee breakpoints for applicable Funds, the expense limitations in place for each Fund and the proposed reduction in management fees and/or expense limits for certain Funds and each Fund’s expense ratios. The Board concluded that in the aggregate the Funds’ fee levels reasonably reflect appropriate recognition of economies of scale.

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Other Benefits. The Board considered benefits derived by the Adviser and its affiliates from their relationship with the Funds, including (1) receipt of research from brokerage firms; (2) soft dollars, which pertain primarily to the Funds investing in equity securities; (3) reimbursement of some intermediary fees in the nature of sub-transfer agency fees; (4) fees from Class N shares of the Funds to the Distributor pursuant to the Rule 12b-1 Plan, nearly all of which are paid to third parties; and (5) favorable media coverage. The Board determined that management fees were reasonable in light of these benefits.

Conclusion. Based upon all of the information considered and the conclusions reached, the Board determined that the terms of the Management Agreement continue to be fair and reasonable and that the continuation of the Management Agreement is in the best interests of each Fund.

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Review of Liquidity Risk Management Program

The Board of Trustees (the “Board”) of William Blair Funds previously approved the William Blair Funds Liquidity Risk Management Program Policy (the “Policy”) under Rule 22e-4 under the 1940 Act (the “Liquidity Rule”), which sets forth the terms of the William Blair Liquidity Risk Management Program (the “Program”). The Program (through the Policy) seeks to assess, manage and review each Fund’s liquidity risk. For purposes of the Program, the Policy and the Liquidity Rule, “liquidity risk” is defined as the risk that a Fund could not meet requests to redeem shares issued by a Fund without significant dilution of remaining investors’ interest in the Funds. Among other things, the Liquidity Rule requires that a written report be provided to the Board on an annual basis that addresses the operation of the Program and assesses the adequacy and effectiveness of its implementation, including (if applicable) the operation of any highly liquid investment minimum (“HLIM”) established for a Fund and any material changes to the Program.

The Board designated the Liquidity Risk Management Committee of William Blair Investment Management, LLC, the Funds’ investment adviser, to be the administrator for the Program (the “Program Administrator”). On February 19, 2020, the Board of Trustees reviewed the Program Administrator’s written report (the “Report”) concerning the operation of the Program and the Policy as well as the adequacy and effectiveness of the Program’s and Policy’s implementation for the period from December 1, 2018 through December 31, 2019 (the “Program Reporting Period”). There were no material changes to the Program or to the Policy during the Program Reporting Period.

The Report summarized the operation of the Program and the Policy and the information and factors considered by the Program Administrator in assessing whether the Program and the Policy have been adequately and effectively implemented with respect to each Fund. Such information and factors included, among other things: (1) the liquidity risk framework used to assess, manage, and periodically review each Fund’s Liquidity Risk and the results of this assessment; (2) the classification of each of the Funds’ respective investments into one of four liquidity categories that reflect an estimate of their liquidity under normal and reasonably foreseeable stressed conditions; (3) whether a Fund invested primarily in “Highly Liquid Investments” (as defined under the Liquidity Rule) and whether an HLIM should be established for any Fund; (4) whether a Fund invested more than 15% of its assets in “Illiquid Investments” (as defined under the Liquidity Rule); (5) specific liquidity events arising during the Program Reporting Period, including the impact on Fund liquidity caused by extended non-U.S. market closures; and (6) the nature and quality of the services provided by the service provider engaged to assist with determining liquidity classifications for the Funds. Based on this review, the Report concluded that the Program and the Policy meet the requirements of the Liquidity Rule and are operating effectively.

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Trustees and Officers (Unaudited).^†The trustees and officers of the William Blair Funds, their year of birth, their principal occupations during the last five years, their affiliations, if any, with William Blair, and other significant affiliations are set forth below. The address of each officer and trustee is 150 North Riverside Plaza, Chicago, Illinois 60606.

Name and Year of Birth	Position(s) Held with Trust	Term of Office⁽¹⁾ and Length of Time Served	Principal Occupation(s) During Past 5 Years	Number of Portfolios in Trust Complex Overseen by Trustee*	Other Directorships Held by Trustee During Past 5 Years**
Interested Trustees
Stephanie G. Braming, 1970⁽²⁾	Chairman of the Board and President, previously Senior Vice President	Chairman of the Board and President since 2018, and Senior Vice President 2014-2018	Global Head of Investment Management since 2017, portfolio manager (2014–2017) and Partner, William Blair	20	Chairman, William Blair SICAV
Arthur J. Simon, 1954⁽²⁾	Trustee	Since 2018	General Counsel and Partner, William Blair	20	Director, William Blair SICAV
Non-Interested Trustees
Vann A. Avedisian, 1964⁽³⁾	Trustee	Since 2012	Principal, Highgate Holdings (hotel investments) (since 2009); formerly, co-founder and Managing Director, Oxford Capital Partners Inc. (1994 to 2006)	20	Potbelly Corporation (2001 to 2015)
Kathleen T. Barr, 1955	Trustee	Since 2013	Retired; Vice Chairman, Independent Directors Council (since 2019); formerly, President, Productive Capital Management, Inc. (registered investment adviser to public entities) and Owner, KT Barr Consulting, LLC (mutual fund and investment management consulting) (2010 to 2013); prior thereto, Chief Administrative Officer, Senior Vice President and Senior Managing Director of Allegiant Asset Management Company (merged with PNC Capital Advisors, LLC in 2009) (2004 to 2010); Chief Administrative Officer, Chief Compliance Officer and Senior Vice President of PNC Funds and PNC Advantage Funds (f/k/a Allegiant Funds) (2003 to 2010)	20	Muzinich BDC, Inc. (since 2019); Board of Governors, Investment Company Institute (since 2019); Professionally Managed Portfolios (since 2018); Council Member, Independent Directors Council; AmericaFirst Quantitative Funds (5 portfolios) (2012 to 2016)

†	William Blair Investment Management, LLC and William Blair & Company, L.L.C. are collectively referred to in this section as “William Blair”, each of which is a wholly owned subsidiary of WBC Holdings, L.P., which is wholly owned by certain William Blair employees (employee owners are referred to as ‘partners’).
*	The number shown does not include three additional series of the Trust that are in existence, but not currently offered to the public.
**	Includes directorships of public companies and other registered investment companies held during the past five years.

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Name and Year of Birth	Position(s) Held with Trust	Term of Office⁽¹⁾ and Length of Time Served	Principal Occupation(s) During Past 5 Years	Number of Portfolios in Trust Complex Overseen by Trustee*	Other Directorships Held by Trustee During Past 5 Years**
Daniel N. Leib, 1966⁽³⁾	Trustee	Since 2016	Chief Executive Officer, Donnelley Financial Solutions, Inc. (since 2016); formerly, Executive Vice President and Chief Financial Officer, (2011 to 2016) and Group Chief Financial Officer (2009 to 2011), R.R. Donnelley & Sons Company	20	Donnelley Financial Solutions, Inc. (since 2016)
Dorri C. McWhorter, 1973	Trustee	Since 2019	Chief Executive Officer, YWCA Metropolitan Chicago (since 2013); formerly Partner, Crowe LLP (2008-2013)⁽⁴⁾	20	Skyway Concession Company, LLC (since 2018); Illinois CPA Society (since 2017); Lifeway Foods, Inc. (since 2020); American Institute of Certified Public Accountants (2013-2016); Chicago Finance Exchange (2009-2017)
Thomas J. Skelly, 1951	Trustee	Since 2007	Advisory Board Member for various U.S. companies (since 2005); formerly, Managing Partner of various divisions at Accenture (1994-2004)	20	Mutual Trust Financial Group (provider of insurance and investment products)
Steven R. Zenz, 1954	Trustee	Since 2018	Consultant, Steven R. Zenz Consulting LLC (merger and acquisition transactions and SEC reporting and filings) (since 2011); formerly, Partner, KPMG LLP (1987-2010)⁽⁵⁾	20	Frankly Inc. (technology products and services for media industry) (since 2016); Insignia Systems, Inc. (in-store advertising services for consumer packaged goods manufacturers) (2013-2019)

(1)	Each Trustee serves until the election and qualification of a successor, or until death, resignation or retirement, or removal as provided in the Trust’s Declaration of Trust. Retirement for Independent Trustees occurs no later than at the conclusion of the calendar year that occurs after the earlier of (a) the Independent Trustee’s 75th birthday or (b) the 17th anniversary of the date that the Independent Trustee became a member of the Board of Trustees.
(2)	Ms. Braming and Mr. Simon are interested persons of the Trust because they are partners of William Blair, and with respect to Ms. Braming also due to her position as an officer of the Trust.
(3)	The Funds and William Blair use Donnelley Financial Solutions, Inc. (“DFS’’) for financial printing and other services. DFS is a public company. The Funds and William Blair in the aggregate paid DFS approximately $122,000 and $188,000 in 2018 and 2019, respectively, for the services provided. DFS’s revenue was approximately $1 billion in 2018 and approximately $900 million in 2019. Mr. Leib, as the Chief Executive Officer of DFS, is not directly involved in any of the services provided to the Funds or William Blair and his compensation is not materially affected by the fees DFS receives from the Funds and William Blair.
(4)	As a former partner of the audit firm Crowe LLP (formerly, Crowe Horwath LLP), Ms. McWhorter receives distributions of her capital in the firm over time and those distributions are expected to be completed in March 2021. The Funds and William Blair made no payments to Crowe LLP over the past three years.
(5)	The Funds engage KPMG to provide foreign tax services in Taiwan. KPMG does not provide audit or audit-related services to the Funds. Mr. Zenz is a former partner of KPMG and receives pension/retirement funds from KPMG.

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Name and Year of Birth	Position(s) Held with Trust	Term of Office and Length of Time Served⁽¹⁾	Principal Occupation(s) During Past 5 Years

Officers

Marcelo Assalin, 1973	Senior Vice President	Since 2020	Associate, William Blair (since 2020); formerly, NN Investment Partners (2013-2020)

Michael P. Balkin, 1959	Senior Vice President	Since 2008	Partner, William Blair

Thomas Clarke, 1968	Senior Vice President	Since 2011	Partner, William Blair

Daniel Crowe, 1972	Senior Vice President	Since 2016	Partner, William Blair

Robert J. Duwa, 1967	Senior Vice President	Since 2019	Partner, William Blair

Simon Fennell, 1969	Senior Vice President	Since 2013	Partner, William Blair

Andrew G. Flynn, 1961	Senior Vice President	Since 2013	Partner, William Blair

David C. Fording, 1967	Senior Vice President	Since 2006	Partner, William Blair

James S. Golan, 1961	Senior Vice President	Since 2005	Partner, William Blair

James E. Jones, 1977	Senior Vice President	Since 2019	Partner, William Blair

Chad M. Kilmer, 1975	Senior Vice President	Since 2006	Partner, William Blair

Robert C. Lanphier IV, 1956	Senior Vice President	Since 2003	Partner, William Blair

Mark T. Leslie, 1967	Senior Vice President	Since 2005	Partner, William Blair

Kenneth J. McAtamney, 1966	Senior Vice President	Since 2008	Partner, William Blair

Todd M. McClone, 1968	Senior Vice President	Since 2005	Partner, William Blair

David S. Mitchell, 1960	Senior Vice President	Since 2003	Partner, William Blair

John C. Murphy, 1969	Senior Vice President	Since 2014	Partner, William Blair

Casey K. Preyss, 1976	Senior Vice President	Since 2015	Partner, William Blair

David P. Ricci, 1958	Senior Vice President	Since 2006	Partner, William Blair

Lisa D. Rusch, 1970	Senior Vice President Vice President	Since 2020 2018-2020	Partner, William Blair (since 2020); formerly, Associate, William Blair

Ward D. Sexton, 1974	Senior Vice President	Since 2016	Partner, William Blair

Brian D. Singer, 1960	Senior Vice President	Since 2011	Partner, William Blair

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Name and Year of Birth	Position(s) Held with Trust	Term of Office and Length of Time Served⁽¹⁾	Principal Occupation(s) During Past 5 Years

Dan Zelazny, 1971	Senior Vice President	Since 2019	Associate, William Blair (since 2019); formerly Managing Director, AQR Capital Management (2011-2019)

Ruta Ziverte, 1973	Senior Vice President	Since 2020	Associate, William Blair (since 2019); formerly, Oppenheimer Funds (2015-2019)

Kathleen M. Lynch, 1971	Vice President	Since 2020	Associate, William Blair

Marco Ruijer, 1975	Vice President	Since 2020	Associate, William Blair (since 2020); formerly, NN Investment Partners (2013-2020)

Paul J. Sularz, 1971	Vice President	Since 2009	Associate, William Blair

John M. Raczek, 1970	Treasurer Assistant Treasurer	Since 2019 2010-2019	Associate, William Blair

Andrew T. Pfau, 1970	Secretary	Since 2009	Associate, William Blair

David M. Cihak, 1982	Assistant Treasurer	Since 2019	Associate, William Blair

Walter R. Randall, Jr., 1960	Chief Compliance Officer and Assistant Secretary	Since 2009	Associate, William Blair

Robert J. Toner, 1967	Assistant Secretary	Since 2016	Associate, William Blair

(1)

The Trust’s officers, except the Chief Compliance Officer, are elected annually by the Board of Trustees. The Trust’s Chief Compliance Officer is designated by the Board of Trustees and may only be removed by action of the Board of Trustees, including a majority of independent trustees. Length of Time Served for all officers indicates the year the individual became an officer of the Trust.

The Statement of Additional Information for the William Blair Funds includes additional information about the trustees and is available without charge by calling 1-800-635-2886 (in Massachusetts 1-800-635-2840) or by writing the Fund.

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(Unaudited)

Proxy Voting

A description of the policies and procedures that the Funds use to determine how to vote proxies relating to portfolio securities and information regarding how the Funds voted proxies relating to portfolio securities for the most recent 12-month period ended December 31 are available without charge, upon request, by calling 1-800-635-2886 (in Massachusetts 1-800-635-2840), at www.williamblairfunds.com and on the SEC’s website at http://www.sec.gov.

Quarterly Portfolio Schedules

Each Fund files its complete schedule of portfolio holdings with the SEC for the first and third fiscal quarters of each fiscal year (quarters ended March 31 and September 30) on Form N-PORT. The Funds’ Forms N-PORT are available on the SEC’s website at http://www.sec.gov.

Additional Federal Income Tax Information: (unaudited)

Under Section 852(b)(3)(C) of the Code, the Funds hereby designate the following amounts as capital gain dividends for the fiscal year ended December 31, 2019 (in thousands):

Fund	Capital Gain Dividend
Growth	$	23,906
Large Cap Growth		18,020
Mid Cap Growth		6,879
Small-Mid Cap Growth		231,889
Small-Mid Cap Value		105
Small Cap Growth		15,356
Small Cap Value		47,335
Global Leaders		2,859
Emerging Markets Leaders		382
Emerging Markets Growth		24,009

June 30, 2020

William Blair Funds

179

Useful Information About Your Report (Unaudited)

Please refer to this information when reviewing the Expense Example for each Fund.

Expense Example

As a shareholder of a Fund, you incur two types of costs: (1) transaction costs and (2) ongoing costs, including management fees, distribution (12b-1) fees (for Class N shares, as applicable), and other Fund expenses. The example is intended to help you understand your ongoing costs (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. To do so, compare the Fund’s 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of other funds. The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire six-month period from January 1, 2020 to June 30, 2020.

Actual Expenses

In each example, the first line for each share class in the table provides information about the actual account values and actual expenses. These expenses reflect the effect of any expense cap applicable to the share class during the period. Without this expense cap, the costs shown in the table would have been higher. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During the Period” to estimate the expenses you paid on your account during the period.

Hypothetical Example for Comparison Purposes

In each example, the second line for each share class in the table provides information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses. This is not the Fund’s actual return. The hypothetical account values and expenses may not be used to estimate your actual ending account balance or the expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the Fund to the costs of investing in other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of other funds.

Please note that the expenses shown in both examples are meant to highlight your ongoing costs only and do not reflect any transactional costs or account type fees, such as IRA administration fees. These fees are discussed in the prospectus. Therefore, the second line of each share class in the table is useful in comparing ongoing costs only and will not help you determine the relative costs of owning different funds. In addition, if these transactional costs or account fees were included, your costs would have been higher.

180

Semiannual Report

June 30, 2020

Fund Expenses (Unaudited)

Expense Example	Beginning Account Value 1/1/2020		Ending Account Value 6/30/2020		Expenses Paid During the Period (a)		Annualized Expense Ratio
Growth Fund
Class N-actual return	$	1,000.00	$	1,077.25	$	6.20		1.20	%
Class N-hypothetical 5% return	$	1,000.00	$	1,044.03	$	6.10		1.20
Class I-actual return	$	1,000.00	$	1,079.11	$	4.86		0.94
Class I-hypothetical 5% return	$	1,000.00	$	1,045.33	$	4.78		0.94
Class R6-actual return	$	1,000.00	$	1,079.93	$	4.55		0.88
Class R6-hypothetical 5% return	$	1,000.00	$	1,045.62	$	4.48		0.88
Large Cap Growth Fund
Class N-actual return	$	1,000.00	$	1,096.27	$	4.69		0.90
Class N-hypothetical 5% return	$	1,000.00	$	1,045.52	$	4.58		0.90
Class I-actual return	$	1,000.00	$	1,097.59	$	3.39		0.65
Class I-hypothetical 5% return	$	1,000.00	$	1,046.77	$	3.31		0.65
Class R6-actual return	$	1,000.00	$	1,098.33	$	3.13		0.60
Class R6-hypothetical 5% return	$	1,000.00	$	1,047.02	$	3.05		0.60
Mid Cap Growth Fund
Class N-actual return	$	1,000.00	$	986.35	$	5.93		1.20
Class N-hypothetical 5% return	$	1,000.00	$	1,044.03	$	6.10		1.20
Class I-actual return	$	1,000.00	$	988.26	$	4.70		0.95
Class I-hypothetical 5% return	$	1,000.00	$	1,045.28	$	4.83		0.95
Class R6-actual return	$	1,000.00	$	988.27	$	4.45		0.90
Class R6-hypothetical 5% return	$	1,000.00	$	1,045.52	$	4.58		0.90
Small-Mid Cap Core Fund
Class I-actual return	$	1,000.00	$	895.13	$	4.48		0.95
Class I-hypothetical 5% return	$	1,000.00	$	1,045.28	$	4.83		0.95
Class R6-actual return	$	1,000.00	$	896.07	$	4.24		0.90
Class R6-hypothetical 5% return	$	1,000.00	$	1,045.52	$	4.58		0.90
Small-Mid Cap Growth Fund
Class N-actual return	$	1,000.00	$	1,006.69	$	6.74		1.35
Class N-hypothetical 5% return	$	1,000.00	$	1,043.29	$	6.86		1.35
Class I-actual return	$	1,000.00	$	1,007.78	$	5.49		1.10
Class I-hypothetical 5% return	$	1,000.00	$	1,044.53	$	5.59		1.10
Class R6-actual return	$	1,000.00	$	1,008.15	$	5.24		1.05
Class R6-hypothetical 5% return	$	1,000.00	$	1,044.78	$	5.34		1.05
Small-Mid Cap Value Fund
Class N-actual return	$	1,000.00	$	761.14	$	5.34		1.22
Class N-hypothetical 5% return	$	1,000.00	$	1,043.93	$	6.20		1.22
Class I-actual return	$	1,000.00	$	763.70	$	4.25		0.97
Class I-hypothetical 5% return	$	1,000.00	$	1,045.18	$	4.93		0.97
Class R6-actual return	$	1,000.00	$	761.90	$	4.03		0.92
Class R6-hypothetical 5% return	$	1,000.00	$	1,045.43	$	4.68		0.92
Small Cap Growth Fund
Class N-actual return	$	1,000.00	$	971.17	$	7.35		1.50
Class N-hypothetical 5% return	$	1,000.00	$	1,042.54	$	7.62		1.50
Class I-actual return	$	1,000.00	$	972.75	$	6.13		1.25
Class I-hypothetical 5% return	$	1,000.00	$	1,043.78	$	6.35		1.25
Class R6-actual return	$	1,000.00	$	972.76	$	5.89		1.20
Class R6-hypothetical 5% return	$	1,000.00	$	1,044.03	$	6.10		1.20
Small Cap Value Fund
Class N-actual return	$	1,000.00	$	736.26	$	6.13		1.42
Class N-hypothetical 5% return	$	1,000.00	$	1,042.94	$	7.21		1.42
Class I-actual return	$	1,000.00	$	736.58	$	5.05		1.17
Class I-hypothetical 5% return	$	1,000.00	$	1,044.18	$	5.95		1.17
Class R6-actual return	$	1,000.00	$	737.27	$	4.84		1.12
Class R6-hypothetical 5% return	$	1,000.00	$	1,044.43	$	5.69		1.12

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181

Fund Expenses (Unaudited)

Expense Example	Beginning Account Value 1/1/2020		Ending Account Value 6/30/2020		Expenses Paid During the Period (a)		Annualized Expense Ratio
Global Leaders Fund
Class N-actual return	$	1,000.00	$	1,022.12	$	5.78		1.15	%
Class N-hypothetical 5% return	$	1,000.00	$	1,044.28	$	5.85		1.15
Class I-actual return	$	1,000.00	$	1,023.44	$	4.53		0.90
Class I-hypothetical 5% return	$	1,000.00	$	1,045.52	$	4.58		0.90
Class R6-actual return	$	1,000.00	$	1,024.11	$	4.28		0.85
Class R6-hypothetical 5% return	$	1,000.00	$	1,045.77	$	4.32		0.85
International Leaders Fund
Class N-actual return	$	1,000.00	$	987.28	$	5.68		1.15
Class N-hypothetical 5% return	$	1,000.00	$	1,044.28	$	5.85		1.15
Class I-actual return	$	1,000.00	$	988.42	$	4.45		0.90
Class I-hypothetical 5% return	$	1,000.00	$	1,045.52	$	4.58		0.90
Class R6-actual return	$	1,000.00	$	988.96	$	4.20		0.85
Class R6-hypothetical 5% return	$	1,000.00	$	1,045.77	$	4.32		0.85
International Growth Fund
Class N-actual return	$	1,000.00	$	1,002.70	$	7.22		1.45
Class N-hypothetical 5% return	$	1,000.00	$	1,042.79	$	7.36		1.45
Class I-actual return	$	1,000.00	$	1,003.95	$	5.78		1.16
Class I-hypothetical 5% return	$	1,000.00	$	1,044.23	$	5.90		1.16
Class R6-actual return	$	1,000.00	$	1,004.61	$	5.33		1.07
Class R6-hypothetical 5% return	$	1,000.00	$	1,044.68	$	5.44		1.07
Institutional International Growth Fund
Institutional Class-actual return	$	1,000.00	$	1,006.92	$	4.94		0.99
Institutional Class-hypothetical 5% return	$	1,000.00	$	1,045.08	$	5.03		0.99
International Small Cap Growth Fund
Class N-actual return	$	1,000.00	$	968.95	$	7.54		1.54
Class N-hypothetical 5% return	$	1,000.00	$	1,042.34	$	7.82		1.54
Class I-actual return	$	1,000.00	$	970.67	$	6.22		1.27
Class I-hypothetical 5% return	$	1,000.00	$	1,043.68	$	6.45		1.27
Class R6-actual return	$	1,000.00	$	971.53	$	5.64		1.15
Class R6-hypothetical 5% return	$	1,000.00	$	1,044.28	$	5.85		1.15
Emerging Markets Leaders Fund
Class N-actual return	$	1,000.00	$	955.28	$	6.81		1.40
Class N-hypothetical 5% return	$	1,000.00	$	1,043.04	$	7.11		1.40
Class I-actual return	$	1,000.00	$	957.22	$	5.60		1.15
Class I-hypothetical 5% return	$	1,000.00	$	1,044.28	$	5.85		1.15
Class R6-actual return	$	1,000.00	$	957.18	$	5.35		1.10
Class R6-hypothetical 5% return	$	1,000.00	$	1,044.53	$	5.59		1.10
Emerging Markets Growth Fund
Class N-actual return	$	1,000.00	$	1,032.19	$	7.78		1.54
Class N-hypothetical 5% return	$	1,000.00	$	1,042.34	$	7.82		1.54
Class I-actual return	$	1,000.00	$	1,033.29	$	6.57		1.30
Class I-hypothetical 5% return	$	1,000.00	$	1,043.54	$	6.61		1.30
Class R6-actual return	$	1,000.00	$	1,033.72	$	6.07		1.20
Class R6-hypothetical 5% return	$	1,000.00	$	1,044.03	$	6.10		1.20
Emerging Markets Small Cap Growth Fund
Class N-actual return	$	1,000.00	$	1,010.12	$	7.75		1.55
Class N-hypothetical 5% return	$	1,000.00	$	1,042.29	$	7.87		1.55
Class I-actual return	$	1,000.00	$	1,011.24	$	6.50		1.30
Class I-hypothetical 5% return	$	1,000.00	$	1,043.54	$	6.61		1.30
Class R6-actual return	$	1,000.00	$	1,011.22	$	6.25		1.25
Class R6-hypothetical 5% return	$	1,000.00	$	1,043.78	$	6.35		1.25
Bond Fund
Class N-actual return	$	1,000.00	$	1,042.94	$	3.05		0.60
Class N-hypothetical 5% return	$	1,000.00	$	1,047.02	$	3.05		0.60
Class I-actual return	$	1,000.00	$	1,042.98	$	2.29		0.45
Class I-hypothetical 5% return	$	1,000.00	$	1,047.76	$	2.29		0.45
Class R6-actual return	$	1,000.00	$	1,043.24	$	2.03		0.40
Class R6-hypothetical 5% return	$	1,000.00	$	1,048.01	$	2.04		0.40

182

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June 30, 2020

Fund Expenses (Unaudited)

Expense Example	Beginning Account Value 1/1/2020		Ending Account Value 6/30/2020		Expenses Paid During the Period (a)		Annualized Expense Ratio
Income Fund
Class N-actual return	$	1,000.00	$	1,031.41	$	4.29		0.85	%
Class N-hypothetical 5% return	$	1,000.00	$	1,045.77	$	4.32		0.85
Class I-actual return	$	1,000.00	$	1,032.22	$	3.54		0.70
Class I-hypothetical 5% return	$	1,000.00	$	1,046.52	$	3.56		0.70
Class R6-actual return	$	1,000.00	$	1,032.48	$	3.28		0.65
Class R6-hypothetical 5% return	$	1,000.00	$	1,046.77	$	3.31		0.65
Low Duration Fund
Class N-actual return	$	1,000.00	$	1,018.58	$	2.76		0.55
Class N-hypothetical 5% return	$	1,000.00	$	1,047.27	$	2.80		0.55
Class I-actual return	$	1,000.00	$	1,019.36	$	2.01		0.40
Class I-hypothetical 5% return	$	1,000.00	$	1,048.01	$	2.04		0.40
Class R6-actual return	$	1,000.00	$	1,018.44	$	1.76		0.35
Class R6-hypothetical 5% return	$	1,000.00	$	1,048.26	$	1.78		0.35
Macro Allocation Fund
Class N-actual return	$	1,000.00	$	929.20	$	6.04		1.26
Class N-hypothetical 5% return	$	1,000.00	$	1,043.73	$	6.40		1.26
Class I-actual return	$	1,000.00	$	930.40	$	4.85		1.01
Class I-hypothetical 5% return	$	1,000.00	$	1,044.98	$	5.14		1.01
Class R6-actual return	$	1,000.00	$	931.34	$	4.42		0.92
Class R6-hypothetical 5% return	$	1,000.00	$	1,045.43	$	4.68		0.92

(a)	Expenses are equal to the annualized expense ratio, multiplied by the average account value over the period, multiplied by the number of days in the period, 182 and divided by 366 (to reflect the one-half year period).

June 30, 2020

William Blair Funds

183

	BOARD OF TRUSTEES

	Vann A. Avedisian Principal, Highgate Holdings Kathleen T. Barr Retired Senior Managing Director, PNC Capital Advisors, LLC Stephanie G. Braming, Chairman and President Partner, William Blair Daniel N. Leib Chief Executive Officer, Donnelley Financial Solutions, Inc. Dorri C. McWhorter Chief Executive Officer, YWCA Metropolitan Chicago Arthur J. Simon Partner, William Blair Thomas J. Skelly Retired Managing Partner, Accenture Steven R. Zenz Retired Partner, KPMG LLP
	Officers
	Marcelo Assalin, Senior Vice President Michael P. Balkin, Senior Vice President Thomas Clarke, Senior Vice President Daniel Crowe, Senior Vice President Robert J. Duwa, Senior Vice President Simon Fennell, Senior Vice President Andrew G. Flynn, Senior Vice President David C. Fording, Senior Vice President James S. Golan, Senior Vice President James E. Jones, Senior Vice President Chad M. Kilmer, Senior Vice President Robert C. Lanphier, IV, Senior Vice President Mark T. Leslie, Senior Vice President Kenneth J. McAtamney, Senior Vice President Todd M. McClone, Senior Vice President David S. Mitchell, Senior Vice President John C. Murphy, Senior Vice President Casey K. Preyss, Senior Vice President David P. Ricci, Senior Vice President Lisa D. Rusch, Senior Vice President Ward D. Sexton, Senior Vice President Brian D. Singer, Senior Vice President Dan Zelazny, Senior Vice President Ruta Ziverte, Senior Vice President Kathleen M. Lynch, Vice President Marco Ruijer, Vice President Paul J. Sularz, Vice President John M. Raczek, Treasurer Andrew T. Pfau, Secretary David M. Cihak, Assistant Treasurer Walter R. Randall, Jr., Chief Compliance Officer and Assistant Secretary Robert J. Toner, Assistant Secretary Investment Adviser William Blair Investment Management, LLC Distributor William Blair & Company, L.L.C. Independent Registered Public Accounting Firm Ernst & Young LLP Transfer Agent DST Asset Manager Solutions, Inc. (formerly known as Boston Financial Data Services, Inc.) For customer assistance, call 1-800-635-2886 P.O. Box 219137 Kansas City, Missouri 64121-9137

184

Semiannual Report

June 30, 2020


William Blair Funds


U.S. EQUITY	GLOBAL EQUITY	FIXED INCOME
Growth Fund	Global Leaders Fund	Bond Fund
Large Cap Growth Fund		Income Fund
Mid Cap Growth Fund	INTERNATIONAL EQUITY	Low Duration Fund
Small-Mid Cap Core Fund	International Leaders Fund
Small-Mid Cap Growth Fund	International Growth Fund	MULTI-ASSET AND
Small-Mid Cap Value Fund	Institutional International Growth Fund	ALTERNATIVE
Small Cap Growth Fund	International Small Cap Growth Fund	Macro Allocation Fund
Small Cap Value Fund	Emerging Markets Leaders Fund
	Emerging Markets Growth Fund
	Emerging Markets Small Cap Growth Fund

	^©	William Blair & Company, L.L.C., distributor
+1 800 742 7272		150 North Riverside Plaza
williamblairfunds.com		Chicago, Illinois 60606	00103188

Item 2.

Code of Ethics

Not applicable to this filing.

Item 3.

Audit Committee Financial Expert

Not applicable to this filing.

Item 4.

Principal Accountant Fees and Services

Not applicable to this filing.

Item 5.

Audit Committee of Listed Registrants

Not Applicable to this Registrant, insofar as the Registrant is not a listed company.

Item 6.

Schedule of Investments

See Schedule of Investments in Item 1.

Item 7.

Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies

Not applicable to this Registrant, insofar as the Registrant is not a closed-end management investment company.

Item 8.

Portfolio Managers of Closed-End Management Investment Companies

Not applicable to this Registrant, insofar as the Registrant is not a closed-end management investment company.

Item 9.

Purchase of Equity Securities by Closed-End Management Investment Companies and Affiliated Purchasers

Not applicable to this Registrant, insofar as the Registrant is not a closed-end management investment company.

Item 10.

Submission of Matters to a Vote of Security Holders

There have been no material changes to the procedures by which shareholders may recommend nominees to the Registrant’s Board of Trustees since the Registrant last provided disclosure in response to this item.

Item 11.

Controls and Procedures

(a) The Registrant’s principal executive and principal financial officers, or persons performing similar functions, have concluded that the Registrant’s Disclosure Controls and Procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940, as amended (the “1940 Act”) (17 CFR 270.30a-3(c)) are effective, as of a date within 90 days of the filing date of this report that includes the disclosure required by this paragraph, based on their evaluation of these controls and procedures required by Rule 30a-3 (b) under the 1940 Act (17 CFR 270.30a-3(b) and Rules 13a-15(b) or 15d-15(b) under the Securities Exchange Act of 1934, as amended to date (17 CFR 240.13a-15(b) or 240.15d-15(b)).

(b) There were no changes in the Registrant’s internal control over financial reporting (as defined in Rule 30a-3(d) under the 1940 Act (17 CFR 270.30a-3(d)) that occurred during 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.

Disclosure of Securities Lending Activities for Closed-End Management Investment Companies

Not applicable to this Registrant, insofar as the Registrant is not a closed-end management investment company.

Item 13.

Exhibits

13. (a) (1) Code of Ethics

Not applicable to this filing.

13. (a) (2) (1)

Certification of Principal Executive Officer Required by Rule 30a-2(a) of the Investment Company Act of 1940 is filed as an exhibit hereto.

13. (a) (2) (2)

Certification of Principal Financial Officer Required by Rule 30a-2(a) of the Investment Company Act of 1940 is filed as an exhibit hereto.

13. (a) (3)

Not applicable to this Registrant.

13. (a) (4)

Not applicable to this filing.

13. (b)

Certifications of the Principal Executive Officer and Principal Financial Officer of the issuer as required by Rule 30a-2(b) of the Investment Company Act of 1940 are filed as exhibits hereto.

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.

		William Blair Funds

		/s/ Stephanie G. Braming
By:		Stephanie G. Braming
		President (Principal Executive Officer)

Date: August 26, 2020

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.

/s/ Stephanie G. Braming

By:

Stephanie G. Braming

President

(Principal Executive Officer)

Date: August 26, 2020

/s/ John M. Raczek

By:

John M. Raczek

Treasurer

(Principal Financial Officer)

Date: August 26, 2020

William Blair Funds N-CSRSCertified semi-annual shareholder report (management investment company)