Q2 2026 13F · SEC CIK 1644956

William Blair Investment Management, LLC

Hedge fundFiled 2026-08-12 for Q2 2026. Open the filing ↗ · All SEC filings ↗

Reported 13F value: $33.3B
Reported positions: 403
Top holdings a year, 3 yrs: +19.6%
Assets under management: $65.6B

William Blair Investment Management, LLC is a hedge fund that reported 403 positions worth $33.3B in its Q2 2026 13F, filed 2026-08-12. Its largest holdings were Taiwan Semiconductor Manufac (TSM, 7.1%), Nvidia Corporation Com (NVDA, 5.2%), Alphabet Inc (GOOGL, 3.4%). A portfolio copying its top holdings returned 19.6% a year over the last 3 years, against 20.4% for the S&P 500.

William Blair Investment Management, LLC holdings largest 50 of 403 positions.

Weights are shares of the filer's total reported 13F value, compared with Q1 2026. Share changes may reflect splits; weight changes also reflect price moves. A 13F shows long US-listed positions only, up to 135 days after the fact.

William Blair Investment Management, LLC 13F holdings
Stock	% of 13F value	Q1 2026	Shares	Share change	Reported value
TSMTaiwan Semiconductor Manufac	7.1%	6.2%	4,936,408	-10.5%	$2.4B
NVDANvidia Corporation Com	5.2%	5.2%	8,599,021	-3.8%	$1.7B
GOOGLAlphabet Inc	3.4%	2.4%	3,191,012	+27.4%	$1.1B
AAPLApple Inc	2.8%	4.0%	3,259,914	-32.3%	$943.3M
AVGOBroadcom Inc	2.3%	2.3%	2,056,135	-6.6%	$776.7M
MSFTMicrosoft Corp	2.3%	3.5%	2,048,642	-29.3%	$764.2M
METAMeta Platforms Inc Class A	1.6%	1.9%	950,115	-6.2%	$535.2M
AMZNAmazon Com Inc Com	1.4%	2.2%	1,987,085	-37.2%	$473.6M
MAMastercard Inc.	1.4%	1.8%	918,005	-13.4%	$471.5M
AMDAdvanced Micro Devices Inc	1.3%	0.7%	763,517	-26.8%	$443.5M
AMATApplied Matls Inc	1.1%	—	497,946	—	$360.0M
GEGe Aerospace	0.9%	—	790,801	—	$295.5M
AZNAstrazeneca PLC Ord	0.9%	1.2%	1,514,795	-22.0%	$283.2M
PRMBPrimo Brands Corporation Class A Com Shs	0.8%	0.8%	11,426,823	-12.5%	$279.3M
PSTGPure Storage Inc - Class A	0.8%	0.6%	3,455,381	+19.9%	$272.2M
APHAmphenol Corp	0.8%	—	1,535,059	—	$270.7M
LINLinde PLC	0.8%	1.0%	504,953	-20.6%	$262.0M
ONTOOnto Innovation Inc	0.8%	0.7%	665,377	-31.0%	$251.8M
BWABorgwarner Inc	0.8%	—	3,784,707	—	$251.3M
CGCarlyle Group Inc	0.7%	1.0%	5,914,905	-6.1%	$249.1M
ARGNFargenx SE Sponsored ADR	0.7%	0.6%	264,617	-0.5%	$245.5M
MLIMueller Inds Inc	0.7%	0.8%	1,986,139	-5.9%	$244.2M
MNSTMonster Beverage Corp New	0.7%	0.7%	2,538,136	-13.5%	$244.0M
FFIVF5 Inc	0.7%	0.6%	586,271	-9.8%	$243.9M
BAPCredicorp Ltd.	0.7%	0.7%	625,144	+0.4%	$243.5M
CWCurtiss Wright Corp	0.7%	0.5%	317,306	+36.7%	$240.4M
ITUBItau Unibanco Hldg S A	0.7%	0.9%	28,283,482	-10.7%	$231.1M
SNOWSnowflake Inc	0.7%	0.6%	901,087	-20.1%	$229.3M
TWSTTwist Bioscience Corp	0.7%	0.8%	2,174,594	-58.7%	$223.7M
TEVATeva Pharmaceutical Inds Ltd	0.7%	—	6,593,221	—	$223.4M
UNHUnitedhealth Group Inc Com	0.7%	0.6%	523,387	-22.3%	$217.5M
CRWDCrowdstrike Hldgs Inc Class A	0.6%	—	281,409	—	$214.8M
RRXRegal Rexnord Corp.	0.6%	0.5%	891,139	+6.4%	$212.3M
KRYSKrystal Biotech Inc	0.6%	—	570,153	—	$211.9M
CRSCarpenter Technology Corp	0.6%	—	332,607	—	$205.2M
POWIPower Integrations Inc	0.6%	—	2,382,007	—	$199.5M
NVTNvent Elec PLC	0.6%	—	1,167,763	—	$198.1M
GHGuardant Health Inc	0.6%	—	1,311,320	—	$196.7M
HALOHalozyme Therapeutics Inc	0.6%	0.5%	2,511,050	-0.6%	$196.5M
TLNTalen Energy Corp	0.6%	0.6%	497,660	-5.2%	$191.2M
TRUTransunion	0.6%	0.7%	2,648,744	-8.4%	$191.1M
CCJCameco Corp Com	0.6%	0.6%	1,858,735	+10.5%	$189.3M
STRLSterling Infrastructure Inc	0.6%	—	223,697	—	$187.8M
COSTCostco Whsl Corp New	0.6%	1.0%	199,355	-34.1%	$186.5M
ALHCAlignment Healthcare Inc	0.6%	—	7,761,403	—	$184.8M
CHRWC H Robinson Worldwide in	0.6%	0.6%	978,297	-6.1%	$184.3M
STXSeagate Technology Hldngs Pl	0.6%	—	190,847	—	$184.2M
DIODDiodes Incorporated	0.6%	—	1,682,686	—	$184.2M
BWXTBwx Technologies Inc	0.6%	0.7%	941,233	-4.1%	$183.2M
AKAMAkamai Technologies Inc	0.5%	0.6%	1,535,467	-5.2%	$181.5M

What William Blair Investment Management, LLC bought and sold in Q2 2026, against Q1 2026.

New positions

Q1 2026's filing was too long to tell new positions apart.

Added to

CW Curtiss Wright Corp+36.7% shares
GOOGL Alphabet Inc+27.4% shares
PSTG Pure Storage Inc - Class A+19.9% shares
CCJ Cameco Corp Com+10.5% shares
RRX Regal Rexnord Corp.+6.4% shares

Reduced

TWST Twist Bioscience Corp-58.7% shares
AMZN Amazon Com Inc Com-37.2% shares
COST Costco Whsl Corp New-34.1% shares
AAPL Apple Inc-32.3% shares
ONTO Onto Innovation Inc-31.0% shares
MSFT Microsoft Corp-29.3% shares
AMD Advanced Micro Devices Inc-26.8% shares
UNH Unitedhealth Group Inc Com-22.3% shares

Left the top 50

Share counts compared with the Q1 2026 13F; a split also changes share counts. The latest filing lists more than 50 positions, so a position that left the top 50 may still be held.

How the holdings did against the S&P 500.

1 year: +8.7% /yr; S&P 500 +20.1%
3 years: +19.6% /yr; S&P 500 +20.4%
5 years: +10.2% /yr; S&P 500 +11.6%

A portfolio of the filer's 20 largest 13F positions, weighted by value and rebuilt each quarter on the day the filing became public. 13Fs show long US-listed positions only, so this is an estimate of the stock picks, not the fund's reported returns.

Reported 13F value by quarter.

13F value by quarter
Quarter	13F value	Positions
Q2 2026	$33.3B	403
Q1 2026	$30.3B	413
Q4 2025	$35.9B	413
Q3 2025	$38.7B	414
Q2 2025	$37.7B	417
Q1 2025	$35.6B	423
Q4 2024	$40.9B	433
Q3 2024	$40.5B	412
Q2 2024	$38.1B	411
Q1 2024	$38.7B	410
Q4 2023	$34.4B	406
Q3 2023	$30.1B	398

Questions about William Blair Investment Management, LLC's portfolio

What stocks does William Blair Investment Management, LLC own?

William Blair Investment Management, LLC's latest 13F, for Q2 2026 and filed Aug 12, 2026, lists 403 positions worth $33.3B. The largest are Taiwan Semiconductor Manufac (TSM) at 7.1%, Nvidia Corporation Com (NVDA) at 5.2%, Alphabet Inc (GOOGL) at 3.4%, Apple Inc (AAPL) at 2.8% and Broadcom Inc (AVGO) at 2.3%.

What did William Blair Investment Management, LLC buy last quarter?

In Q2 2026, William Blair Investment Management, LLC added Curtiss Wright Corp (CW) (+36.7% shares), Alphabet Inc (GOOGL) (+27.4% shares) and Pure Storage Inc - Class A (PSTG) (+19.9% shares), compared with its Q1 2026 filing.

What did William Blair Investment Management, LLC sell last quarter?

In Q2 2026, William Blair Investment Management, LLC cut from its top 50 Servicenow Inc Com (NOW), cut from its top 50 Intuit (INTU), cut from its top 50 Agilent Technologies Inc (A), cut from its top 50 O'Reilly Automotive Inc (ORLY), cut from its top 50 Idexx Labs Inc (IDXX), Twist Bioscience Corp (TWST) (-58.7% shares), Amazon Com Inc Com (AMZN) (-37.2% shares) and Costco Whsl Corp New (COST) (-34.1% shares), compared with its Q1 2026 filing.

How has William Blair Investment Management, LLC's portfolio performed?

A portfolio copying William Blair Investment Management, LLC's 20 largest 13F holdings each quarter, from the day each filing was public, returned +19.6% a year over the last 3 years, against +20.4% for the S&P 500. Over 1 year: +8.7% against +20.1%. Over 5 years: +10.2% a year against +11.6%.

When is William Blair Investment Management, LLC's next 13F filing due?

13F filings are due 45 days after each quarter ends. William Blair Investment Management, LLC's filing for the quarter ending Sep 30, 2026 is due by Nov 14, 2026; this page updates the day after it is published.

How much money does William Blair Investment Management, LLC manage?

William Blair Investment Management, LLC reported $65.6B of regulatory assets under management on its latest SEC Form ADV. Its 13F, which covers only US-listed stocks and options, totals $33.3B.