WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC

View all activity View 13F on SEC

Data as of Q4 2025

Institutional investor tracked via SEC 13F filings. Portfolio snapshot as of 2025-12-31.SEC EDGAR Source

Assets Under Management

$35.9B

Total Positions

413

New This Quarter

Filing Period

2025-12-31

Portfolio Allocation

Top holdings by portfolio weight

NVDA5.53%

TSM5.07%

MSFT4.71%

AAPL4.13%

AMZN2.82%

GOOGL2.75%

AVGO2.45%

META2.19%

MA1.73%

CG1.18%

Other12.45%

Position Outcomes

Best and worst performing positions by estimated return

Top Winners

INSM24Q held

Insmed Inc

Avg $27.79 · $178.6M est. P&L

Est. P&L

+526.45%

TSM29Q held

TAIWAN SEMICONDUCTOR MFG LTD

Avg $49.26 · $1.5B est. P&L

Est. P&L

+508.10%

LITE3Q held

Lumentum Holdings Inc

Avg $94.75 · $38.6M est. P&L

Est. P&L

+291.75%

Top Losers

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View plans

Cost basis estimates based on full filing history using quarter-end prices. Actual transaction prices are not disclosed in 13F filings.

Top Holdings(Showing 25 of 413 — sorted by value)

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Activity:

Stock	Shares	Value	Weight	Price Trend	Avg Buy	Est. P&L	Held	Conviction
NVDA NVIDIA Corp	10.6M	$2B	5.5%	—	$117.25	+59.94%	19 qtrs	Decreased 0
TSM TAIWAN SEMICONDUCTOR MFG LTD	6M	$1.8B	5.1%	—	$49.26	+508.10%	29 qtrs	Decreased 0
MSFT Microsoft Corp	3.5M	$1.7B	4.7%	—	$254.17	+91.79%	29 qtrs	Decreased 0
AAPL Apple Inc	5.4M	$1.5B	4.1%	—	$216.91	+25.78%	7 qtrs	Decreased 0
AMZN Amazon.com Inc	4.4M	$1B	2.8%	—	$125.35	+85.51%	29 qtrs	Decreased 0
GOOGL Alphabet Inc	3.2M	$987.5M	2.8%	—	$243.59	+28.84%	29 qtrs	Increased 68
AVGO Broadcom Inc	2.5M	$877.9M	2.4%	—	$177.43	+97.18%	7 qtrs	Decreased 0
META Meta Platforms Inc	1.2M	$783.4M	2.2%	—	$531.25	+25.36%	29 qtrs	Increased 54
MA Mastercard Inc	1.1M	$619.4M	1.7%	—	$306.90	+87.86%	29 qtrs	Decreased 0
CG Carlyle Group Inc/The	7.1M	$421.6M	1.2%	—	$33.04	+80.79%	13 qtrs	Decreased 0
TRU TransUnion	4M	$340M	0.9%	—	$94.28	-7.73%	7 qtrs	Decreased 0
MELI MercadoLibre Inc	165,579	$333.5M	0.9%	—	$1,011.82	+99.73%	27 qtrs	Decreased 0
NOW ServiceNow Inc	2.1M	$329.2M	0.9%	—	$149.68	+3.04%	11 qtrs	Increased 70
NU NU HLDGS LTD	18.7M	$313M	0.9%	—	$13.98	+20.70%	9 qtrs	Decreased 0
SE Sea Ltd	2.4M	$302.4M	0.8%	—	$110.55	+16.10%	6 qtrs	Decreased 0
IDXX IDEXX Laboratories Inc	441,324	$298.6M	0.8%	—	$416.21	+63.94%	29 qtrs	Decreased 0
SNOW Snowflake Inc	1.3M	$295.5M	0.8%	—	$223.28	-0.55%	2 qtrs	Increased 70
INTU Intuit Inc	442,391	$293M	0.8%	—	$448.27	+49.16%	29 qtrs	Decreased 0
MNST Monster Beverage Corp	3.8M	$288.4M	0.8%	—	$61.17	+26.56%	12 qtrs	Increased 53
AMD Advanced Micro Devices Inc	1.3M	$286.9M	0.8%	—	$164.10	+31.22%	27 qtrs	Increased 54
COST Costco Wholesale Corp	328,468	$283.3M	0.8%	—	$491.82	+75.77%	29 qtrs	Increased 44
A Agilent Technologies Inc	2.1M	$280.7M	0.8%	—	$134.78	+1.92%	10 qtrs	Decreased 0
LIN Linde PLC	643,470	$274.4M	0.8%	—	$365.32	+17.26%	12 qtrs	Increased 52
ONTO Onto Innovation Inc	1.7M	$272.6M	0.8%	—	$114.64	+39.58%	4 qtrs	Decreased 0
ORLY O'Reilly Automotive Inc	3M	$271.9M	0.8%	—	$87.48	+4.56%	13 qtrs	Increased 44
Showing 25 of 413 results.PROUpgrade to see all →

Accumulation Streaks

Positions with 2+ consecutive quarters of increases — persistent directional conviction.

Security

PDFSPDF SOLUTIONS INC

Q1 2024 → Q4 2025+710,544 shares+$17.9M

DFINDonnelley Financial Solutions Inc

Q3 2024 → Q4 2025+199,795 shares+$5.2M

STEPSTEPSTONE GROUP INC

Q4 2024 → Q4 2025+248,522 shares+$19M

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Data sourced from SEC EDGAR 13F filings. Not financial advice. Full disclaimer