BLAIR WILLIAM & CO/IL

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

$37.3B

Total Positions

1,867

New This Quarter

124

Filing Period

2025-12-31

Portfolio Allocation

Top holdings by portfolio weight

MSFT4.64%

AAPL4.34%

AMZN3.76%

NVDA2.75%

GOOG2.63%

GOOGL2.09%

JPM2.00%

IDXX1.82%

V1.82%

SPY1.57%

Other14.64%

Position Outcomes

Best and worst performing positions by estimated return

Top Winners

BELFB14Q held

BEL FUSE INC

Avg $24.09 · $1.2M est. P&L

Est. P&L

+617.68%

IDCC13Q held

InterDigital Inc

Avg $51.33 · $181,041 est. P&L

Est. P&L

+532.00%

MU29Q held

Micron Technology Inc

Avg $49.01 · $73.1M est. P&L

Est. P&L

+497.11%

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 1864 — sorted by value)

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Activity:

Stock	Shares	Value	Weight	Price Trend	Avg Buy	Est. P&L	Held	Conviction
MSFT Microsoft Corp	3.6M	$1.7B	4.6%	—	$123.66	+294.21%	29 qtrs	Decreased 0
AAPL Apple Inc	5.9M	$1.6B	4.3%	—	$102.27	+166.77%	29 qtrs	Decreased 0
AMZN Amazon.com Inc	6.1M	$1.4B	3.8%	—	$114.59	+102.93%	29 qtrs	Increased 59
NVDA NVIDIA Corp	5.5M	$1B	2.8%	—	$118.12	+58.77%	29 qtrs	Decreased 0
GOOG Alphabet Inc	3.1M	$978.7M	2.6%	—	$95.36	+229.86%	29 qtrs	Decreased 0
GOOGL Alphabet Inc	2.5M	$780.5M	2.1%	—	$101.51	+209.18%	29 qtrs	Decreased 0
JPM JPMORGAN CHASE & CO.	2.3M	$744.3M	2.0%	—	$105.79	+204.34%	29 qtrs	Increased 50
IDXX IDEXX Laboratories Inc	1M	$677.5M	1.8%	—	$189.63	+259.81%	29 qtrs	Decreased 0
V Visa Inc	1.9M	$676.6M	1.8%	—	$132.86	+165.61%	29 qtrs	Decreased 0
SPY SPDR S&P 500 ETF TR	857,803	$585M	1.6%	—	$325.26	+111.22%	29 qtrs	Decreased 0
MA Mastercard Inc	955,188	$545.3M	1.5%	—	$200.68	+187.29%	29 qtrs	Decreased 0
META Meta Platforms Inc	736,202	$486M	1.3%	—	$457.25	+45.64%	29 qtrs	Increased 54
COST Costco Wholesale Corp	521,182	$449.4M	1.2%	—	$312.63	+176.51%	29 qtrs	Decreased 0
GEV GE Vernova Inc	652,306	$426.3M	1.1%	—	$399.32	+65.07%	7 qtrs	Increased 51
APH Amphenol Corp	2.7M	$358.6M	1.0%	—	$46.48	+193.02%	29 qtrs	Decreased 0
LLY Eli Lilly & Co	324,796	$349.1M	0.9%	—	$265.19	+306.49%	29 qtrs	Increased 48
NOW ServiceNow Inc	2.2M	$339.3M	0.9%	—	$145.58	+5.94%	29 qtrs	Increased 71
UBER Uber Technologies Inc	4.1M	$335.6M	0.9%	—	$51.69	+58.87%	27 qtrs	Decreased 0
IVV ISHARES TR	488,420	$334.5M	0.9%	—	$384.47	+79.45%	29 qtrs	Increased 48
PGR Progressive Corp/The	1.4M	$320.4M	0.9%	—	$90.99	+137.65%	29 qtrs	Decreased 0
DHR Danaher Corp	1.4M	$314.2M	0.8%	—	$111.85	+106.24%	29 qtrs	Increased 44
AVGO Broadcom Inc	896,446	$310.3M	0.8%	—	$177.01	+97.65%	29 qtrs	Increased 44
ABBV AbbVie Inc	1.3M	$305.6M	0.8%	—	$97.20	+134.46%	29 qtrs	Increased 46
SYK Stryker Corp	844,899	$297M	0.8%	—	$180.55	+95.64%	29 qtrs	Decreased 0
FAST Fastenal Co	7M	$281.5M	0.8%	—	$28.20	+44.17%	29 qtrs	Increased 44
Showing 25 of 1,864 results.PROUpgrade to see all →

Accumulation Streaks

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

Security

ELDWISDOMTREE TR

Q1 2024 → Q4 2025+10 shares+$598

STWDStarwood Property Trust Inc

Q1 2024 → Q4 2025+432,696 shares+$7.1M

SUSBISHARES TR

Q1 2024 → Q4 2025+5,909 shares+$177,243

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