William Blair & Co.
Institutional investor · Portfolio as of Q2 2026
Top Holdings1,998 positions
 Apple Inc. | 5.7M | $1.7B | 4.3% | $54.92 | +538.59% | 31 qtrssince 2018-Q4 | Decreased 0 |
 Amazon.com, Inc. | 5.9M | $1.4B | 3.6% | $98.19 | +171.84% | 31 qtrssince 2018-Q4 | Decreased 0 |
 Microsoft Corporation | 3.4M | $1.3B | 3.3% | $123.78 | +340.43% | 31 qtrssince 2018-Q4 | Decreased 0 |
 NVIDIA Corporation | 5.4M | $1.1B | 2.8% | $50.26 | +255.46% | 31 qtrssince 2018-Q4 | Decreased 0 |
 Alphabet Inc. | 3M | $1B | 2.7% | $57.19 | +400.10% | 31 qtrssince 2018-Q4 | Decreased 0 |
 Alphabet Inc. | 2.4M | $858.6M | 2.2% | $69.20 | +316.40% | 31 qtrssince 2018-Q4 | Decreased 0 |
 GE Vernova Inc. | 659,673 | $775M | 2.0% | $411.98 | +101.30% | 9 qtrssince 2024-Q2 | Decreased 0 |
 JPMorgan Chase & Co. | 2.3M | $743.2M | 1.9% | $104.59 | +227.06% | 31 qtrssince 2018-Q4 | Decreased 0 |
 STATE STR SPDR S&P 500 ETF T | 848,034 | $633.3M | 1.6% | $324.74 | +131.78% | 31 qtrssince 2018-Q4 | Increased 50 |
 Visa Inc. | 1.8M | $631.8M | 1.6% | $133.30 | +216.69% | 31 qtrssince 2018-Q4 | Decreased 0 |
 Costco Wholesale Corporation | 524,692 | $490.8M | 1.3% | $317.26 | +236.06% | 31 qtrssince 2018-Q4 | Increased 50 |
 IDEXX Laboratories, Inc. | 918,556 | $483.6M | 1.3% | $189.80 | +272.31% | 31 qtrssince 2018-Q4 | Decreased 0 |
 Amphenol Corporation | 2.5M | $441.6M | 1.2% | $10.40 | +676.08% | 31 qtrssince 2018-Q4 | Decreased 0 |
 Mastercard Incorporated | 842,350 | $432.6M | 1.1% | $201.56 | +225.37% | 31 qtrssince 2018-Q4 | Decreased 0 |
 INVESCO EXCHANGE TRADED FD T | 2M | $421.8M | 1.1% | $185.20 | +19.30% | 31 qtrssince 2018-Q4 | Increased 58 |
 Palo Alto Networks, Inc. | 1.2M | $418.3M | 1.1% | $84.83 | +290.05% | 31 qtrssince 2018-Q4 | Decreased 0 |
 Eli Lilly and Company | 347,098 | $416.3M | 1.1% | $326.78 | +332.08% | 31 qtrssince 2018-Q4 | Increased 53 |
 Meta Platforms, Inc. | 670,881 | $377.9M | 1.0% | $454.44 | +41.13% | 31 qtrssince 2018-Q4 | Decreased 0 |
 VANGUARD INTL EQUITY INDEX F | 4.5M | $375.1M | 1.0% | $61.59 | +32.29% | 31 qtrssince 2018-Q4 | Increased 47 |
 Micron Technology, Inc. | 315,878 | $364.6M | 0.9% | $77.42 | +846.99% | 31 qtrssince 2018-Q4 | Decreased 0 |
| Quarter | Reported value in US dollars | Reported value change |
|---|---|---|
| 2025-Q1 | $33,156,792,888 | -3.55395973108% |
| 2025-Q2 | $36,002,454,589 | 8.58243953392% |
| 2025-Q3 | $37,569,258,454 | 4.35193623014% |
| 2025-Q4 | $37,259,505,965 | -0.824483904518% |
| 2026-Q1 | $34,895,892,190 | -6.34365301896% |
| 2026-Q2 | $38,388,159,607 | 10.0076748231% |
William Blair & Co. manages $38.4B across 1998 positions as of Q2 2026. Top holdings: AAPL (4.3%), AMZN (3.6%), MSFT (3.3%). Fund DNA: Balanced Allocator. HoldingsIntel Score: 3.5/5.0.
Active quarter - 167 new positions, 91 exits, 892 increased. Top move: RSP (INCREASED, conviction 58). Portfolio: $38.4B across 1998 positions.
Top holdings by portfolio weight
Portfolio allocation by GICS sector
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Position Outcomes
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Cost basis estimates based on full filing history using quarter-end prices. Actual transaction prices are not disclosed in 13F filings.
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Data sourced from SEC EDGAR 13F filings. Not financial advice. Full disclaimer
Verify source filings on SEC EDGAR