Institutional Manager · CIK 0000902367
BLAIR WILLIAM & CO/IL
Chicago, IL · File #028-04871
Latest AUM
$37.26B
Positions
1,920
Top-10 Concentration
48.1%
Filings
9
Portfolio Value Over Time
2024-03
2024-06
2024-09
2024-12
2025-03
2025-06
2025-09
2025-12
Biggest QoQ Changes
Ranked by conviction flow (share change × current price) so mark-to-market moves don't dominate. Price effect column shows how much of the $ change was just the stock moving.
| Action | Issuer | Ticker / CUSIP | Δ Shares | Flow ($) | Price Effect |
|---|---|---|---|---|---|
| REDUCE | MICROSOFT CORP | MSFT | -3,601,136 | -$1.74B | -$123.8M |
| REDUCE | APPLE INC | AAPL | -5,983,541 | -$1.63B | +$103.3M |
| REDUCE | AMAZON COM INC | AMZN | -5,999,499 | -$1.38B | +$67.6M |
| REDUCE | NVIDIA CORPORATION | NVDA | -5,626,968 | -$1.05B | -$451,621 |
| REDUCE | ALPHABET INC | GOOG | -2,521,010 | -$789.1M | +$176.6M |
| REDUCE | IDEXX LABS INC | 45168D104 | -1,031,085 | -$697.6M | +$38.8M |
| REDUCE | MASTERCARD INCORPORATED | MA | -974,823 | -$556.5M | +$2.0M |
| REDUCE | COSTCO WHSL CORP NEW | 22160K105 | -550,986 | -$475.1M | -$34.9M |
| REDUCE | META PLATFORMS INC | META | -676,880 | -$446.8M | -$50.4M |
| REDUCE | BROADCOM INC | AVGO | -885,356 | -$306.4M | +$14.4M |
Sector Allocation
Filing History
- 13F HOLDINGS REPORTQ/E Dec 20251,920 pos · $37.26B
- 13F HOLDINGS REPORTQ/E Sep 20251,844 pos · $37.57B
- 13F HOLDINGS REPORTQ/E Jun 20251,824 pos · $36.00B
- 13F HOLDINGS REPORTQ/E Mar 20251,801 pos · $33.16B
- 13F HOLDINGS REPORTQ/E Dec 20241,816 pos · $34.38B
- 13F HOLDINGS REPORTQ/E Sep 20241,821 pos · $34.05B
- 13F HOLDINGS REPORTQ/E Jun 20241,822 pos · $32.42B
- 13F HOLDINGS REPORTQ/E Mar 20241,787 pos · $31.84B
- 13F HOLDINGS REPORTQ/E Dec 20231,791 pos · $26.08B
Top 20 Holdings — Dec 2025
| # | Issuer | Ticker | Shares | Value | % of Portfolio |
|---|---|---|---|---|---|
| 1 | MICROSOFT CORP | MSFT | 3,568,598 | $1.73B | 8.14% |
| 2 | APPLE INC | AAPL | 5,940,694 | $1.62B | 7.61% |
| 3 | AMAZON COM INC | AMZN | 6,057,038 | $1.40B | 6.59% |
| 4 | NVIDIA CORPORATION | NVDA | 5,476,206 | $1.02B | 4.81% |
| 5 | ALPHABET INC | GOOG | 3,118,759 | $978.7M | 4.61% |
| 6 | ALPHABET INC | GOOG | 2,488,616 | $778.9M | 3.67% |
| 7 | JPMORGAN CHASE & CO. | VYLD | 2,309,809 | $744.3M | 3.51% |
| 8 | IDEXX LABS INC | 45168D104 | 1,000,674 | $677.0M | 3.19% |
| 9 | VISA INC | V | 1,929,237 | $676.6M | 3.19% |
| 10 | SPDR S&P 500 ETF TR | SPY | 857,803 | $585.0M | 2.76% |
| 11 | MASTERCARD INCORPORATED | MA | 953,414 | $544.3M | 2.57% |
| 12 | META PLATFORMS INC | META | 734,225 | $484.7M | 2.28% |
| 13 | COSTCO WHSL CORP NEW | 22160K105 | 520,610 | $448.9M | 2.12% |
| 14 | GE VERNOVA INC | GEV | 652,306 | $426.3M | 2.01% |
| 15 | AMPHENOL CORP NEW | 032095101 | 2,653,891 | $358.6M | 1.69% |
| 16 | ELI LILLY & CO | LLY | 324,796 | $349.1M | 1.65% |
| 17 | SERVICENOW INC | NOW | 2,211,455 | $338.8M | 1.60% |
| 18 | UBER TECHNOLOGIES INC | UBER | 4,107,558 | $335.6M | 1.58% |
| 19 | ISHARES TR | 464287200 | 488,420 | $334.5M | 1.58% |
| 20 | PROGRESSIVE CORP | 743315103 | 1,407,032 | $320.4M | 1.51% |