WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC

New 13F: Q3 2026

WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC filed its 13F for the quarter ended Sep 30, 2026 on Nov 6, 2026: $13.4B in AI and semiconductor stocks; $1.1B bought and $1.5B sold against its previous quarter, at the quarter's prices.

WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC declares $13.5B in 60 of the 230 AI and semiconductor companies tracked on Silicon Floor, as of Jun 30, 2026 (Form 13F): 40.7% of its $33.3B 13F portfolio. Largest positions: TSMC (0.10% of the company) and NVIDIA (0.04% of the company). Over time: $13.5B in 60 of these companies for Q2 2026, against $3.1B in 27 for Q4 2019 (13F values as filed). From Mar 31, 2026 to Jun 30, 2026, it bought $1.5B and sold $2.9B of these stocks, at the quarter's prices: a net sale of $1.5B; 10 new positions and 7 sold out.

Performance of its AI picks

The AI-stock portfolio WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC declared for Q2 2026 (Form 13F), held unchanged, returned +1.5% in Q3 2026 (SMH -7.1%), ranked 1200 of 1,785 active managers. Over the last 12 months, quarter after quarter: +32.4% (SMH +87.2%), ranked 454 of 1,360 active managers. Over three years, quarter after quarter: +180.0% (SMH +325.8%), ranked 143 of 784 active managers. Over five years, quarter after quarter: +158.6% (SMH +389.8%), ranked 270 of 535 active managers. Trades made during a quarter are not visible in 13F filings: this measures its declared picks, not the return of its funds.

Largest positions

  1. TSMC (TSM): $2.4B, 4.9M shares, 0.10% of the company, 7.1% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
  2. NVIDIA (NVDA): $1.7B, 8.6M shares, 0.04% of the company, 5.2% of its portfolio (trimmed this quarter); held since Q2 2021
  3. Alphabet (GOOGL): $1.1B, 3.2M shares, 0.03% of the company, 3.4% of its portfolio (added this quarter); held since Q4 2019 or earlier
  4. Apple (AAPL): $943.3M, 3.3M shares, 0.02% of the company, 2.8% of its portfolio (trimmed this quarter); held since Q2 2024
  5. Broadcom (AVGO): $776.7M, 2.1M shares, 0.04% of the company, 2.3% of its portfolio (trimmed this quarter); held since Q2 2024
  6. Microsoft (MSFT): $764.2M, 2.0M shares, 0.03% of the company, 2.3% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
  7. Meta Platforms (META): $535.2M, 950,115 shares, 0.04% of the company, 1.6% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
  8. Amazon (AMZN): $473.6M, 2.0M shares, 0.02% of the company, 1.4% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
  9. AMD (AMD): $443.5M, 763,517 shares, 0.05% of the company, 1.3% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
  10. Applied Materials (AMAT): $360.0M, 497,946 shares, 0.06% of the company, 1.1% of its portfolio (added this quarter); held since Q4 2023
  11. Amphenol (APH): $270.7M, 3.1M shares, 0.12% of the company, 0.81% of its portfolio (added this quarter); held since Q1 2026
  12. Onto Innovation (ONTO): $251.8M, 665,377 shares, 1.4% of the company, 0.76% of its portfolio (trimmed this quarter); held since Q1 2025
  13. Snowflake (SNOW): $229.3M, 901,087 shares, 0.26% of the company, 0.69% of its portfolio (trimmed this quarter); held since Q3 2025
  14. CrowdStrike (CRWD): $214.8M, 1.1M shares, 0.11% of the company, 0.65% of its portfolio (new position this quarter)
  15. Power Integrations (POWI): $199.5M, 2.4M shares, 4.3% of the company, 0.60% of its portfolio (added this quarter); held since Q1 2026

By sector

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