PRIMECAP MANAGEMENT CO/CA/

New 13F: Q3 2026

PRIMECAP MANAGEMENT CO/CA/ filed its 13F for the quarter ended Sep 30, 2026 on Nov 12, 2026: $74.1B in AI and semiconductor stocks; $830.8M bought and $1.3B sold against its previous quarter, at the quarter's prices.

• trimmed Micron (MU): -$634.6M at the quarter's price
• added to Intel (INTC): +$241.7M at the quarter's price
• added to Synopsys (SNPS): +$166.0M at the quarter's price
• trimmed Alphabet (GOOGL): -$151.2M at the quarter's price
• added to Amazon (AMZN): +$149.3M at the quarter's price
• added to Xcel Energy (XEL): +$94.9M at the quarter's price
• trimmed NetApp (NTAP): -$85.2M at the quarter's price
• trimmed Autodesk (ADSK): -$80.5M at the quarter's price
• added to Flex (FLEX): +$74.9M at the quarter's price
• trimmed Microsoft (MSFT): -$71.1M at the quarter's price

PRIMECAP MANAGEMENT CO/CA/ declares $80.3B in 61 of the 230 AI and semiconductor companies tracked on Silicon Floor, as of Jun 30, 2026 (Form 13F): 47.5% of its $169.1B 13F portfolio. Largest positions: Micron (1.7% of the company) and Intel (1.4% of the company). Over time: $80.3B in 61 of these companies for Q2 2026, against $40.6B in 45 for Q4 2019 (13F values as filed). From Mar 31, 2026 to Jun 30, 2026, it bought $277.2M and sold $5.8B of these stocks, at the quarter's prices: a net sale of $5.6B.

Performance of its AI picks

The AI-stock portfolio PRIMECAP MANAGEMENT CO/CA/ declared for Q2 2026 (Form 13F), held unchanged, returned -6.9% in Q3 2026 (SMH -7.1%), ranked 1588 of 1,785 active managers. Over the last 12 months, quarter after quarter: +101.2% (SMH +87.2%), ranked 29 of 1,360 active managers. Over three years, quarter after quarter: +260.0% (SMH +325.8%), ranked 46 of 784 active managers. Over five years, quarter after quarter: +275.7% (SMH +389.8%), ranked 29 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. Micron (MU): $22.2B, 19.2M shares, 1.7% of the company, 13.1% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
2. Intel (INTC): $10.5B, 75.3M shares, 1.4% of the company, 6.2% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
3. Alphabet (GOOGL): $7.2B, 20.3M shares, 0.16% of the company, 4.3% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
4. KLA (KLAC): $6.2B, 20.5M shares, 1.6% of the company, 3.7% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
5. Flex (FLEX): $3.8B, 23.4M shares, 6.3% of the company, 2.2% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
6. NVIDIA (NVDA): $3.4B, 17.1M shares, 0.07% of the company, 2.0% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
7. Amazon (AMZN): $2.9B, 12.0M shares, 0.11% of the company, 1.7% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
8. Microsoft (MSFT): $2.7B, 7.1M shares, 0.10% of the company, 1.6% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
9. Texas Instruments (TXN): $2.5B, 8.5M shares, 0.93% of the company, 1.5% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
10. NetApp (NTAP): $1.4B, 9.0M shares, 4.6% of the company, 0.83% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
11. Analog Devices (ADI): $1.2B, 3.1M shares, 0.65% of the company, 0.73% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
12. Jabil (JBL): $1.2B, 3.2M shares, 3.1% of the company, 0.72% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
13. Adobe (ADBE): $1.1B, 5.2M shares, 1.3% of the company, 0.63% of its portfolio (added this quarter); held since Q4 2019 or earlier
14. Corning (GLW): $1.1B, 4.1M shares, 0.48% of the company, 0.62% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier
15. Caterpillar (CAT): $928.3M, 871,700 shares, 0.19% of the company, 0.55% of its portfolio (trimmed this quarter); held since Q4 2019 or earlier

By sector

• Memory & storage: $24.1B, 30% of its AI holdings, 5 companies
• Chips & compute: $19.8B, 25% of its AI holdings, 14 companies
• Cloud & AI giants: $13.9B, 17% of its AI holdings, 6 companies
• Equipment & test: $9.2B, 11% of its AI holdings, 9 companies
• Servers & systems: $6.5B, 8% of its AI holdings, 5 companies
• AI software: $3.6B, 5% of its AI holdings, 10 companies
• Power, electrical & cooling: $1.3B, 2% of its AI holdings, 4 companies
• Optics: $1.2B, 2% of its AI holdings, 3 companies
• Interconnect: $592.5M, 1% of its AI holdings, 4 companies
• Neoclouds & data centers: $7.5M, 0% of its AI holdings, 1 company

Biggest changes this quarter

• trimmed Micron (MU): -$3.1B at the quarter's price
• trimmed KLA (KLAC): -$1.2B at the quarter's price
• trimmed Texas Instruments (TXN): -$339.7M at the quarter's price
• trimmed Flex (FLEX): -$328.1M at the quarter's price
• trimmed Alphabet (GOOGL): -$160.2M at the quarter's price
• added to Adobe (ADBE): +$101.7M at the quarter's price
• trimmed Applied Materials (AMAT): -$94.9M at the quarter's price
• trimmed Qualcomm (QCOM): -$86.2M at the quarter's price
• added to HP Inc. (HPQ): +$74.9M at the quarter's price
• trimmed Intel (INTC): -$71.4M at the quarter's price

Schedule 13D/G declarations

• Flex (FLEX): 13G filed Aug 6, 2026: 23.4M shares as of Jun 30, 2026, 6.4% as declared
• NetApp (NTAP): 13G filed Nov 14, 2025: 9.6M shares as of Sep 30, 2025, 4.8% as declared
• Flex (FLEX): 13G filed Nov 13, 2025: 29.6M shares as of Sep 30, 2025, 7.9% as declared
• Flex (FLEX): 13G filed Aug 14, 2025: 33.7M shares as of Jun 30, 2025, 9.0% as declared
• Wolfspeed (WOLF): 13G filed May 13, 2025: 6.7M shares as of Mar 31, 2025, 4.3% as declared
• NetApp (NTAP): 13G filed Feb 13, 2025: 12.2M shares as of Dec 31, 2024, 6.0% as declared

Other holders of this size

• BANK OF MONTREAL /CAN/: $78.3B in 199 of these companies
• American Century Companies, Inc.: $81.1B in 197 of these companies
• CANADA PENSION PLAN INVESTMENT BOARD: $78.1B in 160 of these companies
• RAYMOND JAMES FINANCIAL INC: $85.4B in 215 of these companies
• National Pension Service: $77.8B in 102 of these companies
• Valor Management LLC: $86.0B in 1 of these companies
• AQR: $76.7B in 211 of these companies
• Sumitomo Mitsui Trust Group, Inc.: $86.7B in 133 of these companies

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