Three Stocks Are Now 21% of the S&P 500, the Most Ever

NVIDIA, Apple, and Microsoft now dominate the S&P 500 at a concentration level that makes the 1980s tech giants look like small players, and what that means for anyone holding an index fund is more unsettling than most realize.

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At the close on October 6, 2026, the S&P 500 finished at a record 7,818.93, up 0.58%. Three companies now account for an unusually large share of that level.

NVIDIA (NASDAQ:NVDA | NVDA Price Prediction), Apple (NASDAQ:AAPL) and Microsoft (NASDAQ:MSFT) make up over 21% of the index. Research data puts that as the highest three-stock concentration in the index’s history. The closest example came in the mid-1980s, when IBM, AT&T and ExxonMobil peaked at a combined 13.4%.

All three moved modestly on the session. NVIDIA rose 0.14% to $239.24 after touching an intraday record of $243.37. Apple gained 0.22% to $333.63, and Microsoft added 0.78% to $529.30.

The concentration record came from months of steady gains. NVIDIA is up 28.58% year to date, and Apple is up 23.06%. The SPDR S&P 500 ETF Trust (NYSEARCA:SPY) is up 14.25% over the same stretch. If you own an S&P 500 index fund, more than a fifth of your money sits in three companies, stretching the usual meaning of diversification.

The over 21% figure describes the index itself. SPY’s own holdings, dated the prior session, show NVIDIA at 8.63%, Apple at 7.25% and Microsoft at 5.82%. That is a combined fund holdings weight of 21.70%, and the top ten holdings add up to 39.27%.

A cap-weighted index sizes each company by market value, so its biggest winners keep gaining weight as they grow. This means the index acts like a momentum strategy even though it is passively managed.

NVIDIA, worth about $5.78 trillion, reported fiscal second-quarter revenue of $96.22 billion, up 105.8%. Data Center sales made up $89.02 billion of that, and the company guided third-quarter revenue to $108.0 billion.

Apple, at about $4.87 trillion, posted fiscal third-quarter revenue of $109.42 billion, up 16.4%. However, management called memory pricing a “100-year flood” for its hardware costs.

Microsoft, at about $3.93 trillion, reported fiscal fourth-quarter revenue of $90.01 billion. Azure passed $100 billion in annual revenue, and commercial signed backlog rose 84% to $678 billion.

Only 25% of S&P 500 stocks trade above their 50-day moving averages. Most of the index sits below its own recent trend even as the index hits a record.

Thin breadth like this can last a while. The picture likely changes only when lagging stocks begin rising, or the three leaders start to decline.

All three depend on the same AI spending cycle. NVIDIA sells the hardware, and Microsoft buys it at scale, with fiscal 2027 capital spending guided near $175 billion. Apple competes for the same limited memory and chip capacity.

Still, net margins of 55.6% at NVIDIA, 26.9% at Apple and 40.3% at Microsoft show this weight rests on real earnings, unlike past concentration in money-losing companies.

SPY remains a widely held core index fund, and its largest weights are highly profitable businesses. But holding it also means holding a large, linked technology position. If you also own NVIDIA, Apple, or Microsoft shares directly, you own them twice once SPY is counted (riding a concentrated market like this is fine as long as you plan the exit, which is the whole subject of our free bubble survivor’s handbook).

For investors concerned about concentration, the iShares S&P 500 3% Capped ETF (NYSEARCA:TOPC) offers a different approach. It tracks the S&P 500 with a 3% cap on how much any one company can account for.

Track NVIDIA’s next earnings report against its $108.0 billion guidance, and whether breadth climbs back above half of S&P 500 members. A miss combined with weak breadth would likely strengthen the case for a capped approach to the index.

Contact [email protected] for any questions or corrections.

Omor Ibne Ehsan is a writer at 24/7 Wall St. He is a self-taught investor with a focus on growth, cyclical, and dividend equities that have strong fundamentals, value, and long-term potential. He also has an interest in high-risk, high-reward investments such as penny stocks.

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