How top-heavy is the stock market?
As of July 2026, the 5 largest US companies make up 27.5% of total large-cap market value, and the top 10 make up 38.9% — up from about 13.0% and 22.4% in 2010. The biggest single weight is NVIDIA Corporation (NVDA) at 6.8%. The chart shows that share month by month — switch between the top 1, 3, 5 and 10.
Share of the market held by the largest companies#
Share of total market value of the ~500 US large caps we track (approximately the S&P 500, equal to its full market-cap weight rather than float weight). Bands are rank slots — the bottom band is whichever company is largest that month. Hover for names and weights.
The top 10 today#
| # | Company | Market cap | Weight |
|---|---|---|---|
| 1 | NVIDIA Corporation (NVDA) | $4.72T | 6.8% |
| 2 | Apple Inc. (AAPL) | $4.54T | 6.5% |
| 3 | Alphabet Inc. Class A (GOOGL) | $4.40T | 6.3% |
| 4 | Microsoft Corporation (MSFT) | $2.90T | 4.2% |
| 5 | Amazon.com Inc. (AMZN) | $2.61T | 3.8% |
| 6 | Space Exploration Technologies Corp. (SPCX) | $2.13T | 3.1% |
| 7 | Broadcom Inc. (AVGO) | $1.72T | 2.5% |
| 8 | Tesla Inc. (TSLA) | $1.49T | 2.1% |
| 9 | Meta Platforms Inc. (META) | $1.48T | 2.1% |
| 10 | Micron Technology Inc. (MU) | $1.10T | 1.6% |
Methodology#
Best-effort reconstruction from month-end prices and SEC-filed share counts for the ~500 US large caps we track (approximately the current S&P 500 membership, plus a few large US listings outside the index — foreign ADRs excluded). Weights are shares of that universe's total market value using full market cap, so they run slightly below official S&P float-adjusted weights, and the denominator uses today's membership rather than each month's historical roster. Share counts come from our SEC EDGAR fundamentals pipeline normalized for splits; companies with heavy spin-off histories (GE, AT&T) are undercounted in early years because their price history is spin-off adjusted. Data since 2010 — the start of reliable structured SEC share-count filings. Not investment advice.
FAQ
- How much of the S&P 500 is the top 10 stocks?
- As of July 2026, the 10 largest companies account for about 38.9% of total US large-cap market value, versus roughly 22.4% in 2010. By full market cap the current top 10 is NVDA, AAPL, GOOGL, MSFT, AMZN, SPCX, AVGO, TSLA, META, MU.
- Is the stock market more concentrated than ever?
- Within this chart's window (since 2010) the top-10 share peaked at 41.7% in October 2025. Longer-run studies show comparable concentration in the early 1930s and the Nifty Fifty era, but today's level is extreme by half-century standards — in the 2010s the top 10 hovered near 22.4%.
- Why does index concentration matter?
- When a handful of stocks dominate the index, its return and risk increasingly ride on those few names: diversification quietly shrinks, sector weights tilt toward whatever the giants do (mostly tech), and cap-weighted index investors hold much more of the leaders than an equal-weighted portfolio would. It isn't automatically bad — the giants earn a large share of all profits — but it changes what owning "the market" means.
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