The 10 biggest US companies are now 40% of the 500 biggest
The top 10’s share of the 500 largest US companies’ value doubled in eleven years, from 19% in 2015 to 40% today.
- Top 10’s share of the 500 largest
- 40%
- August 2015
- 19%
- September 2026
- 40%
What we found
The ten largest US companies made up 19% of the value of the 500 largest in August 2015. In September 2026 they made up 40%.
An S&P 500 fund is more and more a bet on ten companies.
The full results
The 10 largest each year, and their share (16 rows)
| Date | Share of the 500 largest | Share of all | The 10 largest |
|---|---|---|---|
| Dec 2011 | 23% | 21% | XOM, AAPL, IBM, MSFT, CVX, WMT, PG, GE, JNJ, T |
| Dec 2012 | 22% | 20% | AAPL, XOM, WMT, MSFT, GE, IBM, CVX, PG, T, JNJ |
| Dec 2013 | 20% | 18% | AAPL, XOM, MSFT, GE, WMT, JNJ, WFC, CVX, PG, JPM |
| Dec 2014 | 20% | 18% | AAPL, XOM, MSFT, JNJ, WFC, WMT, PG, GE, JPM, CVX |
| Dec 2015 | 21% | 19% | AAPL, GOOGL, MSFT, XOM, BRK-B, AMZN, GE, META, WFC, JNJ |
| Dec 2016 | 21% | 19% | AAPL, GOOGL, MSFT, BRK-B, XOM, AMZN, JPM, META, JNJ, WFC |
| Dec 2017 | 23% | 20% | AAPL, GOOGL, MSFT, AMZN, META, BRK-B, JPM, JNJ, XOM, BAC |
| Dec 2018 | 24% | 21% | AAPL, MSFT, AMZN, GOOGL, BRK-B, META, JPM, JNJ, XOM, V |
| Dec 2019 | 25% | 23% | AAPL, MSFT, GOOGL, AMZN, META, BRK-B, JPM, V, JNJ, BAC |
| Dec 2020 | 30% | 27% | AAPL, MSFT, AMZN, GOOGL, META, TSLA, BRK-B, V, JNJ, WMT |
| Dec 2021 | 31% | 28% | AAPL, MSFT, GOOGL, AMZN, TSLA, META, NVDA, BRK-B, JPM, UNH |
| Dec 2022 | 26% | 23% | AAPL, MSFT, GOOGL, AMZN, BRK-B, UNH, XOM, JNJ, V, JPM |
| Dec 2023 | 32% | 29% | AAPL, MSFT, GOOGL, AMZN, NVDA, META, TSLA, BRK-B, V, LLY |
| Dec 2024 | 38% | 34% | AAPL, NVDA, MSFT, GOOGL, AMZN, META, TSLA, AVGO, BRK-B, WMT |
| Dec 2025 | 40% | 37% | NVDA, AAPL, GOOGL, MSFT, AMZN, META, AVGO, TSLA, BRK-B, LLY |
| Sep 2026 | 40% | 36% | NVDA, AAPL, GOOGL, MSFT, AMZN, META, AVGO, TSLA, MU, BRK-B |
“All” is every US 10-K filer with a market cap that month.
What concentration means for an index fund
In 2011 the ten largest US companies were a mix of oil, technology, retail, consumer goods and industrials. Today they are mostly technology, and together they are 40% of the 500 largest. An S&P 500 fund is less diversified than its 500 names suggest, and a fund marketed as an alternative often holds the same ten.
Check your own funds
The compare page’s Holdings tab shows how much two ETFs have in common, and each ETF page breaks its holdings down by company and sector and, with Pro, by revenue and earnings.
How it was measured
- Point-in-time market caps at each month-end: share counts from SEC filings times that day’s price, one share class per company.
- Visa and Berkshire Hathaway use Yahoo Finance share counts, because their filings have none usable.
Caveats
- The universe is companies filing 10-Ks with the SEC, so foreign listings are excluded.
Questions
- How concentrated is the S&P 500?
- The ten largest US companies are about 40% of the value of the 500 largest (September 2026), up from 19% in August 2015.
- Is an S&P 500 fund still diversified?
- Less than its 500 names suggest: four tenths of it rides on ten companies, mostly technology and internet businesses.
More research
- Market fact“Sell in May” cut risk and return by about the same amount
- Data studyBacktest on today’s biggest stocks and you double your return
- Market factThe 200-day rule sat out all 10 best and all 10 worst days of the last 20 years
For information only. Not investment advice. Published Nov 2026. Data: Prices to Sep 25, 2026.