The market capitalization of the S&P 500 (Index: SPX) increased during the third quarter of 2026, rising 1.9% above where it finished in the second quarter.
The S&P 500's 503 stocks, covering all 500 firms that compose the index, collectively grew by a little over $1.26 trillion to reach a total valuation of a little shy of $68.45 trillion.
That topline number however conceals a major split within the index. Most of the index' gain in valuation was concentrated within the top ten stocks, which increased from $24.50 trillion to $26.80 trillion as their share of the index' value rose from 36.5% to 39.2% of its total value.
That increase offset a decline in the combined market capitalization of the remaining 493 stocks of the S&P 500, which fell 2.4% from $42.69 trillion to $41.64 trillion.
The following chart shows the relative shares of the top 10 stocks in the S&P 500 at the close of trading on 30 September 2026, the end of the third quarter of 2026.
The membership of the S&P 500's Top 10 stocks remained the same as at the end of 2026-Q2, but several changed their rank within the elite group. Meta Platforms (A) (NASDAQ: META) surged from ninth place to seventh as the company released its Muse agentic AI tool, knocking both Broadcom (NASDAQ: AVGO) and Tesla (NASDAQ: TSLA) down one place each to eighth and ninth place within the index. Here are the ranked Top 10 stocks of the S&P 500 as of 30 September 2026.
- Nvidia (NASDAQ: NVDA) $5,441,663,080,695 (7.95%)
- Apple (NASDAQ: AAPL) $4,750,332,299,374 (6.94%)
- Microsoft (NASDAQ: MSFT) $3,778,362,289,992 (5.52%)
- Amazon (NASDAQ: AMZN) $2,662,650,236,969 (3.89%)
- Alphabet (A) (NASDAQ: GOOGL) $2,156,130,654,615 (3.15%)
- Alphabet (C) (NASDAQ: GOOG) $2,012,388,610,974 (2.94%)
- Meta Platforms (A) (NASDAQ: META) $1,813,887,693,565 (2.65%)
- Broadcom (NASDAQ: AVGO) $1,642,766,213,040 (2.40%)
- Tesla (NASDAQ: TSLA) $1,375,816,703,421 (2.01%)
- Micron Technology (NASDAQ: MU) $1,170,470,926,791 (1.71%)
The S&P 500 index has twelve stocks whose market caps exceed $1 trillion. Berkshire Hathaway (NYSE: BRK.B) and Eli Lilly & Company (NYSE: LLY) round out the membership of the index' trillion-dollar club.
Top ranked Nvidia's market cap increased to $5.44 trillion, accounting for almost 8% of the entire value of the S&P 500 by itself.
References
Standard and Poor. S&P 500 Factsheet. [PDF Document]. 30 September 2026. Accessed 1 October 2026.
SlickCharts. S&P 500 Component Weights. 30 September 2026. Accessed 1 October 2026.
Labels: market cap, SP 500
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