The S&P 500 is a stock market index that tracks the performance of 500 of the largest publicly traded companies in the United States. It is widely regarded as a key indicator of overall U.S. stock market performance and a reflection of the country's economic health. The index includes leading companies from various sectors, such as technology, healthcare, energy, and finance, offering investors a broad view of the market. As of December 31, 2025, the S&P 500 had an aggregate market cap of over $61.1 trillion.
The S&P 500 is maintained by S&P Dow Jones Indices, a joint venture majority-owned by S&P Global. Established on March 4, 1957, the index is float-adjusted and market capitalization-weighted. This means that companies with larger market caps have a greater influence on the index's value. The components of the S&P 500 are selected by a committee that assesses factors like market capitalization, liquidity, and sector representation. The index is rebalanced quarterly, typically in March, June, September, and December. As of February 11, 2026, the S&P 500 Index value is around $6,962.07. While you cannot invest directly in the S&P 500, you can invest in index funds or exchange-traded funds (ETFs) that track its performance.