S&P 500 is a stock market index tracking the stock performance of 500 leading companies listed on stock exchanges in the United States. It is one of the most commonly followed equity indices and includes approximately 80% of the total market capitalization of U.S. public companieswith an aggregate market cap of more than $61.1 trillion as of December 312025. The S&P 500 index is a public float weighted/capitalization-weighted index. The ten largest companies on the list of S&P 500 companies account for approximately 38% of the market capitalization of the index and the 50 largest components account for 60% of the index. As of September 2025the 10 largest components arein order of highest to lowest weighting: NvidiaMicrosoftAppleAlphabetAmazonMeta PlatformsBroadcomTeslaBerkshire Hathawayand JPMorgan Chase. The components that have increased their dividends in 25 consecutive years are known as the S&P 500 Dividend Aristocrats. Companies in the S&P 500 derive a collective 72% of revenues from the United States and 28% from other countries. Wikipedia