The Standard and Poor's 500, or simply the S&P 500, is a stock market index that tracks 500 large companies listed on stock exchanges in the United States. It is one of the most commonly followed equity indices. As of December 31, 2020, more than $4.6 trillion was invested in assets tied to the performance of the index.
The S&P 500 index is a free-float weighted/capitalization-weighted index and the 10 largest companies in the index account for 26.4% of the market capitalization of the index. The 10 largest companies in the index, in order of weighting, are Apple Inc., Microsoft, Amazon.com, Facebook, Alphabet Inc. (Class A & C), Tesla, Inc., Berkshire Hathaway, JPMorgan Chase & Co., and Johnson & Johnson. For a list of the components of the index, see the List of S&P 500 companies. The components that have increased their dividends in 25 consecutive years are known as the S&P 500 Dividend Aristocrats.