what is s&p 500

The S&P 500 is a stock market index that tracks the share prices of 500 of the largest public companies in the United States. It was launched in 1957 by the credit rating agency Standard and Poors. The index is market-capitalization-weighted, meaning that the market capitalizations of the companies in the index are adjusted by the number of shares available for public trading. The S&P 500 is widely regarded as the best single gauge of large-cap U.S. equities, covering approximately 80% of available market capitalization. The index is not an exact list of the top 500 U.S. companies by market cap because there are other criteria that the index includes. The S&P 500 is seen as an accurate representation of the U.S. economy, and periods of economic growth and recessions are reflected in the index fund throughout history. The S&P 500 is a float-weighted index, meaning that only large-cap companies who fit pre-specified criteria are included in the index. As of June 30, 2023, the nine largest companies on the list of S&P 500 companies accounted for 30.5% of the market capitalization of the index.