Financial Terms / S - T / S&P 500

S&P 500

The S&P 500, or the Standard and Poor's 500, is the U.S. stock market index that tracks the performance of the 500 largest publicly listed U.S. companies. The 500 companies are weighted in the S&P 500 based on their market capitalization. The S&P 500 serves as a good barometer to gauge the performance of the U.S. stock market.