The S&P 500, or the Standard & Poor 500, is a stock market index based on the common stock prices of 500 top publicly traded American companies. It differs from other stock market indices like the Dow Jones Industrial Average and the Nasdaq Composite because it tracks a different number of stocks and weights the stocks differently. It is one of the most commonly followed indices and many consider it the best representation of the market and a bellwether for the U.S. economy. It is a free-float capitalization-weighted index.
