Standard & Poor’s 500 is an American stock market index consisting of 500 large companies having common stock listed on the NYSE or NASDAQ and their market capitalizations. It captures approximately 80% coverage of available market capitalization. Because it includes both growth stocks and value stocks it is one of the most followed equity indices and is considered to be one of the best representations of the U.S. stock market and a trend indicator for the U.S. economy. S&P introduced its first index in 1923 and its present day form on March 4,1957. It was developed and continues to maintained by S&P Dow Jones Indices, a joint venture majority owned by McGraw Hill Financial.