The S&P 500, or the Standard & Poor’s 500, is a large-cap American stock market index of 500 top-performing companies listing on the NYSE or NASDAQ. First released in 1957, the S&P 500 is a leading indicator of the performance of the US market.1)http://www.investopedia.com/terms/s/sp500.asp Retrieved 4 February 2015. The diversity of its companies makes the S&P 500 a popular tool for economic outlook; the index represents about 80% of available market capitalization2)http://us.spindices.com/indices/equity/sp-500 Retrieved 4 February 2015.. There are a number of products based on the S&P 500 are available, but individual investors in the indices is uncommon because of its number of companies. The S&P 500 is free-float capitalization-weighted.
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