S&P 500 index

The S&P 500 Index is a market weighted index of 500 U.S. stocks, selected and monitored by Standard and Poors. The index dates back to 1923, when Standard and Poors introduced an index containing 233 companies. The index of 500 stocks was introduced in 1957. The S&P 500 index measures returns of the large cap segment of the U.S. stock market. It comprises 75% of the U.S. market capitalization of stocks.

S&P 500 index funds
Vanguard was the first investment company to offer an S&P 500 index fund (1976). . In 2012, over $1.3 trillion dollars was invested in S&P 500 index investment products.

Historical returns
The following table and charts provide historical total return data for the S&P 500 index from 1923 to the latest year. Chart 1. graphically illustrates the year to year variation in index returns. The annual returns also highlight the major bear markets in the index history, including the Great Depression; the 1973-1974 market; the 2000-2002 market; and the 2008 market, Since real returns are of primary importance to long term investors, Charts 2-4 examine index returns and inflation. Chart 2 shows the annual relationship between inflation and index returns; Chart 3. graphically illustrates the year to year variation in inflation-adjusted annual returns. Chart 4. illustrates the long term cumulative return of the index (assuming an initial $100 dollar investment), in both nominal and real values.