The Standard and Poor's 500 index was first published on March 4, 1957, according to SPIndices.com. The S&P 500 traded at $44.06 when it debuted in 1957 and closed at $1,969.41 on Sept. 8, 2015, according to Yahoo Finance. The index is tracked under ticker symbol SPX, states SPIndices.com. The companies in the S&P 500 are the 500 most widely held publicly traded U.S. companies with market capitalizations of $5.3 billion or more, states About.com.
As of July 2012, the S&P 500 index is a publication of S&P Dow Jones Indices LLC, states SPIndices.com. McGraw Hill acquired Standard and Poor's in 1966, states McGraw Hill Financial. As of September 2015, the largest companies by volume in the index are Apple, Microsoft, Exxon Mobil, Johnson & Johnson, and General Electric, according to SPIndices.com. Information technology stocks account for 20 percent of the index as of August 2015, and financial and health care companies each make up about 15 percent of the total index.
The S&P 500 tracks about 80 percent of the U.S. market, according to SPIndices.com. The index does not capture any foreign companies and captures fewer technology companies than the Nasdaq, according to About.com. The index tracks many more companies than the 30 company Dow Jones Industrial Average, but contains fewer large-cap companies than the Dow Jones.