The symbols for the Standard & Poor's 500 index are ticker symbols representing company names. The 500 companies and their symbols are tabulated along with shares outstanding and market cap on the Chicago Board Options Exchange website. An interactive list of companies and their symbols are posted on CNN's website.
The symbol for the S&P 500 index itself is SPX. The companies are selected based on both market value and influence on the U.S. economy, and the companies are selected from all three major U.S. stock exchanges: the New York Stock Exchange, the American Stock Exchange and the Nasdaq, according to PR Newswire.
The composition of the S&P 500 has changed over time, explains PR Newswire. Its composition is determined by the S&P Index committee. As of 2007, only 86 companies were part of the original 500 when the index was formally created in 1957. The committee maintains a contingency pool should any of the 500 companies file for bankruptcy or otherwise be disqualified from the index. The committee also makes changes based on a company's evolving role in the economy.
Funds known as exchange traded funds or ETFs are designed to mimic the behavior of the S&P 500, as reported by PR Newswire. A list of these funds and their exchange symbols are found on S&P Dow Jones Indices.