Index options on the S&P 100 are traded with the ticker symbol "OEX". Because of the popularity of these options, investors often refer to the index by its ticker symbol.
The S&P 100, a subset of the S&P 500, includes 100 leading U.S. stocks with exchange-listed options. Constituents of the S&P 100 are selected for sector balance and represent about 57% of the market capitalization of the S&P 500 and almost 45% of the market capitalization of the U.S. equity markets. The stocks in the S&P 100 tend to be the largest and most established companies in the S&P 500. In past years, turnover among stocks in the S&P 100 has been even lower than the turnover in the S&P 500.
(as of June 29, 2012)