A stock-market index based on Fortune magazineÂ’s annual list of the largest 500 U.S.-based public and private companies that produce and file annual reports with the Securities and Exchange Commission. The companies are ranked by revenue. The list is a market-
capitalization-weighted index whose value is calculated during 15-second intervals during the trading session. It was set at a base level of 1,000.00 using the closing price on December 31, 1999.