Capitalize on the around-the-clock liquidity of E-mini S&P 500 futures (ES), and take advantage of one of the most efficient and cost-effective ways to gain market exposure to the S&P 500 Index, a broad-based, capitalization-weighted index that tracks 500 of the largest companies of the US economy and a key indicator of the stock market’s health. With ES futures, you can take positions on S&P 500 performance electronically.