Under normal market conditions, the fund generally invests substantially all, but at least 80%, of its total assets in the securities comprising the index. The index is designed to measure the performance of the large-, mid-, and small-capitalization segments of the U.S. equity market. The index consists of those stocks included in the S&P 500 Index, the S&P MidCap 400 Index, and the S&P SmallCap 600 Index.