Strategy. The fund normally invests at least 80% of its net assets (plus any borrowings for investment purposes) in stocks that are included in its benchmark index. Any derivatives that provide exposure to the investment focus suggested by the funds name, or to one or more market risk factors associated with the investment focus suggested by the funds name, are counted (as applicable) toward compliance with the funds 80% investment policy. The fund attempts to track the investment return of large-cap U.S. stocks by seeking to track, before fees and expenses, the performance of its benchmark index, the S&P 500 Index (Index). The Index is made up of primarily large-cap companies that represent a broad spectrum of the U.S. economy and … Show more… The fund normally invests at least 80% of its net assets (plus any borrowings for investment purposes) in stocks that are included in its benchmark index. Any derivatives that provide exposure to the investment focus suggested by the funds name, or to one or more market risk factors associated with the investment focus suggested by the funds name, are counted (as applicable) toward compliance with the funds 80% investment policy. The fund attempts to track the investment return of large-cap U.S. stocks by seeking to track, before fees and expenses, the performance of its benchmark index, the S&P 500 Index (Index). The Index is made up of primarily large-cap companies that represent a broad spectrum of the U.S. economy and a substantial part of the U.S. stock markets total capitalization. (Market capitalization is the number of a companys outstanding shares multiplied by the market price per share.) The fund uses a full replication strategy, which involves investing substantially all of its assets in all of the stocks in the index in proportion to each stocks weighting in the Index. T. Rowe Price compares the composition of the fund to that of the index. If a material misweighting develops, the portfolio manager seeks to rebalance the portfolio in an effort to realign it with the Index. Using a committee process, S&P Dow Jones Indices LLC (SPDJI) constructs the Index by applying certain eligibility factors to common stocks of U.S. companies. Eligibility factors include, but are not limited to, domicile, exchange listing, organizational structure and share type, market capitalization, liquidity, ownership (investable weight factor), sector representation, and financial viability. Index constituents are weighted by float-adjusted market capitalization. Because the fund typically holds securities in proportion to their weight in the Index, the fund intends to be diversified in approximately the same proportion as the Index is diversified. The fund may become nondiversified, as defined under the Investment Company Act of 1940, solely as a result of changes in the composition of the Index. While most assets are invested in common stocks, the fund may also purchase stock index futures contracts. These investments would typically be used to help realign the funds portfolio with its benchmark index, facilitate trading, gain broad market or sector exposure, or to reduce cash balances in the fund and increase the level of fund assets exposed to common stocks represented in the funds benchmark index. Show less