The iShares S&P 500 Index Fund - Class A (BSPAX) is a mutual fund that seeks to track the performance of the S&P 500 Index, a widely recognized benchmark of the overall U.S. stock market. This fund is managed by iShares, a leading provider of exchange-traded funds (ETFs) and other investment products. As a Class A fund, it may have lower fees and expenses compared to other share classes, making it an attractive option for investors seeking broad exposure to the U.S. stock market.