Exchange-traded funds are more popular than ever, but for nearly a quarter-century, the SPDR S&P 500 ETF (NYSEMKT:SPY) has helped index investors track the investment performance of the S&P 500 Index (SNPINDEX:^GSPC). If you're looking for diversified exposure to the broader U.S. stock market, then this ETF is worth looking at more closely.

In the following slideshow, you'll learn everything you need to know about the SPDR S&P 500 ETF, including its investment objective, returns, and holdings, as well as basic characteristics of the fund. Also, you'll find out some of the key factors you'll need to decide whether the ETF is right for you. For passive investors, index ETFs like the SPDR S&P 500 can be extremely valuable in giving you a low-cost way to invest in stocks.