Exchange-traded funds are more popular than ever, but for nearly a quarter-century, the SPDR S&P 500 ETF (SPY 0.95%) has helped index investors track the investment performance of the S&P 500 Index (^GSPC 1.02%). 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.

The $15,978 Social Security bonus most retirees completely overlook
If you're like most Americans, you're a few years (or more) behind on your retirement savings. But a handful of little-known "Social Security secrets" could help ensure a boost in your retirement income. In fact, one MarketWatch reporter argues that if more Americans knew about this, the government would have to shell out an extra $10 billion annually. For example: one easy, 17-minute trick could pay you as much as $15,978 more... each year! Once you learn how to take advantage of all these loopholes, we think you could retire confidently with the peace of mind we're all after. Simply click here to discover how you can take advantage of these strategies.