Just 10 Stocks Make Up Nearly 40% of the S&P 500. Here's an ETF That Can Help You Diversify

An S&P 500 Index (SNPINDEX: ^GSPC) fund, such as the Vanguard S&P 500 ETF (NYSEMKT: VOO), is widely considered one of the easiest ways to build a diversified portfolio. However, there's a catch: Just 10 stocks account for nearly 40% of the index's value. That's up from only 17% in 2015 and is its highest level since the mid-1960s.