How mutual funds work — the $18.7 trillion industry fueling retirement in the U.S.

5:30 AM ET Thu, 2 May 2019

Mutual funds are big part of most people's retirement portfolios, especially those with employer-sponsored 401(k)s. In fact, an estimated 100 million Americans own a mutual fund, as of 2017. Here's how they work, and how to avoid the most common pitfall with mutual funds.