You could be losing out on 15% of your mutual fund and ETF returns, researchers say—how to keep more of your money

To find out how well a mutual fund or exchange-traded fund has performed over a certain period, you typically look at total return.

That number bakes in a few assumptions. Namely, that you put a chunk of money into the fund and let it sit there the entire time, periodically reinvesting any dividends that may have come in.

Of course, that’s not how real people invest. After you buy a fund, you might end up adding a few more shares if the fund gets hot. Or maybe you sell a chunk if you find another investment you like better.

For this reason, even if you’ve held a fund for a decade, the 10-year return you see on your portfolio page is unlikely to match the official return on the fund’s website. And, on average, investors’ returns are lower than those of the funds they own.

Over the 10 years ended December 2024, the average dollar invested in U.S. mutual funds and ETFs returned an annualized 7%, according to Morningstar’s 2025 “Mind the Gap” study. Over the same period, those funds returned 8.2%, on average.