Mutual fund fees and expenses are charges that may be incurred by investors who hold mutual funds. Operating a mutual fund involves costs, including shareholder transaction costs, investment advisory fees, and marketing and distribution expenses. Funds pass along these costs to investors in several ways.

Some funds impose "shareholder fees" directly on investors whenever they buy or sell shares. In addition, every fund has regular, recurring, fund-wide "operating expenses". Funds typically pay their operating expenses out of fund assets—which means that investors indirectly pay these costs. Although they may seem negligible, fees and expenses can substantially reduce an investor's earnings when the investment is held for a long period of time.

For the reasons cited above, it is important for a prospective investor to compare the fees of the various funds under consideration. Investors should also compare fees against industry benchmarks and averages. There are many different types of fees, as discussed below. To facilitate the comparison of funds, it is helpful to compare the total expense ratio. The following table shows the weighted average total expense ratios for different types of mutual funds organized in the United States as of December 31, 2020, as published by Morningstar, Inc.