The higher fees often accompany funds that try to beat market indexes by actively buying and selling securities. Index funds, which track benchmarks such as the Standard & Poor's 500, don't require active management and typically charge lower fees.
With stocks having hit record highs before being clobbered in recent days, many investors have been on edge over the market's ups and downs. But experts say timing the market is nearly impossible. By contrast, investors can increase their returns by limiting their funds' fees.
Most stock funds will match the performance of the entire market over time, so those with the lowest management costs will generate better returns, said Russel Kinnel, director of research for Morningstar.
"Fees are a crucial determinant of how well you do," Kinnel said.
The difference in costs can be dramatic.
Each fund discloses its "expense ratio." This is the cost of operating the fund as a percentage of its assets. It includes things like record-keeping and legal expenses.
For one of its stock index funds, Vanguard lists an expense ratio of 0.05 percent. State Farm lists it at 0.76 percent for a similar fund. The ratio jumps to 1.73 percent for a Nasdaq-based investment managed by ProFunds.
"ProFunds are not typical index mutual funds but are designed for tactical investors who frequently purchase and redeem shares," said ProFunds spokesman Tucker Hewes. "The higher-than-normal expense ratios of these non-typical funds reflect the additional cost and efforts necessary to manage and operate them."
Average fees also tend to vary based on the size of an employer's 401(k) plan. The total management costs for individual companies with plans with more than $1 billion in assets has averaged 0.35 percent a year, according to BrightScope, a firm that rates retirement plans. By contrast, corporate plans with less than $50 million in assets have total fees approaching 1 percent.