Why an expense ratio is not the whole cost of owning a fund

Key takeaways

• Investor.gov defines the expense ratio as the percentage of a fund's average net assets used each year to pay the fund's operating expenses, and it says the figure appears in the prospectus fee table.
• Investor.gov's 2025 bulletin says the prospectus fee table separates annual operating expenses from shareholder fees and notes that the expense ratio does not show every cost an investor may pay.
• Investor.gov says ETF investors may still face brokerage commissions, changes in premiums or discounts to NAV, and other costs that are not shown in the ETF's prospectus fee table.

The expense ratio is useful, but it is only one layer

Investor.gov defines the expense ratio as the percentage of a fund's average net assets used each year to pay the fund's operating expenses. That makes it a useful standardized number for comparing one fund's recurring operating-cost burden against another's.

But the same site also points readers back to the prospectus fee table and broader fee disclosure, which is the first clue that the ratio is an important headline, not the whole bill.

What the fee table is actually showing

Investor.gov's 2025 bulletin says mutual funds and ETFs are required to provide a standardized table of fees and expenses in their prospectuses, divided into annual operating expenses and shareholder fees. The expense ratio reflects total annual fund operating expenses in that framework.

The bulletin also lists the kinds of operating expenses that can sit inside that number, such as management fees, 12b-1 fees where applicable, and other expenses. That helps readers understand what the ratio is measuring before they compare two products.

• Use the expense ratio as a standardized operating-cost signal.
• Read the prospectus fee table to see what types of costs sit behind the number.
• Do not assume a low ratio means there are no other investor costs.

What can still reduce returns outside the ratio

Investor.gov says the prospectus fee table does not show all the other fees an investor may pay, such as brokerage commissions and other fees to financial intermediaries. It also says ETF investors may bear changes in discounts and premiums to NAV.

The same bulletin adds that there can be indirect costs not included in the expense ratio, such as transaction costs when the fund buys and sells underlying securities. For Hynexly readers, the lesson is direct: a fund can look cheap on the ratio line and still cost more than the headline number suggests.

Source evidence snapshot