Expense ratios and fund costs: what you pay and how it compounds

Every fund charges for running itself, and you pay whether the fund goes up or down. The charge rarely appears as a bill. It is taken quietly from the fund's assets, a sliver every day, so the only place you notice it is in a return that's a little lower than it would otherwise have been. Over a weekend that sliver is invisible. Over a working lifetime it can be a third of the money.

This guide explains exactly how the expense ratio is charged, works through what different fee levels do to an investment over 10, 20 and 40 years, and covers the costs that do not appear in the expense ratio at all: sales loads, trading costs inside the fund, bid-ask spreads, and advisory fees layered on top. It ends with where to find each number and a free calculator that does the arithmetic for any fund.

What the expense ratio is

The SEC defines the expense ratio as a fund's total annual fund operating expenses, expressed as a percentage of its average net assets. In the prospectus fee table it is the sum of:

• Management fees, paid to the investment adviser for running the portfolio;
• Distribution and/or service (12b-1) fees, which pay for marketing and selling the fund (mutual funds have them far more often than ETFs);
• Other expenses, such as custody, legal, accounting, transfer-agent and administrative costs; and
• Acquired fund fees and expenses, if the fund invests in other funds.

A fund may show a fee waiver that lowers the net expense ratio for a period; the fee table states when the waiver ends, after which the higher gross figure can apply.

For a sense of scale, as of October 2026 BlackRock lists 0.03% for both the iShares Core S&P 500 ETF (IVV) and the iShares Core US Aggregate Bond ETF (AGG), and State Street lists a gross expense ratio of 0.0945% for SPY. Actively managed stock funds commonly charge many times those amounts.

How it is charged: a little every day

The fund accrues its expenses daily and subtracts them from its assets before calculating each day's net asset value (NAV). You never write a check; the NAV, and therefore your holding, is simply a bit lower.

The math over decades

A few dollars a year sounds trivial. The cost is in the compounding: every dollar paid in fees this year is a dollar that never earns a return in any later year.

Notice that the difference after 10 years, about $1,800 between the cheapest and dearest fund, is easy to shrug off. It grows to about $6,800 by year 20 and about $47,800 by year 40, more than 25 times the 10-year gap. Costs compound exactly the way returns do, in reverse.

The hurdle a costlier fund must clear

A fund with a higher expense ratio has to earn more before costs just to keep up. A fund charging 1.00% must beat a 0.03% fund holding similar assets by about 0.97 percentage points a year, every year, simply to match it. The SEC's investor bulletin makes the same point: a fund with higher costs must perform better than a low-cost fund to generate the same returns. For index funds tracking the same index, that extra return can't come from anywhere, so the cheaper one should win almost every time (see Index investing: passive vs. active funds and what the data shows).

Costs outside the expense ratio

The expense ratio is the most visible cost, not the only one.

Sales loads and shareholder fees

Some mutual funds charge shareholder fees directly to you: front-end sales loads taken from your purchase, back-end loads or contingent deferred sales charges when you sell, redemption fees on quick round trips, exchange fees and small-account fees. A 5% front-end load on $10,000 means $500 is gone before anything is invested, a cost the expense ratio never shows. As of 2026, FINRA Rule 2341 caps aggregate sales charges at 8.5% of the offering price (lower in many cases) and limits asset-based sales charges to 0.75% and service fees to 0.25% a year. Mutual funds explained: NAV, share classes, loads and 12b-1 fees covers loads and share classes in detail.

Trading costs inside the fund

When a fund buys and sells securities it pays commissions and crosses bid-ask spreads, and large trades can move prices against it. These costs are not part of the expense ratio. They show up as slightly lower returns. The SEC's fee bulletin lists them among the indirect costs the expense ratio leaves out. The prospectus gives a clue: the portfolio turnover rate. A turnover of 100% means the fund replaced roughly its entire portfolio in a year; an S&P 500 index fund's turnover is typically in the low single digits.

Costs of trading an ETF yourself

ETF investors pay the bid-ask spread on every trade and may buy at a premium or sell at a discount to NAV. Some brokers still charge commissions. For a long-term holder of a large, liquid ETF these are tiny, often a penny a share; for a frequent trader of a small ETF they can exceed the expense ratio.

Advice and account fees

An adviser who charges, say, 1% of assets a year adds that on top of every fund's expense ratio. A "wrap" or managed account may bundle advice and trading into one percentage. The SEC also warns about funds marketed as zero-expense or no-expense: others may be collecting fees for the services the fund isn't charging for, through separate commissions or asset-based advisory fees.

Where to find every number

1. The prospectus fee table: shareholder fees on top, annual operating expenses below, with any fee waiver and its end date.
2. The expense example right after it: what $10,000 would cost over 1, 3, 5 and 10 years, using a standard assumed return, with and without redeeming. It is the quickest apples-to-apples comparison between funds with different fee structures.
3. The shareholder report, sent twice a year, which repeats the expenses in dollars for a hypothetical holding.
4. The fund's website and fact sheet, for the current expense ratio and turnover.

For side-by-side comparisons, Investor.gov points investors to the FINRA Fund Analyzer, a free tool that covers more than 18,000 mutual funds, ETFs and exchange-traded notes. It estimates how fees and expenses affect an investment's value over time and lists each fund's loads and available discounts. Investor.gov's own compound interest calculator can also show how a lower net return compounds.

Pitfalls to avoid

Judging by last year's return. A high-fee fund's good year says little about the next; its fee is the one number you know will repeat.

Comparing only expense ratios across different strategies. A 0.03% S&P 500 fund and a 0.40% international small-cap fund do different jobs. Compare costs between funds that do the same job.

Forgetting the fee waiver end date. A temporary waiver can make a fund look cheaper than it will be next year.

Ignoring turnover in a taxable account. High turnover raises hidden trading costs and usually produces more taxable capital gains distributions.

Overlooking the layers. Expense ratio, advisory fee, account fee and trading costs add up. Ask for the all-in figure in dollars.

How Finabase helps

Each fund's symbol page shows its price history and the dividends it has paid, which is where the expense ratio's drag ends up, in returns slightly below the index. The comparison tool lays several funds' period returns side by side so two funds tracking the same market can be checked against each other, and portfolios record what you own, with history, allocation and dividend reports. Finabase does not charge fund fees or manage money; for fee details, the prospectus and the FINRA Fund Analyzer are the sources of record.

Frequently asked questions

What is a good expense ratio?

It depends on the strategy. As of October 2026, broad US stock and bond index ETFs from large sponsors can cost 0.03% a year, while actively managed and specialized funds charge more. The useful comparison is with other funds that do the same job.

Is the expense ratio charged once a year?

No. It is accrued every day and deducted from the fund's assets before each day's NAV is calculated, so you pay it continuously and never see a separate bill.

Do ETFs have expense ratios?

Yes. ETFs charge an expense ratio just like mutual funds, but they rarely have sales loads or 12b-1 fees. ETF investors also pay the bid-ask spread when they trade.

Does the expense ratio include trading costs?

No. Commissions and spreads the fund pays when it trades its portfolio are reflected in its returns, not its expense ratio. The portfolio turnover rate in the prospectus hints at how large they might be.

Summary

Fund costs are certain in a way returns never are. The expense ratio, a fund's annual operating cost as a share of its assets, is deducted a little every day, and because the money taken never compounds, a 1% fee on $10,000 at 7% a year leaves about $47,800 less after 40 years than a 0.03% fee, far more than the $16,300 in fees actually paid. Loads, trading costs inside the fund, spreads and advisory fees come on top and are not in the expense ratio. The prospectus fee table, its 10-year expense example and the FINRA Fund Analyzer put every fund's costs on the same footing, and comparing them among funds that do the same job is one of the few investing decisions with a predictable payoff.