Short answer: Fidelity reports a 0.015% gross expense ratio for FXAIX as of April 29, 2026, while iShares lists a 0.03% expense ratio for its IVV ETF in current prospectus information. These are low-cost examples, not a complete ranking of every S&P 500 fund. Fees and account terms can change, so verify the current prospectus and your brokerage’s terms before investing.
Low-cost S&P 500 fund examples
The products below are examples with official fee information available for different dates and wrappers. Their figures should not be read as a fully comparable, market-wide ranking.
| Ticker | Fund type | Stated expense ratio | Source and date |
|---|---|---|---|
| FXAIX | Mutual fund | 0.015% gross | Fidelity fund page; as of April 29, 2026 |
| IVV | ETF | 0.03% | iShares product page; current prospectus information accessed October 8, 2026 |
| SWPPX | Mutual fund | 0.02% in a historical comparison | Fidelity FAQ, December 2018; not a verified current rate |
FXAIX’s figure is explicitly described as gross. Check each fund’s current prospectus for the applicable expense ratio and whether it reports gross or net expenses. The SWPPX figure is included only as a dated historical reference; it should not be compared with the 2026 FXAIX figure as though both were current.
What is the cheapest S&P 500 index fund?
The available figures do not establish a definitive answer across the whole market. A valid ranking would need to define which products count—such as retail mutual funds, ETFs, or eligible institutional share classes—and compare current fees and purchase terms on the same basis. The 0.015% FXAIX gross expense ratio is the lowest among the dated examples listed here, but that does not prove it is the lowest available fund or share class for every investor.
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What an expense ratio tells you
An expense ratio is an ongoing fund operating cost expressed as a percentage of assets. A quoted rate is not the entire cost of owning or buying a fund: access, minimums, transaction costs, and, for ETFs, trading spreads can also matter. A lower stated ratio alone does not establish which option will cost an individual investor less.
Is an S&P 500 ETF cheaper than an index mutual fund?
Not necessarily. The examples show that an ETF and a mutual fund can both have low stated expense ratios, but the figures alone do not settle the full cost comparison. IVV is an ETF; ETFs trade intraday, so an investor’s brokerage, trading pattern, any transaction costs, and the bid-ask spread may affect the amount paid. Verify those terms for your account rather than assuming that either wrapper is always cheaper.
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What is the difference between FXAIX and IVV?
FXAIX is a Fidelity mutual fund; IVV is the iShares Core S&P 500 ETF. Both seek to track the S&P 500, but they use different wrappers and have separately disclosed fees. Fidelity’s fund materials describe the S&P 500 as a market-capitalization-weighted index of 500 common stocks selected to represent U.S. equity performance. Read each fund’s objective and prospectus rather than relying on a similar name or benchmark alone.
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What to check before choosing a fund
- Current fee and date: Use the latest prospectus for the exact ticker and share class. Record whether the expense ratio is gross or net and when the figure applies.
- Availability and minimums: Confirm that the fund or share class is available in your account, along with any minimum initial investment and automatic-investment options.
- Trading costs: For an ETF, check your brokerage’s transaction charges and the bid-ask spread for the way and time you expect to trade.
- Benchmark objective: Confirm that the specific fund seeks to follow the S&P 500; a similar product name does not guarantee the same strategy.
- Account and tax context: Do not assume one wrapper is universally more tax-efficient. The relevant comparison depends on account type and personal circumstances.
How to verify the current cost
- Open the provider’s current prospectus or official fund page for the exact ticker and share class.
- Find the expense-ratio disclosure and note its value, whether it is gross or net, and the date or reporting period.
- Check your brokerage account for eligibility, minimums, transaction charges, and available automatic-investment features.
- If comparing an ETF, review the spread and consider how your order type and trading time may affect execution.
- Compare all options using the same fee basis and account assumptions; do not treat figures from different dates as a current ranking.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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