Short answer: FXAIX, VOO and SWPPX are all very cheap S&P 500 index funds, charging 0.015%, 0.03% and 0.02% a year according to their prospectuses. Over the ten years to December 31, 2025, their returns were within 0.03 percentage points a year of each other, so the real difference is how you buy them: FXAIX and SWPPX are mutual funds, and VOO is an ETF.
If you want an S&P 500 index fund, three names come up again and again: the Fidelity 500 Index Fund (FXAIX), the Vanguard S&P 500 ETF (VOO) and the Schwab S&P 500 Index Fund (SWPPX). They track the same index, hold the same 500 or so companies and cost only a few hundredths of a percent a year.
So which one should you pick? The honest answer is that the portfolio barely differs. What differs is how you buy them, where you can hold them, and a few small costs around the edges. This comparison uses each fund’s own prospectus and SEC filings, so every number can be checked.
For the bigger picture of what every S&P 500 index fund charges, see our S&P 500 fee analysis.
The short version
| Fidelity 500 Index Fund | Vanguard S&P 500 ETF | Schwab S&P 500 Index Fund | |
|---|---|---|---|
| Ticker | FXAIX | VOO | SWPPX |
| Type | Mutual fund | ETF (share class of Vanguard 500 Index Fund) | Mutual fund |
| Expense ratio | 0.015% | 0.03% | 0.02% |
| Minimum initial investment | None | Price of one share, or less with fractional shares at your broker | None |
| 10-year return (to Dec. 31, 2025) | 14.81% | 14.78% (NAV) | 14.78% |
| S&P 500, same period | 14.82% | 14.82% | 14.82% |
| Portfolio turnover (latest fiscal year) | 3% | 2% | 3% |
| Fund inception | 1988 | Fund 1976; ETF shares 2010 | 1997 |
Figures come from each fund’s prospectus or summary prospectus filed with the SEC and, for inception dates, the fund companies’ official fund pages. Sources are listed at the end.
In ten years, the gap between the best and the “worst” of these three was 0.03 percentage points a year. All three tracked the index extremely closely.
What they have in common
Before looking at the differences, it’s worth being clear about how much is the same:
- Same index. All three follow the S&P 500, about 500 of the largest U.S. companies, weighted by market value.
- Same holdings. Because they copy the same index, they own the same companies in almost exactly the same proportions. A few basis points of difference in cash or timing is all that separates them.
- Same dividend income. The dividends they pass on come from the same companies, so the income you receive, before costs, is essentially the same.
- Low turnover. All three reported portfolio turnover of 2% to 3% in their latest fiscal year, meaning they rarely need to trade.
- No sales loads and no 12b-1 fees. None of the three charges a sales commission or a yearly distribution fee, which isn’t true of every S&P 500 fund. Our articles on sales loads and 12b-1 fees list the ones that do.
Cost: all three are very cheap
The expense ratio is the yearly fee taken from the fund’s assets. On a $10,000 investment, the difference between these three funds is tiny:
| Fund | Expense ratio | Yearly cost on $10,000 |
|---|---|---|
| FXAIX | 0.015% | about $1.50 |
| SWPPX | 0.02% | about $2 |
| VOO | 0.03% | about $3 |
Over decades, even that adds up a little, but far less than the choice of index fund versus an expensive share class of the same index. In our full comparison, the median S&P 500 share class charged 0.29% a year, and some charged more than 1%. Any of these three puts you at the very bottom of that range.
There are a couple of costs outside the expense ratio worth knowing:
- Vanguard’s account service fee. Vanguard’s mutual fund prospectus says: “Vanguard may charge a $25 account service fee on fund accounts that have a balance below $5,000,000 for any reason, including market fluctuation.” It applies to Vanguard’s mutual fund accounts, such as the Admiral Shares (VFIAX). VOO’s own fee table doesn’t list it.
- Buying a fund away from its home broker. Fidelity’s prospectus notes that “you may be charged a transaction fee if you buy or sell shares through a non-Fidelity broker or other investment professional.” Schwab’s prospectus says investors “may only invest in the fund through an account at Charles Schwab & Co., Inc. (Schwab) or another financial intermediary.” In practice, check your own broker’s fee schedule before buying another company’s mutual fund.
- ETF trading costs. VOO’s prospectus reminds buyers that ETF trades can involve a brokerage commission and the “bid-ask spread,” the small difference between buying and selling prices. For an ETF as heavily traded as VOO, the spread is usually tiny.
Tracking: almost identical
The prospectus return tables show how closely each fund followed the S&P 500:
| Period ended Dec. 31, 2025 | S&P 500 | FXAIX | VOO (NAV) | SWPPX |
|---|---|---|---|---|
| 1 year | 17.88% | 17.86% | 17.84% | 17.88% |
| 5 years | 14.42% | 14.41% | 14.38% | 14.40% |
| 10 years | 14.82% | 14.81% | 14.78% | 14.78% |
Over ten years, FXAIX trailed the index by 0.01 points a year and VOO and SWPPX by 0.04 points. That’s roughly their expense ratios, which is exactly what you’d expect from a well-run index fund. Our article on tracking difference explains why a fund can’t match its index exactly.
Past returns don’t predict future ones, and one year’s small differences can easily reverse. On tracking alone, there’s no meaningful winner.
What 30 years of fee differences look like
To put the three expense ratios in perspective, here’s a hypothetical $10,000 investment left for 30 years, earning 7% a year before costs:
| Fund | Expense ratio | Value after 30 years |
|---|---|---|
| FXAIX | 0.015% | about $75,800 |
| SWPPX | 0.02% | about $75,700 |
| VOO | 0.03% | about $75,500 |
The gap between the cheapest and the most expensive of the three is roughly $300 over 30 years. The 7% is an illustration, not a forecast, and real results depend on the market, not on these small fee differences.
What about SPY, IVV and other S&P 500 ETFs?
These three aren’t the only low-cost ways to own the S&P 500. According to their fund pages, the iShares Core S&P 500 ETF (IVV) charges 0.03%, and the State Street SPDR Portfolio S&P 500 ETF (SPYM, formerly SPLG) charges 0.02%. The original S&P 500 ETF, the SPDR S&P 500 ETF Trust (SPY), costs 0.0945% a year. It’s hugely popular with traders for its liquidity, but for a buy-and-hold investor it’s about three times the cost of VOO or IVV.
In a 30-year example like the one above, SPY’s higher fee would leave you with roughly $74,100 instead of about $75,500 for VOO. Small, but there’s no reason to pay it if you’re not trading.
How you buy them: the real difference
This is where the three funds genuinely differ.
FXAIX and SWPPX: mutual funds
- You buy at the end-of-day price. Orders placed during the day are filled at that day’s net asset value (NAV).
- No minimum. Both prospectuses say so: Fidelity’s “There is no purchase minimum for fund shares,” and Schwab’s “There is no minimum initial investment for the fund.”
- Exact-dollar investing is easy. You can invest $50 or $5,000 and get fractional shares automatically.
- Automatic investing is straightforward at the fund’s home company.
- Easiest at their own brokerage. FXAIX is simplest to hold at Fidelity and SWPPX at Schwab. Holding them elsewhere may cost a fee, or may not be available.
VOO: an ETF
- You buy on the stock exchange, during the day, at the market price, through any brokerage account. The prospectus notes: “Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy.”
- Portable. Because it’s an ETF, you can hold it at almost any broker and usually transfer it between brokers without selling.
- Fractional shares and automatic investing depend on your broker. Many offer both now.
VOO is also one share class of the Vanguard 500 Index Fund, which has mutual fund classes too. If you prefer a mutual fund at Vanguard, the Admiral Shares (VFIAX) hold the same portfolio at 0.04% a year, with a minimum of “generally $3,000” to open an account, according to its prospectus.
Our general comparison of index mutual funds and ETFs covers these trade-offs in more detail.
Taxes
Inside an IRA or 401(k), the tax differences between these funds don’t matter day to day.
In a regular taxable account, the fund structure can matter a little. ETFs can often avoid distributing capital gains, and VOO’s prospectus shows no capital gains distributions in any of the five years from 2021 through 2025. The two mutual funds are also very tax-efficient for mutual funds, because broad S&P 500 funds trade little: Schwab’s fund page shows no capital gains distributions in December 2023, 2024 or 2025. For all three, the main taxable item in a typical year is the dividend income from the companies they own, which is the same for any S&P 500 fund.
If you’re investing in a taxable account for the long term and value portability and the ETF structure, VOO has a slight structural edge. If you’re buying inside a retirement account, it’s close to irrelevant.
Size and staying power
All three are among the largest index funds in the United States. In their most recent annual reports to the SEC on Form N-CEN, the funds reported average net assets of about:
- Vanguard 500 Index Fund (all share classes, including VOO): about $1.41 trillion
- Fidelity 500 Index Fund: about $684 billion
- Schwab S&P 500 Index Fund: about $115 billion
Size isn’t a virtue in itself, but it does make it very unlikely that any of these funds will close or merge, and it’s part of why their costs are so low. Our count of how many index funds there are shows how concentrated index fund money has become in the largest funds.
So which one should you choose?
For most people, the best choice depends on where you already invest:
- If you have (or want) a Fidelity account: FXAIX is the lowest-cost of the three and easy to buy there with no minimum.
- If you have (or want) a Schwab account: SWPPX is nearly as cheap, with no minimum.
- If you want flexibility to use any broker, or you’re investing in a taxable account: VOO is portable, trades like a stock and has the ETF structure’s tax edge.
- If you’re choosing inside a 401(k): use whichever S&P 500 option your plan offers, and check that you’re in its cheapest share class.
The differences between these three are measured in hundredths of a percent. The difference between any of them and an expensive share class of the same index can be measured in whole percentage points. Picking one of the three and sticking with it matters far more than which one you pick.
Common questions
Can I own more than one of them? You can, but there’s little point. They hold essentially the same companies in the same proportions, so owning two adds no diversification.
Is VOO the same as VFIAX? They’re two share classes of the same Vanguard 500 Index Fund, with the same portfolio. VOO is the ETF class (0.03%); VFIAX is the Admiral mutual fund class (0.04%, with a $3,000 minimum to open an account).
Should I switch if I already own one? Usually not in a taxable account, since selling can trigger capital gains tax that wipes out years of fee savings. Inside a retirement account, switching has no immediate tax cost, but the savings between these three are so small that it’s rarely worth the effort.
This article is general information based on public filings, not personal advice. Fees and fund details change; always check the current prospectus. See our Financial Disclaimer.
Sources
- Fidelity 500 Index Fund, summary prospectus dated April 29, 2026: expense ratio, returns, minimum, turnover; prospectus dated April 29, 2023, for the non-Fidelity broker transaction fee wording; Fidelity fund literature for the inception date.
- Vanguard 500 Index Fund, ETF Shares summary prospectus and Admiral Shares summary prospectus, both dated April 28, 2026: expense ratios, returns, minimums, turnover, trading costs; full prospectus for inception dates and capital gains distributions; Admiral Shares prospectus for the account service fee.
- Schwab S&P 500 Index Fund, prospectus dated February 26, 2026: minimum, turnover, where to buy; summary prospectus for expense ratio and returns; Schwab Asset Management fund page for inception date and distribution history.
- SEC, Form N-CEN data sets, 2025 Q3 to 2026 Q2: average net assets reported by each fund.
- Other S&P 500 ETFs: iShares Core S&P 500 ETF (IVV), State Street SPDR Portfolio S&P 500 ETF (SPYM) and SPDR S&P 500 ETF Trust (SPY) fund pages: expense ratios, checked October 25, 2026.
Sources checked on September 30, 2026.