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• What’s different
• Fees in dollars
• SPLG → SPYM
• Why SPY costs more
• FXAIX
• Which fits your account
• Should you switch?
• FAQ

Expense ratios verified on issuer sites November 6, 2026.

Same 500 Stocks: What’s Actually Different?

The index and the holdings are the same; the fee, the fund structure, and where you can buy are not.

All five funds follow the S&P 500, so they own about the same companies in about the same weights. Before costs, they earn nearly the same return by design.

What changes is the wrapper. SPY is a unit investment trust, an older structure. VOO, IVV and SPYM are open-end ETFs that trade all day. FXAIX is a mutual fund priced once a day at the market close.

This page compares S&P 500 funds with each other. For a different index, see VTI vs VOO, QQQ vs VOO, or SCHD vs VOO. New to all this? Start with how to invest in the S&P 500.

For the basics behind these columns, see investment fees and index funds vs ETFs.

The Fee Gap in Dollars

From cheapest to costliest the gap is $7.95 a year per $10,000, which looks tiny and still adds up over decades.

• FXAIX

  COST PER $10K: $1.50

  WHO IT’S FOR: Fidelity accounts, especially automatic dollar-amount investing.

• SPYM

  COST PER $10K: $2.00

  WHO IT’S FOR: Anyone who wants the lowest-cost ETF at any broker.

• VOO

  COST PER $10K: $3.00

  WHO IT’S FOR: Buy-and-hold investors at any broker, including Vanguard accounts.

• IVV

  COST PER $10K: $3.00

  WHO IT’S FOR: Buy-and-hold investors at any broker. Same fee as VOO.

• SPY

  COST PER $10K: $9.45

  WHO IT’S FOR: Options users and active traders.

Scale it up and the pattern holds. On $100,000, the yearly fee is $15 for FXAIX, $20 for SPYM, $30 for VOO or IVV, and $94.50 for SPY.

A fund’s total cost is its expense ratio plus its trading spread. For funds this large, the spread is close to zero, so the expense ratio is the cost that matters.

The practical point: for new money, the cheaper fund is a free choice. For money already invested, the fee gap is small, and acting on it can carry a tax cost. That’s the subject of the switching section.

What Happened to SPLG? It’s Now SPYM

State Street renamed SPLG to SPYM on October 31, 2025, with the same index, the same holdings, and the same 0.02% fee.

It’s a name and ticker change, not a new fund. Holders kept their shares under the new symbol. The options exchanges published the change in advance (see the MIAX notice). We know of no taxable event for holders from the rename; State Street’s notice and your broker’s confirmation are the places to check.

One history note. Until January 24, 2020, the fund tracked a different index, the SSGA Large Cap Index. Performance charts that reach back past that date aren’t pure S&P 500 history.

COST PER $10K: $2.00 for SPYM.

WHO IT’S FOR: Anyone who wants the lowest-cost S&P 500 ETF and isn’t tied to one broker.

Why SPY Costs More, and Who Should Still Use It

SPY costs more partly because of how it’s built, and its real edge is for traders, not for buy-and-hold savers.

SPY, launched in 1993, is a unit investment trust. That structure limits the trust’s ability to run securities-lending programs, a way other funds earn a little extra income to offset costs.

It also can’t reinvest dividends between distribution dates. Cash sits uninvested until it’s paid out. This is a small cash drag that slightly hurts in rising markets and slightly helps in falling ones. The trust also has a fixed termination date written into its documents. Confirm all three points in the SPY prospectus.

The upside is liquidity. SPY has the most liquid options market in the world. Covered calls, protective puts and hedges are easier, cheaper and more flexible to run with SPY than with the others.

COST PER $10K: $9.45 for SPY.

WHO IT’S FOR: Options traders and active traders who value that liquidity more than the extra $6.45 per $10,000 a year versus VOO.

FXAIX: Cheapest, but Fidelity-Only

FXAIX is the cheapest of the five at $1.50 per $10,000 a year, but it’s a Fidelity mutual fund, not an ETF.

That has practical effects. It prices once a day at the market close, so you can’t trade it during the day. At Fidelity there’s no minimum, and you can invest exact dollar amounts, which makes automatic investing simple.

Outside Fidelity, FXAIX is often unavailable or comes with a transaction fee. Check your broker.

In a taxable account there’s one more thing to look at. Mutual funds can distribute capital gains to shareholders, and ETFs usually distribute fewer. How much that matters for FXAIX depends on its actual distribution record, which Fidelity publishes on the fund’s page. Index funds trade rarely, so the effect can be small. Check the record before you assume it either way.

Moving brokers is also different. FXAIX is Fidelity’s own fund, and another broker may not accept it in kind, so a move could mean selling first. Ask both brokers, and see how to transfer stocks without selling.

COST PER $10K: $1.50 for FXAIX.

WHO IT’S FOR: People who invest at Fidelity, especially in an IRA or with small automatic deposits.

Which Fund Fits Your Account?

The best fit depends more on the account and the broker than on the small differences between the funds.

Should You Switch? The Tax Math

Inside an IRA or 401(k), switching costs no tax; in a taxable account, the tax on your gain can outweigh the fee savings for many years.

Paying tax now mainly gives up deferral. If you’d sell later anyway, the true cost is smaller. If you’d hold for life, the step-up in basis at death can erase the gain, which makes the tax today the full amount. Rules differ by situation, so a tax professional can confirm yours.

Keep the old fund and send new money to the cheaper one, and you capture the lower fee on every new dollar without selling anything. If you do want to switch a taxable holding, the capital gains tax guide explains how your rate is set.

The wash-sale gray area

If you sell at a loss and buy something "substantially identical" within 30 days before or after, the wash-sale rule can disallow the loss. The IRS has not said whether two funds from different issuers that track the same index count as substantially identical. That is a gray area, and there is no definitive answer here. It only comes up when you sell at a loss. Read the wash sale rule guide, try the tax-loss harvesting calculator, and ask a tax professional before relying on a swap.

What Doesn't Matter Much

Three things people argue about matter far less than the fee and the account.

Small yield differences. The funds hold the same stocks, so their yields are close. Gaps mostly come from fee differences, share prices and payment timing.

Fund size. All five are very large and trade without trouble. A bigger asset total doesn't make a fund a better buy-and-hold choice.

Small tracking gaps. Differences between each fund and the index are tiny, in the same range as the fee gaps above. Pick on fee, account and broker, then stop checking.

FAQ

Sources. Fund pages and prospectuses: Vanguard VOO, iShares IVV, State Street SPY, State Street SPYM, Fidelity FXAIX. Tax basics: IRS Publication 550 and Investor.gov.

Last updated: November 6, 2026

This article is general information, not investment or tax advice. Expense ratios were verified on issuer websites on November 6, 2026. Calculator results are estimates using assumed returns, and past performance does not predict future results.