VOO vs VFIAX: Which Vanguard S&P 500 Share Class Should You Buy?

Fund data from Vanguard fact sheets F0968 (VOO) and F0540 (VFIAX), as of June 30, 2026, and the April 28, 2026 summary prospectuses on SEC EDGAR, fetched October 6, 2026. Yields, tax-cost ratios, trading volume and bid-ask spreads are omitted because these documents do not report them. For education only, not investment advice.

Sources: Vanguard VOO fact sheet (PDF); Vanguard VFIAX fact sheet (PDF); VOO summary prospectus; VFIAX summary prospectus. Annual cost is our arithmetic from the stated expense ratios.

What is the difference between VOO and VFIAX?

There is one portfolio behind both tickers. Vanguard's April 28, 2026 prospectuses describe VOO as the ETF Shares of Vanguard 500 Index Fund and VFIAX as its Admiral Shares. The differences are the wrapper: VOO costs 0.03% and trades on an exchange, while VFIAX costs 0.04%, needs $3,000 and prices once a day.

As of June 30, 2026, VOO’s ETF share class held $979.0 billion (58% of the fund) and VFIAX’s Admiral class held $680.5 billion (41%), out of $1,675.0 billion fund-wide. The rest sits in Vanguard’s institutional share classes. VOO is the largest single class of the fund.

Which costs less, VOO or VFIAX?

VOO is cheaper by 0.01 percentage point a year. Vanguard's prospectus example puts the cost of $10,000 held 10 years at $39 for VOO and $51 for VFIAX, a $12 gap. VOO buyers may also pay a brokerage commission and the bid-ask spread, which the example leaves out.

The example above is copied from each summary prospectus, which assumes $10,000, a 5% yearly return and unchanged expenses. The VOO prospectus adds that the example “does not include the brokerage commissions that you may pay to buy and sell ETF Shares.” Many brokers no longer charge commissions on ETF trades, but check yours.

How have VOO and VFIAX performed?

Returns are nearly identical. Over 10 years to June 30, 2026, VOO's NAV returned 15.47% a year and VFIAX 15.46%, against 15.51% for the S&P 500, per Vanguard. One-year figures were 22.28% and 22.27%. Past performance does not guarantee future results.

VFIAX trailed the S&P 500 in 10 of the 10 calendar years from 2016 to 2025, by 0.03 to 0.05 point a year, which is about what a 0.04% fee implies. A $10,000 investment in VFIAX at the end of 2015 grew to $39,682 by December 31, 2025, against $39,827 for the index, per the fact sheet.

Is VOO more tax-efficient than VFIAX?

On Vanguard's own after-tax figures, there is no meaningful gap. Both prospectuses show a 10-year return after taxes on distributions of 14.32% for VOO and 14.32% for VFIAX to December 31, 2025. These use the highest federal rates and ignore state taxes.

Each prospectus assumes the shareholder “was in the highest individual federal marginal income tax bracket at the time of each distribution” and states that state and local income taxes are not reflected. The figures do not apply inside an IRA or 401(k). WealthyBud does not estimate your personal after-tax return for either share class.

How do you buy and sell VOO versus VFIAX?

VOO trades like a stock through a broker during market hours, at a price that can sit slightly above or below NAV. VFIAX is bought from and sold back to the fund at the net asset value, which mutual funds generally calculate once each business day after the major U.S. exchanges close, per the SEC.

• VOO’s prospectus says ETF Shares “may only be bought and sold in the secondary market through a brokerage firm” at the market price, which may be a premium or discount to NAV.
• VFIAX orders go to the fund and fill at the next NAV, so every buyer that day gets the same price.
• VFIAX lets you invest an exact dollar amount, such as $250 a month. With VOO, exact-dollar investing depends on whether your broker supports fractional shares.
• Admiral Shares of Vanguard funds can be harder to hold outside Vanguard; VOO is available at nearly any brokerage.

The SEC’s investor.gov glossary explains that mutual funds “generally must calculate their NAV at least once every business day, typically after the major U.S. exchanges close.”

Is there a minimum investment for VOO or VFIAX?

The VFIAX summary prospectus says opening an Admiral Shares account directly with Vanguard generally requires $3,000, and additions can be as small as $1. The VOO prospectus says there is no minimum dollar amount or number of shares unless your brokerage firm sets one. That makes VOO easier for small first purchases.

What do VOO and VFIAX hold?

Both hold the same portfolio. Vanguard listed 506 stocks in the fund as of June 30, 2026, against 503 in the S&P 500 Index, with a median market cap of $455.6 billion. The top 10 holdings, led by NVIDIA and Apple, were 37.9% of assets.

Largest sectors on both fact sheets (GICS classification), as of June 30, 2026:

• Information Technology: 38.0% of the fund
• Financials: 11.8% of the fund
• Communication Services: 9.7% of the fund
• Consumer Discretionary: 9.3% of the fund
• Health Care: 8.9% of the fund

For the whole U.S. market instead of the S&P 500, compare VOO vs VTI and VTI vs VTSAX. For the fund page with price history, see VOO; for a State Street alternative, see SPY.

Should you buy VOO or VFIAX?

Choose VOO if you invest through any brokerage, want the lower 0.03% fee, or are starting below $3,000. Choose VFIAX if you hold assets at Vanguard and want automatic purchases in exact dollar amounts at NAV. Both own the same S&P 500 stocks, so this is a convenience choice, not a portfolio choice.

VOO fits you if:

• You use a brokerage other than Vanguard, or might move accounts later.
• You want the lowest fee available to individual investors in this fund (0.03%).
• You are starting with less than $3,000.

VFIAX fits you if:

• Your account is at Vanguard and you want scheduled purchases in exact dollar amounts.
• You prefer one end-of-day price and no bid-ask spread on each purchase.
• You are fine paying 0.01 point more a year for that convenience.

Either way, an S&P 500 fund leaves out small and mid-size U.S. companies, international stocks and bonds. See ETF vs mutual fund statistics and index fund statistics for the wider picture.

Frequently asked questions

Key takeaways

• VOO and VFIAX are share classes of one fund, Vanguard 500 Index Fund, with one S&P 500 portfolio.
• VOO costs 0.03% a year; VFIAX costs 0.04%, per the April 28, 2026 prospectuses.
• VFIAX generally needs $3,000 to open at Vanguard; VOO has no fund-set minimum.
• 10-year returns to June 30, 2026: VOO NAV 15.47% a year, VFIAX 15.46%.
• Pick by account type and buying habits, not by holdings.