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VOO vs VFIAX: ETF or Vanguard Mutual Fund in 2026?
Bottom line
Same fund, two wrappers. VOO is cheaper at 0.03% and trades intraday. VFIAX (0.04%) is simpler for dollar-amount auto-investing at Vanguard.
The 10 universal facts
VOO Vanguard S&P 500 ETF
vs
VFIAX Vanguard 500 Index Fund Admiral Shares
0.03%
Expense ratio
0.04%
$3
Annual cost / $10k
$4
$1.51T
AUM
~$455B
Sep 7, 2010
Inception
Nov 13, 2000
518
Holdings
~507
~13.1%
10y CAGR (total return)
~13.1%
~1.2%
Dividend yield
~1.2%
Quarterly
Dividend frequency
Quarterly
Open-end ETF
Structure
Open-end mutual fund
Vanguard
Issuer
Vanguard
Performance & backtest
Investing $10,000 from Sep 2010 How this is calculated Dividends reinvested every month. Monthly adjusted-close prices from Yahoo Finance. Past performance doesn't predict future returns.
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Final portfolio value
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- Growth
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What's specific to VOO vs VFIAX
Same underlying fund
VOO is a share class of VFIAX
Vanguard's structure makes VOO a share class of the same Vanguard 500 Index Fund that holds VFIAX. The two own the same portfolio in the same proportions - performance differences come only from the 1 basis-point fee gap and intraday vs once-daily pricing.
At Vanguard
Convert VFIAX to VOO tax-free
Because they are share classes of the same fund, Vanguard lets you convert VFIAX into VOO without triggering capital gains. No other mutual-fund-to-ETF pair offers this. Outside Vanguard, conversion is a taxable sale-then-buy.
Minimum buy
$3,000 vs ~$650/share
VFIAX requires $3,000 to open the position; subsequent buys are any dollar amount. VOO costs one share price (~$650) per buy unless your broker supports fractional shares. Below $3,000, VOO is the only option.
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Frequently asked questions
Are VOO and VFIAX the same fund?
Functionally yes. VOO and VFIAX are share classes of the same underlying Vanguard 500 Index Fund. They hold the same stocks in the same weights and produce essentially identical returns before fees. The differences are wrapper-level: VOO is an ETF that trades intraday at 0.03%, VFIAX is a mutual fund priced once daily at 0.04%.
Can I convert VFIAX to VOO without paying tax?
Yes, but only at Vanguard. Vanguard offers a tax-free share-class conversion from VFIAX to VOO because they are legally share classes of the same fund. The conversion does not trigger capital gains and your cost basis carries over. At Schwab, Fidelity, or any other broker, converting means selling VFIAX and buying VOO - a taxable event in a taxable account.
What is the minimum investment for VFIAX vs VOO?
VFIAX has a $3,000 minimum initial investment, with no minimum on subsequent buys. VOO has no minimum from Vanguard's side - you just need enough to buy one share (currently around $650), or any dollar amount at brokers that support fractional shares. For balances below $3,000, VOO is the only option.
Is VFIAX or VOO better for a Roth IRA?
At Vanguard, VFIAX is slightly more convenient for recurring contributions in odd dollar amounts and removes the "what time of day should I buy" question entirely. The 0.01% extra fee is negligible inside a Roth. Outside Vanguard, use VOO - it trades commission-free at every broker while VFIAX usually carries a transaction fee or is not available at all.
Why is VOO cheaper than VFIAX if they're the same fund?
Different share classes carry different expense ratios. Vanguard's ETF share class (VOO) runs more efficiently than the Admiral mutual-fund share class (VFIAX) because the ETF creation-redemption mechanism shifts most of the administrative cost to authorized participants rather than the fund itself. The 1 basis-point gap ($1 per $10,000 per year) is the practical result.