UseFidelity.com is an independent site and is not affiliated with Fidelity Investments or Vanguard. This is general information, not investment advice. Investing involves risk, including loss of principal, and past performance does not guarantee future results. Fund fees and data change, so confirm current figures on each fund company’s website. Data as of September 30, 2026 unless noted. Last reviewed November 2026.
Short answer: FXAIX (Fidelity 500 Index Fund) and VOO (Vanguard S&P 500 ETF) both track the S&P 500 and have delivered virtually identical returns. FXAIX is a mutual fund with a 0.015% fee; VOO is an ETF with a 0.03% fee. The cost gap is about $1.50 a year per $10,000. The right choice mostly depends on where you invest and whether you prefer a fund or an ETF.
FXAIX vs VOO at a glance
| FXAIX | VOO | |
|---|---|---|
| Provider | Fidelity | Vanguard |
| Type | Mutual fund | ETF |
| Index | S&P 500 | S&P 500 |
| Expense ratio | 0.015% | 0.03% |
| Cost per $10,000 per year | about $1.50 | about $3.00 |
| Inception | 02/17/1988 | 09/07/2010 |
| Holdings (09/30/2026) | 508 | 505 |
| Distributions | Typically quarterly | Quarterly |
| How it trades | Once a day at end-of-day price | All day like a stock |
Performance (annualized, through 09/30/2026)
| 1 year | 3 years | 5 years | 10 years | |
|---|---|---|---|---|
| FXAIX | +15.72% | +22.87% | +13.78% | +15.32% |
| VOO | +15.70% | +22.85% | +13.75% | +15.29% |
FXAIX is ahead by 0.02 to 0.03 percentage points in every period, about the size of the fee difference. Both returns are net of fees at NAV, and your actual return depends on when you bought, dividends reinvested and taxes.
How they differ in practice
- Trading: VOO trades all day and can be bought in fractional shares at many brokers. FXAIX is bought in dollar amounts and priced once a day.
- Taxes in a taxable account: ETFs are often slightly more tax-efficient because of how shares are created and redeemed. FXAIX’s turnover is only 3%, so its capital-gain distributions have been small. In an IRA or 401(k), the difference does not matter.
- Automatic investing: mutual funds like FXAIX make recurring dollar-based purchases simple.
- Where you can buy: FXAIX is a Fidelity fund. If you invest at another broker, VOO is usually the easier choice and may have no commission.
Which should you choose?
- You invest at Fidelity: FXAIX is the lower-cost, simple option, especially for automatic investing.
- You invest at Vanguard or another broker: VOO is the natural choice.
- You want intraday trading or the most tax efficiency in a taxable account: consider the ETF.
- Either is fine in a Roth IRA. The returns are essentially the same, so do not delay investing over this decision.
Frequently asked questions
Is FXAIX the same as VOO?
They track the same index and hold almost the same stocks, but they are different products with different fees and structures.
Is FXAIX better than VOO?
On cost and returns, FXAIX has a tiny edge (0.015% vs 0.03%). VOO has more flexibility as an ETF.
Can I buy VOO at Fidelity?
Yes. VOO is an ETF and can be bought in a Fidelity brokerage account. Check the commission schedule for your account.
Which is better for a Roth IRA?
Either works. Choose the one that matches your broker and how you invest.
Related guides
Sources: Fidelity 500 Index Fund fact sheet (9/30/2026); Vanguard S&P 500 ETF fund facts (9/30/2026).