VTI vs VOO vs FSKAX.
Which index fund?
The most searched personal finance comparison that nobody explains clearly. Side-by-side breakdown, the total market vs S&P 500 debate, and the honest answer.
VTI, VOO, and FSKAX are effectively interchangeable. VTI = total U.S. market (~4,000 stocks), VOO = S&P 500 (~500 stocks), FSKAX = Fidelity total market. All charge 0.015–0.035%. The 10-year return difference between them is typically <0.5%/yr. Pick whichever your brokerage offers and stop deliberating.
- VTI (Vanguard): 0.03% ER, ~4,000 stocks, includes small- and mid-caps that VOO doesn't.
- VOO (Vanguard): 0.03% ER, ~500 stocks. The S&P 500 represents ~80% of U.S. market cap.
- FSKAX (Fidelity): 0.015% ER, ~4,000 stocks. Functionally identical to VTI but cheaper by 0.015%.
- Performance difference over 10 years: typically <0.3–0.5% cumulative. Small-cap tilt in VTI/FSKAX is marginal.
- The real decision is total market vs. S&P 500. For most people, the answer doesn't matter enough to agonize over.
The comparison
| FUND | TYPE | ER | HOLDS | WHERE |
|---|---|---|---|---|
| VTI | Total US ETF | 0.03% | ~4,000 | Anywhere |
| FSKAX | Total US Mutual | 0.015% | ~3,500 | Fidelity |
| VOO | S&P 500 ETF | 0.03% | 500 | Anywhere |
| FXAIX | S&P 500 Mutual | 0.015% | 500 | Fidelity |
| SPY | S&P 500 ETF | 0.0945% | 500 | Anywhere |
| VT | Total World ETF | 0.07% | ~9,800 | Anywhere |
Total market vs S&P 500: historically, the performance difference has been negligible, within 0.1%/year over most rolling periods. Either is fine.
SPY vs VOO: SPY charges 0.0945%, over 3x what VOO charges for the same index. No reason to buy SPY in a long-term portfolio.
The honest answer: FSKAX in a Fidelity account. VTI in a Vanguard or any brokerage account. The difference between all of these is negligible. Just pick one and automate it. Do not let analysis paralysis delay investing by even one month.
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Last updated 2026-04-15. Expense ratios per fund prospectuses.
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