VTI vs VOO: Which Vanguard Index Fund Should You Buy?

If you’ve settled on low-cost index investing, you’ll almost certainly run into the internet’s favorite showdown: VTI vs VOO. Both are Vanguard funds. Both charge rock-bottom fees. Both hold the same giant companies at the top. So does the choice even matter — and if it does, which one should you actually buy?

The short answer: for most long-term investors we lean VTI, but not for the reason you’ve probably been told. This guide compares the two using Vanguard’s own current fund data, shows you where they truly differ, and walks through who each one suits.

1. VTI vs VOO at a Glance

Both funds come from Vanguard, charge the same 0.03% expense ratio, and pay dividends quarterly. The core difference is scope: VOO owns the S&P 500 (America’s ~500 largest companies), while VTI owns the entire U.S. stock market — large, mid, small, and micro-cap.

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2. What Each Fund Actually Holds

VOO tracks the S&P 500 Index — 504 of the largest U.S. companies, chosen by a committee and weighted by market value. It is a pure large-cap fund.

VTI tracks the CRSP US Total Market Index, which Vanguard describes as representing “approximately 100% of investable companies in the U.S. equity market.” That’s 3,507 stocks spanning large-, mid-, small-, and micro-cap names across growth and value styles.

Here’s the part that surprises people: the top holdings are identical. Both funds’ ten largest positions — as of March 31, 2026 — are NVIDIA, Apple, Alphabet, Microsoft, Amazon, Broadcom, Meta, Tesla, and Berkshire Hathaway, in the same order (VTI rounds out its top ten with Eli Lilly where VOO has JPMorgan Chase). Because both are cap-weighted, those mega-caps dominate both funds.

The real difference sits below the surface: VTI adds roughly 3,000 additional mid-, small-, and micro-cap companies that VOO simply doesn’t hold. That’s the whole story of VTI vs VOO in one sentence — VTI is VOO plus a long tail of smaller companies.

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3. The Overlap: How Similar Are They Really?

Very. Because the S&P 500’s giant companies make up the bulk of the total market’s value, the S&P 500 accounts for roughly 82% of VTI’s weight. Estimates of the two funds’ overlap by weight generally land in the 80–85% range depending on the measurement date and method.

The practical takeaway: on any given day, VTI and VOO move almost identically. You are not making a big directional bet by picking one over the other — you’re deciding whether you also want that extra ~18% slice of smaller U.S. companies.

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4. Fees, Yield, and Tax Efficiency

This is where the “winner” is a tie.

• Expense ratio: both 0.03%. On a $10,000 balance that’s about $3 a year for either fund.
• Structure: both are ETFs using Vanguard’s in-kind creation/redemption process, which makes them highly tax-efficient — capital-gains distributions are rare for both.
• Dividends: both pay quarterly and hold the same dividend-paying giants, so yields are very close.
• Minimum: either can be bought for the price of a single share, and most major brokers now allow fractional shares from as little as $1.

On cost and tax treatment, there is no meaningful difference between VTI and VOO. Don’t let fees decide this one — they’re the same.

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5. Performance: Does “Total Market” Actually Win?

Here’s the myth worth killing: many people assume that because VTI is “more diversified,” it must earn more. Recent history says otherwise. Using Vanguard’s reported NAV total returns for the period ended March 31, 2026:

Read that carefully: over the last 5 and 10 years, VOO (the S&P 500) actually beat VTI. Only in the most recent year did VTI edge ahead. Why? The past decade was dominated by mega-cap tech — exactly the stocks that make up a bigger slice of VOO. VTI’s small- and mid-cap tail was, on balance, a drag, not a boost.

The honest point: “Total market” does not mean “higher returns.” Small caps have historically sometimes outperformed large caps over long stretches, and sometimes lagged — the last decade was a lagging stretch. Choosing VTI is a bet on breadth and future-proofing, not a promise of beating the S&P 500.

This is educational information, not personalized investment advice. Past performance does not guarantee future results, and all investing involves risk of loss. Verify current figures with the fund issuer and consider speaking with a licensed advisor before investing.

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6. VTI vs VOO: Which Should You Choose?

Since costs, taxes, and long-run returns are effectively a wash, the decision comes down to philosophy and portfolio fit. For most long-term, buy-and-hold investors, we give the slight edge to VTI — here’s the honest case for each.

Our slight lean, and why: VTI captures the whole market with one decision and one holding. You never have to wonder whether you should add a mid- or small-cap fund, and you automatically own future large-caps during their high-growth years before they’re promoted into the S&P 500. That completeness — not a return advantage — is why we edge toward VTI for a simple core holding. If you like the idea but only have an S&P 500 fund in your plan, VOO is a completely reasonable stand-in; the two behave nearly the same.

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7. The Mutual-Fund Versions: VTSAX vs VFIAX

Prefer mutual funds to ETFs? Vanguard offers near-identical mutual-fund twins:

• VTSAX — Vanguard Total Stock Market Index Fund Admiral Shares (the mutual-fund version of VTI).
• VFIAX — Vanguard 500 Index Fund Admiral Shares (the mutual-fund version of VOO).

Both Admiral share classes carry a 0.04% expense ratio (a hair above the ETFs’ 0.03%) and a $3,000 minimum initial investment. The trade-offs: mutual funds trade once a day at the closing net asset value and let you invest exact dollar amounts and set up automatic contributions easily; the ETFs (VTI/VOO) trade all day, have no investment minimum beyond one share, and edge out slightly on cost and tax efficiency. For most people the difference is negligible — pick the format that fits how you like to invest. For a deeper breakdown, see our guide on ETF vs index fund.

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8. How to Buy Either Fund

1. Open a brokerage or retirement account — a taxable brokerage account, IRA, or your workplace 401(k) if it offers these funds. New to this? See brokerage vs. IRA: where to start.
2. Fund the account and decide how much to invest. Consider dollar-cost averaging — investing a fixed amount on a schedule — to smooth out market timing.
3. Search the ticker — VTI or VOO (or VTSAX / VFIAX for the mutual funds) — and place your order.
4. Automate and hold. These are long-term core holdings. Set recurring contributions, reinvest dividends, and avoid tinkering. See how a steady contribution can compound with our compound interest calculator.

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9. Frequently Asked Questions

Is it worth owning both VTI and VOO?

Generally no. With ~80–85% overlap, holding both mostly duplicates the same large-caps and adds complexity without meaningful diversification. Pick one as your U.S. core. If you want to diversify further, pair either with an international fund instead.

Is VTI riskier than VOO?

Marginally. VTI’s three-year standard deviation (12.60%) is slightly higher than VOO’s (12.06%) because small- and mid-caps can be more volatile. In practice the gap is small, and both are diversified across thousands or hundreds of companies.

Which is better for a Roth IRA?

Both work well in any account. Because both are already very tax-efficient, there’s no special advantage to holding one over the other in a Roth IRA — choose based on whether you want total-market (VTI) or large-cap (VOO) exposure.

Does VTI include the S&P 500?

Effectively yes. VTI holds the S&P 500 companies plus roughly 3,000 additional smaller U.S. stocks. The S&P 500 makes up about 82% of VTI’s weight.

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10. Bottom Line

VTI vs VOO is one of the lowest-stakes decisions in investing — and that’s good news. Same 0.03% fee, same tax efficiency, nearly identical top holdings, and long-run returns that have traded places over different periods. You cannot really go wrong.

If you want a single, complete, own-the-whole-market core holding, we lean VTI — for its breadth and simplicity, not because it promises higher returns (over the last decade, VOO actually returned more). If you specifically want large-cap exposure or are building around an S&P 500 option, VOO is an excellent choice. Pick one, automate your contributions, and let time and compounding do the heavy lifting.

Still weighing whether index funds are right for you at all? Start with Should you invest in the S&P 500?