Last updated: July 24, 2026
Quick Answer
VOO tracks the S&P 500, holding about 500 of the largest US companies. VTI tracks the total US stock market, holding several thousand companies including small and mid-caps. They overlap roughly 85% by weight, carry the same expense ratio, and have delivered very similar returns. For most investors the honest answer is that either one is a good choice, and which you pick matters far less than owning one and continuing to buy it.
Key Takeaways
- VOO is the S&P 500. VTI is the entire investable US market. VTI adds small and mid-cap companies that VOO leaves out.
- Because the largest companies dominate both funds by market-cap weighting, the two overlap around 85% and move almost identically day to day.
- Both charge the same rock-bottom expense ratio, so cost is not a deciding factor between them.
- Owning both is not diversification. It is mostly buying the same large companies twice, plus a small tilt toward small-caps from the VTI portion.
- If you already own one in a taxable account, switching to the other can trigger a capital gains tax bill that dwarfs any difference between the funds. Inside a retirement account, you can switch freely.
What Each Fund Actually Holds
Both funds are Vanguard index funds, both are among the largest and most popular in the world, and both do the same basic job of giving you broad, cheap ownership of US stocks. The difference is how wide they cast the net.
VOO tracks the S&P 500 index. That is roughly the 500 largest US companies by market capitalization, covering approximately 80% of the total value of the US stock market. When people say “the market was up today” and quote a number, they are usually talking about the S&P 500.
VTI tracks a total US stock market index. Instead of the largest 500, it holds essentially every investable US company, which is several thousand names spanning large, mid, and small companies. It is the whole domestic market in one fund.
So the entirety of VOO sits inside VTI. VTI is VOO plus everything smaller.
The reason they behave so similarly comes down to weighting. Both funds are market-cap weighted, meaning bigger companies take up proportionally more of the fund. The largest US companies are so enormous that they dominate both funds. The thousands of smaller companies that VTI adds and VOO lacks make up only a small slice of VTI’s total weight. You are adding a lot of names but not a lot of weight.
That is why the two funds’ returns have historically tracked each other very closely.
Head to Head
| Feature | VOO | VTI |
|---|---|---|
| Index tracked | S&P 500 | Total US stock market |
| Approximate holdings | ~500 | Several thousand |
| Company sizes | Large-cap | Large, mid, and small-cap |
| Weighting | Market-cap | Market-cap |
| Expense ratio | Very low, identical to VTI | Very low, identical to VOO |
| Mutual fund equivalent | VFIAX | VTSAX |
| Overlap with the other | ~85% by weight | ~85% by weight |
Confirm the current expense ratios and holding counts on Vanguard’s site before relying on them, since these figures update over time.
The practical read of this table: on every dimension that usually decides a fund purchase, cost and structure and provider, these two are effectively tied. The only real difference is scope, large-cap only versus the whole market.
So Which One Should You Buy?
Here is a direct answer rather than a fence-sitting one, because the fence-sitting version is what most articles give you and it is not helpful.
Choose VTI if you want to own the entire US market and never think about it again. It is the more complete answer to “give me American stocks,” it captures small and mid-cap companies that have historically added a diversification benefit, and it means you will never wonder whether you are missing part of the market. For a set-and-forget core holding, VTI is the slightly more logical default.
Choose VOO if you specifically want the S&P 500, perhaps because you want to mirror the index everyone quotes, because your 401(k) options are S&P 500 based and you want consistency across accounts, or simply because you prefer the largest, most established companies. VOO is not a worse choice. It is a marginally narrower one.
The truth most comparisons bury: the gap between these two funds is small enough that it will almost certainly be swamped by other factors, whether you keep investing consistently, whether you panic-sell in a downturn, how much you contribute, and your asset allocation across stocks and bonds. Picking the “wrong” one of these two costs you far less than any of those behaviors. Choose one, automate your contributions, and move on. The decision does not deserve the agonizing it usually gets.
Should You Own Both?
This is one of the most searched follow-up questions, and the answer is more useful than a simple yes or no.
Owning both is not meaningful diversification. Because they overlap around 85%, holding both mostly means owning the same large companies twice. You are not spreading risk in any material way. The only thing the VTI portion adds on top of VOO is exposure to small and mid-cap stocks, and you could get that more precisely with a dedicated extended-market or small-cap fund if that is what you actually want.
It is not harmful, just redundant. There is no penalty for owning both. Your portfolio will behave almost exactly as if you owned either one alone. It just adds complexity for no real benefit, and complexity is a small tax on your future attention.
One case where it happens legitimately: you own one in a taxable account with large unrealized gains, you would prefer the other going forward, and selling would trigger a tax bill. In that situation, keeping the old fund and directing new money to the preferred one is a reasonable way to shift over time without a taxable event. That is not really “owning both” as a strategy, it is a sensible transition.
A cleaner alternative to owning both: if your goal in holding both is total-market exposure with an S&P 500 core, just own VTI. It already contains everything VOO holds plus the rest. One fund, same result, less to track.
The Tax Trap Nobody Warns You About
This is the section that separates a useful comparison from a specs sheet, so read it before you act on any decision to switch.
Suppose you own VOO in a taxable brokerage account, you have read that VTI is marginally more diversified, and you decide to switch. You sell your VOO and buy VTI.
You just triggered a taxable event.
Selling an appreciated fund in a taxable account realizes capital gains, and you owe tax on the gain. If you have held VOO for years and it has grown substantially, that tax bill can easily run into thousands of dollars. You would be paying real money to swap between two funds that behave almost identically and have nearly the same expected return. That is one of the worst trades in personal finance: a large, certain cost to chase a tiny, uncertain benefit.
The rules that actually matter here:
Inside a retirement account, switch freely. In a 401(k), traditional IRA, or Roth IRA, buying and selling does not trigger capital gains tax. If you want to move from VOO to VTI or vice versa inside a retirement account, do it in an afternoon at no tax cost.
In a taxable account, think hard before selling. The tax cost of switching usually exceeds any benefit. The better approaches are to keep what you own and simply direct new contributions to your preferred fund, or to decide that the fund you already hold is completely fine, because it almost certainly is.
If you must switch in a taxable account, do it deliberately. If you have a low-income year and room in the 0% long-term capital gains bracket, that can be a window to realize gains at no federal tax and reset into the fund you prefer. That is an advanced move worth understanding before you use it, and it connects directly to how the 0% bracket works. And keep your cost basis records straight, because they determine exactly how large the taxable gain is.
The general principle: choosing between VOO and VTI is a real decision when you are starting fresh. Switching between them after years of gains in a taxable account is usually a mistake dressed up as optimization.
ETF or Mutual Fund Version?
Both of these are exchange-traded funds, but each has an identical-strategy mutual fund sibling. VOO’s mutual fund equivalent is VFIAX. VTI’s is VTSAX. Same index, same manager, essentially the same cost.
The practical differences:
ETFs (VOO, VTI) trade throughout the day like a stock, generally have no minimum investment beyond the price of one share, and can be bought at most brokerages. Many brokers also support buying fractional shares, which removes the share-price barrier entirely.
Mutual funds (VFIAX, VTSAX) trade once per day at the closing price, sometimes carry an initial minimum investment, and support automatic dollar-based investing very cleanly, meaning you can set up “invest exactly $500 on the 1st of every month” without worrying about share prices.
For most people the choice comes down to your brokerage and your habits. If you want painless automatic monthly investing in exact dollar amounts, the mutual fund version is often smoother. If you want flexibility, low or no minimums, and the ability to trade intraday, the ETF is the pick. In a taxable account, ETFs also tend to be marginally more tax-efficient due to how they are structured, though for these particular Vanguard funds the difference has historically been small.
What Actually Determines Your Results
Stepping back, because this is the part that matters more than the VOO versus VTI question you came here to answer.
The evidence from decades of investor behavior is consistent: the fund you choose between two good low-cost index funds is one of the least important decisions you will make. What actually moves your long-term outcome:
Your savings rate. How much you contribute dwarfs the difference between two nearly identical funds. Doubling your monthly contribution changes your future far more than any fund selection between these two.
Staying invested. The investors who do worst are the ones who sell during downturns and buy back after recoveries. A cheaper or “better” fund does not help someone who panic-sells.
Your overall allocation. How you split between stocks and bonds, US and international, drives your risk and return far more than VOO versus VTI, both of which are 100% US stocks and leave out international entirely. Neither fund gives you any international exposure, which is worth knowing if you want a globally diversified portfolio.
Cost, which you have already solved. By looking at two of the cheapest funds in existence, you have already made the single most important product decision correctly. Low cost is most of the battle, and both of these win it.
Pick one. Contribute consistently. Leave it alone. That sequence matters more than the choice between these two funds ever will.
Frequently Asked Questions
What is the difference between VOO and VTI?
VOO tracks the S&P 500, holding about 500 large US companies. VTI tracks the total US stock market, holding several thousand companies across all sizes. VTI contains everything VOO holds plus smaller companies, but because both are market-cap weighted, they overlap around 85% and perform very similarly.
Is it better to own VOO or VTI?
Neither is clearly better. VTI is slightly more diversified because it includes small and mid-cap stocks, making it a marginally more complete “own the US market” choice. VOO gives you the specific S&P 500. The difference in returns has historically been small, so consistency and contributions matter more than which you pick.
Is it bad to own both VOO and VTI?
It is not harmful, but it is redundant. Because they overlap around 85%, owning both mostly means owning the same large companies twice rather than adding meaningful diversification. If you want total-market exposure, VTI alone already includes everything VOO holds.
Do VOO and VTI overlap?
Yes, heavily. They overlap roughly 85% by weight, because the large companies that make up all of VOO also make up the majority of VTI. The thousands of additional small and mid-cap companies in VTI add many names but only a small share of its total weight.
Should I switch from VOO to VTI or VTI to VOO?
Inside a retirement account, you can switch freely with no tax consequences. In a taxable account, selling an appreciated fund triggers capital gains tax, which usually costs more than any benefit of switching between two nearly identical funds. Consider directing new contributions to your preferred fund instead of selling.
Do VOO and VTI include international stocks?
No. Both hold only US companies. If you want international exposure, you need a separate international or total-world fund in addition to either of these.
What is the expense ratio for VOO and VTI?
Both carry the same very low expense ratio, which is among the lowest available anywhere. Cost is not a meaningful differentiator between them. Confirm the current figure on Vanguard’s site, since expense ratios can change.
Are VOO and VTI good for beginners?
Yes. Both are broadly diversified, extremely low cost, and simple to understand, which makes either one a reasonable single core holding for a beginner. The main thing they lack is international exposure.
This article is for informational purposes only and is not investment or tax advice. All investing involves risk, including possible loss of principal. Past performance does not guarantee future results. Fund characteristics such as expense ratios and holdings change over time, so verify current figures with the fund provider. Consider consulting a fee-only financial advisor about your specific situation.
