Total Stock Market vs S&P 500: What the 3,025 Extra Stocks Actually Do

One fund holds 506 stocks. The other holds 3,531. Over the past ten years, the difference in their annual returns was 0.43 percentage points — and it went the direction most people don’t expect.

The total stock market vs S&P 500 question comes up the moment anyone opens a brokerage account and sees two nearly identical index funds sitting next to each other at the same 0.03% expense ratio. This post shows you exactly what those 3,025 extra stocks contribute, what the ten-year track record says, and the one factor that should actually decide it for you — which, spoiler, isn’t performance.

Total Stock Market vs S&P 500: The One-Number Answer

If you want the short version: the correlation between these two funds is so high that the choice barely qualifies as a decision.

Vanguard’s own fund documentation reports an R-squared of 0.99 between the S&P 500 ETF and the Dow Jones U.S. Total Stock Market Float Adjusted Index over trailing 36-month returns, with a beta of 0.96. In plain terms, 99% of the movement in one is explained by movement in the other. You are choosing between two funds that go up and down together on essentially every trading day.

Why so similar? Because the S&P 500 already captures roughly 80% of available U.S. market capitalization, according to S&P Dow Jones Indices. The thousands of companies a total market fund adds are, collectively, a small slice of the pie by weight. They multiply your holdings sevenfold and change your portfolio by a rounding error.

That said, “barely qualifies as a decision” isn’t the same as “identical,” and the differences that do exist are worth understanding before you commit thirty years of contributions to one of them.

The Comparison Table: The Two Funds Side by Side

Here are Vanguard’s Total Stock Market ETF (VTI) and S&P 500 ETF (VOO), the largest and most widely held representatives of each approach, using data from their official fact sheets as of June 30, 2026.

Source: Vanguard fund fact sheets for VTI and VOO, data as of June 30, 2026. Returns are net asset value total returns, net of expenses. Past performance does not guarantee future results.

Three things jump out of that table.

The expense ratios are identical, so cost is not a tiebreaker here. That’s unusual — in most fund comparisons, fees do the deciding, and the impact of an expense ratio compounded over thirty years dwarfs almost every other variable. Here, both are 0.03%, so you can set that consideration aside entirely.

The S&P 500 fund won over five and ten years, by 1.12 and 0.43 percentage points annualized. That is the opposite of what “more diversification is better” would predict, and it reflects a long stretch in which large-cap U.S. stocks outran smaller ones.

The total market fund won over the most recent one-year period, 23.16% to 22.28%. Small differences, flipping direction depending on the window you pick. Which is the real lesson of the table.

What the 3,025 Extra Stocks Actually Add

The honest case for a total market fund isn’t that it has beaten the S&P 500. Recently it hasn’t. The case rests on three structural arguments.

You own the entire market, so you never have to guess. The CRSP US Total Market Index that VTI tracks is designed to represent approximately 100% of investable companies in the U.S. equity market. If small and mid caps have a decade like the early 2000s, you capture it automatically. You are not making a call on market cap; you are declining to make one.

Slightly less concentration at the top. The S&P 500 fund’s ten largest holdings account for 37.9% of assets. The total market fund’s account for 33.4%. Its largest position, NVIDIA, is 6.4% of the fund versus 7.5% in the S&P 500 version. That’s a real if modest difference in single-stock exposure, and it matters more now than it did a decade ago — information technology alone is 38.0% of the S&P 500’s sector weight.

No committee decides what you own. S&P 500 membership is set by a committee at S&P Dow Jones Indices, which means additions and deletions are judgment calls. Total market indexes are rules-based and capture new public companies without waiting for an invitation. Tesla, famously, was profitable and enormous for a long stretch before it was added to the S&P 500 in 2020 — total market investors had owned it the whole time.

None of these are performance promises. They’re arguments about what kind of bet you’d rather not be making. If you’re building a three-fund portfolio, the total market fund is the more natural U.S. building block precisely because it requires zero further decisions about domestic allocation.

Where the S&P 500 Has the Edge

Two practical points favor the narrower index, neither of which is “it returns more.”

Availability inside employer plans. Many 401(k) menus offer an S&P 500 index fund and no total market option at all. If that’s your situation, the decision is made for you, and you have lost essentially nothing — 0.99 R-squared means you own the same market exposure with a slightly different tilt. This is worth remembering before you roll money around chasing a fund type; the rollover decision when you change jobs should turn on fees and account structure, not on this.

Marginally simpler tax-loss harvesting pairs. In a taxable account, holding an S&P 500 fund and a total market fund from different providers gives you two similar-but-not-substantially-identical positions to swap between. Which one you start with matters less than knowing the pairing exists. Related considerations around ETF versus mutual fund tax treatment will move more dollars in a taxable account than the index choice will.

How to Choose Between Total Stock Market vs S&P 500

Here is the decision, compressed.

That third row deserves emphasis, because it is where people actually lose money on this question. Selling an appreciated position in a taxable account to switch index flavors triggers capital gains tax today in exchange for a difference that may not even persist. The historical record shows the gap flipping direction depending on the measurement window — total market ahead over one year, S&P 500 ahead over five and ten. That is not a pattern you should pay taxes to chase.

Once you’ve picked one, the rest of the work is maintenance, not selection: keep contributing, and decide how often you’ll rebalance between stocks and bonds. Those two habits will outweigh this choice by an order of magnitude.

A Note From Chris

I hold the total market version, and I want to be clear that I can’t defend it on returns. Over the ten years through mid-2026, the S&P 500 fund would have done slightly better. I picked total market because I liked that it required me to never revisit the question, and because it removed a committee from the process. As a software engineer, I have a bias toward systems that don’t need a human in the loop, and a rules-based index that owns everything scratches that itch.

What I find more interesting than the answer is how much energy people pour into this particular comparison. It’s a difference of a few basis points a year between two funds that move in near lockstep, debated at far greater length than asset allocation or savings rate — both of which are orders of magnitude more consequential. That’s a behavioral pattern worth noticing in yourself: we gravitate toward the decisions that are easy to research rather than the ones that are hard to execute.

Frequently Asked Questions

Is a total stock market fund more diversified than an S&P 500 fund?
Yes, by holding count — 3,531 stocks versus 506 as of June 2026. But because both are weighted by market capitalization and the S&P 500 already covers roughly 80% of U.S. market cap, the practical difference is small. Their trailing three-year returns show an R-squared of 0.99.

Which has performed better historically?
It depends entirely on the window. Through June 30, 2026, the S&P 500 ETF returned 15.47% annualized over ten years and 13.36% over five, versus 15.04% and 12.24% for the total market ETF. Over the trailing one-year period, the total market fund was ahead, 23.16% to 22.28%.

Should I own both?
There’s no benefit. Since the S&P 500’s holdings are a subset of the total market index, owning both simply gives you a total market fund with an extra large-cap tilt you didn’t explicitly choose. Pick one for your U.S. equity allocation.

Do the fees differ?
Not at Vanguard — both VTI and VOO carry a 0.03% expense ratio as of their mid-2026 fact sheets. Other providers price similar funds differently, so compare the specific funds available in your account rather than assuming parity.

Should I switch if I already own the “wrong” one?
Inside a tax-advantaged account like an IRA or 401(k), switching costs nothing but a few minutes. In a taxable account, selling an appreciated position triggers capital gains tax, which will almost certainly exceed any expected benefit from the total stock market vs S&P 500 difference. Redirect future contributions instead if you want to shift.

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Written by Chris Steve

Chris Steve is a software engineer with a deep interest in personal finance, behavioral economics, and AI. He started Money & Planet to share clear, research-backed money guides — the kind that explain the math instead of pushing products. His writing focuses on long-term wealth building, the psychology behind spending and investing decisions, and the practical tools regular people can use to make smarter financial choices.