The same stocks, bought twice

Most investors buy a second or third ETF to spread their risk. We took the 15 most widely-held US ETFs, read their official holdings, and did the look-through math. The short version: a lot of "diversification" is the same mega-caps, wearing different tickers. Here's the data — and how to check your own portfolio in ten seconds.

1. Some "different" funds are the same fund

Overlap here is weight-based: for every stock two funds share, we take the smaller of the two weights and add them up. It answers a plain question — what share of your money ends up in the same stocks either way? Here's how the popular pairs score.

VOO and IVV are both S&P 500 funds, so 99.6% is expected — yet plenty of people hold both, thinking two providers means two bets. The more surprising ones are the growth funds: VUG and SCHG are 79% the same basket, and half of QQQ is already inside a plain S&P 500 fund.

2. The stocks you own no matter what

Cut it the other way — which companies show up across the most funds? Of the 15 popular ETFs we looked at, a handful appear in two-thirds or more of them. Buy almost any mix and you're buying these again.

Note what's not here: no single household name dominates the list the way you'd guess. It's semiconductors and quiet compounders — Texas Instruments, Broadcom, Fastenal, Costco — riding along inside index after index.

3. Even a "three-fund diversified" portfolio

Take the combination people reach for when they want to feel spread out: an S&P 500 fund, the Nasdaq, and a dividend fund — VOO + QQQ + SCHD, equal amounts in each. Three funds, three different ideas. Run the look-through and 123 stocks turn out to be held by more than one of them, and your ten biggest positions still add up to 28.1% of the whole portfolio:

NVIDIA alone is over 5% of the portfolio, arriving through both VOO and QQQ. The dividend fund (SCHD) is doing the real diversifying — it's the only one of the three pulling in names the other two don't.

Why this keeps happening

Almost every popular ETF is cap-weighted: the bigger the company, the more of it the fund holds. Since the same dozen mega-caps are the biggest companies in nearly every slice of the US market, they float to the top of nearly every fund. Stack two cap-weighted funds and you don't get twice the diversification — you get a heavier bet on the same giants. It isn't a flaw in any one fund; it's arithmetic that only shows up when you look through the wrappers to the stocks underneath.

Check your own portfolio

Every number above came from a free tool anyone can run. Enter your funds and dollar amounts and you'll see your true combined exposure — which stocks you really own, and how much:

See the VOO + QQQ + SCHD breakdown live →

Prefer it in the language of the old Morningstar Instant X-Ray? That tool was retired in 2025; the free Morningstar Instant X-Ray alternative rebuilds its stock-intersection view.

Methodology & reuse

Holdings come from official issuer files and SEC filings — no third-party estimates. Overlap is the sum of the smaller weight across every shared holding, matched by security identifier; portfolio look-through weights each fund by its dollar amount and sums each stock's weight through. Full detail is on our methodology page, and every figure is reproducible in the calculator. Numbers are a snapshot as of July 2026 and shift as holdings update.

Journalists and writers: you're welcome to cite these figures with a link to this page. The underlying pair and holdings data is browsable at overlapcheck.com/etfs and /stocks if you want to check a specific fund or company.