Free ETF Overlap & Fee Drag Calculator — Compare Any Two ETFs

ETF overlap is the silent killer of “diversified” retail portfolios. People buy 5 funds thinking they are spreading risk, then find out 70% of their money is in the same 20 stocks. Fee drag compounds the problem: even tiny percentage differences in expense ratios cost thousands over a decade.

What is ETF overlap? 1 min read

ETF overlap measures how many of the same stocks two ETFs hold. If you own SPY and VOO, both track the S&P 500, so the overlap is essentially 100%. If you own SPY and a clean energy ETF, the overlap might be 5% or less. The calculator gives you that percentage as one clear number.

Why this matters: owning multiple ETFs feels like diversification. But two ETFs with 85% overlap give you almost no diversification benefit. You are paying two sets of fees for nearly the same portfolio.

• 0 to 20% overlap — meaningful diversification
• 20 to 50% overlap — partial overlap, some diversification
• 50 to 80% overlap — heavy overlap, limited diversification
• 80 to 100% overlap — almost identical, paying twice for the same exposure

How fee drag compounds 1 min read

Fee drag is the cumulative cost of paying expense ratios year after year. The number sounds small in any single year but the compounding is real.

Example: $50,000 invested for 20 years, 7% average annual return.

0.03% fee ETF (like VOO): final value roughly $193,000. Lifetime fees roughly $850.

0.95% fee ETF (like an active fund): final value roughly $162,000. Lifetime fees roughly $14,500.

Same underlying market exposure. The investor in the lower-fee ETF keeps $31,000 more, all from a 0.92% per year difference. That is the math the calculator surfaces.

Common overlapping ETF pairs 1 min read

How to read the holdings comparison 1 min read

The output table shows each shared holding with its weight in both ETFs. The right column flags whether the stock is in both funds, ETF 1 only, or ETF 2 only.

If the “unique to each ETF” stocks make up less than 20% of either fund, owning both is mostly fee duplication.

Common mistakes when comparing ETFs 2 min read

Assuming different names mean different exposures. SPY and IVV are both S&P 500 trackers. Their names are different. Their holdings are the same.
→ Fix: Always check overlap before adding a “different” ETF to a portfolio.

Ignoring expense ratios because the numbers look small. 0.03% sounds the same as 0.50%. Over 20 years on $100,000, the difference is roughly $35,000.
→ Fix: Use the calculator to see the real lifetime cost of each fee. Then choose the cheapest fund with the exposure you actually want.

Thinking 5 ETFs equals diversification. If all 5 ETFs are US large-cap tech-heavy funds, you have one position in five wrappers.
→ Fix: Compare every ETF in your portfolio against each other. Real diversification requires intentional exposure to different markets, sectors, or sizes.

Picking the most expensive S&P 500 ETF by mistake. There are dozens. They differ in fees from 0.03% to nearly 1%. The holdings are essentially identical.
→ Fix: When two ETFs track the same index, fees are the only meaningful difference. Always go cheap.

Forgetting that overlap changes over time. Active and smart-beta ETFs change holdings. Overlap today may differ from overlap next quarter.
→ Fix: Re-check overlap once or twice a year, especially after major market moves.

When overlap is acceptable 1 min read

Overlap is not automatically bad. Sometimes you want it.

Tax-loss harvesting: investors swap between similar-but-not-identical ETFs (SPY and VOO) to lock in losses while keeping exposure.

Different account types: holding the same index in a tax-advantaged and a taxable account is normal.

Intentional overweight: if you want extra US large-cap exposure, owning two large-cap ETFs is a deliberate choice.

Fee arbitrage: sometimes a slightly different ETF from the same family has a lower fee but the same exposure. Worth checking.

What the calculator does: it makes the overlap visible. What to do about it is your call.

Worked example: SPY vs QQQ overlap 2 min read

References

1. SPY (SPDR S&P 500 ETF Trust) prospectus, State Street Global Advisors. Holdings refreshed monthly.
2. QQQ (Invesco QQQ Trust) prospectus, Invesco. Tracks the Nasdaq 100 Index.
3. VOO (Vanguard S&P 500 ETF) prospectus, Vanguard. Tracks the S&P 500.
4. Morningstar, “Fee compounding research”. Reference for the long-term impact of expense ratios.
5. SEC, “Mutual Fund and ETF Fees and Expenses”. Investor education on fund costs.