BacktestPortfolios.com
Backtest any portfolio free - stocks, ETFs, crypto & gold, history back to 1871.

ETF Overlap Calculator

Check how much two ETFs or funds overlap before you own both. This free fund overlap tool measures return overlap (how much they move together), sector overlap (how similar their sector mixes are), compares their growth, and - for near-identical index funds - estimates which one is cheaper.

vs
99.2%
return overlap - essentially the same exposure. Over the last 10 years, 99.2% of VTI's monthly movement is explained by VOO (correlation 0.996). VOO returned 0.79%/yr more over their shared window - potentially the lower-fee pick, though their holdings differ slightly too.
VOO (Vanguard S&P 500 ETF) vs VTI (Vanguard Total Stock Market ETF) · 2010-10-31 → 2026-07-31
Return overlap (R²)99.2%
Correlation (10y)0.996
Sector overlap88.9%
VOO CAGR14.77%
VTI CAGR14.10%
Common history16 yrs

Sector mix side by side (sector overlap 88.9%)

Sector mixes inferred from each fund's return behavior (returns-based style analysis); single stocks use their sector directly.

Growth of $10,000 over their common history

Want the full head-to-head - drawdowns, annual returns, Sharpe? Compare VOO vs VTI → Or check how they fit a whole portfolio in the portfolio analyzer.

Popular overlap checks

ETF overlap questions, answered

How much ETF overlap is too much?

There is no single cutoff, but a useful rule: if two funds' returns overlap above roughly 90%, holding both adds complexity without adding diversification - they will rise and fall together, so you may as well hold the cheaper one. Overlap below about 50% means the funds genuinely behave differently and can reduce portfolio risk when combined.

Is ETF overlap bad?

Overlap is not automatically bad - it is hidden concentration that many investors do not realize they have. Holding VOO and VTI feels like two funds but behaves like one. The problem is believing you are diversified when you are not. Check the overlap, and if it is high, decide deliberately: keep the cheaper fund, or swap one for something that actually diversifies.

How do I check the overlap between two ETFs?

Enter the two tickers above. The calculator measures how much of one fund's monthly movement is explained by the other (return overlap), compares their sector mixes (sector overlap), charts their growth side by side, and - for near-identical funds - estimates which one is cheaper from the return gap. It works for ETFs, index funds, and individual stocks.

How is overlap calculated without holdings data?

Return overlap is the squared correlation (R-squared) of the two funds' monthly returns over the last ten years - the share of one fund's movement the other explains. Sector overlap decomposes each fund onto the 11 GICS sectors (returns-based style analysis) and sums the shared portion, the same formula holdings-overlap tools use, applied at sector level. Behavior is what determines diversification, and behavior is measured directly.

What is fund overlap?

Fund overlap is the degree to which two funds own the same underlying exposure. Explicit overlap is shared holdings (VOO and VTI share their largest ~500 positions); behavioral overlap is shared movement, which also catches funds that hold different stocks but track the same risks - like two different S&P 500 funds from different issuers, or a tech fund and a growth fund.