What is ETF overlap?
Funds are wrappers; stocks are what you own. Overlap is the share of your money that lands in the same stocks no matter which wrapper you bought.
A useful definition: weight overlap
For every stock held by both funds, take the smaller of the two weights, then add them up. Example: Fund A holds 3% Apple, Fund B holds 5% Apple → Apple contributes 3 percentage points to overlap. Do that across every shared holding and you get a single number: "X% of my money is in the same stocks either way."
You'll also see count overlap ("they share 101 of 102 holdings"). It's intuitive but misleading on its own: sharing many tiny positions matters little, while sharing a few large positions can produce substantial shared holdings weight. Count and weight answer different questions, so use the measure that matches what you are checking.
Why it sneaks up on people
Many US index funds are market-cap weighted, so the same mega-cap stocks can have large weights across broad-market and growth funds. An S&P 500 fund, a total-market fund, and a growth fund can therefore share substantial stock exposure even though the fund labels differ. The labels on a statement do not show how much underlying exposure is repeated.
How should an overlap score be read?
OverlapCheck uses these house ranges to organize its pair pages:
| Weight overlap | Reading |
|---|---|
| 70%+ | High shared holdings weight; inspect the shared positions and each fund's stated objective |
| 30% to under 70% | Moderate shared holdings weight; inspect which positions contribute most |
| Under 30% | Lower shared holdings weight within the available holdings snapshots |
These are OverlapCheck house heuristics, not industry standards or investment guidance. Holdings overlap does not measure correlation, volatility, geographic or factor exposure, fees, or suitability. For example, overlap between an S&P 500 fund and a technology fund may be expected from their mandates; the score only describes their shared stock weights.
Check it in ten seconds
Every comparison on this site is computed from official issuer holdings files — see a few popular ones below, or use the free ETF overlap checker to enter your whole portfolio and see your true combined exposure.
FAQ
What is ETF overlap?
ETF overlap measures how much two funds hold the same underlying stocks. One common calculation is weight-based overlap: for every stock held by both funds, take the smaller of the two portfolio weights, then sum. The result describes shared holdings weight; it does not measure correlation, volatility, geographic or factor exposure, fees, or suitability.
What is the difference between weight overlap and count overlap?
Count overlap is the number of shared holdings (for example, "two funds share 101 of 102 stocks"). Weight overlap also accounts for position sizes, so two funds can share relatively few names but still have substantial shared holdings weight when those names are large positions. Neither measure determines overall diversification or suitability on its own.
What can ETF overlap tell me?
ETF overlap shows where two funds repeat the same stock exposure and how much portfolio weight is shared. It can help you inspect repeated holdings, but a high or low score is not inherently good or bad. The score does not measure correlation, volatility, geographic or factor exposure, fees, or whether either fund suits an investor.