By Kestutis Balciunas — European long-term investor, 11+ years self-directed. Reviewed against my editorial process on 4 June 2026.
Last reviewed: 4 June 2026. Some broker links are affiliate links — see my affiliate disclosure. Not investment advice.
ETF Overlap Calculator: Are Your Funds Diversifying or Doubling Up?
A surprising number of European portfolios are far less diversified than they look. Hold a FTSE All-World fund and add an S&P 500 fund “for more US growth,” and you have not diversified — you have just bought the same Apple, Microsoft and Nvidia shares twice and paid two management fees to do it. This tool shows the exposure overlap between popular UCITS ETFs as a percentage and as a visual, so you can see instantly whether two funds complement each other or simply duplicate.
Related reading: Best Brokers for Buying MSCI World ETFs in Europe.
Check the overlap between two or three ETFs
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The free 12-page Starter Kit turns them into decisions: your first fund, a safe broker, and the tax basics for your country.
Worth reading next: VWRL factsheet.
Why overlap quietly wrecks a portfolio
Diversification is the one genuinely free lunch in investing — but only if your funds hold different things. When two funds overlap heavily, three things go wrong: you pay two TERs for one exposure; you think you are diversified when you are actually concentrated (usually in US megacap tech); and when that concentrated slice falls, both funds fall together. The classic example is a beginner who owns VWCE, VUAA and a Nasdaq fund and believes they hold three different investments — in reality the US large-caps inside all three move almost as one.
Worth reading next: how many ETFs you should actually own.
Worth reading next: our VUAA vs VUAG 2026 guide.
How this calculator estimates overlap
True share-by-share overlap requires every fund’s full holdings file. Instead of pretending to a precision it cannot have, this tool models each fund by its index exposure across nine market segments — US mega/tech, US large (ex-tech), US growth outside the S&P 500, US mid/small, developed Europe, developed Asia-Pacific, Canada, emerging markets and bonds — and computes the overlap as the sum of the shared weight in each segment. For broad, cap-weighted funds this is a close proxy for actual share-level overlap, because they hold the same large companies in similar proportions. It deliberately does not try to model style funds (value, dividend, sector) where two funds can share a region but hold different individual stocks; for those, check the issuer factsheet directly. The result is an honest estimate, not a holdings audit.
Worth reading next: our SPDR vs iShares S&P 500 ETF 2026 guide.
The overlap traps Europeans fall into most
- All-World + S&P 500 (e.g. VWCE + VUAA) — about 48% overlap. The S&P 500 is already roughly half of a global fund, so adding it just tilts you harder toward the US. Fine if that is your intention; pointless if you wanted diversification.
- Two funds tracking the same index (e.g. VUAA + CSPX, or VWCE + WEBN) — ~100% overlap. There is no diversification benefit at all; pick the cheaper or better-executing one and consolidate.
- World + S&P 500 (IWDA + VUAA) — about 57% overlap, same US-doubling story.
- Adding a Nasdaq-100 fund on top of an All-World or S&P 500 holding — roughly 39–52% overlap, and it sharply increases your concentration in a handful of mega-cap tech names. It is a conviction bet, not a diversifier.
What actually adds diversification
If a fund overlaps your core by only a little, it is doing real work. A broad developed-or-global equity fund paired with emerging markets (≈9% overlap with All-World) or with global bonds (0% equity overlap) genuinely broadens the portfolio. That is why most simple, robust European portfolios are one broad equity fund plus, optionally, an EM sleeve and a bond sleeve — not three overlapping equity funds. Once you have settled the building blocks, compare the specific funds on TER, domicile and tax in the UCITS ETF comparison tool, and sanity-check a full allocation against the balanced ETF portfolio guide. To buy your chosen core, my top pick for opening an account is Freedom24, with Trade Republic, Interactive Brokers and XTB as alternatives.
Worth reading next: our Trade Republic ETF List (2026) guide.
Frequently asked questions
Do VWCE and VUAA overlap?
Yes — by roughly 48%. VWCE (FTSE All-World) already holds the entire S&P 500 as about half its weight, so VUAA (S&P 500) duplicates that half. Holding both does not diversify; it overweights the US. If you want a global fund, VWCE alone already contains the S&P 500.
Is it bad to hold two ETFs that overlap?
It is wasteful rather than dangerous. You pay two fees for one exposure and you concentrate risk while believing you are diversified. Some overlap is unavoidable and fine if it reflects a deliberate tilt (e.g. you genuinely want more US). The problem is unintentional overlap — owning three funds that secretly move as one.
How is the overlap percentage calculated?
Each fund is modelled by its index exposure across nine market segments (US mega/tech, US large, US growth, US small, Europe, Asia-Pacific, Canada, emerging markets, bonds). The overlap is the sum of the shared weight in each segment. For broad cap-weighted funds this closely approximates share-level overlap; it is an estimate, not an exact holdings comparison, and it is not designed for style or sector funds.
Which ETFs pair well together without overlapping?
A broad developed-or-global equity fund (MSCI World or FTSE All-World) plus an emerging-markets fund (≈9% overlap) and/or a global bond fund (0% equity overlap). These combine into a genuinely broader portfolio. Stacking a second developed-market or S&P 500 fund on top of a global one does the opposite.
Does high overlap mean high correlation?
Largely, yes, for broad equity funds — if two funds hold mostly the same companies, their prices move together. That is the practical takeaway: a high overlap number means adding the second fund gives you little extra protection when markets fall. This tool reports exposure overlap, which for cap-weighted funds is a good stand-in for correlation; it does not compute a statistical correlation from price history.
Next: compare the funds you keep in the UCITS ETF comparison tool, check their domicile withholding tax, and decide accumulating vs distributing for your country.