Fund Overlap Calculator
Holding three funds feels like diversification, and it frequently is not. Funds are marketed and reported one at a time, so nobody ever sees the combined position, and the natural assumption is that adding a fund adds an exposure. Often it just adds weight to something already held. A global fund and a United States fund are not two different investments; the second is a concentrated slice of the first, and buying both moves your portfolio further into the market you were trying to dilute. This page adds your funds together and shows the result. Enter the market allocation from each fund's factsheet, which is free and published monthly or quarterly by every managed fund and exchange traded fund in the country, along with what you hold in each. It returns the portfolio you actually own across all of them, the dollars of exposure that arrive through more than one fund, how similar each pair is, and how much of each individual fund is exposure another one already provides. That last figure is the one that changes decisions, because a fund which is fully duplicated is not doing the job it was bought for. None of this says duplication is wrong. Deliberately overweighting a market is a decision, and a defensible one. Doing it by accident while believing the opposite is the error worth finding.
Combined allocation sums those exposures across every fund, then divides by the total invested. This is the portfolio actually held.
Duplicated exposure = for each market, total exposure minus the largest single fund's contribution to it, summed across markets. Defined this way it never double counts, and it answers how much exposure you could have obtained from one fund instead of several.
Pairwise similarity = the sum across markets of the smaller of the two funds' weights. Two identical funds score 100%, two with no market in common score 0%.
Shared and unique per fund splits each holding by whether any other fund also has exposure in that market. A fund with no unique exposure is providing weight rather than diversification.
Markets are user-entered from published factsheets. No fund composition data is supplied or assumed by this page, and no provider is named, ranked or recommended.
A fund whose weights do not total 100% has unaccounted assets and every figure derived from it is understated. The calculator flags this rather than silently rescaling.
Excluded: holdings-level overlap within a market, currency hedging, fund fees, and the difference between an index's large-company and total-market versions.
Not financial advice. Last verified: August 2026.
The portfolio you actually own
| Market | From A | From B | From C | Total | Share |
|---|---|---|---|---|---|
| United States | $12,400.00 | $10,000.00 | $0.00 | $22,400.00 | 64.00% |
| Other developed markets | $4,800.00 | $0.00 | $0.00 | $4,800.00 | 13.71% |
| Emerging markets | $2,000.00 | $0.00 | $0.00 | $2,000.00 | 5.71% |
| New Zealand | $0.00 | $0.00 | $3,000.00 | $3,000.00 | 8.57% |
| Australia | $800.00 | $0.00 | $2,000.00 | $2,800.00 | 8.00% |
| Bonds and cash | $0.00 | $0.00 | $0.00 | $0.00 | 0.00% |
| Total | $20,000.00 | $10,000.00 | $5,000.00 | $35,000.00 | 100.00% |
Nothing reports this to you. Each fund is shown separately, so the combined position is the one figure nobody sees.
Where the duplication sits
| Market | Total held | Largest single fund | Duplicated | Funds involved |
|---|---|---|---|---|
| United States | $22,400.00 | $12,400.00 | $10,000.00 | A, B |
| Australia | $2,800.00 | $2,000.00 | $800.00 | A, C |
| Other developed markets | $4,800.00 | $4,800.00 | $0.00 | A |
| Emerging markets | $2,000.00 | $2,000.00 | $0.00 | A |
| New Zealand | $3,000.00 | $3,000.00 | $0.00 | C |
| Total | $35,000.00 | $24,200.00 | $10,800.00 | 30.86% |
Duplicated means exposure you could have obtained from a single fund instead of several. It is not automatically a problem, but it should be a decision.
How similar each pair is
| Pair | Similarity | Overlapping exposure | Reading |
|---|---|---|---|
| Fund A and Fund B | 62.00% | $10,000.00 | Substantially the same investment |
| Fund A and Fund C | 4.00% | $800.00 | Largely distinct |
| Fund B and Fund C | 0.00% | $0.00 | No market in common |
Similarity is the share of each pair's allocation that sits in the same markets. Two identical funds score 100%.
What each fund is actually contributing
| Fund | Held | Also covered elsewhere | Unique to it | Unique share |
|---|---|---|---|---|
| Fund A | $20,000.00 | $13,200.00 | $6,800.00 | 34.00% |
| Fund B | $10,000.00 | $10,000.00 | $0.00 | 0.00% |
| Fund C | $5,000.00 | $2,000.00 | $3,000.00 | 60.00% |
A fund with no unique exposure is adding weight rather than diversification. That is a legitimate choice and a poor accident.
Counting Funds Measures Nothing
Diversification comes from what the funds hold. The number of funds is not a proxy for it, and treating it as one is how portfolios end up more concentrated than the single fund they started with.
On the worked example the three funds combine into a portfolio that is 64.00% United States shares. The largest of the three funds is 62% United States on its own. Adding two more funds made the portfolio more concentrated, not less.
Worked Example: Three Funds, $35,000
Fund A holds $20,000.00 in a global allocation of 62% United States, 24% other developed markets, 10% emerging markets and 4% Australia.
Fund B holds $10,000.00, entirely in United States shares.
Fund C holds $5,000.00, split 60% New Zealand and 40% Australia.
Combined, $10,800.00 of the $35,000.00 arrives through more than one fund, which is 30.86% of the portfolio. Almost all of it is the $10,000.00 of United States exposure that Fund A was already providing.
The Fund That Is Doing Nothing
Fund B is 100.00% duplicated. Every market it invests in is already covered by Fund A, so it contributes $0.00 of exposure that was not already there.
That does not make it a bad fund. It makes it a weighting decision dressed as a diversification decision. If the intention was to hold more United States shares than a global weighting gives, Fund B does exactly that and does it cheaply.
If the intention was to spread the money more widely, it achieved the opposite, and the money would have done that job in emerging markets, bonds or anything the portfolio does not already own.
Similarity Is Not All Or Nothing
Funds A and B are 62.00% identical. Funds A and C are 4.00% identical. Funds B and C have nothing in common at all.
That spread is the useful part. A pair above roughly 60% is substantially the same investment held twice. A pair in the middle is a deliberate tilt. A pair near zero is genuine diversification.
Run the numbers before assuming which category a pair falls into, because fund names are marketing and allocations are facts.
The Granularity This Page Does Not Reach
This compares market exposure, which is what factsheets publish. It does not compare individual shares.
Two funds both holding United States shares will show as overlapping here even if one holds the largest 500 companies and the other holds the whole market including small companies. In portfolio terms they are close substitutes, which is the right answer for the question being asked, but they are not identical.
Where that distinction matters, the fund's own holdings disclosure is the source, and the practical test is usually simpler: if two funds track closely related indices, they will behave closely alike whatever the share counts say.
What To Do With The Answer
Three responses are reasonable and one is not.
Keep it and own the decision. If the concentration is what you want, nothing needs to change except that it is now deliberate.
Redirect new contributions. The cheapest correction, since it needs no selling and no tax event. Our portfolio rebalance calculator works out the amounts.
Consolidate. A single global fund removes the overlap question and the rebalancing between funds, at the cost of controlling the weights yourself. Our one fund vs multi-fund calculator prices both sides.
The response that is not reasonable is adding a fourth fund to fix the problem, which is how most portfolios get here.
Check The Home Market Line Too
On the worked example New Zealand is 8.57% of the portfolio, which sounds modest and is enormous relative to New Zealand's share of global markets.
Home bias is the most consequential allocation error made in this country and it rarely shows up as duplication, because usually only one fund provides it. Our home bias calculator compares your figure against the global benchmark directly.
Related NZ Portfolio Calculators
- One Fund vs Multi-Fund Calculator: the cost of assembling it yourself.
- Home Bias Calculator: your NZ weight against the global benchmark.
- Sector Exposure Calculator: the same exercise by sector rather than market.
- Portfolio Rebalance Calculator: the trades to get back to target.
- Fund Fee Drag Calculator: what the fees cost over a long horizon.
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