Key answer
Measure overlap as the weighted-minimum common holding: match holdings by ISIN, take the smaller weight of each shared stock, and sum. Above roughly 30–40% between two equity funds, holding both mostly adds cost — not diversification.
The problem overlap hides
Buying several funds feels like diversifying. But two large-cap funds in India often draw from the same short list of index heavyweights — the same banks, the same IT majors, the same energy names. If Fund A and Fund B each put 8% into the same stock, you are not spreading that risk by owning both; you are doubling it. Overlap is what makes that visible.
How overlap is measured
The honest way to measure it is the weighted-minimum common holding. For every stock that appears in both funds, you take the smaller of the two portfolio weights, and you add those up:
- Match holdings across the two funds by ISIN, not by company name — names differ, ISINs don't.
- For each shared stock, take
min(weight in Fund A, weight in Fund B). - Sum those minimums. That total is the overlap — the portion of the two portfolios that is genuinely the same position.
A count of "how many stocks appear in both" is misleading, because two funds can share fifty tiny positions and still behave very differently. The weighted minimum captures how much of your actual money is doubled up.
What counts as high overlap?
There is no regulatory line, but as a rule of thumb: overlap under about 20% means the funds are doing genuinely different things; 30–40% and above means they are largely the same bet, and holding both mostly adds expense ratios and effort rather than diversification. Index funds tracking the same index can approach 100% overlap — that is expected, and it's a reason not to hold two of them.
Checking overlap between funds
To check overlap you need each fund's latest disclosed portfolio. Indian AMCs publish month-end portfolio disclosures, and OmniAsset reads those directly, matches holdings by ISIN, and computes the weighted-minimum overlap for any two funds — including funds you don't own. You can search a fund, compare it against another, and see both the overlap figure and the specific shared holdings driving it, each traceable to the disclosure it came from.
A worked example
Two large-cap funds, matched by ISIN. For each shared stock take the smaller weight:
| Stock | Fund A | Fund B | min() |
|---|---|---|---|
| HDFC Bank | 9% | 8% | 8% |
| Reliance | 7% | 6% | 6% |
| Infosys | 5% | 7% | 5% |
| ICICI Bank | 6% | 5% | 5% |
Add the minimums: 8 + 6 + 5 + 5 = 24% overlap — nearly a quarter of the two portfolios is the same position, before counting the rest of their holdings.
How OmniAsset treats this. OmniAsset reads official month-end portfolio disclosures, matches holdings by ISIN (never by name), and reports the weighted-minimum overlap for any two funds — with the exact shared holdings and the disclosure date behind every figure. A fund without a usable dated disclosure is withheld, never guessed.
Sources
- AMFI / AMC month-end portfolio disclosures — the statutory monthly holdings each figure is built from
- ISIN — the identifier used to match holdings across funds — /data-sources/
Common questions
What is a good fund overlap percentage?
There's no single threshold, but overlap above roughly 30–40% between two equity funds means they're largely the same bet — holding both adds cost and concentration without much diversification. Lower overlap means the funds are genuinely different.
How is fund overlap calculated?
Take each fund's latest disclosed holdings, match them by ISIN, and for every stock held by both funds sum the smaller of the two weights. That weighted-minimum common holding is the overlap — it reflects how much of the two portfolios is genuinely shared.
Does fund overlap change over time?
Yes. Overlap is computed from month-end portfolio disclosures, so it shifts as managers rebalance. It's usually stable month to month for index and large-cap funds and moves more for active mid- and small-cap funds.
Check the overlap between any two funds, straight from official disclosures.
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