Mutual Funds
What is mutual fund overlap?
Answer
Mutual fund overlap occurs when multiple funds in a portfolio own many of the same securities. This can make a portfolio appear more diversified than it actually is, because different funds may ultimately expose the investor to the same companies, sectors or investment factors.
Why overlap happens
Overlap is not a mistake anybody makes deliberately. It is what happens when funds are bought one at a time, years apart, each on its own merits.
Three things drive it. First, category definitions: SEBI's scheme categorisation requires a large-cap fund to hold at least 80% of its assets in the top 100 companies by market capitalisation, so any two large-cap funds are choosing from the same hundred names. Second, index gravity: a fund measured against the Nifty 50 rarely strays far from it, and the five largest Indian companies are a substantial share of that index. Third, accumulation: an investor who buys a well-reviewed fund every couple of years ends up with six funds picked by six similar processes from the same universe.
How overlap is calculated
Overlap between two funds is the sum, across every security both hold, of the smaller of the two weights. If Fund A holds HDFC Bank at 8% and Fund B holds it at 5%, that company contributes 5 percentage points of overlap. Adding that across all common holdings gives a figure between 0% and 100%: two funds holding identical portfolios in identical proportions overlap 100%, two funds with no common holding overlap 0%.
Pairwise overlap answers "are these two funds the same fund". It does not answer the question that actually matters, which is what the whole portfolio is exposed to. For that, every fund is resolved to its underlying securities, each security's weight is multiplied by that fund's share of the portfolio, and the results are summed across funds. That produces one look-through weight per company — and it is the only number that tells an investor how much of their money is in any one business.
A worked example
An investor holds four equity funds in equal amounts: two large-cap funds, one flexi-cap and one ELSS. Each holds between forty and sixty stocks, so the portfolio appears to hold roughly two hundred companies.
Resolved to underlying holdings, the picture changes. If all four funds hold HDFC Bank — at 8%, 7%, 6% and 7% respectively — then the look-through weight is (8 + 7 + 6 + 7) ÷ 4 = 7% of the entire portfolio in one company. Repeat for the handful of large Indian companies that appear in almost every large-cap mandate and it is common to find that the top ten look-through holdings account for forty to fifty per cent of a portfolio that looked like two hundred stocks.
The investor has not done anything wrong. They simply cannot see this from four fund names and four NAVs, which is the whole problem.
When overlap becomes significant
There is no regulatory threshold, and any single number offered as one is a rule of thumb rather than a finding. What can be said is what overlap is doing.
Two funds overlapping below about 30% are doing meaningfully different things. Between 30% and 60% they share a core and differ at the edges — often reasonable, sometimes simply redundant. Above roughly 70%, the second fund is mostly a more expensive way to hold the first, and the diversification the investor believes they bought is not there.
The portfolio-level question is sharper and matters more: what share of the portfolio sits in its top ten look-through holdings, and is any single company above the weight the investor would knowingly accept. A portfolio can have modest pairwise overlap everywhere and still be dangerously concentrated once the weights are added up.
Overlap versus diversification
They are not opposites and treating them as such leads to bad decisions. Diversification is about exposure to independent sources of return. Overlap is about whether the instruments held are delivering independent exposures.
Some overlap is unavoidable and harmless — two Indian equity funds will both hold large Indian companies, because that is the market. The failure mode is not overlap itself; it is an investor paying four expense ratios and holding four sets of paperwork for what is substantially one exposure, while believing they are diversified and sizing their risk accordingly.
How to reduce overlap
- Measure first. Look through the funds to their holdings and compute portfolio-level weights before changing anything. Overlap that is obvious from fund names is usually not the largest overlap in the portfolio.
- Consolidate within a category. Two funds with the same mandate and high overlap rarely both earn their place. Keeping the one with the better cost and process, and redirecting future contributions to it, fixes most of the problem without a single redemption.
- Diversify by mandate, not by count. Adding a fifth large-cap fund adds overlap. Adding an exposure the portfolio genuinely lacks — mid-cap, international, debt of a different duration — adds diversification.
- Use new money first. Redirecting contributions changes weights over time with no capital gains event. Selling to rebalance realises tax and should be the second instrument, not the first.
- Re-measure. Overlap changes as funds trade. A portfolio checked once is a portfolio measured at one moment.
How Vestmind analyses overlap
VestFolio resolves every mutual fund and ETF in a portfolio to its disclosed holdings, multiplies each security's weight by the fund's share of the portfolio, and sums across funds to produce one look-through weight per company. It reports pairwise overlap between funds, the share of the portfolio in its top look-through holdings, and any single-company exposure above the threshold appropriate to that investor — each with the holdings that produced it. The full method is in the portfolio analysis methodology.
Related questions
How much mutual fund overlap is too much?
There is no regulatory threshold. As a working guide, two funds overlapping above roughly 70% are largely the same exposure and the second is unlikely to be earning its cost; between 30% and 60% they share a core and differ at the edges. The more useful question is at portfolio level: what share of the whole portfolio sits in its top ten look-through holdings, and is any single company above the weight you would knowingly accept. A portfolio can show modest overlap between every pair of funds and still be concentrated once the weights are summed.
Does overlap mean I should sell a fund?
Not by itself. High overlap between two funds with the same mandate means the second is probably not earning its cost, but selling realises capital gains, while redirecting future contributions to the fund you prefer changes the weights over time at no tax cost. Measure first, stop adding to the redundant fund, and treat selling as a decision about tax and cost rather than a consequence of the overlap figure.
Do index funds overlap with active funds?
Frequently, and often more than investors expect. A large-cap active fund benchmarked to the Nifty 50 is constrained to hold mostly the same companies as a Nifty 50 index fund, and its overlap with that index fund is commonly well above half. Holding both is not necessarily wrong, but it is not the diversification it looks like.
Can two funds from different fund houses still overlap?
Yes, and the fund house is largely irrelevant. Overlap is driven by mandate: SEBI's categorisation requires a large-cap fund to hold at least 80% of its assets in the top 100 companies, so two large-cap funds from unrelated houses are choosing from the same hundred names. Different AMCs reduce operational concentration, not exposure overlap.
Sources
- SEBI — Categorization and Rationalization of Mutual Fund Schemes — defines the scheme categories and what each may hold
How Vestmind does this
VestFolio is Vestmind's AI portfolio analysis product. It reads an Indian investor's holdings — stocks, mutual funds and ETFs — and reports what the portfolio is actually exposed to: concentration, mutual fund overlap, sector and factor tilts, asset allocation drift and the risks those create.