Mutual Fund Overlap Analysis
Mutual fund overlap analysis is the process of identifying the degree to which two or more mutual fund schemes hold the same underlying securities, expressed as a percentage of overlapping stocks or bonds relative to the combined portfolio, helping investors assess whether multiple funds in their portfolio provide genuine diversification or simply replicate each other at a higher combined cost.
Investors who hold multiple mutual funds often assume they are diversifying their equity exposure. In reality, two large-cap funds from different AMCs may hold 60-75% of the same stocks — HDFC Bank, Reliance Industries, Infosys, ICICI Bank, and TCS appearing in both portfolios because SEBI's scheme categorisation mandates minimum 80% allocation to the top 100 companies. This structural overlap is not a failure of the fund managers; it is an inherent consequence of a narrow investable universe for large-cap mandates. The problem intensifies when an investor combines three or four equity funds across large-cap, flexi-cap, and multi-cap categories without examining the actual holdings.
Portfolio overlap is typically computed using the Jaccard Index or a simple weighted common holding ratio. The Jaccard approach identifies stocks present in both Fund A and Fund B, then divides the count of common holdings by the total unique holdings across both funds. A more precise method accounts for portfolio weights: if a stock constitutes 8% of Fund A and 7% of Fund B, the weighted overlap contribution from that stock is significant even if it is only one of 50 or 60 holdings. Several third-party tools in India — including Value Research Online, Morningstar India, Paisa Bazaar, and Kuvera — provide free portfolio overlap calculators where investors can input two or more schemes and receive a percentage overlap figure.
In the Indian context, large-cap fund overlaps are structurally high. An analysis of the top 10 holdings of any two large-cap schemes will almost always reveal 7-8 common names, simply because the top-100 universe is dominated by index heavyweights. The overlap challenge is less severe for mid-cap and small-cap funds, where the investable universe spans hundreds of stocks and fund managers exercise greater differentiation. Multi-cap funds — which must hold minimum 25% each in large, mid, and small caps — show intermediate overlap levels depending on how the manager constructs the cross-cap allocation.
Practically, an investor holding a large-cap fund, a Nifty 50 index fund, and a flexi-cap fund may have 70-80% of their total equity mutual fund corpus effectively concentrated in the same 20-30 stocks. The diversification benefit they perceive from holding three funds is largely illusory. The rational response is to either consolidate into fewer schemes with different mandates — for instance, a large-cap index fund plus a pure small-cap active fund — or accept the overlap consciously as a feature (essentially a high-conviction concentration in quality large-caps) rather than treating it as diversification.
For debt funds, overlap analysis is less commonly performed but equally valid. Two short-duration debt funds may hold the same PSU bonds, state government securities, and AAA-rated corporate bonds, providing no diversification benefit in the event of a credit event affecting those issuers. Analysing the credit rating distribution, sector concentration (banking vs. PSU vs. NBFC), and top issuer exposure across debt fund holdings is a more relevant overlap metric than the equity equivalent. Tools like AMFI's portfolio disclosure database and AMC factsheets updated monthly provide the raw data needed for this analysis.