The Diversification Illusion
Why 15 funds can still be one bet in disguise
An investor once showed us a portfolio of 14 mutual funds across large cap, flexi cap, focused, and thematic categories. On paper it looked well spread. When we mapped the underlying holdings, three stocks appeared in eleven of the fourteen funds, and financial services alone accounted for close to 40% of the combined portfolio. Fourteen funds. One concentrated bet.
That overlap didn't show up on any single fund's fact sheet. It only became visible once every fund was opened up and the underlying holdings were combined.
This newsletter unpacks portfolio concentration: what it actually means, how it hides inside portfolios that look diversified on the surface, and how to check for it before it becomes a problem.
SECTION 1: WHAT CONCENTRATION ACTUALLY MEANS
Concentration risk is the risk that a portfolio's outcome is disproportionately driven by a small number of stocks, sectors, or investment themes, rather than by a broad set of independent return drivers. It builds up in a portfolio in three distinct ways.
| Type | How It Builds Up | What It Looks Like |
|---|---|---|
| Stock-level | Multiple funds independently hold the same large-cap names | One stock crosses 8-10% of total portfolio value across all funds combined |
| Sector-level | Funds chase the same theme (BFSI, IT, capex) in different wrappers | A single sector exceeds 30-35% of combined equity exposure |
| Style-level | All funds run similar market-cap or growth/value tilt | Portfolio moves as one block in every market cycle |
These three types rarely appear in isolation. A portfolio that is heavy in one large private bank at the stock level is usually heavy in financial services at the sector level, and a portfolio built entirely from growth-oriented funds carries the same style tilt into every market cycle. Each layer reinforces the others, which is why a check at only one level can miss the real exposure.
Concentration is also easy to overlook because it does not feel like a mistake while it is being built. Each fund is chosen on its own merits, each one looks reasonable on its fact sheet, and the portfolio only reveals its true shape once every holding is added together. The sections that follow show how that plays out and how to check for it.
SECTION 2: FOUR FUNDS, ONE BANK
Consider an investor with Rs. 40 lakhs spread across four “different” funds:
| Fund | Category | Allocation | Top Holding |
|---|---|---|---|
| Fund 1 | Large Cap | Rs. 12 lakhs | Large Private Bank |
| Fund 2 | Flexi Cap | Rs. 10 lakhs | Large Private Bank |
| Fund 3 | Focused 25 | Rs. 10 lakhs | Large Private Bank |
| Fund 4 | BFSI Thematic | Rs. 8 lakhs | Large Private Bank |
The same bank shows up as the top holding across all four funds. Depending on individual weightings, the effective single-stock exposure across this “diversified” portfolio can run well above what any single fund's mandate would permit on its own. The investor did not choose this concentration. It accumulated as a byproduct of selecting funds independently, without ever looking at combined underlying exposure.
SECTION 3: WHY THIS HAPPENS
Concentration typically builds up for reasons that feel individually sensible:
Large cap, flexi cap, and focused funds in India frequently draw from the same pool of index heavyweights, since fund managers are benchmarked against similar indices.
Adding a thematic or sectoral fund on top of diversified funds compounds exposure to that theme rather than adding a new one.
Fund selection is often done fund-by-fund, based on past returns or ratings, without checking what is already held elsewhere in the portfolio.
SECTION 4: SECTOR CONCENTRATION IN PRACTICE
The same pattern repeats at the sector level. Here is what combined sector exposure can look like once every fund's holdings are added together:
SECTION 5: HOW TO CHECK FOR IT
A basic concentration check does not require complex tools. It requires looking at the portfolio the way an underwriter would, not the way a fund fact sheet presents it.
The Concentration Checklist
List the top 10 holdings of every fund in the portfolio, weighted by allocation. Combine them into one list and sum exposure to each stock across all funds. Flag any single stock exceeding roughly 8-10% of total portfolio value. Group holdings by sector and flag any sector exceeding roughly 30-35%. Check overlap between any two funds directly; overlap above 50-60% means one of them is largely redundant.
THE FINIDEAS TEST
THE FINIDEAS TEST
An investor holds 5 mutual funds. Which is the strongest sign of hidden concentration risk?
A) The funds have different fund managers
B) The funds are from different AMCs
C) The same 4-5 stocks appear among the top holdings of most funds
D) The funds have different expense ratios
Answer (read reversed): C rewsnA
PREVIOUS ISSUES IN THIS SERIES
| Issue | Topic |
|---|---|
| 01 | Direct vs. Regular Mutual Funds |
| 02 | The Past Returns Trap |
| 03 | Understanding Drawdowns |
| 04 | Risk-Adjusted Returns and the Sharpe Ratio |
| 05 | Rolling Returns: A Better Lens Than Point-to-Point |
SECTION 6: THE BOTTOM LINE
Concentration is not solved by adding more funds. It is solved by knowing what any given portfolio actually owns, once every fund is opened up and the underlying holdings are added together.
Fourteen funds can still be one bet. Count what you own, not how many wrappers you own it in.
That single exercise, done once and revisited periodically, tells an investor more about true diversification than the number of funds in their portfolio ever will.
