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Finance & Investment · Risk & Portfolio

Portfolio Concentration Calculator

Measure concentration risk in a stock or fund portfolio: the share of your largest 1, 3, 5 and 10 holdings, the Herfindahl–Hirschman Index (HHI), the effective number of holdings, and which positions exceed a limit you set.

Your inputs

Quick start — try a typical case

8 rows · you can paste rows from Excel or Google Sheets

Group is optional here; it's used to show sector concentration too.

%

Your result Live

Concentration — Highly concentrated

HHI 1948

Behaves like 5.1 equal-sized holdings (you have 8)

Largest Holding
Stock A: 32.9%
Top 3
67.7%
Top 5
86.7%
Top 10
100.0%
Holdings Above 15%
Stock A, Stock B, Stock C — ₹3,59,000 above the limit in total
  • Stock A32.9%
  • Stock B19.6%
  • Stock C15.2%
  • Stock D11.4%
  • Stock E7.6%
  • Everything else13.3%

How this is calculated

HHI = Σ wᵢ² (×10,000) · Effective number = 1 ÷ Σ wᵢ²

wᵢ
Weight of holding i
Bands
Below 1,000 well diversified · 1,000–1,800 moderate · above 1,800 highly concentrated

Owning 30 stocks doesn't make a portfolio diversified if three of them are half its value. The Herfindahl–Hirschman Index sums squared weights: it rises sharply when a few positions dominate. Its inverse — the effective number of holdings — is an intuitive measure of how diversified the portfolio really is.

Assumptions & sources

  • HHI bands follow the conventional 1,000 / 1,800 thresholds used in competition analysis, adapted to portfolios as a rule of thumb.
  • A diversified fund counts as one holding unless you split it into its components.
  1. 1Horizontal Merger Guidelines — Herfindahl–Hirschman Index — U.S. Department of Justice & FTC
  2. 2Investments (Bodie, Kane & Marcus), chapters on returns, compounding and the time value of money — McGraw-Hill

Calculator ID FIN-PORT-CONC-001 · version 1.0.0

Common questions

What HHI is too high?

Above about 1,800 (on a 10,000 scale) the portfolio depends heavily on a few positions. A portfolio of 20 equal holdings has an HHI of 500.

Should I sell big winners to reduce concentration?

Concentration often comes from winners growing. Consider trimming gradually, adding new money elsewhere, and the tax cost of selling.