How many holdings does a diversified portfolio need?

There is no single right number, but research gives the answer a clear shape: the first holdings added to a portfolio reduce its risk a lot, and each further one reduces it less. For individual stocks spread across sectors, most of the risk that diversification can remove is gone at around 20 to 30 positions. A single broad index fund, holding hundreds or thousands of companies, goes further than that on its own.

Why the benefit flattens out

With $N$ equally weighted stocks that each have volatility $\sigma$ and an average correlation $\rho$ with each other, the portfolio's variance is:

\sigma_p^2 = \frac{\sigma^2}{N} + \left(1 - \frac{1}{N}\right) \rho \, \sigma^2

The first term — the company-specific risk — shrinks as $N$ grows. The second — the market risk shared by all stocks — does not. As $N$ becomes large, the portfolio's volatility approaches $\sigma \sqrt{\rho}$ , and adding more stocks no longer helps.

A simple illustration

With a typical single-stock volatility of 35% and an average correlation of 0.3 between stocks:

Number of stocks	Portfolio volatility
1	35.0%
5	23.2%
10	21.3%
20	20.3%
50	19.6%
very many	19.2%

Almost all of the benefit arrives with the first ten holdings; the rest is the market risk no number of stocks removes.

Going from one stock to ten removes most of the risk that can be removed; going from 20 to 50 changes little.

Where the count misleads

Weights matter more than numbers. Twenty stocks of which one makes up half the value are not diversified. The effective number of positions accounts for this.
Spread matters too. Twenty banks are one bet on banking; twenty stocks from one country are one bet on that country.
Funds change the count. One world equity ETF contains more diversification than fifty hand-picked stocks. A second broad ETF on top often adds overlap rather than diversification.

Too many holdings

Beyond a certain point, more positions add work without adding diversification: more transactions and fees, more records to keep, and many holdings too small to matter. A portfolio of forty individual stocks usually behaves much like an index fund, at a higher cost and with more effort. For broad diversification, a few broad funds achieve it most simply; individual stocks make sense as deliberate additions on top.

A worked example

Worked through on a sample portfolio. The figures below are that portfolio’s, not yours.

Do I own too many positions?

Here are the facts from your portfolio that relate to position count and concentration.

Metric	Value
Number of holdings	11
Value of the portfolio	90.989,80 €
Value in cash	5.510,23 €
Top holding weight (%)	18,41%
Top 5 weight (%)	65,64%
Allocation buckets (count)	5

What this means: you hold 11 positions across stocks, ETFs, crypto, cash and precious metal. Your largest single position is 18,41% of the portfolio and the top five positions together make up 65,64%. You also carry 5 distinct asset-class buckets.

If you want, I can show a ranked list of your holdings, a breakdown by asset class, or a visual of concentration so you can inspect where the positions sit inside the portfolio.

See these numbers for your own portfolio

Floreo works out every figure on this page from your own holdings — returns, risk, allocation, currencies — and the assistant explains them the way this page does. Import from your broker, or try it on the sample portfolio first.

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