Naive Diversification: Risk vs Number of Holdings

What Naive Diversification Is

Naive diversification refers to the practice of adding more assets to a portfolio with the hope that this will reduce total risk. This approach assumes that by spreading investments across multiple holdings, the impact of any single asset's poor performance can be mitigated.

In an equally-weighted portfolio, each holding is given equal weight in the overall investment mix. As more holdings are added, the portfolio’s total risk tends to decrease, approaching a systematic-risk floor determined by the average pairwise correlation among the assets.

Why It Happens

The reduction in risk through diversification is primarily due to the statistical concept of covariance. When assets are uncorrelated or negatively correlated, their returns tend to move independently of each other. This independence can lead to a reduction in overall portfolio volatility.

However, as more holdings are added, the benefits of diversification diminish because the average pairwise correlation among the assets starts to play a larger role in determining the portfolio’s total risk.

Real-World Examples

A practical example of naive diversification is seen in mutual funds, which typically hold hundreds or thousands of different stocks. By investing in such a fund, an investor can benefit from the reduced volatility compared to holding individual stocks.

Another real-world application is seen in pension funds and other large institutional investors who spread their investments across various asset classes including stocks, bonds, and commodities.

Limitations of Naive Diversification

While diversification can be an effective strategy for reducing risk, it is not a guarantee against losses. Factors such as market conditions, economic cycles, and the overall performance of the asset classes in which the portfolio is invested can still impact returns.

Moreover, adding too many holdings to a portfolio may increase transaction costs and administrative complexity without necessarily providing additional benefits.

Frequently asked questions

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