Diversification: Spreading Investments to Manage Risk

Diversification is a risk-management approach: money is spread among different investments rather than being concentrated in a single security or asset class. It can happen in two ways: among asset classes, and within an asset class. The purpose is to reduce concentration risk, not to eliminate investment risk altogether.

Concentration risk arises when too much emphasis is placed on one security or asset class. Diversification can reduce this risk because a poorly performing investment or sector may be offset by other holdings. However, the benefit depends partly on how holdings respond to economic conditions. Assets with different or less-related responses may provide more diversification than assets that tend to move together.

First, investors can diversify among asset classes by spreading investments across different kinds of assets. Second, they can diversify within an asset class—for example, by spreading investments across different areas within that class. Simply adding more holdings is not enough if those holdings are narrowly focused or tend to move together. The relevant question is whether the holdings reduce overreliance on the same source of risk.

1. An investor owns ten stocks, all in the same narrow industry. Is the portfolio necessarily well diversified? No. The number of holdings alone does not show whether the underlying risks are meaningfully different.

2. What is concentration risk? It is the risk created by depending too heavily on one security, sector, asset class, or other common source of exposure.

3. Why can correlation matter? Holdings that respond differently to economic conditions can provide more diversification benefit than holdings that tend to move together.

4. Does diversification guarantee a positive return? No. It can reduce some concentration risks, but broad market declines can still produce losses.

5. What should you examine in two funds before assuming they diversify one another? Their holdings, sector and asset exposures, and the extent to which those exposures overlap.