Systematic risk and what diversification cannot fix

Two kinds of risk, only one of them cheap to remove

Non-systematic risk is specific to one company or one industry: a failed product, a lost lawsuit, a strike, a regulator that acts against a single sector. It is sometimes called business risk or unsystematic risk. Because these events are unrelated to each other, holding many of them together means a bad outcome in one position is usually offset by ordinary outcomes elsewhere, and the portfolio as a whole barely notices.

Systematic risk is the risk of the market itself. A recession, a rate shock, a war, a broad loss of confidence — these move almost everything in the same direction at the same time. Adding more shares does not shelter a portfolio from that, because the new shares fall with the old ones. As the SEC puts it, diversification can’t guarantee that your investments won’t suffer if the market drops.

The practical consequence is that diversification has limits. Spreading a portfolio across many companies and sectors dilutes what is company-specific, but what remains still moves with the market, and an investor who feels safe purely because the list is long has misread what the length achieved.

A hedge is the other tool and it works differently. Instead of spreading exposure, a hedge takes a position that gains when a specific risk materializes: a protective put under a holding, or a position that offsets a currency exposure. The options disclosure document, for example, speaks of investors using index options to hedge a diversified portfolio against market risk; such protection is bought rather than assembled.

An allocation drifts, because some investments grow faster than others. Rebalancing brings the portfolio back to its original asset allocation. It can be done by selling from the categories that are now over-weighted, buying into the under-weighted ones, or directing new contributions to the under-weighted ones. A 60/40 target that has drifted to 80/20 after a strong year for stocks is rebalanced toward 60/40, not reset to 80/20.

Exam terms

Non-systematic risk

Risk specific to one company or industry; reduced by diversification.

Systematic risk

Market-wide risk; diversification can’t guarantee against a market drop.

Business risk

The chance that a particular company performs badly.

Diversification

Spreading holdings so that one bad outcome does not dominate.

Correlation

How closely two holdings move together.

Hedge

A position taken specifically to offset an identified risk, at a cost.

Worked example

Two portfolios are compared through two different bad events: one holds four technology shares, the other holds forty shares across ten industries.

1. The first event is company-specific. One holding writes off a failed product and its shares fall by half.
2. In the concentrated portfolio that is a quarter of the money taking a large hit, and the whole portfolio drops sharply. In the diversified portfolio it is one holding in forty, and the effect is barely visible.
3. The second event is market-wide. Rates rise sharply, a recession is forecast, and shares fall across every sector.
4. Now both portfolios fall, and by broadly similar amounts. The forty holdings offered no shelter, because they were all exposed to the same underlying event.
5. The lesson is that the diversified portfolio was genuinely safer against the first event and no safer against the second. Only a hedge or a smaller allocation to equities would have changed the second outcome.

Check yourself

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Related practice

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