Sharpe Ratio

The Sharpe ratio measures excess return per unit of total risk, so you can compare funds on equal risk footing.

Common confusion

It penalises only volatility, not the direction; a smooth downhill still scores poorly, correctly.

Why it matters

It rewards efficient risk-taking rather than raw returns.

A real-world scenario

A volatile tech fund posts a 40% year and tops the performance charts. Its Sharpe ratio, however, is middling because the fund swung 30% along the way. A boring balanced fund returns half as much with a fraction of the volatility, and its Sharpe is higher — it delivered more return per unit of risk. The investor who chases the headline return will feel the 30% swings; the one who reads the Sharpe gets the smoother ride to similar outcomes.

Worked example

How investors use it

Use Sharpe to compare funds within the same category, and look at it over a full cycle, not a bull market where everything looks good. A Sharpe above 1 is strong; below 0 means the fund trailed cash per unit of risk.

Key takeaway

The Sharpe ratio is the fair scorecard for comparing returns per unit of risk, because raw returns reward the reckless. It divides the excess return over cash by the volatility, so a calmer fund with lower returns can score better than a wild one that made more money. Use it within a category over a full cycle, and remember it penalises upside swings as much as downside. For most investors, a good risk-adjusted ride beats a scary one that ends in the same place.

Definitions reviewed by the Investing Glossary editorial team.