Sharpe vs Sortino Ratio Explained
These ratios measure return per unit of risk — the key to comparing investments fairly. Here’s how they differ.
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Comparing two funds by return alone is misleading if one took far more risk. The Sharpe ratio and Sortino ratio measure return per unit of risk, letting you compare investments fairly.
The Sharpe ratio
Sharpe = (return − risk-free rate) ÷ total volatility (standard deviation). It tells you how much excess return you earned for each unit of risk taken.
- Higher Sharpe = better risk-adjusted return.
- Two funds returning 12% aren’t equal — the one with the higher Sharpe achieved it with less volatility.
The Sortino ratio
Sortino is a refinement: it uses only downside volatility (the bad, negative swings) in the denominator, instead of total volatility.
- Why it’s useful — investors don’t mind upside volatility (big gains); they fear downside. Sortino focuses on the risk that actually hurts.
- Higher Sortino = better downside-risk-adjusted return.
Sharpe vs Sortino — when to use which
- Sharpe — the standard, penalises all volatility equally (up and down).
- Sortino — better for investments with uneven (asymmetric) returns, since it only penalises harmful downside moves. A fund with big upside swings may look risky on Sharpe but better on Sortino.
How to use them
- Compare within a category — Sharpe/Sortino are most meaningful between similar funds over the same period.
- Don’t rely on one number — read them alongside returns, consistency (rolling returns) and beta.
- Longer periods give more reliable readings.
The takeaway
Returns without risk context can mislead. Sharpe and Sortino reward funds that deliver more return for less risk — with Sortino focusing on the downside you actually care about. Use them to compare like-for-like, not as the sole decider. Education only, not a recommendation.
