Sharpe Ratio: What a Good Risk-Adjusted Return Really Tells You
A 12% return means nothing until you know what risk bought it. That is exactly what the Sharpe ratio measures: excess return per unit of volatility. The formula is trivial — the interpretation is not. Knowing the benchmarks and the metric’s weak spots lets you read your portfolio far more precisely.
Formula and realistic benchmarks
Sharpe ratio = (portfolio return − risk-free rate) / volatility. Example: 9% return, 2.5% risk-free rate, 16% volatility → (9 − 2.5) / 16 = 0.41 — a typical value for a pure equity portfolio over long periods. Context is everything: a Sharpe ratio of 0.4 is normal for a global equity portfolio, but weak for a supposedly market-neutral hedge fund.
| Sharpe ratio | Reading (long-term, liquid portfolios) |
|---|---|
| < 0.2 | Weak — risk barely compensated |
| 0.3–0.5 | Market-typical for broad equity portfolios |
| 0.5–1.0 | Good — above-average risk efficiency |
| > 1.0 | Rare over long periods; often a period effect or hidden risks |
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The weak spots — and when Sortino is the better choice
Three blind spots you should know:
- Symmetry: the Sharpe ratio penalises upside and downside swings alike. A strategy with strong upward jumps looks “riskier” than it is. The Sortino ratio fixes this by using downside volatility only.
- Period dependence: the same strategy can show a Sharpe ratio of 1.2 over 3 years and 0.4 over 15. Without the time frame, the number is worthless.
- Tail risks: strategies with rare, extreme losses (option selling, carry trades) post stellar ratios for years — until they blow up. Complement it with metrics like maximum drawdown and value at risk.
Applying it to your own portfolio
The metric becomes useful in comparison: your portfolio versus a fitting benchmark (e.g. MSCI ACWI) over identical periods. If your Sharpe ratio sits below it persistently, you are taking risks the market does not pay for — common causes are single-stock concentration or unintended sector bets. MoneyPeak’s portfolio analysis shows the Sharpe and Sortino of your real portfolio continuously, instead of a once-a-year manual calculation.
Frequently asked questions
What is a good Sharpe ratio?
It depends on context: 0.3–0.5 is normal for broad equity portfolios long-term, and values above 1 are the exception over long periods. The comparison against a fitting benchmark over the same period matters more than the absolute number.
Sharpe or Sortino ratio — which should I use?
Sortino is the fairer metric for strategies with asymmetric returns, since it only penalises downside swings. For broad buy-and-hold portfolios both usually paint a similar picture.
Which risk-free rate belongs in the formula?
Typically a short-term money market rate in your own currency — in the eurozone, the €STR. What matters is consistency: same rate and same period for all portfolios you compare.
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