Sortino ratio is a risk-adjusted performance metric that improves on the Sharpe ratio by only penalizing downside volatility. While Sharpe treats all volatility as bad, Sortino recognizes that upside volatility (big wins) is actually desirable—it’s only the losses that hurt your portfolio.
- Sortino ratio above 2.0 is good; above 3.0 is excellent
- Only penalizes downside volatility, making it fairer for asymmetric strategies
- Particularly useful for strategies with occasional large wins
How Sortino Ratio Works
The Sortino ratio modifies the Sharpe ratio by replacing standard deviation with downside deviation in the denominator. This means only negative returns count against you.
Sortino Ratio = (Portfolio Return - Risk-Free Rate) / Downside Deviation
Where downside deviation only considers returns below the minimum acceptable return (MAR), typically 0% or the risk-free rate.
Quick Reference
| Sortino Ratio | Interpretation | Risk Assessment |
|---|---|---|
| Below 0 | Losing money | Poor downside control |
| 0 to 1.0 | Marginal | Needs improvement |
| 1.0 to 2.0 | Acceptable | Decent risk management |
| 2.0 to 3.0 | Good | Strong downside protection |
| Above 3.0 | Excellent | Superior risk control |
Example Calculation
Let’s calculate Sortino ratio for a trading strategy:
Monthly Returns Over 12 Months: +5%, -2%, +8%, +3%, -4%, +6%, -1%, +10%, +4%, -3%, +7%, +2%
Step 1: Calculate Average Return Average = (5-2+8+3-4+6-1+10+4-3+7+2) / 12 = 2.92% monthly
Step 2: Identify Downside Returns Negative months: -2%, -4%, -1%, -3%
Step 3: Calculate Downside Deviation Downside Deviation = √[((-2)² + (-4)² + (-1)² + (-3)²) / 12] = √(30/12) = 1.58%
Step 4: Calculate Sortino (assuming 0% risk-free) Sortino = 2.92% / 1.58% = 1.85
This indicates acceptable risk-adjusted returns with good downside management.
Sortino ratio measures risk-adjusted returns using only downside volatility. Unlike Sharpe ratio which penalizes all volatility, Sortino recognizes that upside swings are desirable. A Sortino above 2.0 is good, and above 3.0 is excellent.
Sortino vs Sharpe: A Practical Comparison
Consider two traders with different return patterns:
Trader A: Consistent small gains, occasional large losses
- Returns: +2%, +1%, +2%, -8%, +1%, +2%
- Sharpe Ratio: 0.15
- Sortino Ratio: 0.20
Trader B: Occasional large gains, consistent small losses
- Returns: -1%, -1%, +12%, -1%, -1%, +10%
- Sharpe Ratio: 0.80
- Sortino Ratio: 2.40
Trader B has much higher Sortino because their volatility comes from upside—exactly what you want. Sharpe undervalues this strategy because it treats winning volatility as bad.
Why Sortino Matters for Active Traders
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Asymmetric strategies shine – Many trading strategies aim for occasional large wins with small frequent losses. Sortino properly values this approach.
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More intuitive – Traders understand that big winning days shouldn’t count against them. Sortino aligns with this intuition.
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Better for options sellers – Strategies that collect premium and occasionally have large losses show their true nature better with Sortino.
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Trend following evaluation – Trend strategies often have many small losses and few large wins. Sortino captures their true risk-adjusted value.
Common Mistakes
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Confusing with Sharpe – Higher Sortino than Sharpe indicates positive skew (more upside than downside volatility). Lower Sortino than Sharpe indicates negative skew.
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Using wrong MAR – The minimum acceptable return affects results. Using 0% vs risk-free rate vs your target return gives different Sortinos.
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Insufficient data – Like all risk metrics, Sortino needs enough data points. At least 30-50 periods for reliability.
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Ignoring both ratios – Don’t use Sortino exclusively. Compare it with Sharpe to understand your return distribution.
How JournalPlus Tracks Sortino Ratio
JournalPlus calculates both Sharpe and Sortino ratios automatically, letting you compare them side by side. By analyzing the gap between these ratios, you can understand whether your strategy has positive or negative skew—and whether your wins are bigger than your losses in a risk-adjusted sense.
