Sortino Ratio

Sortino Ratio is a financial metric used to measure the risk-adjusted return of an investment, similar to the Sharpe Ratio. However, unlike the Sharpe Ratio, the Sortino Ratio only considers downside risk, making it a more precise tool for evaluating investments where investors are primarily concerned with losses.

1 Definition

The Sortino Ratio is calculated as:

• Sortino Ratio = (R_p - R_f) / σ_d

where:

• R_p – Return of the portfolio.
• R_f – Risk-free rate (e.g., U.S. Treasury rate).
• σ_d – Downside deviation (standard deviation of negative returns).

2 Interpretation

• Sortino Ratio > 1.0 – Indicates strong risk-adjusted performance with low downside risk.
• 0 < Sortino Ratio ≤ 1.0 – Suggests moderate performance but with noticeable downside risk.
• Sortino Ratio < 0 – Indicates that the investment underperforms relative to the risk-free rate, meaning higher risk without sufficient return.

3 Example Calculation

Suppose:

• Portfolio return (R_p) = 12%
• Risk-free rate (R_f) = 3%
• Downside deviation (σ_d) = 5%

The Sortino Ratio is:

• (12% - 3%) / 5% = 1.8

4 Advantages

• Focuses on downside risk
  • Only penalizes volatility that leads to losses.
• Better than Sharpe Ratio for asymmetrical returns
  • More effective for assets with skewed return distributions.
• More relevant for conservative investors
  • Provides a clearer risk-adjusted measure for funds aiming to minimize losses.

5 Limitations

• Requires downside deviation calculation
  • More complex than standard deviation used in the Sharpe Ratio.
• Can be misleading for low-volatility assets
  • A low-risk asset with low returns may still have a high Sortino Ratio.
• Sensitive to the threshold for downside risk
  • Different investors may define "negative returns" differently.

6 Applications

• Portfolio Management
  • Used by fund managers to evaluate performance relative to downside risk.
• Risk-Adjusted Investment Analysis
  • Helps investors choose funds or stocks with better downside protection.
• Hedge Funds and Alternative Investments
  • Often preferred over the Sharpe Ratio for non-traditional assets.

7 Comparison with Sharpe Ratio

Metric	Formula	Risk Considered
Sharpe Ratio	(Rp - Rf) / σp	Total risk (both upside and downside)
Sortino Ratio	(Rp - Rf) / σd	Only downside risk

8 See Also

• Sharpe Ratio
• Information Ratio
• Risk-Adjusted Return
• Volatility (Finance)
• Portfolio Management