How does the Sortino ratio use target return for risk-adjusted performance?

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AcadiFi · Accepted Answer

The Sortino ratio is (Return - Target) / Downside Deviation, where downside deviation is the standard deviation of returns below the target (not below the mean). Formula: Sortino = (R_p - MAR) / DD, where MAR is Minimum Acceptable Return (often 0%, risk-free rate, or liability-funding rate), and DD = sqrt(E[min(0, R - MAR)^2]).

Comparison with Sharpe: Sharpe = (R - Rf)/σ treats upside and downside volatility equally. For positively skewed return distributions, Sharpe understates attractiveness. Sortino captures that upside volatility is desirable. Example: fund with 12% return, 15% total volatility, and 8% downside deviation versus a 4% MAR. Sharpe = (12-4)/15 = 0.53; Sortino = (12-4)/8 = 1.00. The Sortino reveals the fund's downside risk profile is favorable despite the same total volatility as a symmetric counterpart.

Use cases:
• Asymmetric strategies (options selling, trend following) where skew matters.
• Liability-driven investing where MAR equals required funding rate.
• Alternative investments with non-normal returns.
• Investor profiles emphasizing loss aversion.

Pitfalls: downside deviation requires enough negative observations for stable estimation—short samples or high-return periods make estimation unstable. Sortino is sensitive to MAR choice: higher MAR inflates downside deviation and reduces ratio. Standardization across funds requires consistent MAR. Combine Sortino with Calmar ratio (return/max drawdown) and Omega ratio (probability-weighted up/down) for full picture. Industry use has expanded as investors demand asymmetric risk metrics, particularly in hedge fund due diligence.

How does the Sortino ratio use target return for risk-adjusted performance?

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