Week 41 Day 2: Risk-Adjusted Returns: The Only Fair Comparison

Your friend brags: 'My portfolio returned 18% last year!' Sounds great. But their portfolio was 100% in volatile tech stocks (standard deviation 30%). Your VTI/SCHD/BND portfolio returned 11% (standard deviation 12%). Risk-adjusted: Friend's Sharpe: (18% - 5%) / 30% = 0.43. Yours: (11% - 5%) / 12% = 0.50. Your risk-adjusted return was BETTER. You got paid more per unit of risk.

Why risk adjustment matters: (1) It prevents apples-to-oranges comparisons. Comparing a 100% stock portfolio to a 60/40 portfolio on raw return is unfair. The stock portfolio takes more risk and SHOULD earn more. The question is: did it earn ENOUGH more to justify the extra risk? (2) It exposes false alpha. A hedge fund charging 2% fees that returns 15% seems impressive -- until you learn its volatility is 40% (Sharpe: 0.25). VTI at 10% with 16% volatility has a Sharpe of 0.31. The hedge fund's 'alpha' is actually negative on a risk-adjusted basis. (3) It guides allocation decisions. Adding SCHD (Sharpe approximately 0.45) to VTI (Sharpe approximately 0.45) improves the portfolio Sharpe ratio because the correlation between them is less than 1.0. The diversification between VTI and SCHD (approximately 0.85 correlation) creates a portfolio with a higher risk-adjusted return than either held alone. Practical use: when evaluating any investment, always ask both questions: (a) 'What was the return?' AND (b) 'What was the risk (volatility)?' If someone only tells you the return, they are hiding half the picture. A 30% return on a 60%-volatility investment is WORSE than a 12% return on a 15%-volatility investment (Sharpe: 0.42 vs. 0.47).

Risk adjustment is the foundation of modern portfolio evaluation. Beyond the Sharpe ratio, several alternative risk-adjusted metrics are used: (1) Sortino ratio = (Return - Risk-free rate) / Downside deviation. Penalizes only downside volatility. Useful when upside volatility is desirable (as in growth stocks). (2) Information ratio = (Portfolio return - Benchmark return) / Tracking error. Measures the consistency of a manager's outperformance relative to a benchmark. An information ratio > 0.5 is considered very good. (3) Treynor ratio = (Return - Risk-free rate) / Beta. Measures return per unit of systematic risk (beta) rather than total risk (standard deviation). Appropriate for investors who hold diversified portfolios (where idiosyncratic risk is diversified away). (4) Calmar ratio = Annualized return / Maximum drawdown. Measures return per unit of peak-to-trough risk. Useful for evaluating strategies with large drawdowns. (5) Omega ratio = Probability-weighted gain / Probability-weighted loss at a given threshold. Captures the full return distribution, not just the first two moments. For individual investors, the Sharpe ratio is usually sufficient because it is intuitive, widely reported, and useful for the primary decision (what allocation of stocks/bonds/cash maximizes risk-adjusted return). The other metrics are useful for specialist applications (evaluating hedge fund managers, comparing strategies with very different risk profiles, or assessing tail risk).