What is the Pain Index?
The Pain Index (also called the Ulcer Index) measures the average depth of drawdowns over an investment period. Unlike standard deviation, which treats upside and downside volatility equally, the Pain Index focuses exclusively on declines from peak values. Since investors experience losses roughly twice as painfully as equivalent gains, this downside-focused metric better captures the actual psychological burden of an investment.
Calculation and Interpretation
The Pain Index averages the percentage drawdown at each point in time. A fund that consistently sets new highs has a Pain Index near 0%. One that frequently experiences deep, prolonged drawdowns has a high value. A Pain Index of 5% means the fund is, on average, 5% below its peak. Lower values indicate smoother, less stressful investment experiences.
The Pain Ratio
The Pain Ratio divides excess return by the Pain Index, analogous to the Sharpe ratio but using downside risk. A fund with a high Sharpe ratio but large drawdowns will score poorly on the Pain Ratio. For retirees withdrawing from their portfolio, the Pain Ratio is arguably more relevant than the Sharpe ratio because drawdowns during withdrawal directly threaten portfolio longevity.