Ulcer Index
In short
Measures depth and duration of drawdowns — how 'painful' was the recovery
Named because large, long drawdowns cause stress (ulcers). It penalizes both deep drops AND slow recoveries. A fund that drops 20% and takes 2 years to recover scores much worse than one that drops 20% and recovers in 2 months.
The Ulcer Index combines the magnitude and duration of drawdowns. It calculates the root-mean-square of percentage drawdowns over a period. Unlike max drawdown, it reflects the total pain of all drawdown episodes, not just the single worst one.
Formula
UI = √(Σ((Di - Peak_i)/Peak_i)² ÷ n) × 100Thresholds
- <5
- Low stress — quick recoveries
- 5-10
- Moderate
- 10-20
- High stress
- >20
- Very painful drawdown profile
Related concepts
- Maximum Drawdown — If your portfolio hit $10,000 then fell to $6,000 before recovering, the max drawdown is 40%. It measures the worst experience a real investor would have endured.
- Calmar Ratio — Calmar asks how much return you earned per dollar of maximum pain. If a portfolio returned 15% annually over the period measured but suffered a 30% drop from peak to trough at its worst point, the Calmar ratio is 0.5 — half a percent of return for every percent of that worst loss.
- Sortino Ratio — Sharpe ratio penalizes all volatility, even upside gains. Sortino only penalizes bad volatility (downside). A fund that has big gains but small losses looks better on Sortino than Sharpe.