Martin Ratio

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The most underused risk-adjusted ratio. Captures depth AND duration of pain.

Quick Answer

What is Martin Ratio?

Martin ratio is excess return divided by the Ulcer Index — a measure that captures both the depth and the duration of drawdowns. Where Calmar penalizes the single worst drawdown, Martin penalizes the entire underwater experience, weighted by how long the portfolio spent below its prior peak.

Martin = (Rp − Rf) / Ulcer Index

Formula

Martin = (Rp − Rf) / UI
Rp − Rf = annualized excess return · UI = Ulcer Index = sqrt of mean squared drawdown over the window

Numerator: excess return (same as Sharpe). Denominator: Peter Martin's Ulcer Index, which captures both how deep drawdowns went and how long they lingered.

Intuition — what is this number telling you?

For investors who experience drawdowns as psychological pain over time (which is everyone), Martin is the most behaviorally honest ratio. Two strategies with the same Calmar but very different time-underwater profiles get very different Martin scores — and the higher Martin is the one that actually felt better to live through.

Worked example

Step-by-step

Excess return: 7.5%. Ulcer Index: 6.2%.

Martin = 7.5% / 6.2% = 1.21

Solid — above 1.0 means your return rate exceeds your average underwater pain.

What's a good Martin Ratio value?

Martin above 1.0 is strong; above 2.0 is exceptional. The S&P 500 typically runs around 0.4–0.6.

Related metrics

Ulcer Index  ·  Calmar Ratio  ·  Sterling Ratio  ·  Maximum Drawdown

Frequently asked questions about Martin Ratio

How is Martin different from Calmar?

Calmar penalizes the single worst drawdown. Martin penalizes the entire drawdown experience — including how long it lasted.

When should I use Martin?

For evaluating strategies you intend to hold through drawdowns, especially with hard liquidity needs. It is the most behaviorally honest single-number ratio.

Why is Martin not more widely used?

Ulcer Index is less intuitive than max drawdown. Calmar and Sharpe are easier to explain. But Martin is mathematically more complete.

Does Foliolytic compute Martin?

Yes — it appears in the risk-adjusted section of the metrics panel alongside Sharpe, Sortino, Calmar, and Sterling.

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