What Is the Ulcer Index? The Risk Metric Most Investors Have Never Heard Of

Max drawdown has one blind spot. It captures the worst single moment in a portfolio's history but says nothing about how long investors had to live with that loss before recovering. The Ulcer Index was built to fill that gap.

Developed by Peter Martin and Byron McCann in 1987, the Ulcer Index measures both the depth and the duration of drawdowns. A portfolio that drops 15% and recovers in three months gets a very different score than one that drops 15% and spends two years crawling back. The name is intentional: it is not about sudden, sharp pain. It is about the slow, grinding kind that causes investors to second-guess their strategy and eventually abandon it at exactly the wrong moment.

What the Ulcer Index Actually Measures

For every period where a portfolio sits below its previous peak, the Ulcer Index measures how far below and for how long. Those squared deviations are averaged across all underwater periods and then square-rooted, similar in structure to standard deviation but applied only to losses, not gains.

The result is a single number that rewards fast recoveries and penalizes lingering drawdowns. Across the 70 portfolios in the PortfolioDB database, Ulcer Index values range from 2.16 (Trend Following Bonds by Paul Novell) to 12.87 (Ultimate Buy and Hold Portfolio 8 by Paul Merriman). The widely-used US 60/40 Portfolio lands at 6.03, which makes for a useful baseline when comparing strategies.

How It Differs From Max Drawdown and Standard Deviation

Max drawdown captures one thing: the worst peak-to-trough decline in a portfolio's history. That is important, but it is a snapshot rather than a full picture. Two portfolios with identical max drawdowns can produce completely different experiences for the investors who held them.

Standard deviation has a different limitation. It penalizes upside volatility equally with downside volatility. A portfolio with explosive up years gets dinged on its Sharpe Ratio the same way a portfolio with explosive down years does. For most investors who care about losses far more than gains, that symmetry does not reflect their actual experience of risk.

The Ulcer Index sidesteps both problems by only counting the bad periods and rewarding the ones that end quickly.

A real example from the database makes this concrete. Ray Dalio's All-Weather Portfolio has a max drawdown of -21.16% and an Ulcer Index of 3.95. The US 60/40 Portfolio has a max drawdown of -29.68% and an Ulcer Index of 6.03. The All-Weather has a worse max drawdown than the 60/40, yet its Ulcer Index is meaningfully lower. When the All-Weather fell, it recovered quickly. The 60/40 spent far more cumulative time underwater, particularly through the extended bear markets of 2000-2002 and 2008-2009. Max drawdown recorded one bad moment. The Ulcer Index recorded the whole story.

The Permanent Portfolio makes the contrast even sharper: max drawdown -15.52%, Ulcer Index 3.02. Both a shallow worst-case and fast recoveries explain why it consistently ranks near the top of low-Ulcer-Index portfolios despite a CAGR of 8.68%.

The Ulcer Index is pushing beyond raw numbers for decision making and creating a level of difficulty signal for an investors ability to stay in a portfolio during turbulant markets.

The Ulcer Performance Index

Once you have the Ulcer Index, a natural next step is using it as the denominator in a risk-adjusted return calculation. That is the Ulcer Performance Index (UPI).

UPI is built like the Sharpe Ratio, with excess return divided by a risk measure, but it replaces standard deviation with the Ulcer Index. The result is a metric that specifically rewards portfolios for fast recovery rather than low volatility in general.

Five portfolios from the database show what this reveals:

The 60/40's UPI of 0.82 is the lowest of the group despite a CAGR that is competitive with All-Weather and Permanent Portfolio. It is not generating bad returns. It is spending too much time underwater relative to what it earns.

The Defensive Asset Allocation strategy, built by Wouter Keller and Hugo Keuning, sits at the other end: 13.67% CAGR, a max drawdown of just -16.61%, and a UPI of 2.25. The Vigilant Asset Allocation G4 Aggressive goes further with a 16.14% CAGR and a UPI of 2.31, nearly three times the 60/40's score. Both are rules-based tactical strategies designed to move to defensive assets when momentum signals weaken, reducing the time spent underwater after a market decline.

While rules-based strategies may not move investors out of an asset prior to the market taking a toll on their portfolio, the goal is to adjust the portfolio before the absolute worst and find a recovery asset as soon as possible.

Why This Matters More as You Approach Retirement

Standard deviation and Sharpe Ratio were built for long-horizon institutional investors. For a 30-year-old in the accumulation phase, volatility is mostly noise because time absorbs it.

For investors within ten years of retirement, prolonged drawdowns are a more concrete risk. Sequence-of-returns risk means a deep, extended decline in the final working years can permanently impair a retirement outcome even if long-run returns eventually recover. An 18-month drawdown at 62 is a fundamentally different experience than the same drawdown at 35.

The Ulcer Index captures that risk more directly than any other single metric. This is why UPI is included alongside Sharpe and Sortino in PortfolioDB's methodology, not as a replacement for those measures but as an addition that rewards portfolios for spending less time underwater, not just falling less far.

How to Use It in the Portfolio Screener

In the PortfolioDB Portfolio Screener, both Ulcer Index and UPI are available as sliders under "Advanced Filters." Setting a maximum Ulcer Index of 4.0, for example, immediately shows which of the 70 portfolios clear that bar alongside CAGR, Sharpe, and max drawdown.

At that cutoff, the results include the Permanent Portfolio, Ray Dalio's All-Weather, Defensive Asset Allocation, and several tactical strategies with strong historical recovery speeds. Each represents a different trade-off between return potential and time spent underwater.

For investors who prioritize staying invested over maximizing returns, the Ulcer Index is one of the most honest metrics available. It does not ask how bad things got. It asks how long you had to live with it. For most investors, that is the more important question.

Definitions for Ulcer Index and Ulcer Performance Index are in the Glossary of Terms.