Ulcer index indicator: what it measures and how traders use it
The ulcer index helps traders assess downside risk by focusing on drawdowns rather than total volatility. This guide explains how it works, how it’s calculated and how traders use it to assess risk alongside other technical indicators.
Takeaways
- The ulcer index measures only downside risk – unlike standard deviation, it ignores upside price moves entirely.
- It rises when price spends time below a recent peak and falls back toward zero when price reaches new highs.
- The default look-back is 14 periods; shorter periods respond faster but produce noisier readings.
- A low ulcer index confirms a low-stress trending environment where trend-following strategies tend to perform well.
- The Martin ratio pairs the ulcer index with return data to measure risk-adjusted performance specifically for drawdown risk.
- Because it has no fixed scale, readings are most useful when compared to the same instrument's historical range, not in absolute terms.
What is the ulcer index?
The ulcer index is a technical indicator that measures downside risk by quantifying the depth and duration of price drawdowns over a defined look-back period. Developed by Peter Martin and Byron McCann and published in their 1989 book The Investor's Guide to Fidelity Funds, the indicator was designed to capture a specific type of risk: not short-term price movement in both directions, but the experience of holding through sustained losses below a prior peak.
Unlike standard deviation, which treats upside and downside price movements equally, the ulcer index only focuses on drawdowns. It rises when price spends time below a recent high, and rises further when the decline is deeper or lasts longer. It then falls back toward zero when price recovers to new highs. A high ulcer index reading signals significant drawdown stress. A low reading signals that price has remained close to its recent peaks. The indicator’s name reflects its original purpose: measuring the discomfort of watching a position lose value.
How is the ulcer index calculated?
The ulcer index uses a multi-step calculation that turns drawdown depth and duration into a single readable number. This can help traders compare downside risk across instruments and time periods.
The formula
The ulcer index uses a three-step calculation over a look-back period. The default setting is usually 14 periods.
| Step | Calculation | What it shows |
|---|---|---|
| 1 | Drawdown(i) = ((Close(i) − Max Close over N periods) / Max Close over N periods) × 100 | The percentage drawdown from the highest close in the look-back period |
| 2 | Squared Average = Sum of [Drawdown(i)²] / N | The average of the squared drawdowns |
| 3 | Ulcer index = √(Squared Average) | The final ulcer index reading |
Because drawdowns are always zero or negative, squaring them produces positive values. The square root in the final step brings the result back to a scale comparable with the original percentage drawdown figures.
Worked example
Assume a five-period look-back. Over the most recent five sessions, the highest close was 500. The closing prices and resulting drawdowns are:
- Squared drawdowns: 4 + 16 + 25 + 9 + 0 = 54.
- Squared average = 54 / 5 = 10.80.
- Ulcer index = √10.80 = 3.29.
If the subsequent close were 510, a new high, the drawdowns in the look-back window would begin to reset and the ulcer index would drop sharply.
Using the ulcer index on a price chart
The ulcer index is typically displayed as a separate sub-panel below the price chart. It oscillates between zero, where price is at or above all recent closes in the look-back window, and higher values that reflect the severity of the current or recent drawdown. There is no fixed scale. The absolute value of the ulcer index depends on the instrument’s price level and volatility, so readings are most meaningful when compared over time on the same instrument or when used to compare relative drawdown risk between similar instruments.
Past performance is not a reliable indicator of future results.
How the ulcer index works in trading
Understanding how to read and apply the ulcer index can help turn it from a theoretical measure into a practical trading tool.
Reading ulcer index levels
The ulcer index has no universal overbought or oversold thresholds, unlike RSI’s commonly watched 30/70 levels. Traders therefore interpret it in relative terms. For a given instrument, reviewing historical ulcer index levels can help identify what has previously counted as low, moderate or high drawdown stress. Periods when the ulcer index is at multi-month lows often coincide with price holding near recent highs, which may suggest a more stable trending environment. Periods when the ulcer index is at multi-month highs indicate sustained drawdown stress, which may coincide with corrections, trend changes or elevated market uncertainty.
Rising vs falling readings
A rising ulcer index signals that price is moving away from its recent high, so the drawdown is deepening or lasting longer. A falling ulcer index signals that price is recovering toward recent highs, reducing drawdown stress. The rate of change matters as much as the absolute level. A sharply rising ulcer index during what looked like consolidation can act as an early warning that a deeper correction may be underway, even before price breaks obvious support levels. Conversely, an ulcer index that begins falling steadily from an elevated reading can signal that the drawdown phase may have eased and that recovery momentum may be building.
The ulcer index as a risk filter
One common use of the ulcer index is as a trade filter. When the ulcer index is elevated, indicating significant ongoing drawdown, some traders avoid opening new long positions in the affected instrument until the reading falls back toward lower levels. The rationale is that elevated drawdown stress can persist, and entering new long positions during deep drawdowns can mean buying into continued weakness. Conversely, a falling ulcer index during a recovery can act as confirmation that the drawdown phase may be ending and upward momentum may be reasserting.
Past performance is not a reliable indicator of future results.
Possible ulcer index settings for different trading styles
The ulcer index’s look-back period directly affects how quickly the indicator responds to new drawdowns and recoveries. Traders often match the setting to their timeframe and trading style.
| Setting | Typical use | Main benefit | Main limitation |
|---|---|---|---|
| 7 periods | Short-term and intraday trading | Responds quickly to changing drawdown conditions | Can produce noisier readings |
| 14 periods | Swing and position trading | Balances responsiveness and stability | May still react to short-term price shocks |
| 28 periods | Longer-term analysis | Smooths short-term noise and highlights broader drawdown behaviour | Responds more slowly to recoveries and new drawdowns |
Core ulcer index trading strategies
The ulcer index is most useful when its drawdown readings are combined with price-based signals. This allows traders to place the indicator in context rather than treating it as a standalone entry tool.
- Drawdown recovery entry: after a significant drawdown, some traders watch for the ulcer index to peak and start falling as price begins to recover. A declining ulcer index, higher lows and a move back towards resistance may suggest drawdown pressure is easing. Traders may then look for a separate entry trigger, such as a support bounce, moving average crossover or bullish candlestick reversal.
- Low-ulcer trending environment: a low ulcer index, relative to recent history, suggests price is staying close to recent highs with limited drawdown. This may support trend-following approaches that use signals such as moving average crossovers, MACD or RSI. The ulcer index doesn’t confirm direction, but it can add context to the trend signal.
- Position management: for open positions, the ulcer index can help show whether drawdown stress is rising or easing. A rapidly rising reading may prompt a review of stop-loss levels or position size. A falling reading may suggest drawdown pressure is easing, reducing the urgency to exit.
- Instrument comparison: traders can compare ulcer index readings across similar instruments over the same period. All else being equal, a lower reading suggests the instrument has experienced less drawdown stress. This is most useful when comparing markets in the same asset class or sector.
Combining the ulcer index with other indicators
Pairing the ulcer index with directional and momentum indicators helps address its main limitation: it measures risk levels, but does not generate directional trade signals on its own.
Moving averages
Moving averages provide trend direction context that pairs naturally with the ulcer index’s drawdown measurement. When price is above a rising 200-day moving average (MA) and the ulcer index is low, the combination may indicate an uptrend with limited drawdown stress. This can support a trend-following long-entry framework. When price breaks below the 200-day MA and the ulcer index is rising, the combination signals that the trend may have changed and drawdown stress is increasing. This may prompt a review of existing long positions.
RSI
The relative strength index (RSI) and the ulcer index provide complementary perspectives. RSI measures momentum and overbought or oversold conditions based on recent price changes. The ulcer index measures the depth and duration of a decline from a recent peak.
When RSI reaches oversold territory, typically below 30, and the ulcer index is simultaneously elevated, both indicators suggest that selling pressure has been significant.
A rising RSI from oversold, combined with a peaking and then falling ulcer index, can provide an early signal that the drawdown phase may be easing.
MACD
Moving average convergence/divergence (MACD) crossovers can provide potential entry signals that the ulcer index filters for quality. A bullish MACD crossover may be more relevant when the ulcer index is low, meaning the instrument has not been in significant drawdown, than when it appears during an elevated ulcer index reading, where the instrument may still be under drawdown pressure. Using the ulcer index as a quality filter for MACD signals can reduce the frequency of entries into instruments still experiencing sustained downside pressure.
The Martin ratio
The Martin ratio, also called the ulcer performance index, combines the ulcer index with return data to produce a risk-adjusted performance measure: Martin ratio = (Portfolio Return − Risk-Free Rate) / Ulcer Index. A higher Martin ratio indicates better return per unit of downside risk experienced. Traders who evaluate strategy performance often use the Martin ratio alongside the Sharpe ratio. The key difference is that the Martin ratio specifically penalises strategies that achieve returns through deep drawdowns, rather than focusing on total volatility.
The ulcer index’s value comes from what it adds to other indicators, not what it provides on its own. Combining its drawdown-focused perspective with directional tools, such as moving averages for trend and RSI or MACD for momentum, allows traders to assess both the quality of an opportunity and the risk environment around it.
Advanced ulcer index techniques
Beyond its standard applications, the ulcer index can be used in more nuanced ways to assess drawdown dynamics and relative risk.
- Ulcer index divergence: Divergence between price and the ulcer index can suggest a shift in drawdown dynamics.
- Bullish divergence: If price makes a new low but the ulcer index makes a lower high, the latest decline may involve less drawdown pressure than the previous one.
- Fragile recoveries: If price starts to recover but the ulcer index stays elevated, the drawdown may not be fully resolved.
- Multi-timeframe analysis: Using the ulcer index across different timeframes can help show whether drawdown stress is short term or more sustained.
- Daily versus weekly readings: A high daily reading with a low weekly reading may suggest short-term weakness within a healthier longer-term trend.
- Broader drawdowns: If both daily and weekly readings are elevated, the drawdown may be wider and more persistent.
- Percentile ranking: Because the ulcer index has no fixed scale, ranking it against historical readings can make it easier to interpret.
- High and low percentiles: A 90th-percentile reading suggests unusually high drawdown stress, while a 10th-percentile reading suggests unusually low drawdown stress.
Risk management with the ulcer index
The ulcer index has a natural role in risk management because it measures downside risk rather than total volatility.
- Position sizing: The ulcer index can help traders adjust exposure based on current drawdown conditions.
- Higher readings: An elevated ulcer index may signal sustained downside, which some traders use as a cue to reduce position size.
- Lower readings: A lower reading may suggest the instrument is holding closer to recent highs, which some traders may use to reassess exposure.
- Stop-loss calibration: The ulcer index can provide a reference for typical drawdown size when setting stop-loss distances.
- Avoiding premature exits: Stops set tighter than typical drawdown levels may be triggered by normal price moves.
- Wider drawdown behaviour: Instruments with persistently high ulcer index readings may need more room than those with consistently low readings.
- Stop-loss risk: Stop-loss orders aren’t guaranteed. Guaranteed stop-loss orders incur a fee if activated.
- Portfolio monitoring: Applying the ulcer index to portfolio returns can show how much time the portfolio is spending below its recent peak.
- Rising portfolio readings: A rising portfolio-level ulcer index may prompt a review of allocation, hedging or overall exposure.
- Falling portfolio readings: A falling reading may suggest diversification or position changes are reducing overall drawdown stress.
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FAQ
What is the ulcer index?
The ulcer index is a technical indicator that measures the depth and duration of price drawdowns over a defined period. Developed by Peter Martin, it calculates the square root of the average of squared percentage drawdowns from the period’s highest close. Unlike volatility measures based on standard deviation, the ulcer index only considers downside price movement. It rises when price falls below a recent peak and falls back toward zero when price recovers. Traders use it to assess drawdown risk, compare instruments and filter trade entries.
What is a good ulcer index reading?
There is no universally good or bad ulcer index reading because the indicator’s scale depends on the instrument’s price level and volatility. Readings should be interpreted in relative terms and compared with the instrument’s own historical range. For a given instrument, a reading near multi-month lows indicates limited drawdown stress and a price close to recent highs. A reading near multi-month highs indicates significant ongoing drawdown. Percentile ranking, which compares the current reading with its historical distribution, is a useful way to standardise interpretation across different instruments.
What is the difference between the ulcer index and standard deviation?
Standard deviation measures total price volatility, treating upside and downside price movements equally. The ulcer index measures only downside volatility, focusing specifically on drawdown depth and duration. An instrument can have high standard deviation because of strong upside moves with limited drawdowns. In that case, the ulcer index may stay low even though standard deviation is elevated. The ulcer index is often used when the specific concern is loss risk rather than total price variability.
What is the Martin ratio?
The Martin ratio, also called the Ulcer Performance Index, is a risk-adjusted return measure calculated as: Martin ratio = (Return − Risk-Free Rate) / Ulcer Index. It assesses how much return is generated per unit of downside risk experienced, as measured by the ulcer index. A higher Martin ratio indicates more efficient return generation relative to drawdown stress. It is used alongside the Sharpe ratio in strategy evaluation. Its main distinction is that it specifically penalises strategies that achieve returns through deep or prolonged drawdowns.
What is the default period for the ulcer index?
The most commonly used look-back period is 14 periods. On a daily chart, this covers approximately two to three weeks of trading data. Some traders use shorter periods, such as seven days, for more responsive readings. Others use longer periods, such as 28 days, for a smoother view of drawdown behaviour. The appropriate period depends on the trading timeframe and the specific application. Shorter periods respond faster to new drawdowns but produce noisier readings.
Can the ulcer index be used for intraday trading?
Yes. The ulcer index can be applied to any timeframe, including intraday charts. On shorter timeframes, it measures drawdowns within the session or over recent intraday candles rather than multi-day or multi-week periods. On intraday charts, the ulcer index is most useful as a position management tool. Rising intraday readings indicate that a held position is experiencing increasing drawdown relative to the session high. Falling readings indicate recovery. The interpretation principles are the same as on daily charts, scaled to the shorter timeframe.
