Direct Answer
The Sterling ratio compares annualized return with a drawdown measure. It is commonly defined as annualized return divided by the average maximum drawdown plus a fixed 10 percentage point cushion, though other definitions exist. Higher values mean more return per unit of drawdown.
Sterling Ratio: Formula, Meaning, Signals, Examples and How to Use It
How Is Sterling Ratio Calculated?
The Sterling ratio compares annualized return with a drawdown measure. It is commonly defined as annualized return divided by the average maximum drawdown plus a fixed 10 percentage point cushion, though other definitions exist.
Formula: Sterling ratio = annualized return / (average maximum drawdown + 10%); variants subtract 10% or use none
Inputs:
- Annualized return
- Maximum drawdown for each year or period
- Averaging window (often three years)
- The 10 percentage point adjustment, if used
Worked example. An annualized return of 12% and an average maximum drawdown of 15% give a Sterling ratio of 0.48 under the plus-10-point variant. The inputs are illustrative numbers, not market data.
Reading it. Higher values mean more return per unit of drawdown. Always check which denominator a source uses, since the plus 10 points, minus 10 points and plain maximum drawdown versions give different numbers for the same history.
Limits. Results depend on the chosen variant, the averaging window and how drawdowns are measured. Maximum drawdown uses only the single worst decline per period, so it ignores everything else in the path.
What is Sterling Ratio?
The Sterling ratio compares annualized return with a drawdown measure. It is commonly defined as annualized return divided by the average maximum drawdown plus a fixed 10 percentage point cushion, though other definitions exist.
How to use Sterling Ratio
Higher values mean more return per unit of drawdown. Always check which denominator a source uses, since the plus 10 points, minus 10 points and plain maximum drawdown versions give different numbers for the same history. A reading alone is never a buy or sell signal; it needs context from price structure, volume, volatility and the broader market regime.
Strengths
- Using the average of yearly maximum drawdowns gives a denominator that reflects several periods and not a single worst episode.
- The fixed cushion keeps the denominator from collapsing toward zero when drawdowns are very small.
- Reproducible when the formula and data convention are fixed.
Weaknesses and limitations
- The 10 point addition is arbitrary and large relative to small drawdowns, so it dominates the denominator in calm years.
- Where drawdowns are taken per calendar year, a decline that spans a year-end is split between two periods and each part looks smaller.
- Correlated indicators can create false confidence by repeating the same underlying information.
Editorial and risk note
This page is educational content, not individualized investment advice. It should not imply guaranteed prediction, accuracy or outperformance.
Frequently Asked Questions
Is Sterling Ratio a buy or sell signal?
No. Higher values mean more return per unit of drawdown. Results depend on the chosen variant, the averaging window and how drawdowns are measured. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions.
What is the best setting for Sterling Ratio?
Sterling Ratio takes these inputs: annualized return; maximum drawdown for each year or period; averaging window (often three years). There is no universal best setting for the tunable ones, so test them across instruments, regimes and out-of-sample periods and favor stable parameter regions over one historical winner.
Can Sterling Ratio be used by itself?
Results depend on the chosen variant, the averaging window and how drawdowns are measured. Maximum drawdown uses only the single worst decline per period, so it ignores everything else in the path. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone.
Does Sterling Ratio work on every timeframe?
The calculation (Sterling ratio = annualized return / (average maximum drawdown + 10%); variants subtract 10% or use none) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it.
Why does Sterling Ratio give false signals?
The 10 point addition is arbitrary and large relative to small drawdowns, so it dominates the denominator in calm years. Where drawdowns are taken per calendar year, a decline that spans a year-end is split between two periods and each part looks smaller. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated.
How should Sterling Ratio be backtested?
Rebuild Sterling Ratio from annualized return using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline.