Sortino Ratio
Also known as: downside risk-adjusted return, sortino, downside deviation ratio
What is it?
The Sortino ratio measures how much return a strategy earned for each unit of harmful, downside volatility, based on past data. It is a close cousin of the Sharpe ratio, with one important change: instead of penalising every swing in returns, it only counts the swings that fall below a target you care about, usually zero or a minimum acceptable return. The thinking is simple - upside swings are exactly what you want, so it makes little sense to treat a sharp gain as risk in the same way you treat a sharp loss.
= (2% − 0%) / 1% = 2.0
To calculate it, you take the average return above your target, then divide by the downside deviation, which measures only how far returns dropped below that target. For example, suppose a forex strategy earned an average monthly return of 2% over a target of 0%, and its returns below zero had a downside deviation of 1%. That gives a Sortino ratio of about 2.0 historically, meaning it produced roughly two units of excess return for every unit of genuinely bad volatility.
A higher Sortino means the strategy delivered its returns with mostly upside movement rather than painful drawdowns, which is often the swing profile traders actually want to live with. The common pitfall is comparing a Sortino number across different time periods, targets, or sample sizes as if they were equivalent - a Sortino built on twelve calm months tells you little about how a strategy behaves in a crash. Past performance does not guarantee future results, no strategy is risk-free, and your capital is at risk on every trade.
Why it matters: The Sortino ratio rewards strategies that grow through upside moves rather than gut-wrenching drawdowns, so it reflects the risk you actually feel.
Sortino = (average return - target return) / downside deviation
The Sortino ratio captures whether returns came with manageable downside risk, which directly shapes how survivable a strategy is.
Real-world example
A strategy averaging 2% monthly over a 0% target, with a downside deviation of 1%, has a Sortino ratio of about 2.0 historically.
How SignalBots handles it
Where SignalBots reports a Sortino ratio for a strategy or signal feed, it is a historical estimate shown alongside drawdown and a /risk-warning link, so you can judge return against genuinely bad volatility before acting on a signal across any delivery pillar.
Pro tip
Read the Sortino ratio next to the Sharpe ratio - a much higher Sortino than Sharpe signals that most of the volatility was upside, which is the profile you want.
Common pitfalls
Comparing Sortino numbers built on different targets, timeframes, or sample sizes as if they measured the same thing.
Frequently asked questions
How is the Sortino ratio different from the Sharpe ratio?
Both divide excess return by a measure of volatility, but the Sharpe ratio counts all volatility while the Sortino ratio counts only downside volatility below a target. The Sortino ratio therefore does not punish a strategy for having large upside swings.
What is a good Sortino ratio?
Higher is generally better, and many traders treat a value above 2 as strong, but there is no universal cutoff. Always check it against the timeframe and sample size, since these are historical estimates and not guarantees of future results.
What does downside deviation actually measure?
It measures only how far returns fell below your chosen target, ignoring returns above it. This is what lets the Sortino ratio separate harmful volatility from the upside swings traders want.
What target return should I use?
Most people use zero or a minimum acceptable return such as a risk-free rate. The key is to keep the target consistent whenever you compare two strategies, or the numbers are not comparable.
Can the Sortino ratio be negative?
Yes, if the average return falls below your target the ratio turns negative, signalling the strategy underperformed your benchmark over that sample. As with all such metrics it describes past data, and your capital is at risk on every trade.
Trading involves substantial risk of loss. Historical and backtested results do not guarantee future performance. Read the full risk warning.