The longest consecutive series of losing trades or the largest cumulative loss within a contiguous run of losing trades in a backtest or live record.
also: losing streak, max consecutive losses, worst run
Updated
The longest run of losing trades the strategy has already been through, and how much that run cost. It is the number that predicts whether a trader will still be running the EA at the end of a bad stretch.
Most accounts do not fail because of a single catastrophic trade; they fail because someone switched off a working strategy during its worst run. Maximum drawdown says how deep the hole was, and worst streak says how many times in a row the strategy was wrong on the way down — which is the part people actually cannot sit through.
Worst streak (count) = the longest run of consecutive losing trades · Worst streak (value) = the cumulative loss across that run The two definitions do not have to point at the same run. The longest run by count can be a sequence of small losses, while the costliest run by value can be shorter and heavier — so publish both, and say which one a quoted figure refers to.
No single number describes a strategy. These metrics change how this one should be read.
The chance of a run of N losses in a row follows directly from the loss rate, so the expected worst streak can be read off the win rate before any money is deployed.
The streak that feels like the EA has broken is usually the streak the win rate predicted before deployment.
Calculation 0.6⁶ = 0.0467 → a six-loss run appears roughly once every 21 trades at this win rate
Result A ten-loss run is an ordinary feature of a 40% win rate, not evidence of failure
A published streak figure is a floor, not a ceiling — it is the worst the sample happened to contain. Read it against the sample length and the win rate that produced it.
| Range | What it means |
|---|---|
| Quoted without the trade count | Uninterpretable. A short sample cannot contain a long run, so a flattering streak figure may only mean the test was brief. |
| Count only, with no cost attached | Half the picture. Eleven small losses and five heavy ones are different problems for the same account. |
| Both count and cumulative cost, over several hundred trades | The figure worth planning around. It can be turned directly into a rule for when to intervene. |
| Live streak longer than the tested worst | A decision point rather than noise — the strategy is operating outside the behaviour its sample described. |
mt5depot EA pages publish the worst losing streak beside maximum drawdown and the trade count, because the two describe different things a deployer has to survive.
At a 40% win rate, a run of ten losses is an ordinary product of a few hundred trades. Deciding a strategy is broken because it produced the run its own win rate predicts is the most common way a working EA gets switched off.
It is the longest run inside the sample. A longer sample almost always finds a longer run, so the figure is a floor for future expectations rather than a limit.
Streak length and streak cost are separate figures, and a strategy that varies its risk per trade can have its costliest run be one of its shorter ones.
Maximum drawdown is measured from an equity peak and can be produced by a single trade. A losing streak is a run of consecutive closes and can end above the previous peak if the run started from a high. They answer different questions.