Risk of Ruin
Also known as: probability of ruin, blow-up risk
What is it?
Risk of ruin is the estimated probability that an account is drawn down so far that it can no longer realistically recover, in other words the chance of effectively blowing up. It is calculated from a few inputs: the win rate, the payoff or reward-to-risk of the strategy, and crucially the amount risked on each trade. The reason risk of ruin matters so much is that it connects everyday per-trade risk to the ultimate danger, and it reveals a counterintuitive truth: even a strategy with a genuine positive edge can still be ruined if you risk too much on each trade.
A long losing streak, which every strategy eventually hits, can compound a large per-trade risk into a hole the account cannot climb out of. For example, risking 10% of the account on each trade can produce a meaningful risk of ruin even on a winning strategy, simply because a streak of losses stacks up quickly. The practical takeaway is that survivability must come before return: keeping per-trade risk small is what pushes risk of ruin down toward negligible levels and keeps you in the game long enough for any edge to play out.
Two cautions are important. The figure is an estimate built on assumptions about win rate and payoff that may not hold in the future, and no setting reduces it to exactly zero. Past performance does not guarantee future results, no strategy is risk-free, and your capital is always at risk.
Why it matters: It connects per-trade risk to the ultimate danger - going bust - and shows why over-sizing a positive-edge strategy can still ruin it.
Risk of ruin is the ultimate downside; controlling it via small per-trade risk is non-negotiable.
Real-world example
Risking 10% per trade can produce a meaningful risk of ruin even on a winning strategy, simply because a streak can compound.
How SignalBots handles it
SignalBots' risk controls - per-trade caps, max trades, loss limits - exist to keep effective risk of ruin near zero. See /risk-warning.
Pro tip
Keep risk per trade low enough that risk of ruin is negligible; survivability comes before return, always.
Common pitfalls
Assuming a positive expectancy means you cannot blow up - over-sizing makes ruin likely regardless of edge.
Frequently asked questions
Can I have a winning strategy and still go broke?
Yes. Over-sizing a positive-edge strategy can still lead to ruin during a losing streak. Low per-trade risk is what keeps that probability negligible, but it can never reach exactly zero. Capital is at risk.
What is the biggest factor in risk of ruin?
How much you risk per trade. A high per-trade risk lets a losing streak compound into an unrecoverable loss, while a small per-trade risk keeps even a long streak survivable.
Can risk of ruin ever be exactly zero?
No. You can drive it very low with small per-trade risk and sensible limits, but trading always carries the possibility of loss. There is no risk-free strategy and no guarantee against ruin.
Does a high win rate protect me from ruin?
Only partly. A high win rate lowers the odds of long streaks but does not eliminate them, and if you risk too much per trade even a winning strategy can blow up during an unlucky run.
How do I keep risk of ruin negligible?
Keep per-trade risk small, set limits like maximum daily loss and maximum open trades, and avoid increasing size to chase back losses. Survivability should always come before chasing higher returns.
Trading involves substantial risk of loss. Historical and backtested results do not guarantee future performance. Read the full risk warning.