What it is — Risk of Ruin
Risk of ruin is the probability that losses compound far enough to end the game — a blown account, a breached prop limit, or a drawdown so deep the plan is abandoned. It is not a mood; it is arithmetic. Risk too much per trade and ruin becomes likely even with a positive expectancy, because a bad streak only has to hit once at the wrong size.
Why it matters — Risk of Ruin
A strategy that wins 55% of the time still strings six, seven, eight losses together regularly over hundreds of trades. At 1% risk a drawdown of 8% is survivable; at 10% risk the same streak removes most of the account. The market does not know your win rate, so the sequence of losses is not an emergency — it is a schedule.
One worked example
A coin-flip system with a 1.5 reward-to-risk ratio is profitable over time. Risking 20% per trade, a run of four losses leaves about 41% of the account. The next winner gains 30% of what is left, not 30% of what you had. That asymmetry — losses compounding against you — is the engine of ruin. At 2% risk the same four losses cost 8% and the maths barely notices.
Where it misleads
Ruin is not only total wipeout. It is also the point where recovery becomes unrealistic: a 50% drawdown needs a 100% gain just to return to square one. Many traders quietly pass that point months before the account hits zero. And win-rate estimates from small samples understate the tail — ruin is a tail story.
Frequently asked questions — Risk of Ruin
What risk per trade keeps ruin near zero?
For most retail accounts, 0.5% to 2% per trade. At these sizes even historic drawdowns stay recoverable and the plan survives the bad months.
Does a higher win rate lower risk of ruin?
It helps, but size is the dominant lever. Cutting risk does more for survival than adding a few points of win rate ever will.
Related terms — Risk of Ruin
Related tools — Risk of Ruin
🧠 Test yourself: this term appears in the Glossary Quiz — 10 random questions, instant explanations, no sign-up.
Terms · Privacy · Editorial Policy · Affiliate Disclosure · Risk Disclaimer · Contact