The mathematical probability that your account will be wiped out before your strategy's edge has time to play out — the closer to zero, the better.
Risk of ruin is the probability that your account will hit zero (or some "ruin" threshold like -50%) before your strategy's edge can play out. It depends on three things: win rate, average reward-to-risk, and risk per trade. Lower risk per trade = lower risk of ruin. Higher edge = lower risk of ruin.
The insight is sobering. Even a winning strategy can blow up if you size too big. A 55% win rate with 1.5R wins and 5% risk per trade has about a 5% risk of ruin — meaning 1 in 20 traders following the same strategy goes bust. At 1% risk per trade, the same strategy's risk of ruin drops to nearly zero.
Risk of ruin is the mathematical reason why position sizing matters more than entry timing. Get sizing wrong and even great entries can't save you. Get sizing right and even mediocre entries compound into wealth.
The 1998 LTCM blowup was a textbook risk-of-ruin failure — Nobel laureates running a strategy with positive expectancy but catastrophically high leverage. The edge didn't matter once the position sizing failed.
Frequently asked about risk of ruin
What is a risk of ruin in trading?+
The mathematical probability that your account will be wiped out before your strategy's edge has time to play out — the closer to zero, the better.
When will I see risk of ruin used in real trading?+
In serious quant trading discussions, prop firm risk training, and Kelly Criterion calculations.
What is the most common mistake traders make with risk of ruin?+
Believing positive expectancy alone is enough. It's not — you also need survivable sizing. A winning system traded with reckless size will still blow up before the edge plays out.
What do experienced traders know about risk of ruin that beginners don't?+
Always calculate risk of ruin for your strategy before going live. Free calculators online will do this in 30 seconds. If the number is above 1%, your sizing is too aggressive — cut it.
Read the lesson here. Mark the chart on TradingView. Compare brokers with the checklist.
TradingView is the chart workspace most learners already recognize: watchlists, alerts, drawings, and clean multi-market charts. Broker research stays methodology-first: jurisdiction, costs, platform, withdrawals, and risk before any account decision.