AlphaTRADER Academy
Risk of Ruin
Most accounts don't blow up from one bad trade. They blow up from a normal losing streak — variance the trader didn't sized for. Risk of ruin is the math that tells you how likely it is, given your numbers.
"In trading, you don't need to be right. You need to survive long enough for being right to pay off." — paraphrasing Ed Seykota
Expectancy First, Sizing Second
Position sizing only matters if your system has positive expectancy. A losing system at 0.1% risk still bleeds out — slower, not safer. Compute expectancy before opening this calculator.
Expectancy = (WinRate × AvgWin) − (LossRate × AvgLoss)
Example: 50% win rate, 2:1 R:R, risking 1R per trade → expectancy = (0.5 × 2R) − (0.5 × 1R) = +0.5R per trade. Trade 100 times = +50R expected gain. That's an edge. Now sizing protects it.
No edge? No amount of "smart sizing" saves you. Backtest, paper trade 100+ setups, prove the edge, THEN size it.
Risk of Ruin Simulator
Monte Carlo across simulated account paths.
Adjust the four inputs below. The simulator runs account paths of trades each. Ruin = equity drops below 50% of starting balance at any point.
Click Run simulation to see the results. First run is instant; re-runs slightly vary due to randomness.
How to Read These Numbers
Risk of Ruin < 5%
Survivable. Positive expectancy compounds over time. You can withstand normal variance. This is where professional risk profiles sit. Discipline + patience = capital growth.
Risk of Ruin 5-15%
Marginal. Survives the average case but a bad year breaks the system. Either reduce risk per trade, or work on win rate / R:R until ROR drops. Common zone for "experienced" retail traders who don't know their numbers.
Risk of Ruin > 15%
Gambling, not trading. Even with positive expectancy, the variance kills you before the edge plays out. Don't run live capital at these numbers. Cut risk per trade until ROR is below 5%, even if profits look "boring".
Three Levers, Three Trade-offs
You have only three knobs to reduce risk of ruin. Each has a cost:
Win rate ↑
More winners = fewer losing streaks. But chasing higher win rate often means tighter targets and worse R:R.
Lever cost: smaller average win.
R:R ratio ↑
Bigger winners survive longer losing streaks. Cost: wider targets get hit less often → win rate drops.
Lever cost: lower win rate.
Risk per trade ↓
Smallest exposure = smallest blowup risk. Cost: slower compounding, "boring" P&L curve.
Lever cost: capital grows slower.
The asymmetry: a 2x increase in risk per trade roughly squares the risk of ruin. A 2x increase in win rate roughly halves ruin probability. Cutting risk is the cheapest lever to pull.
Different on Prop vs Personal Account
Risk of ruin math is universal, but acceptable ROR differs by account type. Prop firm accounts: target sub-1% ROR because contractual max-DD breach = account closed. Personal accounts: sub-5% ROR acceptable if you can stomach drawdowns.
Full breakdown of constraints, sizing, and mindset differences: Prop Firm vs Personal Account — Risk Management Compared
Key Takeaways
- Positive expectancy is non-negotiable. No sizing strategy saves a losing system.
- 1-2% risk per trade is the standard for a reason — risk of ruin stays sub-5% across most reasonable edges.
- Variance produces losing streaks even on profitable systems. A 50% win rate system will show 10+ losses in a row roughly once per 1000 trades.
- Set daily and weekly loss caps (3-4× per-trade risk daily; 10× weekly). Hit them → stop trading. Variance returns next week, blown accounts don't.
- Re-compute risk of ruin every quarter using your real numbers. Your edge changes with market regime — your sizing should respond.
Test Your Understanding
4 questions — instant feedback, no scoring stored.