Who it's for — For those who believe winning big is more important than not losing. In the world of mathematical investing, "blowing up" is the true and only definitive defeat.
The Risk of Ruin (RoR) is the statistical probability of wiping out your trading account (or bringing it down to a level so low that recovery is impossible), due to a normal series of losing trades (losing streak).
The entire discipline of Risk Management has one giant purpose: Keep the Risk of Ruin at 0% (absolute zero).
In simple terms — Imagine playing Russian roulette. The Risk of Ruin is 1 in 6 (16.6%). The chances of surviving the first round are high (83%). But if you play long enough, the Risk of Ruin will materialize and the game will end forever. In trading, if you risk too much on every trade, or if your system is inherently losing, playing long enough guarantees mathematical failure.
The variables of ruin
The Risk of Ruin spikes if you do not respect the balance between these three factors:
- Risk per Trade (%): If you risk 5% or 10% per trade, the RoR skyrockets, even if you have a great system.
- Win Rate (%): How often you are right. If it is very low, you need a huge R/R to survive.
- Risk/Reward Ratio: How much you make when you are right. If you risk 1 to make 0.5, sooner or later ruin will mathematically arrive.
Underestimating losing streaks
Human beings are terrible at calculating probabilities. Do you think losing 10 trades in a row is "impossible" if you have a 50% Win Rate? Wrong. Out of a sample of 500 or 1,000 trades, a streak of 8, 9, or 10 consecutive losses is not an anomaly: it is a statistical certainty. If your risk per trade is 5-10%, that "inevitable" streak will destroy your account forever. If your risk is 1%, you will take a boring -10% and move on.
Summary Sheet
- The lethal equation: Excessive Size + No Stop Loss + Tilt = 100% Risk of Ruin.
- Golden Rule: If a system has even a 0.01% Risk of Ruin over the long term, that system MUST NOT be traded. You don't mess with infinity.
Links
- capital — What the Risk of Ruin aims to destroy.
- drawdown — The critical phase approaching ruin.
- bronze-path
Module: Module 4 — Risk before profit
The first skill of a trader is survival.
