Ask a trader how they're doing and they'll tell you their win rate or their total P&L. Ask them about their maximum drawdown and most will pause — either because they don't track it or because they'd rather not think about it. Maximum drawdown (MDD) is arguably the single most important risk metric in trading, and it's the one most traders ignore until it's too late. ## What Is Maximum Drawdown? Maximum drawdown measures the largest peak-to-trough decline in your account value before a new peak is reached. In simple terms: it's the biggest hole you've dug. ### The Formula ``` Drawdown at time t = (Peak Value - Current Value) / Peak Value × 100 Maximum Drawdown = The largest drawdown across the entire period ``` ### Example Your account moves like this: | Day | Account Value | Running Peak | Drawdown | |-----|--------------|-------------|----------| | 1 | $10,000 | $10,000 | 0% | | 2 | $10,500 | $10,500 | 0% | | 3 | $10,200 | $10,500 | -2.9% | | 4 | $9,800 | $10,500 | -6.7% | | 5 | $9,500 | $10,500 | **-9.5%** | | 6 | $9,900 | $10,500 | -5.7% | | 7 | $10,600 | $10,600 | 0% (new peak) | | 8 | $10,100 | $10,600 | -4.7% | **Maximum drawdown**: -9.5% (occurred on day 5) Even though the account ended higher than it started, there was a point where it was down 9.5% from its peak. That's the number that matters. ## Why Maximum Drawdown Matters More Than Win Rate Here's a thought experiment: **Trader A**: 60% win rate, +$5,000 over 6 months, maximum drawdown of 8% **Trader B**: 55% win rate, +$8,000 over 6 months, maximum drawdown of 45% Most beginners would prefer Trader B's results — more profit. But professionals would take Trader A every time. Here's why: 1. **Drawdown determines survival.** A 45% drawdown means Trader B was at one point nearly half underwater. One more bad streak could have wiped them out. 2. **Recovery from drawdown is non-linear.** The math of drawdown recovery is brutally asymmetric: | Drawdown | Gain Needed to Recover | |----------