Underwater Curve

The underwater curve (also called the drawdown curve) is one of the most informative single-chart summaries of a strategy's risk character. Unlike the equity curve (which compounds both return and drawdown into a hard-to-decompose growth line) and unlike the max drawdown number (which collapses path-dependent risk into a scalar), the underwater curve preserves the shape of when and how the strategy loses ground.

Construction: for each point in time, compute equity_at_t ÷ max_equity_up_to_t − 1. The result is always ≤ 0 — at new equity highs it equals 0 (the account is at peak); during drawdown periods it descends to the current percentage below peak; recovery back to new highs returns it to 0.

What the curve shape reveals:

• **Frequency of new highs**: a curve that touches 0 frequently indicates a strategy that recovers quickly; one that stays underwater for months reflects either weak edge or path-dependent regime sensitivity • **Depth distribution**: a curve oscillating between 0 and -5% reflects mild risk; one oscillating between -10% and -25% reflects substantially higher risk despite potentially the same nominal max drawdown • **Underwater duration**: the longest period spent below water without making a new high — strategies with 8+ month underwater periods test trader patience even if they recover • **Recovery time after worst drawdown**: how many months to climb back from the deepest point to a new high; strong strategies recover in 3-6 months, weak ones take 12-24

The headline "max drawdown" number compresses all of this into a single percentage. Two strategies with identical 18% max drawdown can have completely different underwater curves — one might spend 80% of its time at new highs with rare 18% spikes; the other might spend 30% of its time at new highs and average -12% drawdown across the remaining 70%. The first is a tolerable safety-tier candidate; the second is psychologically untradeable for most retail audiences.

For EA evaluation, examining the underwater curve is more diagnostic than reading the max-drawdown headline. Vendors publishing only the headline number — without an underwater curve view — are presenting incomplete risk information. The reputable verification platforms (MyFXBook, MQL5 Signals) all display the underwater curve as a standard view.

Practical buyer workflow: on the verification platform, navigate to the equity-curve view and switch to underwater or drawdown visualisation. Look for: time spent at 0 (better is higher), depth of typical excursions (closer to 0 is better), recovery duration after deepest drawdown (faster is better), and frequency of revisiting the deepest 25% of the underwater range (less frequent is better).