Direct answer
Maximum drawdown is the largest percentage decline from a prior peak to a later trough in an account’s equity (value) series. A worked example helps because you can compute it directly from assumed values, with every step and assumption stated.
Mechanism and definition
Assumptions for the example:
- “Equity” means account value over time (after costs are already reflected in the values).
- We use a simple discrete timeline with four recorded points.
- Maximum drawdown is computed as the maximum of (Peak-to-trough drawdown), where drawdown at a point equals (Trough − Peak) ÷ Peak.
- We express drawdown as a positive magnitude by taking the absolute value of the negative return.
Step-by-step mechanics:
- Step A: Identify each “peak” as the highest equity value seen so far up to each time point.
- Step B: For each time point, compute the percentage drawdown from the current peak to the current equity.
- Step C: The maximum drawdown is the worst (most negative) drawdown encountered across the whole series.
Evidence or worked example
Assumed equity series (no real-time data):
- Time 1: Equity = 10,000
- Time 2: Equity = 12,000
- Time 3: Equity = 9,000
- Time 4: Equity = 11,000
- Time 1
- Peak so far = 10,000
- Drawdown = (10,000 − 10,000) ÷ 10,000 = 0% (magnitude 0%)
- Time 2
- New peak = 12,000
- Drawdown = (12,000 − 12,000) ÷ 12,000 = 0% (magnitude 0%)
- Time 3
- Peak so far = 12,000
- Trough at Time 3 = 9,000
- Drawdown = (9,000 − 12,000) ÷ 12,000 = −3,000 ÷ 12,000 = −25%
- Maximum drawdown magnitude so far = 25%
- Time 4
- Peak so far remains 12,000 (because 11,000 is below 12,000)
- Drawdown = (11,000 − 12,000) ÷ 12,000 = −1,000 ÷ 12,000 ≈ −8.33%
- Worst drawdown remains −25% (magnitude 25%)
Result:
- Maximum drawdown for this assumed series = 25%.
How this “works” conceptually:
- The measure ignores how you got from 12,000 to 9,000 and focuses only on the largest peak-to-trough percentage fall within the provided sequence.
Limitations and risks
- Sampling and timing limitations
- If equity values are recorded infrequently, the true trough between samples can be missed. That can understate maximum drawdown.
- Peak definition depends on your chosen series
- Maximum drawdown depends on what “equity” series you use (e.g., different accounting for deposits/withdrawals or cost treatment). Different conventions can change the computed value.
- It does not describe recovery shape
- Two accounts can share the same maximum drawdown magnitude but differ in duration, volatility during recovery, or how quickly the equity returns to the peak.
- It does not guarantee future outcomes
- Historical or simulated drawdowns do not establish future performance. Market conditions and execution can change equity paths.
Verification or next question
You can independently verify the 25% result by recomputing each peak-to-trough drawdown from the same assumed equity points and confirming that the worst percentage decline occurs from the peak of 12,000 to the trough of 9,000.
A useful next question is: “How does the maximum drawdown change when the equity series is sampled more frequently (smaller time steps), or when deposits/withdrawals are treated differently?”