Drawdown（回撤）
Drawdown measures the decline from a prior peak to a subsequent value in a selected return or wealth series. Maximum drawdown is the largest observed peak-to-trough decline in that sample; it is path-dependent and does not establish a maximum future loss.
Why It Matters
Drawdown is the most psychologically important risk metric because it reflects the actual pain investors experience. While standard deviation measures volatility in the abstract, drawdown answers the visceral question: "How much did I actually lose from my highest point?" A 50% drawdown doesn't just halve your wealth — it shakes your confidence, tempts you to sell at the bottom, and takes years to recover. Studies show that investors who experience drawdowns exceeding 25% are significantly more likely to abandon their investment strategy.
The mathematics of recovery are asymmetric and brutal. After a 30% loss, you need a 43% gain to break even. After a 50% loss, you need to double your money. After an 80% loss — which many tech stocks experienced in 2000-2002 — you need a 5x return. This asymmetry is why professional risk management focuses on limiting drawdowns rather than maximizing returns. A strategy that makes 20% annually with 50% drawdowns is far worse than one making 12% with 15% drawdowns, because the former's recovery periods destroy compounding.
Real-World Example
Tesla (TSLA) is a textbook example of extreme drawdowns. In 2022, Tesla stock fell from its November 2021 peak of approximately $414 to around $101 in January 2023 — a drawdown of roughly 75%. Investors who bought near the peak needed Tesla to triple from the bottom just to break even. By mid-2025, Tesla recovered to above $300 but still hadn't fully reclaimed its all-time high.
Compare this with Microsoft (MSFT), which experienced a maximum drawdown of about 37% during the same 2022 period (from ~$370 to ~$213). Microsoft recovered to new all-time highs by early 2024. The difference illustrates why drawdown management matters: smaller drawdowns recover faster, allowing compounding to resume sooner. This is why many institutional investors cap maximum drawdown at 15-20% — beyond that, the math of recovery becomes too punishing.
Common Mistakes
- Ignoring recovery math: Many investors think a 30% loss needs a 30% gain to recover. In reality, it needs 43%. This misconception leads to underestimating the damage of deep drawdowns and taking excessive risk.
- Focusing only on maximum drawdown: The largest drawdown tells you the worst case, but frequency and duration of drawdowns matter too. A strategy with a 15% max drawdown that spends 60% of the time underwater may be worse than one with a 25% max drawdown that recovers quickly.
- Using drawdown in isolation: Drawdown must be paired with return. A 20% drawdown is unacceptable for a bond fund making 3% annually, but entirely reasonable for a growth stock strategy returning 25% per year. Always consider the Calmar ratio (return ÷ max drawdown).
- Looking at asset drawdown instead of portfolio drawdown: Individual stock drawdowns of 40-60% are normal. What matters is your total portfolio drawdown, which diversification should keep much lower.
Pro Tips
Set a personal "circuit breaker": Before investing, define your maximum tolerable drawdown (e.g., 20%). If your portfolio hits that level, automatically reduce equity exposure by 30-50%. This removes emotional decision-making during crashes.
Track drawdown duration, not just depth: The S&P 500's 2000-2002 drawdown lasted 2.5 years, and recovery took another 4 years. The 2020 COVID drawdown was 34% but recovered in just 5 months. Short, deep drawdowns are far less damaging than prolonged shallow ones because of opportunity cost.
Frequently Asked Questions
How is drawdown calculated?
At each point, compare the current value with the highest prior value in the selected series. Drawdown = current value ÷ prior peak − 1. Results depend on data frequency, valuation method, fees, cash flows, and the analysis window.
What is maximum drawdown?
Maximum drawdown is the largest observed decline from a prior peak to a later trough within the selected sample. It is a historical statistic, not a forecast or guaranteed loss limit.
Why does recovery require more than the percentage lost?
Because gains and losses compound from different bases. A 50% decline requires a 100% gain from the trough to return to the prior peak, before fees, taxes, withdrawals, or additional contributions.
Can drawdown compare strategies?
Only with consistent return definitions, frequency, fees, leverage, cash-flow treatment, currency, and sample periods. A strategy with a mild historical drawdown can still experience a larger future decline.