Maximum Drawdown: Measuring How Bad Losses Get

Key Takeaways

• Maximum drawdown is the deepest peak-to-trough loss recorded over a given window; the S&P 500's maximum drawdown in the 2008–2009 crisis was roughly 55%.
• Drawdown recovery is asymmetric: a 50% loss requires a 100% gain to get back to breakeven, not a 50% gain.
• Many investors ignore time-under-water (duration), but a 20% drawdown that lasts four years is far more damaging behaviorally than one that recovers in three months.
• Maximum drawdown that looks small on a short or calm sample understates true strategy risk; always check that the sample includes at least one adverse market regime.

What It Is

A drawdown tracks how far an investment has fallen from its most recent high-water mark. If a portfolio climbs from $100 to $120 and then slides to $90, the current drawdown is 25 percent, measured from the $120 peak. Portfolios experience many drawdowns over their lifetime. Most are small. A few are memorable.

Maximum drawdown, often abbreviated MDD, is the single deepest peak-to-trough decline recorded over a given window. For the S&P 500, the maximum drawdown across the 2007 to 2009 period was roughly 55 percent. That one number captures the worst experience an investor holding the index would have lived through during that stretch.

The Intuition

Volatility numbers and standard deviations can feel abstract. Drawdown does not. It is the loss a real investor saw on a real account statement. Two portfolios can have identical average returns and identical standard deviations and still feel completely different to hold, because one hit a 15 percent drawdown and the other hit a 50 percent drawdown.

Drawdown also speaks to a behavioural truth: people sell at the bottom. A strategy that looks excellent on paper but puts the holder through a 60 percent underwater period is a strategy most humans cannot stick with. Knowing the worst historical drawdown helps you estimate whether you would actually stay invested through the next one.

CFA Institute research notes that mutual fund drawdowns tend to be persistent and carry information about manager skill, which is part of why institutional investors pay close attention to the metric.

How It Works

Drawdown at any point in time is computed from the running peak of the equity curve.

drawdown_t = (equity_t - running_peak_t) / running_peak_t

Where running_peak_t is the maximum equity value observed up to and including time t. Drawdown is zero at every new high and negative everywhere else. Maximum drawdown is the minimum (most negative) value of that series over the sample window.

Plotting drawdown_t over time produces an underwater chart. It sits at 0 percent at every high and dips below whenever the portfolio is off its peak. Wide, deep valleys on the underwater chart are the periods an investor would remember.

Two metrics matter, not one:

• Depth. How far below the peak the portfolio fell. The headline number.
• Duration, or time-under-water. How long the portfolio spent below the previous high before setting a new one. A 20 percent drawdown that recovers in three months hurts far less than a 20 percent drawdown that takes four years to climb back.

Depth answers "how bad was it." Duration answers "how long did it suck." Both belong in any honest performance report.

Worked Example

Drawdowns are asymmetric in a way that surprises beginners. A loss and the matching recovery are not the same percentage.

Start at $100. Suffer a 50 percent drawdown. You now have $50. To get back to $100, you need to gain $50 on a base of $50. That is a 100 percent return, not 50 percent.

The pattern generalises:

required recovery = 1 / (1 - drawdown) - 1

A 10 percent drawdown needs an 11.1 percent gain to recover. A 20 percent drawdown needs a 25.0 percent gain. A 30 percent drawdown needs a 42.9 percent gain. A 50 percent drawdown needs a 100 percent gain. A 75 percent drawdown needs a 300 percent gain.

This convexity is why capital preservation dominates. Small drawdowns are easy to climb out of. Large ones can take a decade. The Nikkei 225 hit roughly a 80 percent drawdown from its 1989 peak and did not reclaim that level until 2024, a time-under-water measured in decades.

Frequently Asked Questions

Q: What is maximum drawdown in simple terms? Maximum drawdown is the biggest drop from a portfolio's high-water mark to its subsequent low over a chosen period. If a portfolio hit $120 then fell to $90, the drawdown is 25%. Maximum drawdown is the worst such decline in the full history.

Q: How does maximum drawdown affect investment decisions? Investors use it to check whether a strategy is psychologically survivable. A strategy with a 60% historical drawdown is one most people will abandon at the bottom, destroying the long-run return even if the math looks good on paper. It also anchors position sizing in risk budgeting.

Q: What is a real-world example of maximum drawdown? The Nikkei 225 hit roughly an 80% maximum drawdown from its 1989 peak and did not reclaim that high until 2024, a time-under-water measured in decades. Knowing this number before investing changes the decision entirely.

Q: How can investors use maximum drawdown to compare strategies? The Calmar ratio divides annual return by maximum drawdown, giving a reward-per-unit-of-drawdown number for direct comparison. Always require the same time window across strategies being compared, since a shorter window almost always produces a smaller maximum drawdown.

Q: How is maximum drawdown different from standard deviation? Standard deviation measures average day-to-day volatility. Maximum drawdown measures the worst-case cumulative experience an investor actually lived through. A strategy can have low volatility for years and then print a severe maximum drawdown in a single crisis month.

Common Mistakes

1. Quoting maximum drawdown without the time window. MDD measured over one year will almost always be smaller than MDD measured over twenty years. A strategy advertised as "MDD of 12 percent" means nothing until you know whether that was over a quiet three-year sample or a full market cycle that includes a real bear market.

2. Ignoring time-under-water. Two strategies can share a 25 percent maximum drawdown. One recovers in six months. The other stays underwater for five years. They are not equivalent, and any evaluation that only cites depth is incomplete.

3. Confusing depth with probability. Maximum drawdown tells you how bad the worst observed event was. It does not tell you the odds of seeing something that bad, or worse, going forward. Future drawdowns can exceed the historical maximum, especially for strategies tested only in calm regimes.

4. Forgetting the asymmetric recovery math. Many retail investors think a 40 percent loss needs a 40 percent gain to recover. The real number is 66.7 percent. This error leads people to underestimate how damaging a large drawdown really is.

5. Measuring drawdown at the wrong frequency. Daily data produces deeper drawdowns than monthly data because intraday lows get captured. Comparing a daily-measured MDD against a monthly-measured MDD is not an apples-to-apples comparison. Use the same frequency across the strategies you compare.

6. Assuming recent calm means low future drawdown. Strategies with long benign histories often hide tail risk. Short-volatility, carry-trade, and selling-insurance strategies can show tiny drawdowns for years and then print a catastrophic one in a single month. February 2018 and March 2020 are textbook examples.

Sources

1. Corporate Finance Institute. "Drawdown." https://corporatefinanceinstitute.com/resources/career-map/sell-side/capital-markets/drawdown/
2. Corporate Finance Institute. "Maximum Drawdown." https://corporatefinanceinstitute.com/resources/career-map/sell-side/capital-markets/maximum-drawdown/
3. CFA Institute. "Maximum Drawdown as Predictor of Mutual Fund Performance and Flows." Financial Analysts Journal, 2022. https://rpc.cfainstitute.org/research/financial-analysts-journal/2022/maximum-drawdown-as-predictor-of-mutual-fund-performance-flows
4. CFA Institute Blogs. "Sculpting Investment Portfolios: Maximum Drawdown and Optimal Portfolio Strategy." https://blogs.cfainstitute.org/investor/2013/02/12/sculpting-investment-portfolios-maximum-drawdown-and-optimal-portfolio-strategy/
5. RCM Alternatives. "The 2 Important Drawdown Measurements: How Deep, How Long?" https://www.rcmalternatives.com/2013/10/the-2-important-drawdown-measurements-how-deep-how-long/

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.