What Is a Maximum Drawdown (MDD)?
Let me explain what maximum drawdown, or MDD, really is. It's the biggest drop an investment experiences from its highest point to its lowest, before it climbs to a new high. As someone analyzing investments, I see MDD as a clear sign of downside risk over a set period, pointing out how volatile a stock might be. You can use it on its own or plug it into other metrics like Return over Maximum Drawdown or the Calmar Ratio.
Key Takeaways
- A maximum drawdown highlights an investment’s most severe historical loss.
- Maximum drawdown is considered to be an indicator of downside risk, with large MDDs suggesting that down movements could be volatile.
- While MDD measures the largest loss, it does not account for the frequency of losses, not the size of any gains.
Formula for Maximum Drawdown
Here's the straightforward formula for MDD: MDD = (Trough Value - Peak Value) / Peak Value. This calculation gives you the percentage decline directly.
Understanding Maximum Drawdown
When I look at maximum drawdown, it's specifically about the biggest drop from a peak to a trough before hitting a new peak. Remember, it only captures the size of that largest loss—it doesn't factor in how often big losses happen. Also, it won't tell you how long recovery took or if the investment even bounced back at all.
I use MDD to compare the riskiness of different stock screening strategies, especially since it emphasizes preserving capital, which matters to most investors. For instance, two strategies might match in average performance, tracking error, and volatility, but their MDDs against a benchmark could differ sharply.
You want a low MDD because it means losses were minimal. If an investment never drops, MDD is zero. The absolute worst is -100%, where it's worth nothing.
To get the most from MDD, consider the time frame carefully. Take a hypothetical U.S. fund Gamma existing since 2000 with a -30% MDD by 2010. That sounds bad, but the S&P 500 fell over 55% from October 2007 to March 2009. From an MDD standpoint, Gamma beat its benchmark significantly, though you'd check other metrics for a full picture.
Example of Maximum Drawdown
Let's walk through an example to make this clear. Suppose your portfolio starts at $500,000, grows to $750,000, then crashes to $400,000 in a bear market. It rebounds to $600,000, drops again to $350,000, and finally climbs to $800,000. What's the MDD?
The MDD here is ($350,000 - $750,000) / $750,000 = -53.33%.
Pay attention to these details: We use the initial peak of $750,000 for the calculation—the $600,000 interim peak doesn't count as it's not a new high. The later $800,000 peak isn't used either, since the drawdown started from $750,000. And we consider the absolute lowest point of $350,000 before any new peak, not just the first drop to $400,000.
