Maximum Drawdown: A Different Way to Measure Risk

Standard deviation tells you how bumpy an investment's ride typically is, on average — maximum drawdown asks a genuinely different, more visceral question: what's the single worst stretch this investment has actually put an investor through, from its highest point to its subsequent lowest point, before a new high was eventually reached? Maximum drawdown is calculated as a percentage decline — if an investment peaked at $100 and later fell to $60 before recovering, that's a 40% maximum drawdown, regardless of how long the decline took or how it compares to the investment's average day-to-day variability.

This is a genuinely complementary, not redundant, measure alongside standard deviation. Standard deviation captures the TYPICAL degree of variability across an investment's entire return history — a statistical average. Maximum drawdown captures the single worst REALIZED outcome an actual investor would have lived through, regardless of how statistically typical or atypical that specific episode was. Many investors find maximum drawdown a more intuitively meaningful risk measure precisely because of this concreteness: "this investment has, at its worst point in history, fallen 45% from a prior peak" maps much more directly onto how people actually experience and remember a bad investment period than a more abstract statistical concept like standard deviation does.