Risk in investing has multiple dimensions that no single metric captures fully. Volatility measures dispersion of returns -- how widely the stock tends to swing around its average. Beta measures market sensitivity -- how much the stock tends to move when the market moves. Maximum drawdown measures the worst observed peak-to-trough decline -- the actual capital loss an investor would have experienced in the hardest period. VaR (Value at Risk) estimates the expected loss at a given confidence interval over a specified horizon. These are different lenses on the same underlying risk question: how much can I lose, under what conditions, and over what timeframe? Using them in combination produces a substantially more complete picture than relying on any one alone.

The Sharpe ratio divides a stock's excess return (return above the risk-free rate) by its standard deviation. It answers: how much return did I receive per unit of volatility risk? A Sharpe above 1.0 is generally considered acceptable; above 2.0 is strong. But the Sharpe ratio has critical limitations -- it penalizes upside volatility equally with downside volatility, which is not how investors experience risk psychologically or economically. The Sortino ratio is a refinement that only penalizes downside volatility (returns below a target threshold), making it more appropriate for evaluating asymmetric risk profiles. A high Sharpe with a significantly lower Sortino indicates the return profile has significant downside volatility that the Sharpe is masking.

Beta is a historical regression coefficient, not a fixed property of a stock. A stock's beta can shift substantially across market regimes: low-beta defensive stocks can exhibit high beta during panics (when correlations spike and everything falls together), and high-beta growth stocks can exhibit low beta in range-bound, low-volatility environments. The practical use of beta is regime-dependent position sizing -- in elevated-risk environments, reducing high-beta exposure defensively before the market moves against you is more valuable than reacting after the fact. A portfolio's aggregate beta should be explicitly managed as a function of conviction about the market regime, not simply left to accumulate.

Maximum drawdown is the most viscerally honest risk metric because it reflects what you would have actually experienced as a holder through the worst period in the observable history. A stock with 15% annualized volatility and a 45% maximum drawdown is structurally different from one with the same volatility and a 20% maximum drawdown: the first stock had concentrated periods of severe loss that the annualized volatility number conceals. The drawdown recovery time -- how long it took price to return to the prior peak after the trough -- is equally important. A 40% drawdown that recovered in three months is different risk from a 30% drawdown that took three years to recover.