Measuring risk

Returns get the headlines, but risk decides whether an investor can actually stay the course, and the exam measures it with two specific numbers. The first is standard deviation, which captures total volatility, how widely a fund’s returns spread around their average. A fund with a standard deviation of 20 swings far more than one at 8, even if both finish the year up the same amount; the higher number simply means a rougher ride, and a rougher ride is what makes nervous investors sell at the bottom. Crucially, standard deviation captures all sources of swing, both market-wide moves and the fund’s own stock-specific wobbles.

The second number is beta, which measures how much a fund moves relative to the market. A beta of 1 means it moves roughly in step; a beta above 1 amplifies market moves and one below 1 dampens them. Put a number on it and it becomes intuitive: a beta of 1.2 means that when the market moves 10%, the fund tends to move about 12%, up or down. The key contrast with standard deviation is scope: beta captures only market-linked (systematic) risk, the part you cannot diversify away, while standard deviation captures the total. Around these two sit the familiar risks a fund carries, market, credit, interest-rate, liquidity and concentration, but when the exam asks you to measure risk, it almost always means one of these two numbers.