How investors get risk wrong

Hire a wealth manager, and one of their first tasks will be to work out your attitude to risk. If you are not sure exactly what this means, the questions are unlikely to help. They range from the inane (“How do you think a friend who knows you well would describe your attitude to taking financial risks?”) to the baffling (“Many television programmes now have a welter of fast whizzing images. Do you find these a) interesting; b) irritating; or c) amusing but they distract from the message of the programme?”). This is not necessarily a sign that your new adviser is destined to annoy you. Instead, it hints at something fundamental. Risk sits at the heart of financial markets. But trying to pin down precisely what it is, let alone how much of it you want and which investment choices should follow, can be maddening.

To get around this, most investors instead think about volatility, which has the advantage of being much easier to define and measure. Volatility describes the spread of outcomes in a bell-curve-like probability distribution. Outcomes close to the centre are always the most likely; volatility determines how wide a range counts as “close”. High volatility also raises the chances of getting an extreme result: in investment terms, an enormous gain or a crushing loss. You can gauge a stock’s volatility by looking at how wildly it has moved in the past or, alternatively, how expensive it is to insure it against big jumps in the future.