Sunday, May 26, 2019

Investor behaviour

May 27, 2019

Returns are almost never average
It seems rational to assume that stock and bond market returns would be clustered around the average with a few outliers. If we go back to 1926 we clearly see this is not the case. The average return for stocks during the 92-year period from 1926 to 2017 was 10.3%. How many times during those 92 years do you think the annual return fell between 8% and 12%? Incredibly, that only happened 6 times based on the chart below.

Why do investors underestimate their vulnerability to bias? 

Below are five (of many) possible explanations:
Overconfidence: Our belief that we are better than others is probably the most obvious explanation; this issue is exacerbated for professional investors as there is undoubtedly a selection bias into fund management roles toward those with exaggerated levels of confidence in their own capabilities.

Cognitive dissonance: Whilst the overconfidence explanation focuses on how we perceive ourselves relative to others, cognitive dissonance is focused on how we judge ourselves internally.

Too complex / too difficult: It may simply be a case that dealing with personal biases is too difficult.

Personal narratives: When objectively and dispassionately observing another person’s investment decisions it is often easy to identify the potential biases that are likely to be influencing their judgment.

The sales message: Perhaps the reticence of professional investors to engage with their own bias is related to a general reluctance to acknowledge mistakes.

None of these potential justifications are a reasonable excuse for understating our own behavioural limitations or failing to actively mitigate them. Given how few genuine edges are available in the investment industry, it is baffling that this one remains widely neglected.