As investors, I suspect we secretly like to think ourselves as a little bit more sensible than the average person, and maybe a bit more rational.
We don't live only for today, pretending there's no tomorrow. We realise we will get old, and that it makes sense to set aside money to better meet that future. Our heads are out of the sand and looking at the far horizon.
Nor do we stash our cash in savings accounts paying peanuts for interest, simply because we can't stand the ups and downs of the stock market. We understand that, over the long term, equities have been wealth-generation machines for those who can put up with their fluctuations.
Maybe we invest in index funds because we've read the data that says the average person - whether a DIY investor or a fund manager - can't beat the market. Instead, we focus on keeping costs low so we retain the biggest proportion of those long-run returns from shares for ourselves.
Or maybe we pick stocks - but we use our analytical minds to find better value companies and shun the fads and manias. Like Warren Buffett, we're sober investors in solid businesses - not gamblers at the casino.
It's a mad world
But should we feel so smug? Sure, we investors are more realistic than a spendthrift banking on lottery tickets to bail out their old age, but are we really Spock-like paragons of intellectual virtue?
Of course not - we're as nutty as anyone else, but in our own ways.
In fact, a whole branch of economics has come to the fore over the past few decades dedicated to unpicking the irrational forces lurking inside our oh-so-rational minds.
Nobel prize-winning economists such as Daniel Kahneman and Robert Shiller have used a mixture of experiments and data to prove investors are not the super-wise beings that classical economics once painted them as.
On the contrary, we're a bundle of contradictions and biases that, at the extreme end, have a tendency for what psychologists call "magical thinking", meaning we believe in relationships or outcomes that cannot be justified by reason.
A good example is anchoring. This is the tendency of investors to focus on a particular price of an asset - perhaps the price they first encountered or the price they paid to own it - when assessing its future value.
Why would I call this magical thinking? I think it's best explained by way of illustration.
Again and again, investors will tell you they're holding some share they've lost money on until they break even. Yet the price they happened to pay in the past for the share is irrelevant in terms of whether continuing to own it is the best investment now available to them.
The market doesn't know or care what price you paid for your shares. All that matters is the future value of the company (or more precisely the future cash flows it will generate) compared to the market price today.
Focusing on the price you paid for your shares makes no more sense than studying the bones of a chicken you roasted on Sunday for clues.
Yet we anchor on prices so routinely we don't even notice we're doing it.
Three of a kind
Behavioural economists have revealed many other distortions like this in our thinking. Here are three more:
Loss aversion - we humans hate losses more than we love gains. In practice, this means we over-value investments where we believe the downside risk is limited while under-valuing those with higher potential rewards. Kahneman demonstrates this to his students with a coin toss where they lose $10 if it's tails. Logically they should accept $20 as the win for it being a heads, but in practice they want more than $20.
Confirmation bias - this describes how we tend to look for evidence that supports our position. The latest GDP figures are strong, so we applaud our decision to buy shares in a bank. But when worse-than-expected unemployment data is released, we whistle to ourselves and decide our fingernails need a trim.
Recency bias - people extrapolate what's happened lately to presume it will continue indefinitely. Recency bias is why people are so gloomy about shares after a crash, when they're actually being offered investments they know they want to own at a much cheaper price than before. But why buy, they think, if shares are just going to keep falling? The same thing happens in bull markets, only then it is presumed the good times will keep on rolling.
Let off for bad behaviour
Are you now blushing at the memory that in 2012 you bought shares in a small-cap oil explorer because such shares had risen strongly for years (recency bias), you kept ignoring warnings that an oil price over $100 was unsustainable to instead concentrate on stories about how peak oil was upon us (confirmation bias), didn't sell your shares when they halved before halving again (loss aversion) and are now determined to hang on until they finally get back to the price you paid for them (anchoring) after conveniently multi-bagging for you?
Well, don't be too hard on yourself. As I said, these behavioural glitches are universal and we've all done similar. Once we're aware of them we can try to be on our guard, but I doubt you can be an active investor without continuing to fall foul now and then.
Instead of getting angry, though, maybe you can get even? Look out for situations where other investors may be falling prey to their emotions and faulty thinking.
Just remember that as the physicist Richard Feynman said: "The first principle is not to fool yourself. And you are the easiest person to fool".
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