The classic, though now dated, ‘right answer’ to the job interview question, “what is your biggest weakness?” is to say that you are a perfectionist. The thinly-veiled subtext is that perfectionism is actually a strength, though perhaps one that has been taken a bit too far: “I’m just so focused on making sure I get everything right all the time that sometimes I work too hard (sigh).”

Of course, attempting to achieve the unachievable can lead to harmful outcomes for you and those around you. But there is more to it than that. The underlying drivers of perfectionism affect pretty much everyone and can interfere with your ability to make rational decisions. In investing, where so much is about maintaining Spock-like rationality, this is probably one of the most common and important psychological issues investors face.

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