Regardless of institutional or retail investors, chances are, they would have committed these sins at one point or another.
1) Placing forecasting at the very heart of the investment process.
An enormous amount of evidence suggests that investors are generally hopeless at forecasting. So using forecasts as an integral part of the investment process is like tying one hand behind your back before you start.
2) Investors seem to be obsessed with information.
Instead of focusing on a few important factors (such as valuations and earnings quality), many investors spend countless hours trying to become experts about almost everything. The evidence suggests that in general more information just makes us increasingly over-confident rather than better at making decisions.
3) The insistence of spending hours meeting company managements
We arent good at looking for information that will prove us to be wrong. So most of the time, these meetings are likely to be mutual love ins. Our ability to spot deception is also very poor, so we wont even spot who is lying.
4) Fourthly, many investors spend their time trying to ‘beat the gun’ as Keynes put it.
Effectively, everyone thinks they can get in at the bottom and out at the top. However, this seems to be remarkably hubristic.
5) Many investors seem to end up trying to perform on very short time horizons and overtrade as a consequence.
The average holding period for a stock on the NYSE is 11 months! This has nothing to do with investment, it is speculation, pure and simple.
6) We all appear to be hardwired to accept stories.
However, stories can be very misleading. Investors would be better served by looking at the facts, rather than getting sucked into a great (but often hollow) tale.
7) Many of the decisions taken by investors are the result of group interaction.
Unfortunately groups are far more a behavioural panacea. In general, they amplify rather
than alleviate the problems of decision making.