30 years of experience.
Every type of investor.
One pattern stands out.
It doesn't start as a mistake. It starts as a small adjustment. Reasonable, cautious. A position is moving against you. The original reasoning was sound — the market simply hasn't agreed yet. So you hold a little longer. Or you reduce slightly to manage the discomfort. Or you tell yourself you'll revisit the thesis when things settle.
These are not dramatic errors. They are small deviations from a sound process. Individually, they seem insignificant. But they are the moment the process broke — and once the process breaks, what follows is no longer analysis. It is rationalisation.
The difficulty is that it feels reasonable while it's happening. That is precisely what makes it so costly, and so persistent.