Trading Biases
Why is the plan easiest to abandon at exactly the moment it matters most?
The idea
FOMO, loss aversion, confirmation bias, recency, and the disposition effect can override a written plan.
In the real world
A trader holds a loser to avoid admitting error and sells a winner too early.
Going deeper
The pressures that break a plan arrive together and each feels like judgement rather than emotion at the time. That is what makes them effective.
The disposition effect is the clearest: realising a loss makes an error concrete, so it is deferred, while banking a gain feels like locking in success. Both preserve comfort at the cost of the plan, and the second is the more expensive, because capping winners removes the outsized results that pay for the losers. Written rules exist precisely because they were decided when none of this pressure was present.
Where it stops applying
Rules mechanically followed can be wrong when circumstances genuinely change. The discipline is that deviations should be reasoned and recorded, not that rules are never revised.
Why it matters
The pressures that break a plan arrive together, and each one feels like judgement at the time.
Try this today
Use predefined rules, a journal, and a cooling-off period.
Test yourself
A trader holds a losing position past its invalidation and takes a winner early. Both feel like discipline in the moment. What is actually happening?
Show the answer
The disposition effect: realising a loss makes the error concrete, so it is deferred, while banking a gain feels like locking in a success. Both decisions preserve comfort at the cost of the plan, and the second caps the winners that pay for the losers.
Learn this in the feed Answering from memory, then again days later, is what makes it stick.