Action Bias
The tendency to prefer doing something over doing nothing, even when action has no expected benefit.
How it is identified
Test: activity is undertaken without evidence that it improves the expected outcome
Unit
qualitative
In depth
Action bias is the mirror of omission bias, and in investing it is the more expensive of the two: every action carries transaction costs, taxes and the risk of a worse decision, while inaction carries none of those. It is strongest under uncertainty and after losses, when doing something feels like regaining control. The evidence that trading activity correlates negatively with returns is among the more robust findings in the field. A written plan specifying when action is warranted is what converts the default from doing something to doing the right thing.
Worked example
A portfolio turned over four times a year at 0.35% per round trip pays 2.8% annually in costs. Doing nothing for those four years would have cost 0% and required no decisions to be right.
Illustrative figures, chosen so the arithmetic is easy to follow. Not a live price and not a valuation of any company.
Educational reference only
This entry explains what “Action Bias” means. It is not investment advice and not a recommendation to buy or sell any security. Any numbers above are illustrative, not live prices, and nothing here predicts price direction or rates a stock. Consider your own circumstances and consult a SEBI-registered investment adviser before acting.