The investor who cannot sit still

Action bias is our tendency to prefer doing something over doing nothing, even when nothing is optimal. Markets punish this expensively.

Checking a portfolio daily increases the number of times you see losses, because short-term price movement is mostly noise. More observed losses means more emotional decisions.

A practical countermeasure is a review calendar: a fixed monthly or quarterly review with a written checklist, and no discretionary changes in between unless a pre-defined rule triggers.

The skill being trained here is patience under uncertainty, which is harder and more valuable than finding one more indicator.