Behavioral Finance: Why Investors Repeat the Same Mistakes

Investors rarely make mistakes because they lack information. More often, they give too much weight to recent performance, social consensus or a story that makes uncertainty feel simple.

Recency bias encourages the extrapolation of a recent trend. Confirmation bias makes contrary evidence easier to dismiss. Loss aversion can turn a small planned adjustment into a long refusal to acknowledge a broken thesis.

The answer is not to pretend that emotion can be removed. It is to design decision rules before they are needed: write down the thesis, define what would invalidate it, set a position limit and decide how new information will be reviewed.

A post-mortem should examine the process rather than only the outcome. A good decision can lose money, and a poor decision can make money. Separating process quality from short-term result is essential to learning.

Behavioral finance becomes useful when it changes the architecture of decisions. The goal is not perfect rationality, but a repeatable process that makes the most expensive errors less likely.