Why Do We Make Irrational Decisions in the Stock Market?

We all like to think we decide with logic and numbers. But when our own money is on the screen and moving in front of us, feelings like fear, regret and excitement slip into the decision without us noticing. That is not a personal flaw, it is how people work, and the good news is that you can learn to notice it.

The mind loves shortcuts

In everyday life the mind makes many quick decisions without working them out in detail, and that saves effort. The trouble is that the stock market is a different place: prices change all session long, green and red numbers are always in front of you, and every move stirs a feeling. So the shortcuts that serve us in daily life can mislead us here.

Research in a field called behavioral finance has noticed that these mistakes are not random. They repeat across many people in much the same way, which is why they have names: fear of missing out, holding on to losers, overconfidence and confirmation bias. Each one has its own lesson in this path.

Same stock, two different feelings

Take a simple example with an invented company. Two people own the same stock, and its price right now is the same for both. The only difference is the price each one paid.

Investor one Bought at12.00 Feels like a loss

Same stock Price now10.00 Same company, same news

Investor two Bought at8.00 Feels like a gain

The price now is the same for both, yet the feeling is completely different.

ExampleThe first bought at 12.00 and is down 2 pounds a share, so he may well say "I will not sell until it gets back to my price". The second bought at 8.00 and is up 2 pounds, so she may feel she has to "lock in the gain". The market itself has no idea what either of them paid, and the stock will not move tomorrow according to anyone's purchase price.

Your purchase price matters for your own records, but the next decision should rest on where the company and the stock stand now: the news, the numbers and the plan you set at the start.

Watch outKnowing about these biases does not switch them off. Even people who understand them well still fall into them. The benefit is catching them early, before they turn into a decision.

A simple habit before any decision

Write down the reasonOne sentence: why do you want to buy or sell now? If the reason is "I have a feeling" or "everyone is doing it", that is a feeling, not a reason.
Name the feelingFear? Regret? Excitement? Simply naming it gives you a little distance from it.
Ask: what if I did not own it?If you did not own this stock, would you buy it today at this price? This question takes your purchase price out of the equation.

The next lesson starts with the best known of these feelings: the fear of missing out.

Review your portfolio calmly

Open your portfolio, look at each stock and ask yourself the third question: if I did not own it, would I buy it today? FoudaLens shows numbers and descriptive analysis; the decision is yours.

Portfolio Learn

Check yourself

1. Two people own the same stock at 10. One paid 12, the other 8. Whose price will the stock follow tomorrow?

The market does not know anyone's purchase price. The next move has its own causes.

2. If you understand the biases well, does that mean you will not fall into them?

Biases are part of how we are built. Knowing them helps you notice, it does not remove them.

Summary

The mind takes shortcuts, and in the market those shortcuts can mislead.
Your purchase price changes how you feel about a stock, not where it goes.
Write down the reason and name the feeling before any decision.

Related lessons

Educational content only, not investment advice. Companies and figures in the examples are invented for illustration.