Loss Aversion, Biases and Overconfidence

Introduction

Trading decisions are not always based only on market information. The way a trader thinks about gains, losses, recent events, and being right or wrong can also influence decisions.

Some of these mental shortcuts are called biases. They are normal parts of human thinking, but in trading they can lead to decisions that are different from the trader’s original plan.

This lesson introduces several common biases and explains how they can appear in everyday trading.

Loss Aversion

Loss aversion means that a loss can feel more unpleasant than a similar-sized gain feels satisfying.

In trading, this can make a trader focus strongly on avoiding a loss. For example, a trader may hold a losing position because closing it would make the loss feel real.

It can also work in the opposite direction. A trader may close a small winning position very quickly because securing the profit feels safer.

The important point is that the market does not know whether the trader entered at a profit or loss. A position should be managed according to the current setup and the trading plan, not according to how emotionally painful the result feels.

Confirmation Bias

Confirmation bias is the tendency to pay more attention to information that supports what we already believe and to pay less attention to information that contradicts it.

A trader who is bullish on a stock may search for positive news, focus on bullish chart signals, and ignore information that weakens the original idea.

This can make a trader defend a position instead of evaluating it objectively.

A simple habit can help: before entering a trade, ask both:

“What supports my idea?”

and

“What would show that my idea is wrong?”

Recency Bias

Recency bias means giving too much importance to events that happened recently.

For example, after several losing trades, a trader may believe that the next trade is also likely to lose and start avoiding valid setups. After several winning trades, the same trader may become more confident and take larger risks.

Recent results are real information, but they are only a small part of the trading history.

A trader should therefore avoid treating a short recent sequence as proof that the entire strategy has changed.

Gambler’s Fallacy

The gambler’s fallacy is the belief that a previous sequence makes an opposite result “due” to happen.

For example, a trader may think:

“I have had five losing trades, so the next one must be a winner.”

But the market does not owe the trader a winning trade. If the next setup is independent of the previous result, the previous losses do not automatically make the next trade more likely to succeed.

The correct question is not whether a result is “due”, but whether the current setup meets the trading plan.

Sunk Cost Fallacy

The sunk cost fallacy occurs when a trader keeps making a decision because time, money, or effort has already been invested in it.

For example, a trader may think:

“I have already held this position for two weeks, so I should not close it now.”

The time already spent cannot be recovered. What matters is whether holding the position still makes sense based on the current market and the trading plan.

The same principle applies to a strategy. The fact that a trader spent a lot of time developing an idea does not mean the idea must continue to be used if the evidence no longer supports it.

Overconfidence

Overconfidence means having more confidence in one’s own judgment or ability than the available evidence justifies.

In trading, overconfidence can appear after a strong winning period. A trader may start believing that they understand the market unusually well and may increase position size, take weaker setups, or ignore risk limits.

Overconfidence can also appear after one particularly successful trade. A single good result does not automatically prove that the trader’s analysis or strategy has a lasting advantage.

Confidence is useful when it supports disciplined execution. It becomes a problem when it removes caution and makes the trading plan seem unnecessary.

How Biases Can Work Together

These biases do not always appear separately.

A trader can become overconfident after several recent wins. Recency bias may make those wins feel more important than the longer trading history. Confirmation bias may then make the trader notice only information supporting the current view.

After a loss, loss aversion may encourage the trader to avoid closing the position. The sunk cost fallacy can then reinforce the decision because the trader has already invested time and money.

Recognizing the combination is useful because a trading mistake often has more than one psychological cause.

Trader Preparation

Biases cannot always be removed from human thinking. The practical goal is to create simple rules that make them easier to recognize.

Before entering a trade:
• write down the reason for the trade;
• write down what would invalidate the idea;
• define the planned risk;
• decide the exit conditions;
• avoid changing the plan only because of the most recent result.

During a trade, ask whether the decision is based on current evidence or on the desire to avoid a loss, prove the original idea right, recover a previous loss, or take advantage of a recent winning streak.

Example

A trader buys a stock after a bullish setup appears. The price then moves against the position.

The trader sees a small amount of positive news and focuses on it while ignoring signs that the setup has weakened. This can be confirmation bias.

The trader also thinks about the time already spent researching the stock and decides not to exit because “too much work has already gone into this trade.” This is the sunk cost fallacy.

If the trader has also had several recent losses, loss aversion may make closing the position even harder.

The solution is simple: return to the predefined trading rules and evaluate the current setup rather than defending the original decision.

Common Mistakes

Common mistakes related to loss aversion, biases, and overconfidence include:
• holding a losing trade simply to avoid realizing the loss;
• looking only for information that supports an existing opinion;
• allowing a short winning or losing streak to change risk decisions;
• believing that a win is “due” after several losses;
• keeping a trade because too much time or effort has already been invested;
• increasing risk because of recent success;
• treating one successful trade as proof of superior trading ability.

Key Terms

Loss Aversion — Veszteségkerülés
Confirmation Bias — Megerősítési torzítás
Recency Bias — Frissességi torzítás
Gambler’s Fallacy — Játékos téveszméje
Sunk Cost Fallacy — Elsüllyedt költség téveszméje
Overconfidence — Túlzott önbizalom

Knowledge Check

1. Why can loss aversion make it difficult to close a losing trade?
2. How can confirmation bias affect the information a trader pays attention to?
3. Why does a series of previous losses not mean that the next trade is automatically more likely to win?