By Marco BösingWhat Is Confirmation Bias?
Confirmation bias is one of the most extensively studied cognitive biases in psychology. In trading, it means that a trader selectively seeks information that confirms their existing market view while overlooking, ignoring, or rationalizing contradictory signals.
This bias affects every human being and is deeply embedded in human cognition. In trading, it can be especially costly because it undermines the foundation of every analysis: objectivity.
How Does Confirmation Bias Show Up in Trading?
The bias manifests in many aspects of daily trading:
Selective Chart Analysis
A trader who is bullishly positioned primarily sees bullish patterns on the chart — support zones, bullish divergences, accumulation areas. The bearish signals on the same chart — resistance zones, declining volume confirmation, bearish market structure — are unconsciously downweighted.
Cherry-Picking News Sources
Traders holding a position tend to consume news sources and analysts that confirm their direction. Bearish analyses are dismissed as "outdated" or "uninformed," while bullish assessments are perceived as "well-founded."
Backtest Distortion
Confirmation bias can also influence backtesting. Traders who believe in a strategy tend to interpret results favorably: losing trades are tagged as "exceptions," while winning trades are seen as confirmation of the strategy.
Ignoring Exit Signals
A particularly dangerous expression of confirmation bias: the trader holds a losing position because they keep finding new reasons why their original thesis is "still intact" — even when the market is clearly moving against them.
Why Is Confirmation Bias So Dangerous?
Confirmation bias undermines decision quality at a fundamental level:
- One-sided analysis: The market assessment is based on an incomplete picture
- Excessive conviction: The trader feels more certain than the data warrants
- Delayed reaction: Reversal or exit signals are recognized too late
- Larger losses: Positions are held too long because contradictory signals are ignored
Strategies to Counter Confirmation Bias
1. Actively Seek Counterarguments
Before every trade, deliberately ask: "What would have to happen for my thesis to be wrong?" Force yourself to seriously consider the opposite side of the trade before entering.
2. Trading Journal with Objectivity Check
In the journal, document not only the trade but also which bearish and bullish arguments existed at the time of entry. Review afterward whether the analysis was one-sided.
3. Use Checklists
A standardized checklist that queries both bullish and bearish criteria forces a balanced analysis and reduces the room for selective perception.
4. Trade Rule-Based
Trading by clearly defined rules reduces the room for subjective interpretation. The trading plan dictates what a valid setup is — not gut feeling or the current market opinion.
Common Mistakes Related to Confirmation Bias
- Following only bullish or only bearish analysts: Consuming exclusively sources that confirm one direction builds an echo chamber. I recommend deliberately following analysts who regularly take a different perspective from your own.
- Cleaning up backtest results: Removing losses from the dataset because you are convinced the strategy "actually works" is confirmation bias in its purest form. It destroys the validity of every backtest.
- Adding to losing positions: Holding onto a thesis and averaging down even though the stop-loss should have been hit means you are trading based on bias, not on your plan. The market is always right, not your personal conviction.
Frequently Asked Questions
Can Confirmation Bias Be Completely Eliminated?
No. Confirmation bias is a fundamental feature of human cognition and cannot be fully switched off. However, systems and processes can be introduced that minimize its influence on trading decisions — for example, through checklists, a structured trading journal, and rule-based trading.
Is Confirmation Bias Stronger in Technical Analysis Than Fundamental Analysis?
Both approaches are equally susceptible. In technical analysis, the bias shows up through selective pattern recognition; in fundamental analysis, through one-sided interpretation of economic data. The bias affects the analyst, not the method.
How Does Confirmation Bias Relate to Overconfidence?
The two biases reinforce each other. Confirmation bias causes only confirming information to be perceived. This inflates confidence in one's thesis beyond what is justified — leading to overconfidence. Overconfidence, in turn, increases the willingness to take on greater risk. The combination is particularly costly because the trader feels increasingly certain while the actual basis for that certainty gets weaker with each piece of contradictory evidence that is ignored.