Self-Attribution Bias: Why You're a Genius When You Win and Unlucky When You Lose
“Heads I win, tails it’s chance.” That quote from researchers Ellen Langer and Jane Roth opens Chapter 14 of Pompian’s book, and honestly, it is the most perfect summary of self-attribution bias I have ever seen.
Here is how it works. You buy a stock and it goes up. You think: I am a smart investor, I saw the opportunity, my analysis was right. You buy another stock and it goes down. You think: the market is irrational, the CEO lied about earnings, the Fed ruined everything. Notice what happened? When things go well, it is your skill. When things go badly, it is someone else’s fault.
This is self-attribution bias, and it is quietly one of the most dangerous biases an investor can have.
Two Sides of the Same Coin
Pompian explains that self-attribution actually has two components.
Self-enhancing bias is when you take too much credit for successes. Your investment went up? Must be your brilliant stock-picking skills.
Self-protecting bias is when you deny responsibility for failures. Your investment went down? Must be bad luck, corrupt management, or unfair markets.
Both of these are happening at the same time, reinforcing each other. Every win makes you feel smarter. Every loss gets explained away. Over time, you build up this completely distorted picture of yourself as a skilled investor, when in reality, you might just be riding a bull market or getting lucky.
There is an old Wall Street saying that Pompian quotes: “Don’t confuse brains with a bull market.” That is basically this entire chapter in one sentence.
The Strengths and Weaknesses Exercise
Dr. Dana Dunn, a psychology professor at Moravian College, does a simple exercise with her students. She asks them to draw a line down the middle of a page, label one column “strengths” and the other “weaknesses,” and list their personal qualities in each. Every time she does this, students list more strengths than weaknesses.
This is self-attribution bias in its purest form. We naturally see ourselves as having more positive qualities than negative ones. And this carries directly into investing. We overestimate our ability to pick stocks, time markets, and evaluate companies.
How Self-Attribution Makes You a Worse Investor
Pompian outlines four specific investment mistakes that come from this bias.
Overconfidence from past success. After a good quarter or a good year, self-attribution investors believe the success was due to their skill. This leads them to take bigger risks. They think they have figured it out. They increase position sizes, concentrate portfolios, maybe even start using leverage. Then when the inevitable bad period comes, the losses are amplified.
Too much trading. If you think your good results come from skill, you start trading more. After all, why not apply your “skill” more frequently? But research consistently shows that more trading means lower returns. Barber and Odean titled one of their famous papers “Trading Is Hazardous to Your Wealth,” and the data backs it up. The more you trade, the worse you do on average. Self-attribution drives the overtrading.
Hearing what you want to hear. When you find information that confirms a decision you already made, self-attribution makes you credit your own brilliance. “See, I knew this was a great company!” This confirmation loop can keep you in bad investments too long or make you double down when you should be getting out.
Underdiversified portfolios. This is especially common among corporate executives and board members who attribute their company’s stock performance to their own efforts. They hold way too much company stock because they believe their personal contribution is driving the price. In reality, stock performance depends on hundreds of factors, including a healthy dose of chance. Holding a concentrated position in any single stock, especially your employer’s, is risky. Self-attribution makes it feel safe.
The “Learning to Be Overconfident” Study
Pompian highlights a research paper by Gervais and Odean called “Learning to Be Overconfident,” and the findings are sobering.
They modeled how novice traders develop overconfidence through self-attribution. The pattern goes like this: a new trader makes some winning trades, credits their own skill, and becomes more confident. They trade more aggressively. During this aggressive phase, their actual profits drop. But because of the self-attribution cycle, they do not recognize the problem.
Three key findings from their research:
After periods of general market prosperity, trading volume goes up significantly. Everyone thinks they are a genius, so everyone trades more.
During these high-confidence, high-volume periods, average profits actually go down. More trading does not mean better trading.
Young, successful traders are the worst offenders. They have the most overconfidence and do the most trading.
Here is the twist that I found fascinating: overconfident traders are not the poorest traders. They survive in the market. Their overconfidence does not destroy them, it just makes them less wealthy than they could be. As Gervais and Odean put it: “Overconfidence does not make traders wealthier, but the process of becoming wealthy can make traders overconfident.”
So the successful traders who think they are the best? They are probably leaving money on the table because of their overconfidence. And they will never know it, because self-attribution prevents them from seeing it.
What to Actually Do
Pompian’s advice comes down to one word: postanalysis. Review your decisions after the fact.
When an investment makes money, do not just celebrate. Ask: why did it go up? Was it something specific about the company? Was the whole market going up? Did I buy at a particularly good time, or would any entry point have worked? Was my original thesis actually correct, or did the stock go up for a completely different reason?
When an investment loses money, do not just blame the market. Ask: what did I miss? Were there red flags I ignored? Did I buy at the wrong time? Was my research superficial?
Look for patterns in your mistakes. Maybe you consistently buy too late in a trend. Maybe you hold losing positions too long because you cannot admit you were wrong. Maybe you always overweight one sector because of your professional background.
Write these patterns down. Create rules for yourself: “I will not buy a stock just because it went up yesterday.” “I will sell any position that drops 15% and reevaluate before buying back in.” Having rules written down makes it harder for self-attribution to overrule your rational brain.
The chapter ends with a simple truth: being humble and learning from your past mistakes is the best way to become a better investor. Your ego is not your friend in the market. The market does not care about your self-image. It only cares about reality.
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Next: Outcome Bias
This is part of a series retelling “Behavioral Finance and Wealth Management” by Michael M. Pompian. Start from the beginning.