The Building Blocks of Bad Money Decisions - Behavioral Finance Chapter 3
Chapter 3 of Behavioral Finance and Investor Types by Michael M. Pompian is where the real meat starts. This is the catalog of all the ways your brain sabotages your investing. Pompian calls them “the building blocks” and splits them into two big groups: cognitive biases and emotional biases.
Here’s the thing. This distinction actually matters. Cognitive biases are thinking errors. You can fix those with better information and education. Emotional biases come from your gut. Those are much harder to fix. You mostly just have to recognize them and work around them.
Cognitive Biases: Your Brain’s Bad Math
Pompian lists 13 cognitive biases, and he splits them into two sub-groups.
Belief Perseverance Biases
These are about clinging to what you already believe, even when the evidence says you’re wrong. There are six of them.
Conservatism bias is when you get new information but barely update your thinking. A company announces bad news, and you keep holding the stock because your original analysis “felt right.” You’re slow to react because changing your mind takes effort.
Confirmation bias is the classic. You only pay attention to information that supports what you already believe. You bought a stock, so now you only read good news about it. Bad news? You skip that article. This one leads to poorly diversified portfolios because you become convinced one company is amazing and ignore all warning signs.
Representativeness bias is when you put new information into old boxes. You see a fund manager with three great years and assume they’re brilliant. But here’s the problem: three years is a tiny sample. You’re pattern-matching based on way too little data.
Illusion of control bias is exactly what it sounds like. You think you can influence outcomes that are basically random. Online traders are especially guilty of this. They think clicking buttons gives them control over the market. It leads to excessive trading and concentrated positions.
Hindsight bias is the “I knew it all along” bias. After something happens, you rewrite your memory to believe you predicted it. This gives you false confidence, which makes you take on more risk next time. It also makes you unfairly judge fund managers by comparing their results to what happened rather than what was expected.
Cognitive dissonance is the mental pain you feel when new information conflicts with your beliefs. Instead of changing your mind, you rationalize. You hold losing stocks because selling them means admitting you were wrong. You throw good money after bad. And sometimes this builds up in a whole crowd of investors until it bursts out as a herd stampede.
Information Processing Biases
These seven are about how you handle data. Not about stubbornness, but about shortcuts your brain takes.
Anchoring and adjustment is when you latch onto a number and can’t let go. You bought a stock at $50, so $50 becomes your reference point for everything. The stock is now worth $30 based on fundamentals? Doesn’t matter. You’re anchored to $50.
Mental accounting is treating money differently depending on where it came from. Salary money feels different from bonus money, which feels different from inheritance money. But money is money. This bias causes people to build layered portfolios where the pieces don’t work well together because they never look at the whole picture.
Framing bias is when your decision changes based on how the question is asked. “70% chance of reaching your goals” sounds way better than “30% chance of falling short.” Same information, completely different reaction. This messes with how people assess their own risk tolerance.
Availability bias is judging probability by how easily you can think of examples. You remember the mutual fund with TV commercials, so you invest there. Never mind the hundreds of better funds that don’t advertise. This one seriously limits your investment options.
Self-attribution bias is taking credit for wins and blaming losses on bad luck. After a good year, you think you’re a genius. After a bad year, the market was unfair. This leads to overtrading and concentrated portfolios.
Outcome bias is judging a decision by its result instead of its process. A manager got lucky for five years? Must be skilled. A good manager had a bad stretch? Must be incompetent. You’re looking at the scoreboard instead of the game.
Recency bias is overweighting what happened recently. If stocks went up last quarter, you assume they’ll keep going up. This is how people buy at peaks and panic at bottoms. Pompian notes this is behind every time someone says “it’s different this time.”
Emotional Biases: Your Gut’s Bad Advice
Now the harder group. Seven emotional biases that you mostly can’t think your way out of.
Loss aversion is the big one. Kahneman and Tversky found that losing money hurts about twice as much as gaining money feels good. So you hold losers too long (hoping they’ll come back) and sell winners too early (locking in gains before they disappear). The result is a portfolio full of bad stocks and missing the good ones.
Overconfidence is believing you’re smarter and better informed than you actually are. It leads to too much trading, poor diversification, and lower returns. This one has both cognitive and emotional elements, but Pompian classifies it as emotional because it’s really hard to tell someone they’re not as smart as they think.
Self-control bias is the investing version of not being able to diet. You know you should save for retirement. But that new car looks great right now. People spend today instead of saving for tomorrow, then take on too much risk later trying to catch up.
Status quo bias is doing nothing when you should be making changes. Your portfolio drifted way off target? Eh, it’s fine. Selling feels like effort. This is pure inertia, and it can leave you holding a portfolio that no longer matches your actual situation.
Endowment bias is valuing something more just because you own it. Grandma left you shares of GE? Those feel special now, even if the investment case is terrible. People demand higher prices to sell something than they’d ever pay to buy the same thing.
Regret aversion is avoiding decisions because you’re scared of making the wrong one. So you stay too conservative, or you follow the herd because it feels safer. If everyone else is buying, at least you won’t feel stupid alone. This keeps people out of the market at exactly the times when prices are cheapest.
Affinity bias is investing based on what reflects your identity or values. You love Range Rovers, so you buy the stock. You buy “sophisticated” investment products because they sound impressive at dinner parties. The actual investment quality? Secondary concern.
So What?
Pompian’s big point in this chapter is that knowing these biases exist is the first step. Cognitive biases can be corrected with education and better processes. Emotional biases are trickier. You can’t just tell someone to stop feeling loss aversion. You have to recognize it and build your investment approach around it.
The next part of the book connects these biases to specific investor personality types. That’s where things get really practical.
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