Twenty-nine posts. Twenty biases. Four investor types. Two guidelines. And one big idea that runs through everything: you are not a rational investor, and that is okay as long as you know it.
Chapter 27 is the final content chapter of the book, and it is the one that brings everything together. After learning about 20 biases, two guidelines, a diagnostic framework, and two case studies, we now get the detailed profiles of all four Behavioral Investor Types.
We have spent the last 23 chapters learning about 20 different biases. That is a lot of biases to keep track of. Even for a financial advisor who does this for a living, diagnosing each client for all 20 biases would take forever.
Chapter 25 is where all the theory from the entire book gets applied to actual people. Well, fictional people. But they feel real enough that you will probably recognize yourself or someone you know in one of them.
After 20 chapters of learning about individual biases, Pompian finally gets to the big question: so what do you actually DO with all this knowledge?
This is the last emotional bias in Pompian’s book, and it is an interesting one because it touches on identity. Affinity bias is about investing based on who you think you are (or who you want to be), rather than what actually makes financial sense.
The opening quote of this chapter is from Harry Markowitz, the father of Modern Portfolio Theory. He said he split his retirement contributions 50/50 between bonds and equities because he wanted to “minimize my future regret.” Not maximize returns. Not optimize the efficient frontier. Minimize regret.
You know that feeling when you are selling something on Craigslist and you think your used couch is worth $500, but nobody will pay more than $200? That is endowment bias in action. The moment you own something, it magically becomes more valuable in your mind.
Machiavelli said it over 500 years ago: “Whosoever desires constant success must change his conduct with the times.” But here we are, centuries later, and most of us still prefer to just… not change anything.
So here is what happened: I read this chapter about self-control bias and immediately thought about every time I bought something I did not really need instead of putting that money into savings. This one hits close to home for pretty much everyone.
If loss aversion is the most damaging emotional bias, overconfidence is probably the most common one. And Pompian goes as far as calling it “one of the most detrimental biases that an investor can exhibit.”
We are now entering Part 4 of Michael Pompian’s book, and this is where things get really interesting. We are moving from cognitive biases (errors in thinking) to emotional biases. And the first one is a big one.
Imagine you are on a cruise ship. Over the entire trip, you see exactly the same number of green boats and blue boats. But most of the green ones pass by toward the end of the trip, and the blue ones are spread out earlier. When you get home, which color do you remember seeing more? Green. Obviously green. You saw so many of them.
Imagine a fund manager who concentrated her entire portfolio into 15 stocks, made two huge winning bets, had four terrible losers, and ended up beating her benchmark by 6% per year over five years. Impressive track record, right? Most investors would look at those returns and throw money at her.
“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.
Quick question: what kills more people in the United States, shark attacks or falling airplane parts? If you said shark attacks, you are wrong. Falling airplane parts are actually 30 times more likely to kill you. But shark attacks are dramatic, they are all over the news, and they make great movie plots. So your brain says: sharks are clearly the bigger threat.
Yogi Berra once said: “You better cut the pizza in four pieces, because I’m not hungry enough to eat six.” It is funny because it is absurd. The amount of pizza does not change based on how you slice it. But here is the thing: when it comes to money and investing, people make exactly this kind of mistake all the time. They just do not realize it.
Let me ask you something. Is the population of Canada greater or less than 20 million? Now, without looking it up, guess the actual number.
Here is a question for you. You find $500 on the street. Same week, you get a $500 check from your mother as a gift. Is this the same money? Logically, yes. A dollar is a dollar. But here is the thing: most people will treat these two amounts completely differently. The street money? Easy come, easy go. Let’s spend it on something fun. Mom’s check? Better save it. She said it was for a rainy day.
David Beckham said “Hindsight is a wonderful thing.” Chapter 9 is the last of the belief perseverance biases in Pompian’s book, and it might be the most relatable one. Because we all do this. Every single one of us.
Abraham Lincoln said: “I claim not to have controlled events, but confess plainly that events have controlled me.” If Lincoln could admit that, why can’t most investors?
Colin Powell said it best: “Fit no stereotypes.” Chapter 7 of Pompian’s book is about representativeness bias, which is basically your brain using shortcuts and stereotypes instead of doing actual math.
Francis Bacon said it centuries ago: humans are “more moved and excited by affirmatives than by negatives.” Chapter 6 of Pompian’s book is about confirmation bias, and honestly, this might be the most dangerous bias in the whole book.
Warren Buffett opens this chapter with a quote about needing a sound framework for decisions and the ability to keep emotions from corroding that framework. Chapter 5 is about one specific way emotions corrode it: by making you too slow to update your beliefs.
You know that feeling when you buy something and then find out there was a better deal elsewhere? That little knot in your stomach? Congratulations, you just experienced cognitive dissonance.
Chapter 3 of Pompian’s book is short but important. It is the setup chapter. Before getting into 20 specific biases over the next 20 chapters, he wants you to understand what biases are, why they matter, and how they break down into categories.
Chapter 2 of Pompian’s book is basically a history lesson. But here’s the thing: it is a surprisingly interesting one. Because when you trace where behavioral finance came from, you realize that humans have been making the same stupid money mistakes for centuries.
There is a great quote at the start of this chapter. Meir Statman from Santa Clara University says: “People in standard finance are rational. People in behavioral finance are normal.” That one sentence pretty much captures the whole idea of this book.
I just finished reading a book that honestly changed how I think about investing. And I’ve been investing for a while now.