What You Will Learn From This Article
- Where the idea of “behavioral investing” actually comes from, and why it isn’t just a Charlie Munger invention
- The difference between the academic and the practical traditions that both arrived at the same conclusions
- A short introduction to every principle covered in this series, with a link through to the full article on each one
- Why this body of work is now, in a real sense, complete
Most investment losses are not caused by bad luck, and they’re usually not caused by a lack of intelligence either. They’re caused by a small, repeatable set of thinking errors that otherwise smart, careful people make under pressure, under excitement, or simply out of habit. This series exists to name those errors clearly, one at a time, using the words and reasoning of the people who identified them most usefully: primarily Charlie Munger and Warren Buffett, with the occasional nod to the psychologists whose research explains why these errors happen in the first place.
Where These Ideas Actually Come From
Neither Munger nor Buffett was an academic, and the term “behavioral finance” wasn’t coined by either of them. The formal, scientific version of this field traces back to two psychologists, Daniel Kahneman and Amos Tversky, who spent the 1970s documenting the specific, repeatable ways real people deviate from purely rational decision-making. Their 1979 paper, “Prospect Theory,” published in the journal Econometrica, provided the first rigorous evidence that losses and gains aren’t felt equally, among other findings, giving a scientific backbone to what Munger would later describe, in plainer language, as loss aversion. Kahneman won the Nobel Memorial Prize in Economic Sciences for this work in 2002. Tversky, who had died in 1996, was acknowledged by name but was ineligible, since Nobel prizes aren’t awarded posthumously. Decades later, economist Richard Thaler built further on their foundation, formally establishing behavioral economics as a mainstream field of study and winning his own Nobel Prize in 2017.
Investing itself had already stumbled onto a version of these same truths decades earlier, purely through observation rather than formal study. In 1949, Benjamin Graham published “The Intelligent Investor,” introducing the “Mr. Market” allegory: an imaginary business partner whose moods swing wildly between euphoric and despairing, entirely unrelated to what the underlying business is actually worth. Graham’s student, a young Warren Buffett, absorbed the lesson completely and spent the next seven decades re-explaining it to Berkshire Hathaway shareholders.
It was Charlie Munger, Buffett’s business partner since the late 1950s and Berkshire Hathaway’s vice chairman from 1978, who pulled these threads together most explicitly. Munger read voraciously across psychology, citing researchers such as Robert Cialdini directly, and in 1995 delivered a Harvard speech titled “The Psychology of Human Misjudgment,” later expanded into a roughly 25-tendency catalogue in the book “Poor Charlie’s Almanack.” Where Kahneman and Tversky were building a scientific case, Munger was building a practical one: a working investor’s field guide to the exact mental errors that had, in his own decades of watching businesses and markets up close, cost people the most money.
Both traditions, the academic and the practical, have now largely passed from their original stewards to the next generation. Munger died on 28 November 2023 at 99. Kahneman died in 2024. Buffett stepped back from Berkshire Hathaway’s chief executive role at the end of 2025, handing the position to Greg Abel. What remains, across speeches, shareholder letters, academic papers, and one very famous book, is a remarkably consistent body of evidence: the biggest threat to most investors’ returns was never really the market. It was, and remains, their own thinking.
How This Series Works
Some of these ideas are closely related enough that separating them would mean repeating ourselves, so a few articles below cover two concepts that genuinely work as a pair. Each entry gets a short introduction here, followed by a link through to the full article once it’s published, where you’ll find the sourcing, the real-world cost of getting it wrong, and how to actually apply it.
1. Two Rules That Keep You Out of Trouble Before You Even Buy
Munger sorted every potential investment into three baskets: yes, no, and too tough to understand, and simply refused to act on the third. Benjamin Graham, Buffett’s mentor, added a second safeguard: never pay full price for anything, always demand a cushion in case you’re wrong. Together, circle of competence and margin of safety do more to prevent losses before they happen than almost anything else in this series.
Read the full article: Two Rules That Keep You Out of Trouble Before You Even Buy
2. Show Me the Incentive: Why Your Advisor’s Pay Structure Matters More Than Their Advice
Munger considered this the single most underestimated force in human behaviour, more powerful than intelligence, and more powerful than good intentions. It explains why honest, well-meaning professionals still steer clients toward decisions that happen to pay the professional best. If you’ve never asked exactly how your advisor gets paid, this is the article to read before you ask them anything else.
Read the full article: Show Me the Incentive
3. The Herd Instinct: Why Copying the Crowd Costs You Money
Munger studied why humans abandon independent judgement under stress and copy the people around them instead. Buffett built an entire investing rule around deliberately doing the opposite. Together they explain both why bubbles form and why almost nobody manages to sell before one bursts.
Read the full article: The Herd Instinct
4. Why Losing Hurts More Than Winning Feels Good
Munger noticed that investors react far more intensely to a loss than to an equivalent gain, which is exactly why so many hold losing positions for years, hoping to simply get back to even. Buffett turned the same insight into perhaps his most famous rule: never lose money, and never forget the first rule. The arithmetic behind why that rule matters is more unforgiving than it sounds.
Read the full article: Why Losing Hurts More Than Winning Feels Good
5. The Ego Traps That Wreck Portfolios
Denial and overconfidence look like opposite problems: one shrinks from bad news, the other charges toward disaster. Munger traced both back to the same root, an inflated, protected sense of self. Learning to spot either one in your own thinking is uncomfortable, and according to Munger, essential.
Read the full article: The Ego Traps That Wreck Portfolios
6. It’s Not Greed That Ruins Investors. It’s Envy.
Munger named envy, not greed, as one of the most destructive and least useful emotions a person can carry, a “stupid sin” with all the pain and none of the fun. In his view, it’s also the actual force behind far more bad investment decisions than greed ever was.
Read the full article: It’s Not Greed That Ruins Investors
7. The One Mistake That Turns a Bad Year Into a Permanent Loss
Munger and Buffett, independently and repeatedly, named the same single factor as one of the few things capable of turning a genuinely sound investment strategy into ruin: borrowed money. A loss you could have easily survived becomes a loss you can’t, the moment leverage enters the picture.
Read the full article: The One Mistake That Turns a Bad Year Into a Permanent Loss
8. Invert, Always Invert
Rather than asking how to win, Munger’s habit was to ask how he could fail, then systematically avoid every path that led there. It’s an unusual way to think at first, and one of the most practical tools in this entire series once it clicks.
Read the full article: Invert, Always Invert
9. Why Doing Less Is a Strategy
Munger’s advice was blunt: find a few good businesses, then sit on your hands. Buffett’s version is a thought experiment, imagine you only get 20 investment decisions for your entire life. Both are arguing against the same instinct: the belief that activity and progress are the same thing.
Read the full article: Why Doing Less Is a Strategy (Coming soon)
10. Meet Mr. Market
Benjamin Graham invented him, and Buffett spent decades reintroducing him in almost every shareholder letter he wrote: an imaginary business partner who shows up daily, wildly moody, offering to buy or sell at whatever price his emotions dictate that day. Understanding what Mr. Market actually is, and isn’t, changes how you read every red or green number on your statement.
Read the full article: Meet Mr. Market
11. Where Your Returns Actually Go
Buffett’s parable about a family called the Gotrocks explains, in a single story, why fees matter more than most investors think. It’s also exactly why the world’s most famous stockpicker put his own wife’s inheritance into a low-cost index fund instead of individual shares.
Read the full article: Where Your Returns Actually Go
Key Takeaways
- Behavioral investing has two parallel origins: a scientific one (Kahneman, Tversky, and later Thaler) and a practical one (Graham, Munger, and Buffett)
- Both traditions arrived at strikingly similar conclusions from completely different directions, through laboratory research on one side and decades of hands-on capital allocation on the other
- This is now a largely completed body of work, its major originators have either passed away or stepped back from public involvement in markets
- The series ahead covers 11 articles built from these ideas, several combining two closely related concepts into one piece
This article was researched and drafted with the assistance of AI tools and reviewed for accuracy. It is general information, not personalised financial advice. Historical and biographical details were verified against publicly available sources at the time of writing, but please confirm any date or fact that matters to you independently before relying on it.
