Twenty Slots
Warren Buffett’s favorite teaching device is a piece of cardboard that does not exist: a punch card with twenty slots, one for every investment you get to make in a lifetime. It sounds like a lesson about stocks. It is actually a lesson about what happens to judgment when decisions become scarce, and it indicts nearly everything about how modern life is arranged.
The device appears whenever Buffett talks to students, and it has for decades, always in roughly the same words. I could improve your ultimate financial welfare, he tells them, by giving you a ticket with only twenty slots in it, so that you had twenty punches, representing all the investments that you got to make in a lifetime. And once you had punched through the card, you could not make any more investments at all. Under those rules, he says, you would really think carefully about what you did, and you would be forced to load up on what you had really thought about. So you would do so much better. The room always laughs a little, the way rooms laugh at things that are simple and true and completely unacceptable. Because look at what the card actually implies. The average holder of an American stock in the middle of the twentieth century kept it for roughly eight years; today the figure, depending on how you count the machines, is measured in months, and some studies put the machine-inclusive number in weeks or less. An entire industry of terminals, applications, notifications, and commission-free buttons exists to make the punching of the card as frictionless, as constant, and as entertaining as possible. Buffett’s cardboard stands against all of it, twenty holes wide.
The obvious reading of the punch card is about concentration, and the obvious reading is well supported by the man’s own record. The Buffett of legend is not a man who did a thousand clever things; he is a man who did a handful of enormous things and then sat still with a Cherry Coke while they compounded. In 1963, when a salad-oil fraud cratered American Express and the consensus held that the company might be ruined, Buffett spent evenings standing behind the cash register of an Omaha steakhouse, watching whether people still used their green cards, concluded that the franchise was intact, and put roughly forty percent of his partnership’s entire capital into a single wounded stock, a position that would violate the risk policy of essentially every institution that exists today and that built the foundation of everything after. Decades later, an iPhone-owning octogenarian punched one of his last great holes into Apple, and that single decision generated more profit than most funds produce in their entire history. His partner Charlie Munger, who spent sixty years as the metaphor’s enforcer, liked to say that a portfolio needed no more than a few ideas a decade, that the real money was made not in the buying and selling but in the waiting, and that the first rule of compounding is never to interrupt it unnecessarily. Sit-on-your-ass investing, he called it, with the satisfaction of a man who had done the math on the alternative.
But I have come to believe the punch card is only superficially about portfolio concentration, and that its real subject is the psychology of scarcity, which is why it belongs to everyone, including people who will never buy a share of anything. The card works by inverting the relationship between a decision and its cost. When decisions are free and infinite, the deciding mind grows casual; each choice is a draft, revocable, one of thousands, and so the standard of evidence collapses toward whatever is trending past the eyes. When decisions are visibly finite, twenty for a lifetime, every single one becomes a capital allocation of the self, and the mind, knowing it cannot diversify away its own carelessness, suddenly demands the kind of proof it would otherwise never bother to gather. The behavioral economists have a drawer full of findings that rhyme with this, the paradox of choice, decision fatigue, the way traders with cheaper and faster buttons trade more and earn less, documented mercilessly in Barber and Odean’s famous study of retail brokerage accounts, which found that the most active traders underperformed the market by whole percentage points a year and summarized itself in a title of four words: trading is hazardous to your wealth. Activity feels like diligence. It is usually its replacement. The punch card is a machine for making diligence mandatory by making activity expensive, and it works on exactly the same principle as the ten-minute turn or the sold airplane: the constraint does not restrict the judgment, it creates it.
Once you see the card this way, it starts auditing the rest of life, rudely. How many of the meetings on this week’s calendar would survive a rule of twenty meetings per quarter? How many of the projects your company is running would be funded if the executive team had a punch card of ten initiatives per decade, and every punch was engraved on the wall of the lobby? Careers are perhaps the purest case: a working life contains maybe seven or eight genuine swings, jobs taken, cities moved to, companies started, and yet people routinely spend more analytical effort on a vacation than on a job offer, precisely because the modern environment has disguised the scarce decisions as abundant ones, an infinite scroll of postings implying infinite chances. Relationships, mentors, even beliefs, the ones you defend in public, all have punch-card economics: few, compounding, ruinously expensive to churn. The industrial infrastructure of the present, and I mean this description technically rather than as complaint, is a system for hiding cards. Feeds, marketplaces, and notification systems earn their revenue by convincing you that today contains dozens of decisions worth making, when the truth, on almost any honest accounting, is that a good year contains perhaps three, and that everything else is throughput wearing the costume of choice.
There is a fair objection to all this, and it deserves better than the punch card’s admirers usually give it. Scarcity thinking can curdle into paralysis; venture capital, a business I study closely, is built on the opposite arithmetic, many small punches because the future is genuinely unknowable and the payoff distribution has a long violent tail; and a young person’s first career moves are supposed to be experiments, cheap punches on purpose, because the information they generate is worth more than the precision they lack. All true, and Buffett himself, it should be said, punched constantly in his early years, arbitraging cocoa beans and windmill makers, earning the right to his later stillness. The reconciliation, I think, is that the card is not a rule about frequency; it is an instrument for locating which of your decisions are actually the load-bearing ones. The skill is not making twenty decisions per lifetime. The skill is knowing, at the moment of decision, whether the thing in front of you is a punch or merely a motion, and the tragedy the card is designed to prevent is spending a life executing ten thousand motions with great energy while the four or five real punches go by unexamined, chosen by default, by drift, by whoever happened to be standing nearby with an opinion.
At the bottom of my lab there is a punch card you can actually punch, twenty slots, and the page remembers forever; no undo, which is the point, and people report that they hover over the first slot far longer than they expect to. That hesitation is the whole lesson delivered in a half-second of mouse-hover: the moment a decision becomes permanent and scarce, your standards arrive, unbidden, like a crowd that was waiting outside the whole time. Buffett’s cardboard has no app, no dashboard, and no business model, which is probably why it has survived forty years of retelling without improvement. It asks one question, and the question does not age: if you could only mean twenty things in your whole life, is this one of them? Most days, for most choices, the honest answer is no, and the card’s gift is that the no costs nothing. But two or three times in a life, the answer is yes, and everything you will ever compound is downstream of whether, on those days, you noticed.
Notes & sources: the twenty-punch formulation is Buffett’s own, delivered for decades in student Q&As and quoted in Alice Schroeder’s The Snowball (2008) and Lawrence Cunningham’s The Essays of Warren Buffett; the American Express “salad oil” position (roughly 40 percent of partnership capital, 1964) per Schroeder and Roger Lowenstein’s Buffett (1995); Munger’s “sit on your ass” and the waiting line from Berkshire and Wesco meeting transcripts and Poor Charlie’s Almanack; average holding periods from NYSE and World Bank turnover data (roughly eight years in the 1950s, months today); Barber & Odean, “Trading Is Hazardous to Your Wealth,” Journal of Finance (2000). Photo: Wikimedia Commons, CC BY-SA 3.0.