I borrowed Fortune’s Formula by William Poundstone from my brother. It’s a fun read, but has limited real-world utility.
It tells the story of the Kelly criterion. This involves romps through gambling, the stock market, mathematics, and the mob. The connections to the underworld are exciting, and I was really sucked into the story towards the middle of the book, but the beginning starts off very choppy. It jumps from person to person, place to place, and you don’t understand where you are, or where you’re going. You might want to start in the middle, and then read the beginning later.
The book reminded me of Zero: The Biography of a Dangerous Idea by Charles Seife. (Of course, the history of the Kelly criterion is much shorter than the history of zero.) Fortune’s Formula was a story about a concept. It explains that concept, the Kelly formula, in a way that’s pretty easy to grasp, but if you want to know how to apply the Kelly criterion, one would have to purchase a book that goes more in-depth. For example, it says the company Long-Term Capital Management was making tons of small bets, but they weren’t really diversified, so it was like making a few huge bets. How do you know what counts as diversified?
Another good tip one can glean is “Don’t Overbet,” but this must be applied while using the Kelly criterion. This means you must do math. This tip isn’t quite as useful in its general form, as I put it.
This is not a criticism of the book, but a note to those who would purchase the book. If you’re looking for a good story, then read this book. If you’re looking to make money, then do some more research on the Kelly criterion.
I wanted to make one final note. I recently read Why Most Things Fail, which also looks at the collapse of Long-Term Capital Management. The two books diagnose the failures differently, but I don’t think the approaches are necessarily mutually exclusive. Fortune’s Formula says LTCM was guilty of overbetting, and wasn’t able to avoid ruin because of that. Why Most Things Fail showed why the type of dip seen isn’t as unlikely as traditionally calculated. These shocks are endogenous to the system, not one in a million events. The odds weren’t calculated right. But this is just all the more reason not to overbet, and to be conservative, because it’s easy to miscalculate the odds.