If money is your bread then nothing else matters.
The Kelly Criterion is something anyone who trades, invests or even gambles must know. I have a brief summary below and some additional resources at the end of the summary.
There is also a great book devoted to this topic, Fortune’s Formula by William Poundstone, a must have book for any serious investor.
The Kelly Criterion, also known as the Kelly strategy, Kelly formula, or Kelly bet, is a mathematical formula designed to help people determine the optimal size of a series of bets. It’s named after John L. Kelly, Jr., who introduced the concept in a 1956 paper titled “A New Interpretation of Information Rate.”
The Kelly Criterion is commonly used in gambling, investing, and other areas where decisions involve uncertainty and risk. The goal of the Kelly Criterion is to maximize the long-term growth of capital by finding the optimal fraction of capital to invest in each opportunity.
The basic formula for the Kelly Criterion is:
The formula tells you what percentage of your current capital should be invested in a particular opportunity, given your assessment of the probability of success and the odds being offered.
It’s important to note a couple of things about the Kelly Criterion:
1. Risk of Ruin: The Kelly Criterion can be aggressive. Betting too much of your capital, even with a positive expectation, can lead to significant losses. The criterion doesn’t consider the risk of ruin, which is the risk of losing your entire capital.
2. Estimates are Crucial: The accuracy of the criterion depends heavily on the accuracy of your probability estimates. If your estimates are inaccurate, the strategy might not perform well.
3. Logarithmic Utility: The formula assumes logarithmic utility, meaning that the investor’s goal is to maximize the expected logarithm of wealth. This utility function helps to balance between risk and reward.
To use the Kelly Criterion, you would apply the formula to each opportunity, and the resulting fraction represents the proportion of your current capital that you should invest.
Keep in mind that many variations and adaptations of the Kelly Criterion exist to address specific situations and concerns. It’s a tool that requires careful consideration and understanding of the underlying assumptions and risks.
To learn more, see these resources
https://www3.cs.stonybrook.edu/~skiena/691/2007/lectures/Kelly.pdf
https://www.economist.com/media/globalexecutive/fortunes_formula_e.pdf
https://towardsdatascience.com/python-risk-management-kelly-criterion-526e8fb6d6fd