Trading Expectancy: The Mathematical Foundation of Sustainable Profitability

Executive Summary

The primary determinant of long-term trading success is not a high win rate, but rather a positive expectancy. Expectancy is a mathematical calculation representing the average amount a trader can expect to make or lose per trade over a large sample size. While many traders focus on the psychological satisfaction of "being right," a high win rate (e.g., 80%) can still result in a net loss if the average losses significantly outweigh the average wins. Conversely, a system with a low win rate (e.g., 40%) can be highly profitable if it generates large wins relative to small losses. To achieve sustainable profitability, traders must shift their focus from individual trade outcomes to the execution of a statistically proven edge  ...