The Motley Fool is a popular and well‐known source of investment information and ideas for individual investors. Operating a website and also producing some books and other publications, this source has advocated that small investors can often do well in the market by applying simple principles. One technique advocated by the Motley Fool was the “Foolish Four,” a system that involved taking the 30 Dow Jones Industrial Average stocks and calculating the ratio of the dividend yield to the square root of the share price. The stock with the highest ratio was ignored, and the next four highest became the Foolish Four. The founders of the Motley Fool claimed that the Foolish Four strategy, which would take only 15 minutes a year to implement, was so effective it would “crush your mutual funds.” A Money Magazine columnist who criticized this technique was severely criticized by Motley Fool followers. Eventually, the founders had to admit that this technique did not work, saying it was a result of faulty analysis of historical data resulting from “finding random correlations and considering them valid and repeatable.”