It is—or should be—obvious that any overly popular investment strategy will enjoy a period of exceptional performance as various “investors” convert to the strategy. Once the strategy is sufficiently popular and the number of followers peaks, the strategy’s superior returns will end. In time, the distortions and overvaluations caused by zealous adherence to any hot investment concept will be reversed. The larger the distortions, the longer and more painful the adjustment. The nifty-fifty, gold and Japanese manias were indeed substantial, and I don’t think indexing has reached their levels of nuttiness—yet. Every year we seem to be getting closer, though.