Despite the well-known advice to buy low and sell high, most people do the opposite. If the stock market is rallying people start putting their money into equities, worried they might miss the rest of the bull run; when it’s tanking they pull their money out. This reflexivity creates momentum that drives rallies (and crashes) farther than the fundamentals dictate as people without much investment experience decide they can’t stay out any longer (or curse their decision to bet on stocks later on). Buying stocks with a second mortgage is sentiment out of control The normal measures of sentiment that…