Labor Day is approaching. Ouch. It always seems to be in September-October when the wheels come off Wall Street. Think 2008. Think 1987. Think 1929. Statistically, there actually is a “September effect.” The market, on average, has done worse in that month than any other. No one really knows why. Some have even blamed the psychological effect of shortening days. But it becomes self-reinforcing: People fear it, so they sell.