What leads to stock crashes? E.E. “Buzzy” Geduld, who oversaw about 60 equity traders 25 years ago, says crashes happen when investors feel they’ve lost control. Today, trading has dropped to its lowest levels since 2008. The 34 percent drop in 2008 and the sudden crash in 2010, not to mention the stock crash in 1987, have investors retreating from equities. If investors are spooked by the volatility, is there anything that can be done to restore their confidence?