Online brokerage TD Ameritrade says it handled 19 percent fewer trades this October as economic uncertainty continued to bother investors and the market was closed two days because of Superstorm Sandy. The Omaha-based company said Thursday that it handled an average of 330,000 trades per day in October. That's down 19 percent from last fall and down 7 percent from this September. Ameritrade says the total client assets it held at the end of October grew 16 percent over last year to $469.9 billion. That's one percent lower than in September.