Costco's introduction of membership card scanners at the front of U.S. stores is still rolling out, but the move is already paying off big for the wholesale club. Morgan Stanley analysts wrote in a note this week that Costco warehouses are seeing as much as low double-digit increases in membership counts after implementing the scanners, and suggested the high conversion rates of previously non-paying customers could lead to the retailer's "Netflix moment." Ticker Security Last Change Change % COST COSTCO WH ...