According to a new survey of 100 bank executives, U.S. banks are increasingly setting their sights on underbanked customers. About 23% of bankers said underbanked customers present the greatest growth opportunity for their bank, up from 12% a year ago. Banks are interested in those customers because they spend more money on fees for cashing checks or ATMs than other customer segments. The survey also found that despite the growth of mobile banking, roughly 41% of bankers polled intend to increase the number of physical branch locations over the next 12 to 19 months, which could broaden their reach to larger segment of underbanked customers.