Big banks are doing a better job than their regional competitors at capturing new customers, according to the J.D. Power and Associates 2010 U.S. Retail Bank New Account Study, released today.

The report says that big banks capture 70% of potential customers shopping for a new bank, compared to a 59% success rate at regional banks. The report is based on responses from 3,770 consumers who shopped for a new bank in the past 12 months

Much of the secret of larger banks’ success is their deeper pockets. Big banks tend to offer more promotional gifts or cash rewards for opening accounts, and they can afford to make their short-term interest rates a little higher than their smaller competitors. Indeed, around one-fourth, 24%, of new bank customers say their primary reason for choosing one bank over another. However, these gifts aren’t buying loyalty and the same number say they’ll either probably or definitely ditch the bank within the next 12 months, compared to 13% of people who chose a bank for another reason, such as proximity to their home, said the same.

“The challenge with these short-term, deep-pocket promotions is by how much to they stem attrition,” says Michael Beird, director of J.D. Power’s banking practice. “If customers still feel the grass is greener somewhere else that’s offering a better toaster, their inclination to switch says that they’re not seeing the value in the services their current bank provides. If they’re looking for promotions, is that enough of a value proposition to keep them?”