An executive with a firm which collects data on financially underserved U.S. consumers maintains that Americans without standard banking relationships or with thin or non-existent credit histories represent an enormous overlooked opportunity for credit unions and banks.

The question is not whether credit unions can afford to serve financially underserved Americans, contended Greg Rable, CEO of FactorTrust, an aggregator of data on financially underserved consumers, but whether they can afford not to do so.

Rable's Atlanta-based firm pointed to a number of factors to back up its assertion, including that consumers without standard banking relationships represent more than $1 trillion in annual income and have an average monthly income exceeding $3,000.

In addition, 54% of American consumers who take out payday advance or equivalent loans have a major credit card and 32% own their own homes, Factor Trust said.

Further, these consumers would likely, as Mississippi's Hope Credit Union also asserts, also be open to mobile banking as 91% of financially underserved Americans have mobile phones and 57% have smart phones, Factor Trust said.