At issue is a capital 'surcharge' on the largest banks that do not satisfy the Fed that they can weather a severe economic downturn.

"We are not reconsidering, at this time, calculation of the surcharges," Yellen said.

The surcharge requires banks to hold more capital to weather an economic downturn rather than return that wealth to investors.

(Reporting By Patrick Rucker; Editing by Andrea Ricci)