The average tier one risk-based capital ratio for U.S. commercial banks at the end of 2009 was 11.43%, according to SNL Financial.

FORBES: Billionaire Banker's Blowout Year

The rules could mean a Tier 1 common risk-based capital ratio requirement to 7% and an addition a surcharge of up to 2.5% for the most complex financial firms.

FORBES: Banks Stocks Surge But For How Long?