Common Equity is a type of Banking Capital used to directly absorb losses.
Under the new Basel III banking agreement large internationally active banks will be required to hold a minimum of 7% of their assets in common equity. This regulation is to be fully effective as of 1 Jan 2019.
Wall Street Journal Monday 13 Sep 2010 "Regulators Agree to Put New Restraints on Banks" p A2 continuation of front page article titled "Banks Get New Restraints" p A1