U.S. bank regulators released a proposal Thursday that would direct the nation's largest banks to raise their capital, arguing a larger cushion is needed to ensure stability.

The proposal, if implemented, would raise capital an aggregate 16% for larger banks, and also apply several stricter rules to banks with over $100 billion in assets. The sweeping plan would overhaul how banks gauge risk in numerous areas, and in turn how much capital they must hold in reserve.