The nation's eight largest banks will have to raise about $68 billion in additional capital to meet rules approved Tuesday intended to help banks weather losses during periods of market stress, federal regulators said.

The so-called "leverage ratio" approved by the Office of the Comptroller of the Currency and the Federal Deposit Insurance Corp will mean the largest banks, including Citigroup and Goldman Sachs will be required to maintain well above the global minimum levels of capital held against all assets on their books. The Federal Reserve is expected to approve the rule at 4pm.