The long-awaited regulation would require banks to put up much more capital to support investments in physical commodities, restrict involvement with power plants and limit the amount of trading banks can do. While the Fed doesn’t have the power to sever banks’ ties to physical commodities, it is seeking massive capital increases for the activities -- especially at Goldman Sachs and Morgan Stanley, which have special legal exemptions to stay in those businesses.

Fed officials estimated that the rule would mean about $4 billion in additional capital for the industry’s current level of investment, though Wall Street has been steadily backing away.