A quarrel among regulators could add up to billions in savingsfor Wall Street banks.

At stake is a proposed rule that has dragged on for years thatcould require firms like JPMorgan Chase & Co. and MorganStanley to set aside tens of billions of dollars in collateral whentrading swaps with their own affiliates. Now, a last-ditch effortby bank lobbyists has helped spur some regulators to second-guesshow strict they should be, according to three people familiar withthe discussions.

The Office of the Comptroller of the Currency (OCC), whichregulates some of the largest banks that deal in swaps, is leaningtoward insisting only an affiliate post collateral to the bank,said the people, who requested anonymity because the final ruleisn't yet public. The Federal Deposit Insurance Corp. (FDIC) hasbacked a version of the rule proposed in September, demanding botha bank and its affiliate put up collateral, the people said.