JPMorgan Chase & Co., Goldman Sachs Group Inc., and the world's largest banks won rollbacks in final Dodd-Frank Act rules that promise to transform the private swaps market by increasing competition.

The Commodity Futures Trading Commission voted 4-1 in Washington last week on rules determining how buyers and sellers must trade credit-default, interest-rate, and commodity swaps in a $633 trillion global market. The rule weakened a proposal by reducing the number of price quotes buyers must seek on swap-execution facilities, after banks and asset managers said a five- quote requirement was onerous and would impair trading.

The vote on the rules represents “the start of a process that could eventually lead to a seismic change in trading of over-the-counter derivatives,” Richard Repetto, an analyst with Sandler O'Neill & Partners LP in New York, said in a telephone interview before the meeting. “It is a switch from an opaque, bilateral market to something where there is some price transparency and a more open and automated market.”