After years of battling to limit the overseas reach of U.S. swaps rules, Wall Street is beginning to hear a more flexible approach from one of its top regulators.

Timothy Massad, who took over as chairman of Commodity Futures Trading Commission (CFTC) in June, told traders today that it's unreasonable to expect identical derivatives regulations around the world. While the agency is striving to ensure coordination with authorities in Europe and Asia, "there will inevitably be differences," he said.

Massad's comments reflect a change in tone from his predecessor Gary Gensler, who argued that extending CFTC rules to other jurisdictions was crucial to protecting the U.S. financial system from a foreign-born crisis. The agency will also delay a provision applying the Dodd-Frank Act to U.S. structured trades that banks book through overseas affiliates, Massad said.