Mark P. Wetjen, a member of the main U.S. derivatives regulator, is stepping down after almost four years of helping to put in place one of the most wide-ranging market oversight rewrites in generations.

Wetjen, a Democrat, pushed for increased coordination with overseas regulators as the U.S. Commodity Futures Trading Commission (CFTC) wrote rules for the swap market required by the Dodd-Frank Act following the 2008 credit crisis. Wetjen was often viewed as a more moderate voice on the commission as he looked to build consensus on cross-border oversight, rules increasing competition on new trading platforms, and limits on commodity market speculation.

“I have sought consensus globally, domestically, and within the commission itself throughout the implementation process, with the stated goals of ensuring the CFTC was properly informed as it pursued its work, and to better ensure that the reform effort would stand the test of time,” Wetjen said in a resignation letter dated Aug. 14 addressed to President Barack Obama.

Wetjen, 41, said his last day will be Aug. 28. A former aide to Senate Minority Leader Harry Reid, Wetjen didn’t specify future job plans.

The commission, which is set up to have five members, has had other departures since early last year when the majority of Dodd-Frank Act regulations were enacted. The agency is still working to complete a handful of additional rules and shifting to enforce restrictions on trades conducted by Goldman Sachs Group Inc., JPMorgan Chase & Co., BP Plc, and other firms.

Timothy Massad, the agency’s current chairman, and commissioners Sharon Y. Bowen, a Democrat, and J. Christopher Giancarlo, a Republican, all started last June. The president has yet to nominate a candidate for the current opening on the commission, when Scott O’Malia left, and he will now need to find a successor to Wetjen as well.

“When Mark arrived, the commission was just beginning the task of implementing the congressional mandate to regulate the swaps market,” Massad said in a statement. “Today, thanks to Mark’s help, the commission has a framework in place to make the swaps market more open, transparent, and competitive.”

Wetjen served alongside former Chairman Gary Gensler and ex-commissioners O’Malia, Bart Chilton, and Jill E. Sommers as they moved to design scores of rules meant to curb risky transactions directly between banks and other traders that proliferated before the 2008 crisis. The industry mounted a lobbying campaign against many of the rules, and when they didn’t win at the agency, they sometimes filed lawsuits to overturn the regulations.

A central debate at the agency has been the cross-border reach of the regulations, with the industry arguing that the CFTC overstepped its authority and hurt global markets. At the same time, advocates for stronger financial rules have pushed Wetjen—along with his colleagues—to take a tougher stance and oppose financial firms’ demands.

Wetjen, who served as acting chairman of the CFTC after Gensler’s departure, frequently commented on the need for higher levels of coordination with overseers in Europe and Asia.

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