The assistant attorney general responsible for overhauling antitrust enforcement under the Obama administration is stepping down. After two years serving as antitrust chief, Christine Varney will be joining the law firm Cravath, Swaine & Moore. A successor has not yet been named.

“I came in with President Obama committed to fulfilling his promise to reinvigorate antitrust law, and I think we've done that,” Varney told the Wall Street Journal on Wednesday. “It's the right time to move on.”

Varney assumed the position in April 2009, promising to come down on businesses that engage in anticompetitive practices.