The Chatter for Sunday, July 21 Hedge fund managers are responsible for exercising appropriate supervision over their employees. Andrew J. Ceresney, co-head of S.E.C. enforcement, after the agency accused Steven A. Cohen, the billionaire hedge fund manager, of "failing to supervise" employees and prevent them from insider trading. This is a difficult step, but the only viable option to address a problem that has been six decades in the making. Gov. Rick Snyder of Michigan, after the city of Detroit filed for bankruptcy, the largest American city ever to take such a course. Senator Elizabeth Warren of Massachusetts, after the Senate confirmed Richard Cordray as the first permanent director of the Consumer Financial Protection Bureau.