Clayton Holdings has long cooperated with members of the Residential MBS Working Group, but a change in personnel at the interagency group and a wide-ranging subpoena have strained the due diligence firm’s relationship with prosecutors, according to court filings. The U.S. Attorney’s Office for the District of Connecticut, on behalf of the RMBS Working Group, is seeking an order to compel Clayton to cooperate with a subpoena issued in early July. The subpoena relates to an investigation into 16 firms that participated in the issuance and underwriting of non-agency MBS from 2005 through 2007. The RMBS Working Group is looking into possible violations of the Financial Institutions Reform, Recovery and Enforcement Act. The subpoena essentially seeks...