Donald F. Donahue, chairman and CEO of Depository Trust & Clearing, argues that there are questions that must be addressed as authorities in Europe and the U.S. consider tougher supervision of over-the-counter derivatives. "Most crucially, how can the necessary improvements be implemented in a way that is consistent with the truly global nature of these markets?" Donahue asks. "Can global infrastructures for these instruments be preserved? Can a truly global set of transparency requirements governing these markets be agreed upon, across multiple regulators and jurisdictions?"