9999999995-12-001663.hdr.sgml : 20120530 20120530001510 9999999995-12-001663 EFFECT 1 20120529 20120530 20120529 Duff & Phelps Corp 0001397821 6211 208893559 DE 1231 EFFECT 33 333-181132 12875642 55 EAST 52ND STREET NEW YORK NY 10055 (212) 871-2000 55 EAST 52ND STREET NEW YORK NY 10055 Duff & Phelps CORP 20070427