PAGE 1 000 B000000 12/31/2008 000 C000000 0000275694 000 D000000 N 000 E000000 NF 000 F000000 Y 000 G000000 Y 000 H000000 N 000 I000000 6.1 000 J000000 U 001 A000000 MASSMUTUAL CORPORATE INVESTORS 001 B000000 811-2183 001 C000000 4132261516 002 A000000 1500 MAIN STREET, P.O. BOX 15189 002 B000000 SPRINGFIELD 002 C000000 MA 002 D010000 01115 002 D020000 5189 003 000000 N 004 000000 N 005 000000 N 006 000000 N 007 A000000 N 007 B000000 0 058 A000000 N 059 000000 Y 060 A000000 Y 060 B000000 Y 061 000000 0 062 A000000 Y 062 B000000 0.0 062 C000000 0.0 062 D000000 0.0 062 E000000 0.0 062 F000000 0.0 062 G000000 0.0 062 H000000 0.0 062 I000000 3.0 062 J000000 0.0 062 K000000 0.0 062 L000000 0.0 062 M000000 0.0 062 N000000 0.0 062 O000000 0.0 062 P000000 92.9 062 Q000000 0.0 062 R000000 18.4 071 A000000 93708 071 B000000 80330 071 C000000 250780 071 D000000 32 072 A000000 12 PAGE 2 074 N000000 244311 074 T000000 208144 075 A000000 0 075 B000000 238245 077 A000000 Y 080 A000000 NATIONAL UNION FIRE INSURANCE COMPANY 080 B000000 NONE 080 C000000 1125 081 A000000 Y 081 B000000 1 082 A000000 N 082 B000000 0 083 A000000 N 083 B000000 0 084 A000000 N 084 B000000 0 085 A000000 Y 085 B000000 N SIGNATURE JAMES M. ROY TITLE V.P. AND C.F.O.