X0303 4 2010-06-30 0000912183 CUBIST PHARMACEUTICALS INC CBST 0001263230 PEREZ ROBERT J 65 HAYDEN AVENUE LEXINGTON MA 02421 1 EVP, Chief Operating Officer Common Stock 2010-06-30 4 J 0 837 16.167 A 16935 D Common Stock 2010-06-30 4 J 0 69 20.60 A 17004 D Shares purchased pursuant to employee stock purchase plan Matching contribution by employer to 401(k) Plan /s/ Benjamin S. Harshbarger - Attorney in fact 2010-07-02