X0306 4 2018-06-20 0 0001235010 MOMENTA PHARMACEUTICALS INC MNTA 0001237257 DOWNEY BRUCE C/O MOMENTA PHARMACEUTICALS, INC. 301 BINNEY STREET CAMBRIDGE MA 02142 1 0 0 0 Common Stock 2018-06-20 4 M 0 5734 0 A 21234 D Stock Option (Right to Buy) 22.30 2018-06-20 4 A 0 8855 0 A 2028-06-20 Common Stock 8855 8855 D Restricted Stock Units 2018-06-20 4 A 0 4356 0 A Common Stock 4356 4356 D Restricted Stock Unit 2018-06-20 4 M 0 5734 0 D Common Stock 5734 0 D Represents an option granted by the Company pursuant to the Company's 2013 Incentive Award Plan. The stock option will vest and become exercisable on the first anniversary of the grant date, subject to Mr. Downey's continued service to the Company. Each restricted stock unit represents a contingent right to receive one share of MNTA common stock. Represents 4,356 restricted stock units, awarded pursuant to the Company's 2013 Incentive Award Plan, 100% of the restricted stock units shall vest on the first anniversary of the grant date, subject to Mr. Downey's continued service to the Company. Restricted Stock Units convert into common stock on a one-for-one basis. Subject to certain criteria, 100% of the restricted stock units shall vest on the first anniversary of the grant date. /s/ Marie T. Washburn as attorney in fact 2018-06-22