X0306 4 2020-05-07 0 0001235010 MOMENTA PHARMACEUTICALS INC MNTA 0001229450 WHEELER CRAIG A C/O MOMENTA PHARMACEUTICALS, INC. 301 BINNEY STREET CAMBRIDGE MA 02142 1 1 0 0 President & CEO Common Stock 2020-05-07 4 M 0 5782 A 14521 D Common Stock 2020-05-08 4 S 0 2602 32.94 D 11919 D Common Stock 36725 I Craig A Wheeler 2016 Annuity Trust Common Stock 48263 I Craig A Wheeler 2018 Annuity Trust Common Stock 474598 I Craig Wheeler Revocable Trust Restricted Stock Units 2020-05-07 4 M 0 5782 0 D Common Stock 5782 17344 D Shares received pursuant to settlement of Restricted Stock Units that were granted on February 7, 2017. Restricted Stock Units convert into common stock on a one-for-one basis. This transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 7, 2017. This transaction was executed in multiple trades at prices ranging from $32.70 to $33.42. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. Each Restricted Stock Unit represents a contingent right to receive one share of MNTA common stock. Subject to the officer's continued employment with the company, the restricted stock units will vest with respect to 25% of the shares on the first anniversary of the grant date, and the remainder will vest in equal quarterly installments over the subsequent three years. Reflects a decrease of 45,925 shares of MNTA common stock transferred to the Craig Wheeler Revocable Trust on April 17, 2020. Reflects the transfer of 45,925 shares of MNTA common stock on April 17,2020 that were previously held in the Craig A. wheeler personal account. /s/ R. Mark Chamberlin as attorney in fact 2020-05-11