X0306 4 2018-07-18 0 0001235010 MOMENTA PHARMACEUTICALS INC MNTA 0001733094 KWON YOUNG C/O MOMENTA PHARMACEUTICALS, INC. 301 BINNEY STREET CAMBRIDGE MA 02142 0 1 0 0 SVP, Corporate Development Common Stock 2018-07-18 4 M 0 8000 13.26 A 122624 D Common Stock 2018-07-18 4 S 0 8000 29.21 D 114624 D Common Stock 2018-07-18 4 M 0 8500 15.44 A 123124 D Common Stock 2018-07-18 4 S 0 8500 29.43 D 114624 D Common Stock 2018-07-18 4 M 0 9164 17.96 A 123788 D Common Stock 2018-07-18 4 S 0 9164 29.46 D 114624 D Common Stock 2018-07-18 4 M 0 2500 13.02 A 117124 D Common Stock 2018-07-18 4 S 0 2500 29.30 D 114624 D Common Stock 2018-07-18 4 M 0 4000 21.56 A 118624 D Common Stock 2018-07-18 4 S 0 4000 29.40 D 114624 D Common Stock 2018-07-18 4 S 0 3000 28.90 D 111624 D Stock Option(Right to Buy) 13.26 2018-07-18 4 M 0 8000 0 D 2015-02-22 2021-02-22 Common Stock 8000 11500 D Stock Option(Right to Buy) 15.44 2018-07-18 4 M 0 8500 0 D 2016-02-14 2022-02-14 Common Stock 8500 0 D Stock Option(Right to Buy) 17.96 2018-07-18 4 M 0 9164 0 D 2018-02-18 2024-02-18 Common Stock 9164 4822 D Stock Option(Right to Buy) 13.02 2018-07-18 4 M 0 2500 0 D 2018-05-18 2025-02-18 Common Stock 2500 19725 D Stock Option(Right to Buy) 21.56 2018-07-18 4 M 0 4000 0 D 2018-05-11 2025-08-11 Common Stock 4000 10000 D This transaction was effected pursuant to a Rule 10b5-1 trading plan. This transaction was executed in multiple trades at prices ranging from $28.90 to $29.90. 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. /s/ Bruce A. Leicher as attorney in fact 2018-07-19