Michelle Robertson notified Momenta Pharmaceuticals, Inc. (the “Company”) of her resignation from her role as the Company's Chief Financial Officer, principal financial officer and principal accounting officer, effective January 8, 2020, to pursue other opportunities. Ms. Robertson's resignation was not the result of any disagreement with the Company on any matter relating to the company's operations, policies or practices. On January 1, 2020, the Company appointed Young Kwon, Ph.D., currently the Company's Chief Business Officer, as the Company's principal financial officer with the title of Chief Financial and Business Officer, and appointed Agnieszka Cieplinska, currently the Company's Vice President, Controller, as the Company's principal accounting officer, with both appointments effective as of January 8, 2020.