MOMENTA PHARMACEUTICALS ADOPTS SHAREHOLDER RIGHTS PLAN

Momenta Pharmaceuticals, Inc. (Nasdaq: MNTA), announced today that its Board of Directors has approved a Rights Agreement pursuant to which the Company's stockholders will receive preferred stock purchase rights. The Rights Agreement, which is similar to plans adopted by many public companies, is designed to protect the long-term value of the stockholders' investment and was not adopted in response to any current third-party attempt to acquire the Company.

PR Newswire (http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/story/11-08-2005/0004211082&EDATE=)