X0303 4 2010-06-16 0 0001235010 MOMENTA PHARMACEUTICALS INC MNTA 0001308911 Bishop John E 675 WEST KENDALL STREET CAMBRIDGE MA 02142 0 1 0 0 Senior VP, Pharmaceutical Scie Common Stock 2010-06-16 4 S 0 429 13.69 D 49549 D This sale was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 9, 2009. This transaction was executed in multiple trades at prices ranging from $13.54 to $13.69. 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 and prices at which the transaction was effected. /s/ Michael Flanagan as attorney in fact 2010-06-18