X0202 4 2005-09-06 0 0001235010 MOMENTA PHARMACEUTICALS INC MNTA 0001294347 Brugger Stephen B C/O MOMENTA PHARMACEUTICALS, INC. 675 WEST KENDALL STREET CAMBRIDGE MA 02142 0 1 0 0 Senior V.P. Common Stock 2005-09-06 4 M 0 59840 0.23 A 62083 D Common Stock 2005-09-06 4 M 0 22670 0.231 A 84753 D Employee Stock Option (right to buy) 0.23 2005-09-06 4 M 0 59840 0.23 D 2003-09-18 2012-09-17 Common Stock 87040 27200 D Employee Stock Option (right to buy) 0.231 2005-09-06 4 M 0 22670 0.231 D 2004-05-29 2013-05-28 Common Stock 51200 28530 D The stock option vested as to 25% of the shares on September 18, 2003 and as to an additional 6.25% of the shares at the end of each successive three-month period thereafter. Reflects a 1.28-for-1 forward stock split, which became effective on May 10, 2004, pursuant to which (i) the number of shares of common stock was multiplied by 1.28 and (ii) the exercise price of the option was divided by 1.28. The stock option vested as to 25% of the shares on May 29, 2004 and as to an additional 6.25% of the shares at the end of each successive three-month period thereafter. Includes 2,243 shares of common stock acquired on January 31, 2005 under the Momenta Pharmaceuticals, Inc. 2004 Employee Stock Purchase Plan. /s/ Steven B. Brugger 2005-09-08