X0202 3 2004-06-21 0 0001235010 MOMENTA PHARMACEUTICALS INC MNTA 0001294356 Whoriskey Susan K C/O MOMENTA PHARMACEUTICALS, INC. 43 MOULTON STREET CAMBRIDGE MA 02138 0 1 0 0 VP, Licensing & Bus Develop Common Stock 93964 D Series A Prime Convertible Preferred Stock Common Stock 18749 D Stock Option (right to buy) 0.231 2004-05-29 2013-05-28 Common Stock 32000 D Reflects a 1.28-for-1 forward stock split, which became effective on May 10, 2004, pursuant to which the number of shares of common stock was multiplied by 1.28. Automatically converts into common stock upon the closing of the Issuer's initial public offering of common stock. N/A Reflects a 1.28-for-1 forward stock split, which became effective on May 10, 2004, pursuant to which each share of Series A Prime Convertible Preferred Stock will automatically convert into approximately 1.28 shares of common stock upon the closing of the Issuer's initial public offering of common stock. 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. 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. /s/ Susan Whoriskey 2004-06-21