X0202 3 2004-06-21 0 0001235010 MOMENTA PHARMACEUTICALS INC MNTA 0001219015 CLARKE JOHN K C/O MOMENTA PHARMACEUTICALS, INC. 43 MOULTON STREET CAMBRIDGE MA 02138 1 0 0 0 Series A Double Prime Convertible Preferred Stock Common Stock 445992 I See Footnote Series B Convertible Preferred Stock Common Stock 1247458 I See Footnote Series C Convertible Preferred Stock Common Stock 407836 I See Footnote 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 Double Prime Convertible Preferred Stock, Series B Convertible Preferred Stock and Series C 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. These shares are owned directly by CHP II, L.P. John Clarke is the Managing General Partner of CHP II Management, LLC, the General Partner of CHP II, L.P. Mr. Clarke may be deemed to beneficially own the shares held by CHP II, L.P. although he disclaims beneficial ownership except to the extent of his proportionate pecuniary interest therein. /s/ John Clarke 2004-06-21