X0202 4 2004-06-25 0 0001235010 MOMENTA PHARMACEUTICALS INC MNTA 0001114126 POLARIS VENTURE MANAGEMENT CO III LLC 0 0 1 0 0001295787 Arnold Stephen D 1000 WINTER STREET SUITE 3350 WALTHAM MA 02451 0 0 1 0 0001295676 Flint Jonathan A 1000 WINTER STREET SUITE 3350 WALTHAM MA 02451 0 0 1 0 0001104639 POLARIS VENTURE PARTNERS III LP 0 0 1 0 0001114889 POLARIS VENTURE PARTNERS ENTREPRENEURS FUND III LP 0 0 1 0 0001114437 POLARIS VENTURE PARTNERS FOUNDERS FUND III LP 0 0 1 0 0001018394 SPOON ALAN G 1150 15TH ST NW WASHINGTON DC 20071 0 0 1 0 0001117003 MCGUIRE TERRANCE C/O POLARIS VENTURE PARTNERS LP 1000 WINTER STREET, SUITE 3350 WALTHAM MA 02154 0 0 1 0 Common Stock 2004-06-25 4 C 0 282607 A 282607 I See Footnote Common Stock 2004-06-25 4 C 0 7338 A 7338 I See Footnote Common Stock 2004-06-25 4 C 0 4454 A 4454 I See Footnote Common Stock 2004-06-25 4 C 0 719943 A 1002550 I See Footnote Common Stock 2004-06-25 4 C 0 18693 A 26031 I See Footnote Common Stock 2004-06-25 4 C 0 11348 A 15802 I See Footnote Common Stock 2004-06-25 4 C 0 1391416 A 2393966 I See Footnote Common Stock 2004-06-25 4 C 0 36128 A 62159 I See Footnote Common Stock 2004-06-25 4 C 0 21932 A 37734 I See Footnote Common Stock 2004-06-25 4 C 0 1561944 A 3955910 I See Footnote Common Stock 2004-06-25 4 C 0 40555 A 102714 I See Footnote Common Stock 2004-06-25 4 C 0 24618 A 62352 I See Footnote Common Stock 2004-06-25 4 C 0 753515 A 4709425 I See Footnote Common Stock 2004-06-25 4 C 0 19564 A 122278 I See Footnote Common Stock 2004-06-25 4 C 0 11875 A 74227 I See Footnote Common Stock 2004-06-25 4 P 0 153591 6.5 A 4863016 I See Footnote Common Stock 2004-06-25 4 P 0 3988 6.5 A 126266 I See Footnote Common Stock 2004-06-25 4 P 0 2421 6.5 A 76648 I See Footnote Series A Preferred Stock 2004-06-25 4 C 0 220787 D Common Stock 282607 0 I See Footnote Series A Preferred Stock 2004-06-25 4 C 0 5733 D Common Stock 7338 0 I See Footnote Series A Preferred Stock 2004-06-25 4 C 0 3480 D Common Stock 4454 0 I See Footnote Series A Prime Preferred Stock 2004-06-25 4 C 0 562456 D Common Stock 719943 0 I See Footnote Series A Prime Preferred Stock 2004-06-25 4 C 0 14604 D Common Stock 18693 0 I See Footnote Series A Prime Preferred Stock 2004-06-25 4 C 0 8866 D Common Stock 11348 0 I See Footnote Series A Double Prime Preferred Stock 2004-06-25 4 C 0 1087044 D Common Stock 1391416 0 I See Footnote Series A Double Prime Preferred Stock 2004-06-25 4 C 0 28255 D Common Stock 36128 0 I See Footnote Series A Double Prime Preferred Stock 2004-06-25 4 C 0 17135 D Common Stock 21932 0 I See Footnote Series B Preferred Stock 2004-06-25 4 C 0 1220269 D Common Stock 1561944 0 I See Footnote Series B Preferred Stock 2004-06-25 4 C 0 31684 D Common Stock 40555 0 I See Footnote Series B Preferred Stock 2004-06-25 4 C 0 19233 D Common Stock 24618 0 I See Footnote Series C Preferred Stock 2004-06-25 4 C 0 588684 D Common Stock 753515 0 I See Footnote Series C Preferred Stock 2004-06-25 4 C 0 15285 D Common Stock 19564 0 I See Footnote Series C Preferred Stock 2004-06-25 4 C 0 9278 D Common Stock 11875 0 I See Footnote These shares are owned directly by Polaris Venture Partners III, L.P. ("PVP III"). Polaris Venture Management Co. III, L.L.C. ("PVM III"), the general partner of PVP III, and Stephen D. Arnold, Jonathan A. Flint, Terrance G. McGuire and Alan G. Spoon, the managing members of PVM III, may be deemed to share voting and dispositive power over the shares held by PVP III. Such persons and entities disclaim beneficial ownership of shares held by PVP III except to the extent of any pecuniary interest therein. These shares are owned directly by Polaris Venture Partners Entrepreneurs' Fund III, L.P. ("PVPEF III"). PVM III, the general partner of PVPEF III, and Stephen D. Arnold, Jonathan A. Flint, Terrance G. McGuire and Alan G. Spoon, the managing members of PVM III, may be deemed to share voting and dispositive power over the shares held by PVPEF III. Such persons and entities disclaim beneficial ownership of shares held by PVPEF III except to the extent of any pecuniary interest therein. These shares are owned directly by Polaris Venture Partners Founders' Fund III, L.P. ("PVPFF III"). PVM III, the general partner of PVPFF III, and Stephen D. Arnold, Jonathan A. Flint, Terrance G. McGuire and Alan G. Spoon, the managing members of PVM III, may be deemed to share voting and dispositive power over the shares held by PVPFF III. Such persons and entities disclaim beneficial ownership of shares held by PVPFF III except to the extent of any pecuniary interest therein. Each share of preferred stock automatically converted into 1.28 shares of common stock upon the closing of the issuer's initial public offering of common stock. Immediately. Not applicable. /s/ Kevin Littlejohn Attorney-in-Fact 2004-07-01