X0202 4 2006-12-18 0 0001062216 MEMORY PHARMACEUTICALS CORP MEMY 0001358310 MPM BioVentures IV LP C/O MPM ASSET MANAGEMENT 200 CLARENDON ST., 54TH FLOOR BOSTON MA 02116 0 0 1 0 0001358309 MPM BioVentures IV QP LP C/O MPM ASSET MANAGEMENT 200 CLARENDON ST., 54TH FLOOR BOSTON MA 02116 0 0 1 0 0001358313 MPM Asset Management Investors BV4 LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON ST., 54TH FLOOR BOSTON MA 02116 0 0 1 0 0001358312 MPM BioVentures IV LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON ST., 54TH FLOOR BOSTON MA 02116 0 0 1 0 0001358311 MPM BioVentures IV GP LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON ST., 54TH FLOOR BOSTON MA 02116 0 0 1 0 Common Stock 2006-12-18 2006-12-18 4 P 0 2315151 1.11 A 11391019 I See Remarks Pursuant to the terms of the certain Securities Purchase Agreement by and among the issuer and various investors, dated as of October 5, 2006, MPM BioVentures IV, L.P. ("BV LP"), MPM BioVentures IV-QP, L.P. ("BV IV QP") and MPM Asset Management Investors BV4 LLC ("AM BV4" and together with BV IV and BV IV QP, the "MPM Entities") purchased shares of common stock of the issuer at a first closing and a second closing. The total shares acquired by the MPM Entities in the first closing and the second closing are held as follows: 226,783 by MPM BioVentures IV, L.P. ("BV IV"), 10,794,902 by MPM BioVentures IV-QP, L.P. ("BV IV QP"), and 369,334 by MPM Asset Management Investors BV4 LLC ("AM BV4"). MPM BioVentures IV GP LLC and MPM BioVentures IV LLC are the direct and indirect general partners of BV IV, BV IV QP and AM BV4. Vaughn Kailian, Ansbert Gadicke, Luke Evnin, Steven St. Peter, William Greene, James Paul Scopa, Ashley Dombkowski and John Vander Vort are the members of the general partner of BV IV, BV IV QP and AM BV4 and members of MPM Asset Management Investors BV4 LLC. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein. The shares acquired by the MPM Entities in the second closing are held as follows: 46,092 by BV IV, 2,193,994 by BV IV QP, and 75,065 by AM BV4. MPM BioVentures IV GP LLC and MPM BioVentures IV LLC are the direct and indirect general partners of BV IV, BV IV QP and AM BV4. Vaughn Kailian, Ansbert Gadicke, Luke Evnin, Steven St. Peter, William Greene, James Paul Scopa, Ashley Dombkowski and John Vander Vort are the members of the general partner of BV IV, BV IV QP and AM BV4 and members of MPM Asset Management Investors BV4 LLC. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein. See Form 4 for Vaughn Kailian for additional members of this joint filing. /s/ Vaughn Kailian, member of MPM BioVentures IV LLC, the general partner of MPM BioVentures IV GP LLC, in its capacity as the general partner of MPM BioVentures IV, L.P. 2007-01-05 /s/ Vaughn Kailian, member of MPM BioVentures IV LLC, the general partner of MPM BioVentures IV GP LLC, in its capacity as the general partner of MPM BioVentures IV-QP, L.P. 2007-01-05 /s/ Vaughn Kailian, member of MPM Asset Management Investors BV4 LLC 2007-01-05 s/ Vaughn Kailian, member of MPM BioVentures IV LLC, in its capacity as the general partner of MPM BioVentures IV GP LLC 2007-01-05 /s/ Vaughn Kailian, member of MPM BioVentures IV LLC, the general partner of MPM BioVentures IV GP LLC, in its capacity as the general partner of MPM BioVentures IV, L.P. 11/01/2006 2007-01-05