X0202 3 2006-10-16 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 9075868 I See footnote Warrant to Purchase Common Stock (Right to Buy) 1.33 2006-10-16 2011-10-16 Common 2847754 I See footnote The shares are held as follows: 180,691 by MPM BioVentures IV, L.P. ("BV IV"), 8,600,908 by MPM BioVentures IV-QP, L.P. ("BV IV QP"), 294,296 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 and Ashley Dombkowski are the members of BV IV, BV IV QP and AM BV4. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein. The shares subject to warrants are held as follows: 56,695 by BV IV, 2,698,726 by BV IV QP, and 92,333 by AM BV4. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein. See Form 3 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. 2006-10-17 /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. 2006-10-17 /s/ Vaughn Kailian, member of MPM Asset Management Investors BV4 LLC 2006-10-17 /s/ Vaughn Kailian, member of MPM BioVentures IV LLC, in its capacity as the general partner of MPM BioVentures IV GP LLC 2006-10-17 /s/ Vaughn Kailian, member of MPM BioVentures IV LLC 2006-10-17