X0202 3 2006-01-25 0 0001340744 Altus Pharmaceuticals Inc. ALTU 0001322709 Warburg Pincus Partners LLC 466 LEXINGTON AVENUE NEW YORK NY 10017 0 0 1 0 0001162870 WARBURG PINCUS LLC 466 LEXINGTON AVENUE NEW YORK NY 10017 0 0 1 0 0000929408 WARBURG PINCUS & CO 466 LEXINGTON AVENUE NEW YORK NY 10017 0 0 1 0 Warrants 4.31 2004-05-21 2011-05-21 Series C Convertible Preferred Stock 1630914 D Series C Convertible Preferred Stock 0.00 2004-05-21 2006-01-31 Common Stock 3263251 D The Series C Convertible Preferred Stock is convertible into Common Stock. Series C Convertible Preferred Stock converts to common stock on a 1-for-0.44077 basis. The stockholder is Warburg Pincus Private Equity VIII, L.P. ("WP VIII"). Warburg Pincus Partners, LLC ("WPP LLC"), a subsidiary of Warburg Pincus & Co. ("WP"), is the sole general partner of WP VIII. WP VIII is managed by Warburg Pincus LLC ("WP LLC"). The address of the Warburg Pincus entities is 466 Lexington Avenue, New York, New York 10017. Jonathan S. Leff and Stewart J. Hen, directors of the Company, are general partners of WP and managing directors and members of WP LLC. Messrs. Leff and Hen disclaim beneficial ownership of all shares held by the Warburg Pincus entities. Charles R. Kaye and Joseph P. Landy are Managing General Partners of WP and Managing Members of WP LLC and may be deemed to control the Warburg Pincus entities. Messrs. Kaye and Landy disclaim beneficial ownership of all shares held by the Warburg Pincus entities. This is the anticipated date of the closing of the Issuer's initial public offering, which will trigger the mandatory conversion of the Series C Convertible Preferred Stock into common stock. /s/ Scott Arenare 2006-02-02 Scott Arenare 2006-02-02 Scott Arenare 2006-02-02