X0202 3 2006-10-17 0 0001298521 Trubion Pharmaceuticals, Inc TRBN 0001117120 ARCH VENTURE FUND V LP 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 0001161740 ARCH V ENTREPRENEURS FUND LP 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 0001222239 HEALTHCARE FOCUS FUND LP 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 0001274406 ARCH VENTURE PARTNERS V LP 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 0001274408 ARCH VENTURE PARTNERS V LLC 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 0001219039 CRANDELL KEITH 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 0001219042 NELSEN ROBERT 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 0001219043 BYBEE CLINTON 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 0001054117 LAZARUS STEVEN 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO IL 60631 0 0 1 0 Common Stock 23762 D Common Stock 158 D Series A Convertible Preferred Stock 0 Common Stock 979880 D Series B Convertible Preferred Stock 0 Common Stock 1161459 D Series A Convertible Preferred Stock 0 Common Stock 6511 D Series B Convertible Preferred Stock 0 Common Stock 7834 D Series A Convertible Preferred Stock 0 Common Stock 61333 D Series B Convertible Preferred Stock 0 Common Stock 71469 D Securities held of record by ARCH Venture Fund V, L.P. ("ARCH V"). ARCH Venture Partners V, L.P. (the "GPLP"), as the sole general partner of ARCH V, may be deemed to beneficially own certain of the shares held of record by ARCH V. The GPLP disclaims beneficial ownership of all shares held of record by ARCH V in which the GPLP does not have an actual pecuniary interest. ARCH Venture Partners V, LLC (the "GPLLC"), as the sole general partner of the GPLP, may be deemed to beneficially own certain of the shares held of record by ARCH V. The GPLLC disclaims beneficial ownership of all shares held of record by ARCH V in which it does not have an actual pecuniary interest. Each of Messrs. Crandall, Nelson, Bybee and Lazarus, as the individual Managing Directors of the GPLLC, may be deemed to beneficially own certain of the shares held of record by ARCH V. Each of Messrs. Crandall, Nelson, Bybee and Lazarus disclaims beneficial ownership of all shares held of record by ARCH V. Securities held of record by ARCH V Entrepreneurs Fund, L.P. ("Entrepreneurs"). The GPLP, as the sole general partner of Entrepreneurs, may be deemed to beneficially own certain of the shares held of record by Entrepreneurs. The GPLP disclaims beneficial ownership of all shares held of record by Entrepreneurs in which the GPLP does not have an actual pecuniary interest. The GPLLC, as the sole general partner of the GPLP, may be deemed to beneficially own certain of the shares held of record by Entrepreneurs. The GPLLC disclaims beneficial ownership of all shares held of record by Entrepreneurs in which it does not have an actual pecuniary interest. Each of Messrs. Crandall, Nelson, Bybee and Lazarus, as the individual Managing Directors of the GPLLC, may be deemed to beneficially own certain of the shares held of record by Entrepreneurs. Each of Messrs. Crandall, Nelson, Bybee and Lazarus disclaims beneficial ownership of all shares held of record by Entrepreneurs. The Series A Convertible Preferred Stock is convertible into Trubion Pharmaceuticals, Inc. ("Trubion") Common Stock on a 1-for-1 basis, was convertible at the date it was acquired, has no expiration date and will convert automatically upon the closing of the initial public offering of Trubion. The Series B Convertible Preferred Stock is convertible into Trubion Common Stock on a 1-for-1 basis, was convertible at the date it was acquired, has no expiration date and will convert automatically upon the closing of the initial public offering of Trubion. Securities held of record by Healthcare Focus Fund, L.P. ("Healthcare"). The GPLP, as the sole general partner of Healthcare, may be deemed to beneficially own certain of the shares held of record by Healthcare. The GPLP disclaims beneficial ownership of all shares held of record by Healthcare in which the GPLP does not have an actual pecuniary interest. The GPLLC, as the sole general partner of the GPLP, may be deemed to beneficially own certain of the shares held of record by Healthcare. The GPLLC disclaims beneficial ownership of all shares held of record by Healthcare in which it does not have an actual pecuniary interest. Each of Messrs. Crandall, Nelson, Bybee and Lazarus, as the individual Managing Directors of the GPLLC, may be deemed to beneficially own certain of the shares held of record by Healthcare. Each of Messrs. Crandall, Nelson, Bybee and Lazarus disclaims beneficial ownership of all shares held of record by Healthcare. /s/ Robert Nelsen, as Managing Director of the general partner of the general partner of ARCH Venture Fund V, L.P. 2006-10-17 /s/ Robert Nelsen, as Managing Director of the general partner of the general partner of ARCH V Entrepreneurs Fund, L.P. 2006-10-17 /s/ Robert Nelsen, as Managing Director of the general partner of the general partner of Healthcare Focus Fund, L.P. 2006-10-17 /s/ Robert Nelsen, as Managing Director of the general partner of ARCH Venture Partners V, L.P. 2006-10-17 /s/ Robert Nelsen, as Managing Director of ARCH Venture Partners V, LLC 2006-10-17 /s/ Keith Crandell 2006-10-17 /s/ Robert Nelsen 2006-10-17 /s/ Clinton Bybee 2006-10-17 /s/ Steven Lazarus 2006-10-17