Exhibit 4.1 STOCK PURCHASE AGREEMENT THIS STOCK PURCHASE AGREEMENT (the "Agreement"), is dated as of August 18, 2002, by and among HILAL CAPITAL, L.P. ("Hilal Capital"), HILAL CAPITAL QP, LP ("Hilal QP"), HILAL CAPITAL INTERNATIONAL LTD. ("HCI"),...Stock Purchase Agreement • August 21st, 2002 • Applied Molecular Evolution Inc • Services-commercial physical & biological research • California
