SERIES B PREFERRED STOCK PURCHASE AGREEMENT
Portions of this exhibit were omitted and filed separately with the Secretary of the Commission pursuant to an
application for confidential treatment filed with the Commission pursuant to Rule 24b-2 under the Securities
Exchange Act of 1934. Such portions are marked by a series of asterisks.
STOCK PURCHASE AGREEMENT
THIS STOCK PURCHASE AGREEMENT (this "Agreement") is made as of December 9, 1999 by and
between ViroPharma Incorporated ("ViroPharma"), a Delaware corporation with its principal place of business
at 405 Eagleview Boulevard, Exton, PA 19341, and American Home Products Corporation ("AHPC"), a
Delaware corporation with its principal place of business at 5 Giralda Farms, Madison, NJ 07940.
WHEREAS, ViroPharma and AHPC (through its Wyeth-Ayerst Laboratories Division) have entered into that
certain Collaboration and License Agreement of even date herewith (the "Collaboration Agreement"); and
WHEREAS, in connection with the Collaboration Agreement, ViroPharma desires to sell to AHPC and AHPC
desires to purchase from ViroPharma shares of Common Stock of ViroPharma in the potential aggregate amount
of $16,000,000 (sixteen million dollars), on the terms and subject to the conditions set forth in this Agreement.
NOW, THEREFORE, in consideration of the foregoing recitals and the mutual covenants and agreements
contained herein, the Parties hereto, intending to be legally bound, do hereby agree as follows:
1. Definitions. Unless otherwise indicated, the capitalized terms used herein shall have the meanings ascribed to
1.1 "Acquiror" means any corporation or other Person that acquires a Party's assets or capital stock or with
which a Party merges or consolidates pursuant to a Change of Control.
1.2 "Affiliate" means, with respect to each Party hereto, any entity or other Person that Controls, is Controlled by
or is under common Control with such Party; provided, however, that "Affiliate" shall not inc