Item 3.02. Unregistered Sales of Equity Securities.

In a Current Report on Form 8-K filed with the Commission on January 27, 2009 (the "January Form 8-K"), Seattle Genetics, Inc. (the "Company"), reported, among other things, that the Company entered into a stock purchase agreement (the "Baker Purchase Agreement") with Baker Brothers Life Sciences, L.P. ("BBLS"). Felix Baker, Ph.D., one of the Company's directors, is a Managing Member of Baker Brothers Life Sciences Capital (GP), LLC, the general partner of BBLS. The Baker Purchase Agreement provided that, subject to stockholder approval and customary closing conditions, BBLS and certain affiliated funds (together, the "Baker Entities") would purchase 1,178,163 shares of the Company's common stock (such shares, the "Baker Shares") at $9.72 per share.

The Company received stockholder approval for the issuance and sale of the Baker Shares pursuant to the Baker Purchase Agreement at the Company's annual meeting of stockholders held on May 15, 2009, and the Company and the Baker Entities closed the issuance and sale of the Baker Shares on May 20, 2009 (the "Closing"). At the Closing, the Company issued and sold the Baker Shares to the Baker Entities for an aggregate cash purchase price of $11,451,744.36, or $9.72 per share. The Company issued and sold the Baker Shares to the Baker Entities in reliance upon exemptions from registration pursuant to Section 4(2) under the Securities Act of 1933, as amended (the "Securities Act"), and Rule 506 promulgated thereunder, and the Baker Entities represented to the Company that each Baker Entity is an "accredited investor" within the meaning of Rule 501 under the Securities Act.

The terms and conditions of the Baker Purchase Agreement described in this report is not complete and is qualified in its entirety by reference to the complete Baker Purchase Agreement filed as Exhibit 10.1 to the January Form 8-K.

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