Seattle Genetics to sell common stock in underwritten public offering

Seattle Genetics, Inc. today announced that it intends to offer and sell shares of its common stock in an underwritten public offering. All of the shares in the offering are to be sold by Seattle Genetics. The offering is subject to market conditions, and there can be no assurance as to whether or when the offering may be completed, or as to the actual size or terms of the offering.

Jefferies & Company, Inc. and J.P. Morgan Securities LLC are acting as joint book-running managers for the proposed offering. Leerink Swann LLC and RBC Capital Markets, LLC are acting as co-lead managers for the proposed offering. Needham & Company, LLC, William Blair & Company, LLC, Oppenheimer & Co. Inc. and ThinkEquity LLC are acting as co-managers for the proposed offering.

A shelf registration statement relating to the shares was filed with the Securities and Exchange Commission and is effective. A preliminary prospectus supplement related to the offering will be filed with the Securities and Exchange Commission (SEC) and will be available on the SEC's website located at www.sec.gov. Copies of the preliminary prospectus supplement and the accompanying prospectus relating to this offering may be obtained from Equity Syndicate Prospectus Department, Jefferies & Company, Inc., 520 Madison Avenue, 12th Floor, New York, NY, 10022, at 877-547-6340, and at [email protected], or from J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717 or by calling 1-866-803-9204.