Item 8.01 Other Events.

Clay B. Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics, Inc. (the "Company"), has entered into a pre-arranged, written stock trading plan (the "Plan") that is intended to satisfy the requirements of Rule 10b5-1(c)(1) under the Securities Exchange Act of 1934, as amended. Sales under the Plan may not occur prior to July 2, 2012 and all sales must be completed prior to February 17, 2014. Pursuant to the Plan, Dr. Siegall may sell up to 81,607 shares of the Company's common stock prior to February 17, 2014, provided the price exceeds a specified price per share. Dr. Siegall has entered into the Plan in order to exercise options pursuant to grants that expire prior to February 2014. Transactions under the Plan will be disclosed publicly through Form 144 and Form 4 filings with the Securities and Exchange Commission, to the extent required by law.

It is possible that other executive officers and directors of the Company may enter into similar stock trading plans in the future. Except as may be required by law, the Company does not undertake to report on stock trading plans by other Company officers or directors, nor to report modifications, terminations or other activities under Dr. Siegall's Plan or the plan of any other individual.

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