FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * SIEGALL CLAY B   2. Issuer Name and Ticker or Trading Symbol SEATTLE GENETICS INC /WA [SGEN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) President and CEO (Last) (First) (Middle) 21823 30TH DRIVE SE 3. Date of Earliest Transaction (Month/Day/Year) 09/20/2011 (Street) BOTHELL, WA 98021 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 09/20/2011   M(1)   5,600 A $ 6.34 1,050,655 D   Common Stock 09/20/2011   S   5,600 D $ 20.0012 (2) 1,045,055 D   Common Stock 09/21/2011   M(1)   24,400 A $ 6.34 1,069,455 D   Common Stock 09/21/2011   S   24,400 D $ 20.1521 (3) 1,045,055 (4) D   Common Stock               85,000 I by Trust

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Non-Qualified Stock Option (right to buy)

$ 6.34

09/20/2011

M

5,600

(5)

02/01/2012

Common Stock

5,600

$ 6.34

84,400

D

Non-Qualified Stock Option (right to buy)

$ 6.34

09/21/2011

M

24,400

(5)

02/01/2012

Common Stock

24,400

$ 6.34

60,000

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
SIEGALL CLAY B 21823 30TH DRIVE SE BOTHELL, WA 98021	X		President and CEO

Signatures

Clay B. Siegall		09/21/2011
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by Dr. Siegall on December 15, 2010 and described in a Form 8-K filed on December 17, 2010.
(2)	20.0012 represents an average price per share for the shares sold on 9/20/2011. The sell price for shares sold on this day ranged from $20.00 to 20.0211.
(3)	20.1521 represents an average price per share for the shares sold on 9/21/2011. The sell price for shares sold on this day ranged from $20.00 to 20.522.
(4)	Amount of securities beneficially owned following reported transactions includes 78,137 Restricted Stock Units subject to vesting.
(5)	Shares shall vest at a rate of 25% on 2/1/03 and monthly thereafter until all the shares are fully vested on 2/1/06.

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