Exhibit 99.5

Trading Data

The following table sets forth all transactions in the Common Stock effected in the past sixty days by the Reporting Person. The price per share is net of commissions.

Name	Trade Date	Buy/ Sell		No. of Shares/ Quantity		Unit Cost(1)			Trade Amount		Where/How Effected	Security
Seattle Genetics, Inc.	May 11, 2018		Sell		29,600	$	19.04102	(2)	$	563,614.25	Open Market/Broker		Common Stock
Seattle Genetics, Inc.	May 14, 2018		Sell		47,667	$	19.16512	(3)	$	913,543.92	Open Market/Broker		Common Stock
Seattle Genetics, Inc.	May 16, 2018		Sell		168,939	$	19.42198	(4)	$	3,281,130.55	Open Market/Broker		Common Stock
Seattle Genetics, Inc.	May 17, 2018		Sell		668,300	$	21.30694	(5)	$	14,239,430.01	Open Market/Broker		Common Stock
Seattle Genetics, Inc.	May 18, 2018		Sell		231,956	$	20.93872	(6)	$	4,856,861.50	Open Market/Broker		Common Stock
Seattle Genetics, Inc.	May 21, 2018		Sell		386,538	$	21.13114	(7)	$	8,167,987.05	Open Market/Broker		Common Stock
Seattle Genetics, Inc.	May 22, 2018		Sell		140,000	$	21.44098	(8)	$	3,001,736.78	Open Market/Broker		Common Stock
Seattle Genetics, Inc.	June 4, 2018		Sell		1,700,000	$	24.70000	(9)	$	41,990,000.00	Block Trade		Common Stock

(1) The prices listed below represent the average prices at which the number of shares of Common Stock listed in each row were sold (full detailed information regarding the Common Stock sold and the corresponding prices will be provided upon request).

(2) The range of prices for these sales was $19.00 to $19.105.

(3) The range of prices for these sales was $19.00 to $19.42.

(4) The range of prices for these sales was $19.00 to $19.62.

(5) The range of prices for these sales was $20.41 to $22.46.

(6) The range of prices for these sales was $20.61 to $21.11.

(7) The range of prices for these sales was $20.84 to $21.53.

(8) The range of prices for these sales was $21.04 to $21.64.

(9) Represents a privately negotiated block trade with a single counterparty.