The Company is authorized to issue 500,000,000 shares of common stock. Holders of common stock are entitled to one vote per share. Holders of common stock are entitled to receive dividends, if and when declared by the Company’s Board of Directors, and to share ratably in the Company’s assets legally available for distribution to the Company’s shareholders in the event of liquidation. Holders of common stock have no preemptive, subscription, redemption or conversion rights. The holders of common stock do not have cumulative voting rights.

The Company is authorized to issue 1,000,000 shares of preferred stock in one or more series and to fix the powers, designations, preferences and relative participating, option or other rights thereof, including dividend rights, conversion rights, voting rights, redemption terms, liquidation preferences and the number of shares constituting any series, without any further vote or action by the Company’s shareholders. As of December 31, 2019 and 2018, the Company had no shares of preferred stock issued or outstanding.

During 2018, the Company’s Board of Directors approved a share repurchase program (the “2018 Share Repurchase Program”), pursuant to which the Company was authorized to repurchase up to $500.0 million of its common stock between February 1, 2018 and December 31, 2019.

During the years ended December 31, 2019 and 2018, the Company repurchased 832,186 and 2,093,891 shares, respectively, of its common stock under the 2018 Share Repurchase Program for an aggregate of $150.0 million and $350.0 million, respectively, including commissions and fees. As of June 30, 2019, the Company had repurchased the entire $500.0 million it was authorized to repurchase of its common stock under the 2018 Share Repurchase Program.

In July 2019, the Company’s Board of Directors approved a new share repurchase program (the “2019 Share Repurchase Program”), pursuant to which the Company is authorized to repurchase up to $500.0 million of its common stock between August 1, 2019 and December 31, 2020. The Company expects to fund further repurchases of its common stock through a combination of cash on hand and cash generated by operations. During the year ended December 31, 2019, the Company repurchased 213,548 shares of its common stock under the 2019 Share Repurchase Program for an aggregate of $36.0 million including commissions and fees. As of December 31, 2019, there is a total of $464.0 million remaining for repurchases under the 2019 Share Repurchase Program.

Under the 2018 and 2019 Share Repurchase Programs, the Company is authorized to purchase shares from time to time through open market or privately negotiated transactions. Such purchases are made pursuant to Rule 10b5-1 plans or other means as determined by the Company’s management and in accordance with the requirements of the SEC.

The purpose of each of the Company’s stock and option plans is to attract, retain and motivate its employees, consultants and directors. Awards granted under these plans can be nonstatutory stock options (“NSOs”), incentive stock options (“ISOs”), restricted stock units (“RSUs”) including performance-based RSUs (“PSUs”), restricted stock (“RSs”), or other equity-based awards, as specified in the individual plans.

Shares issued under all of the Company’s plans are funded through the issuance of new shares. The following table contains information about the Company’s equity plans:



			As of December 31, 2019
Title of Plan	Group Eligible	Type of Award Granted	Awards Outstanding	Additional Awards Authorized for Grant
2013 Stock and Option Plan	Employees, Non-employee Directors and Consultants	NSO, RS, RSU and PSU	9,577,268	15,778,703
2006 Stock and Option Plan	Employees, Non-employee Directors and Consultants	NSO, RS and RSU	651,842	—
		Total	10,229,110	15,778,703

All options granted under the Company’s 2013 Stock and Option Plan (“2013 Plan”) and 2006 Stock and Option Plan (“2006 Plan”) were granted with an exercise price equal to the fair value of the underlying common stock on the date of grant. As of December 31, 2019, the stock and option plan under which the Company is authorized to make new equity awards is the Company’s 2013 Plan. Under the 2013 Plan, no stock options can be awarded with an exercise price less than the fair market value on the date of grant. In the three years ended December 31, 2019, the Company’s shareholders approved increases in the number of shares authorized for issuance pursuant to the 2013 Stock and Option Plan of (i) 5,000,000 shares in 2019, (ii) 8,000,000 shares in 2018 and (iii) 6,750,000 shares in 2017.

During the three years ended December 31, 2019, grants to current employees and directors primarily had a grant date that was the same as the date the award was approved by the Company’s Board of Directors. During the three years ended December 31, 2019, for grants to new employees and directors, the date of grant for awards was the employee’s first day of employment or the date the director was elected to the Company’s Board of Directors. All options awarded under the Company’s stock and option plans expire not more than 10 years from the grant date.



	Stock Options		Weighted-average Exercise Price		Weighted-average Remaining Contractual Life	Aggregate Intrinsic Value
	(in thousands)		(per share)		(in years)	(in thousands)
Outstanding at December 31, 2018	8,551		$	111.46
Granted	1,521		$	184.50
Exercised	(3,327	)	$	95.57
Forfeited	(467	)	$	146.59
Expired	(6	)	$	182.96
Outstanding at December 31, 2019	6,272		$	134.92	7.12	$	522,740
Exercisable at December 31, 2019	3,333		$	114.15	6.06	$	346,943

The aggregate intrinsic value in the table above represents the total pre-tax amount, net of exercise price, that would have been received by option holders if all option holders had exercised all options with an exercise price lower than the market price on the last business day of 2019, which was $218.26 based on the average of the high and low price of the Company’s common stock on that date.

The total intrinsic value (the amount by which the fair market value exceeded the exercise price) of stock options exercised during 2019, 2018 and 2017 was $325.9 million, $258.2 million and $302.8 million, respectively. The total cash received by the Company as a result of employee stock option exercises during 2019, 2018 and 2017 was $317.8 million, $263.4 million and $323.3 million, respectively.



	Options Outstanding				Options Exercisable
Range of Exercise Prices	Number Outstanding	Weighted-average Remaining Contractual Life	Weighted-average Exercise Price		Number Exercisable	Weighted-average Exercise Price
	(in thousands)	(in years)	(per share)		(in thousands)	(per share)
$29.07–$40.00	108	1.58	$	37.62	108	$	37.62
$40.01–$60.00	277	2.55	$	49.69	277	$	49.69
$60.01–$80.00	140	4.31	$	74.55	136	$	74.53
$80.01–$100.00	1,670	6.25	$	89.42	1144	$	90.10
$100.01–$120.00	243	5.11	$	109.23	241	$	109.17
$120.01–$140.00	454	5.67	$	129.77	447	$	129.85
$140.01–$160.00	1,036	8.10	$	155.50	383	$	155.39
$160.01–$180.00	720	8.46	$	168.04	233	$	164.48
$180.01–$189.38	1,624	8.90	$	185.41	364	$	184.85
Total	6,272	7.12	$	134.92	3,333	$	114.15



	Restricted Stock Units (excluding PSUs)				Restricted Stock
	Number of Shares		Weighted-average Grant-date Fair Value		Number of Units		Weighted-average Grant-date Fair Value
	(in thousands)		(per share)		(in thousands)		(per share)
Unvested at December 31, 2018	2,717		$	140.10	480		$	104.91
Granted	1,717		$	181.87	—		$	—
Vested	(974	)	$	133.15	(375	)	$	108.23
Cancelled	(329	)	$	149.83	(13	)	$	100.79
Unvested at December 31, 2019	3,131		$	163.61	92		$	91.97

The total fair value of restricted stock units that vested during 2019, 2018 and 2017 (measured on the date of vesting) was $178.2 million, $104.8 million and $33.2 million, respectively. The total fair value of restricted stock that vested during 2019, 2018 and 2017 (measured on the date of vesting) was $70.7 million, $114.5 million and $157.0 million, respectively.

The potential range of shares issuable pursuant to the Company’s PSU awards range from 0% to 200% of the target shares based on financial and non-financial measures. Fifty percent of PSUs that could be earned have a one-year performance period with the amount actually earned dependent upon the Company’s financial performance and with vesting of the earned shares in three equal installments over a three-year period. The remaining 50% of PSUs that could be earned have a three-year performance period with the amount actually earned dependent upon the achievement of multiple clinical development milestones and with the earned shares cliff vesting at the end of the three-year performance period.



	Performance-Based RSU
	Number of Units		Weighted-average Grant-date Fair Value
	(in thousands)		(per share)
Unvested at December 31, 2018 (1)	759		$	110.50
Granted (2)	449		$	183.48
Vested	(403	)	$	109.23
Cancelled	(71	)	$	104.61
Unvested at December 31, 2019	734		$	143.21

(1) “Unvested” represents the Company’s PSUs at target to the extent performance has not been certified plus the actual number of shares that continue to be subject to service conditions for which the performance has been achieved and certified.
(2) “Granted” represents (i) the target number of shares issuable for grants during 2019 and (ii) any change in the number of shares issuable pursuant to outstanding PSUs based on performance certification during 2019.

The Company has an employee stock purchase plan (the “ESPP”). The ESPP permits eligible employees to enroll in a twelve-month offering period comprising two six-month purchase periods. Participants may purchase shares of the Company’s common stock, through payroll deductions, at a price equal to 85% of the fair market value of the common stock on the first day of the applicable twelve-month offering period, or the last day of the applicable six-month purchase period, whichever is lower. Purchase dates under the ESPP occur on or about May 14 and November 14 of each year. During 2019, the Company’s shareholders approved an increase in the number of shares authorized for issuance pursuant to the ESPP of 2,000,000 shares. As of December 31, 2019, there were 2,199,376 shares of common stock authorized for issuance pursuant to the ESPP.