Stock-based Compensation Expense and Share Repurchase

Stock-based compensation expense

During the three months ended March 31, 2018 and 2017, the Company recognized the following stock-based compensation expense:



	Three Months Ended March 31,
	2018			2017
	(in thousands)
Stock-based compensation expense by type of award:
Stock options	$	26,055		$	26,981
Restricted stock and restricted stock units (including PSUs)	50,418			40,745
ESPP share issuances	2,128			2,064
Stock-based compensation expense related to inventories	(465		)	(351		)
Total stock-based compensation included in costs and expenses	$	78,136		$	69,439

Stock-based compensation expense by line item:
Cost of sales	$	813		$	457
Research and development expenses	48,488			44,837
Sales, general and administrative expenses	28,835			24,145
Total stock-based compensation included in costs and expenses	$	78,136		$	69,439

The following table sets forth the Company’s unrecognized stock-based compensation expense as of March 31, 2018, by type of award and the weighted-average period over which that expense is expected to be recognized:



	As of March 31, 2018
	Unrecognized Expense		Weighted-average Recognition Period
	(in thousands)		(in years)
Type of award:
Stock options	$	203,271	2.79
Restricted stock and restricted stock units (including PSUs)	$	386,253	2.76
ESPP share issuances	$	2,117	0.43

The following table summarizes information about stock options outstanding and exercisable as of March 31, 2018:



	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)
$26.73–$40.00	726	1.63	$	34.46	726	$	34.46
$40.01–$60.00	588	4.24	$	49.43	588	$	49.43
$60.01–$80.00	644	5.96	$	75.25	627	$	75.28
$80.01–$100.00	3,791	7.85	$	89.21	1,357	$	89.45
$100.01–$120.00	972	6.80	$	109.28	622	$	109.15
$120.01–$140.00	1,138	7.35	$	130.20	732	$	129.98
$140.01–$160.00	1,496	9.86	$	155.57	10	$	155.57
$160.01–$163.74	600	9.25	$	162.94	76	$	162.94
Total	9,955	7.30	$	103.03	4,738	$	84.36

Share repurchase program

The Board of Directors has authorized approved a share repurchase program, pursuant to which the Company is authorized to repurchase up to $500.0 million of its common stock between February 1, 2018 and December 31, 2019.

During the three months ended March 31, 2018, the Company repurchased 67,084 shares of its common stock under the share repurchase program for an aggregate of $11.3 million (of which $1.3 million was accrued as of March 31, 2018), including commissions and fees. Under the share repurchase program, the Company is authorized to purchase shares from time to time through open market or privately negotiated transactions and may be 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 Securities and Exchange Commission.

The Company expects to fund any further repurchases of its common stock through a combination of cash on hand and cash generated by operations.