Stock award plan

In 2009, the Company’s shareholders approved the 2009 Equity and Long-Term Incentive Plan, which provides for the granting of stock option awards, restricted stock awards, and other stock-based and cash-based awards, subject to certain adjustments and annual increases.

On March 5, 2013, the Company’s Board of Directors approved the 2013 Stock Incentive Plan, which provides for the granting of stock option awards, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards in the aggregate of 739,937 shares of common stock. On March 5, 2013, the Board approved a grant of 735,324 shares of restricted stock and 4,613 stock options. There are no additional shares available for issuance under this plan.

In May 2013, the Company’s Board of Directors and stockholders increased by 2,500,000 the number of shares authorized under the 2009 Equity and Long Term Incentive Plan, which provides for the granting of stock option awards, restricted stock awards, and other stock-based and cash-based awards. There are no additional shares available for issuance under this plan.

In May 2013, the Company’s Board of Directors and stockholders approved the 2013 Long Term Incentive Plan, which became effective upon the closing of the Company’s IPO. The 2013 Long Term Incentive Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock awards and other stock-based awards. The number of shares of common stock reserved for issuance under the 2013 Long Term Incentive Plan is the sum of (1) 122,296 shares of common stock available for issuance under the Company’s 2009 Equity and Long Term Incentive Plan and 2013 Stock Incentive Plan, (2) the number of shares (up to 3,040,444 shares) equal to the sum of the number of shares of common stock subject to outstanding awards under the Company’s 1998 Employee, Director and Consultant Stock Option Plan, 2009 Equity and Long Term Incentive Plan and 2013 Stock Incentive Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right plus (3) an annual increase, to be added on the first day of each fiscal year until the expiration of the 2013 Long Term Incentive Plan, equal to the lowest of 2,500,000 shares of common stock, 4% of the number of shares of common stock outstanding on the first day of the fiscal year and an amount determined by the Company’s Board of Directors. As of December 31, 2017, awards for 927,478 shares of common stock were available for issuance.

The Board of Directors has the authority to select the individuals to whom options are granted and determine the terms of each option, including (i) the number of shares of common stock subject to the option; (ii) the date on which the option becomes exercisable; (iii) the option exercise price, which, in the case of incentive stock options, must be at least 100% (110% in the case of incentive stock options granted to a stockholder owning in excess of 10% of the Company’s stock) of the fair market value of the common stock as of the date of grant; and (iv) the duration of the option (which, in the case of incentive stock options, may not exceed ten years). Options typically vest over a three- or four-year period.

Inducement stock option awards

Pursuant to the Nasdaq inducement grant exception, during the year ended December 31, 2017, the Company issued options to purchase an aggregate of 640,550 shares of common stock to certain new hire employees at a weighted-average exercise price of $14.16 per share. An aggregate of 316,176 of options previously granted as inducement awards were forfeited during the year ended December 31, 2017 in connection with employee separations from the Company.

A summary of stock option activity is as follows:



	Number of options		Weighted- average exercise price		Weighted- average remaining contractual term	Aggregate intrinsic value
						(in thousands)
Outstanding at December 31, 2014	3,432,972		$	25.00
Granted	2,201,800		$	50.81
Exercised	(656,248	)	$	13.27
Forfeited	(152,047	)	$	49.58
Outstanding at December 31, 2015	4,826,477		$	37.20
Granted	1,500,645		$	27.90
Exercised	(89,216	)	$	10.85
Forfeited	(383,590	)	$	47.42
Outstanding at December 31, 2016	5,854,316		$	34.71
Granted	1,913,873		$	12.34
Exercised	(202,085	)	$	10.80
Forfeited	(1,117,462	)	$	33.65
Outstanding at December 31, 2017	6,448,642		$	29.00	7.28	$	13,435
Vested or expected to vest at December 31, 2017	2,522,747		$	23.29	8.39	$	6,822
Exercisable at December 31, 2017	3,778,544		$	33.19	6.48	$	6,167

The fair values of grants made in the years ended December 31, 2017, 2016 and 2015 were contemporaneously estimated on the date of grant using the following assumptions:



	2017	2016	2015
Risk-free interest rate	1.84 - 2.45%	1.30 - 2.24%	1.48 - 2.18%
Expected volatility	76 - 81%	67 - 78%	67 - 69%
Expected term	5.04 - 10.00 years	5.05 - 10.00 years	5.50 - 9.12 years

The Company assumed no expected dividends for all grants. The weighted average grant date fair value of options granted during the years ended December 31, 2017, 2016 and 2015 was $8.45, $17.31, and $50.81 per share, respectively.

In 2014, the Company modified the terms of stock options granted to a departing member of the executive team. The Company accounted for the modification to the option grants pursuant to ASC Topic 718-20-35 and recognized approximately $1.9 million as additional compensation that was charged to operations during the year ended December 31, 2014.

Restricted Stock Awards—Restricted stock awards are granted subject to certain restrictions, including in some cases service conditions (restricted stock). The grant-date fair value of restricted stock awards, which has been determined based upon the market value of the Company’s shares on the grant date, is expensed over the vesting period.

Restricted Stock Units—Restricted stock units are granted subject to certain restrictions, including in some cases service or time conditions (restricted stock). The grant-date fair value of restricted stock units, which has been determined based upon the market value of the Company’s shares on the grant date, is expensed over the vesting period.

The following table summarizes information on the Company’s restricted stock awards and units:



	Restricted Stock Awards and Units
	Number of Shares		Weighted Average Grant Date Fair Value
Unvested at December 31, 2016	271,651		$	19.76
Granted	365,194		$	11.67
Vested	(180,861	)	$	14.19
Forfeited	(62,973	)	$	14.18
Unvested at December 31, 2017	393,011		$	15.64

Stock Appreciation Rights—Stock appreciation rights (SARs) entitle the holder to receive, upon exercise, an amount of the Company’s common stock or cash (or a combination thereof) determined by reference to appreciation, from and after the date of grant, in the fair market value of a share of the Company’s common stock over the measurement price based on the exercise date.

In May 2016, a total of 897,290 SARs were granted to non-executive employees (the 2016 SARs). The 2016 SARs will vest annually in equal installments over four years and will be settled in cash on each vest date, requiring the Company to remeasure the SARs at each reporting period until vesting occurs. For the period ending December 31, 2017, the Company recorded $1.9 million in compensation expense related to the 2016 SARs.

Employee Stock Purchase Plan—In June 2016, the Company established an Employee Stock Purchase Plan (ESPP or the Plan) for certain eligible employees. The Plan is administered by the Company’s Board of Directors or a committee appointed by the Board. The total number of shares available for purchase under the Plan is one million shares of the Company’s common stock. Employees may participate over a six-month period through payroll withholdings and may purchase, at the end of the six-month period, the Company’s common stock at a purchase price of at least 85% of the closing price of a share of the Company’s common stock on the first business day of the offering period or the closing price of a share of the Company’s common stock on the last business day of the offering period, whichever is lower. No participant will be granted a right to purchase the Company’s common stock under the Plan if such participant would own more than 5% of the total combined voting power of the Company or any subsidiary of the Company after such purchase. For the period ending December 31, 2017, the Company recorded $0.9 million in compensation expense related to the ESPP.

The Company recorded share-based compensation expense in the statement of operations related to incentive stock options, nonstatutory stock options, restricted stock awards, restricted stock units and the ESPP as follows:



	Year ended December 31,
	2017		2016		2015
Research and development	$	15,456	$	16,812	$	16,138
Selling, general and administrative	15,103		18,197		17,841
Total	$	30,559	$	35,009	$	33,979

As of December 31, 2017, there was approximately $38.2 million of total unrecognized compensation cost related to unvested share-based compensation arrangements granted under the Company’s Plans. This cost is expected to be recognized as compensation expense over the weighted average remaining service period of approximately 1.91 years.