Stockholders' Equity

3 Months Ended

Mar. 31, 2017

Equity [Abstract]

Stockholders' Equity

Note 6—Stockholders’ Equity:

Stock-Based Compensation:

The Company’s 2011 Plan was adopted by the Board of Directors on September 15, 2011.  Pursuant to the 2011 Plan, the Company may grant incentive stock options, nonqualified stock options and restricted stock units, as well as other forms of equity-based compensation. Incentive stock options may be granted only to employees, while consultants, employees, officers and directors are eligible for the grant of nonqualified options and restricted stock units under the 2011 Plan. The maximum term of stock options granted under the 2011 Plan is 10 years. The exercise price of incentive stock options granted under the 2011 Plan must be at least equal to the fair value of such shares on the date of grant. Through March 31, 2017, a total of 10,529,412 shares of the Company’s common stock have been reserved for issuance under the 2011 Plan.

Employee stock-based compensation for the three months ended March 31, 2017 and 2016 were as follows (in thousands, except share and per share data):

	Three Months Ended March 31,
	2017		2016
Stock-based compensation:
Options -
Research and development, or R&D	$	20,356	$	23,556
General and administrative, or G&A		6,189		5,882
Performance shares - R&D		—		72
Restricted stock units -
R&D		2,124		—
G&A		1,095		—
Total stock-based compensation expense	$	29,764	$	29,510

Stock Options:

The fair value of options granted to employees was estimated using the Black-Scholes Option Pricing Method (see Note 2—Significant Accounting Policies) with the following weighted-average assumptions used during the three months ended March 31, 2017 and 2016:

	2017			2016
Dividend yield		0.0	%		0.0	%
Expected volatility		70.1	%		66.1	%
Risk-free interest rate		2.0	%		1.6	%
Expected life in years		5.85			5.85

Activity with respect to options granted under the 2011 Plan is summarized as follows:

	Shares			Weighted Average Exercise Price		WeightedAverage Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2016		6,578,522		$	87.52		8.0	$	18,442
Granted		459,375		$	36.46
Forfeited		(60,498	)	$	66.73
Exercised		(33,468	)	$	21.44			$	481
Expired		(28,066	)	$	125.43
Outstanding at March 31, 2017		6,915,865		$	84.47		7.9	$	26,584
Nonvested at March 31, 2017		3,136,492		$	69.39		9.1	$	2,329
Exercisable at March 31, 2017		3,779,373		$	97.16		6.9	$	24,255

At March 31, 2017, total estimated unrecognized employee compensation cost related to nonvested stock options and restricted stock units granted prior to that date were approximately $114.6 million and $23.9 million, respectively. These unrecognized expenses are expected to be recognized over a weighted-average period of 1.7 years for stock options and 2.3 years for restricted stock units. The weighted-average grant date fair value of options granted during the three months ended March 31, 2017 and 2016, were $22.86 per share and $36.28 per share, respectively.

				Weighted
				Average
				Grant-Date
Stock options	Shares			Fair Value
Nonvested shares at December 31, 2016		3,106,083		$	47.78
Granted		459,375			22.86
Vested/Issued		(368,468	)		72.27
Forfeited		(60,498	)		39.80
Nonvested shares at March 31, 2017		3,136,492			41.50

Restricted stock units:

On October 14, 2016, restricted stock units were awarded to certain employees.  These restricted stock units vest over three years in six equal installments on each six month anniversary of the vesting start date, July 19, 2016.

				Weighted
				Average
				Grant-Date
Restricted stock units	Shares			Fair Value
Nonvested shares at December 31, 2016		630,508		$	54.35
Granted		—			—
Vested/Issued		(106,800	)		54.35
Forfeited		(6,747	)		54.35
Nonvested shares at March 31, 2017		516,961		$	54.35