Stock Based Compensation

3 Months Ended

Mar. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Based Compensation

9. Stock Based Compensation

In January 2013, our Board of Directors adopted our 2013 Equity Incentive Plan (the “2013 Plan”), which became effective upon of the closing of our initial public offering in May 2013. On January 1, 2017, the number of shares available for issuance under the 2013 Plan automatically increased by a number of shares equal to 5% of the total common stock outstanding at December 31, 2016. As of March 31, 2017, there were 15,032,633 shares reserved under the 2013 Plan for the future issuance of equity awards.  

Stock Options

The following table summarizes stock option activity under our 2013 Plan and related information during the three months ended March 31, 2017:

	Shares
	Subjectto			Weighted-
	Outstanding			Average Exercise
	Options			Price Per Share
Balance at December 31, 2016		5,817,116		$	25.26
Options granted		1,036,100			27.04
Options exercised		(196,871	)		15.86
Options canceled		(71,202	)		33.34
Balance at March 31, 2017		6,585,143		$	25.73

Performance Stock Options (“PSOs”)

In May 2016, the Compensation Committee of our Board of Directors approved the commencement of granting performance stock option awards to our executive and senior officers. PSOs represent a contingent right to purchase our Common Stock upon achievement of specified conditions. The PSOs granted in May 2016 will vest upon the achievement of certain regulatory and manufacturing goals related to our lead programs. As of March 31, 2017, there was $2.0 million of unrecognized compensation costs related to the PSOs which management currently estimates to be probable of vesting and which we estimate will be recognized over a weighted-average period of 1.4 years.

The following table summarizes PSO activity under our 2013 Plan and related information during the three months ended March 31, 2017:

	Shares
	Subjectto		Weighted-
	Outstanding		Average Exercise
	Options		Price Per Share
Balance at December 31, 2016		180,752	$	23.76
Options granted		—		—
Options exercised		—		—
Options canceled		—		—
Balance at March 31, 2017		180,752	$	23.76

Restricted Stock Units (“RSUs”)

In January 2015, the Compensation Committee of our Board of Directors approved the commencement of granting restricted stock units, to our employees. RSUs are share awards that entitle the holder to receive freely tradable shares of our Common Stock upon vesting.

The following table summarizes RSU activity, under our 2013 Plan and related information:

	Shares
	Subject to			Weighted-
	Outstanding			Average grant date
	RSUs			fair value per share
Balance at December 31, 2016		546,507		$	28.38
RSUs granted		306,050			25.54
RSUs released		(211,882	)		28.26
RSUs canceled		(8,932	)		27.37
Balance at March 31, 2017		631,743		$	27.06

Performance Stock Units(“PSUs”)

In January 2015, the Compensation Committee of our Board of Directors approved the commencement of granting performance stock units to our employees. PSUs are share awards that entitle the holder to receive freely tradable shares of our Common Stock upon achievement of specified conditions. In January 2016, the Compensation Committee of our Board of Directors approved a program to award up to 102,906 PSUs to the management team based on the achievement of certain commercial and regulatory goals related to andexanet alfa and betrixaban, respectively. In January 2017, the Compensation Committee of our Board of Directors approved a program to award up to 143,750 PSUs to the management team based on the achievement of certain regulatory goals related to andexanet alfa.

As of March 31, 2017, there was $0.3 million of unrecognized compensation costs related to the PSUs which management currently estimates to be probable of vesting and which we currently estimate will be recognized over a weighted-average period of 0.6 years.

The following table summarizes PSU activity, under our 2013 Plan and related information:

	Shares
	Subject to			Weighted-
	Outstanding			Average grant date
	PSUs			fair value per share
Balance at December 31, 2016		285,866		$	29.24
PSUs granted		143,750			25.54
PSUs released		(8,917	)		50.30
PSUs canceled		(51,581	)		33.53
Balance at March 31, 2017		369,118		$	26.69

The table below sets forth the functional classification of stock-based compensation expense, net of estimated forfeitures, for the periods presented (in thousands):  

	Three Months Ended March 31,
	2017		2016
Research and development	$	4,150	$	3,030
Selling, general and administrative		4,884		4,039
Total stock-based compensation	$	9,034	$	7,069