Stock‑Based Compensation (Tables)

6 Months Ended

Jun. 30, 2016

Stock-Based Compensation

Summary of stock option activity

	Outstanding Options
					Weighted-
			Weighted-		Average
	Shares		Average		Remaining	Aggregate
	Available for	Number of	Exercise		Contractual	Intrinsic
(in thousands, except for contractual life and exercise price)	Grant	Shares	Price		Life	Value
					(In years)
Balance at December 31, 2015	3,734	9,324	$	3.96
Additional shares authorized	2,014	—
Options granted	(1,900)	1,900	$	9.74
Options exercised	—	(1,279)	$	1.77
Options forfeited/cancelled	534	(534)	$	6.81
Balance at June 30, 2016	4,382	9,411	$	5.26	7.85	$	65,247
Exercisable at June 30, 2016		4,888	$	2.42	6.74	$	47,348
Vested and expected to vest at June 30, 2016		8,867	$	5.04	7.77	$	63,382

Restricted stock units

			Weighted-
			Average
			Grant Date
(in thousands, except for contractual life)	Shares		Fair Value
Balance at December 31, 2015	-		—
Granted	201	$	9.63
Vested	(10)		9.59
Canceled/forfeited	(4)	$	9.59
Balance at June 30, 2016	187	$	9.64
Exercisable at June 30, 2016	-	$	—
Vested and expected to vest at June 30, 2016	164	$	9.63
Weighted average remaining contractual life (years)	3.0

Summary of stock-based compensation expenses

	Three months ended June 30,
	2016						2015
	Employee		Non-Employee		Total		Employee		Non-Employee		Total
	(in thousands)
Cost of revenues	$	157	$	32	$	189	$	88	$	184	$	271
Research and development		716		1		717		309		11		320
Selling, general and administrative		1,940		51		1,991		926		74		1,000
Total	$	2,813	$	84	$	2,897	$	1,323	$	268	$	1,591

	Six months ended June 30,
	2016						2015
	Employee		Non-Employee		Total		Employee		Non-Employee		Total
	(in thousands)
Cost of revenues	$	315	$	7	$	322	$	149	$	206	$	355
Research and development		1,321		—		1,321		558		23		581
Selling, general and administrative		3,401		248		3,649		1,711		93		1,804
Total	$	5,037	$	255	$	5,292	$	2,418	$	322	$	2,740

Schedule of assumptions used in valuation of fair value of employee stock options

	Three months ended June 30,										Six months ended June 30,
	2016					2015					2016					2015
Expected term	5.1		—	5.2		5.9		—	6.1		5.1		—	5.2		5.6		—	6.1
Expected volatility	68.5	%	—	69.2	%	72.0	%	—	73.0	%	68.5	%	—	71.0	%	72.0	%	—	73.0	%
Expected dividend rate				0	%				0	%				0	%				0	%
Risk-free interest rate	1.18	%	—	1.24	%	1.84	%	—	1.88	%	1.18	%	—	1.24	%	1.56	%	—	1.88	%