Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

The following table summarizes the Company’s restricted stock unit activity for 2016:



	Shares (in thousands)		Weighted Average Fair Value per Share at Grant Date
Nonvested at December 31, 2015	—		$	—
Granted	112		10.31
Vested	—		—
Canceled	(9	)	10.35
Nonvested at December 31, 2016	103		10.31



	Shares (in thousands)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2015	2,714		$	17.18
Granted	902		$	10.02
Exercised	(6	)	$	7.27
Canceled	(325	)	$	19.88
Outstanding at December 31, 2016	3,285		$	15.46	7.5	$	2,458
Exercisable at December 31, 2016	1,887		$	17.76	6.5	$	651
Vested and expected to vest at December 31, 2016	3,196		$	15.56	7.5	$	2,340

The assumptions used in the Black-Scholes option-pricing model are as follows:



	Year Ended December 31,
	2016	2015	2014
Stock Options
Risk free interest rate	1.1% to 2.1%	1.5% to 1.9%	1.6% to 2.0%
Expected term	5.1 to 6.1 years	5.1 to 6.1 years	5.1 to 6.1 years
Expected volatility	76.5 to 78.1%	76.7 to 79.2%	79.7 to 84.9%
Expected dividend yield	—%	—%	—%
Weighted-average fair value of option on grant date	$6.69	$8.37	$18.58

Employee Stock Purchase Plan
Risk free interest rate	0.5% to 0.8%	0.1% to 0.5%	0.1%
Expected term	0.5 to 1.0 years	0.5 to 1.0 years	0.5 to 1.0 years
Expected volatility	59.5% to 71.3%	67.4% to 77.8%	65.0% to 83.2%
Expected dividend yield	—%	—%	—%

The Company recognized stock-based compensation expense in continuing operations as follows (in thousands):



	Year Ended December 31,
	2016		2015		2014
Cost of revenue	$	386	$	390	$	467
Research and development	1,924		1,266		1,236
Selling, general and administrative	5,043		5,285		5,833
Total	$	7,353	$	6,941	$	7,536