Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2019

A summary of the Company’s Series A Convertible Participating Perpetual Preferred Stock balance at September 30, 2019 and changes during the nine months ended September 30, 2019, are presented below:



	Preferred Stock
	Shares	Amount
Balance at December 31, 2018	195	$	176,603
Issuance of preferred stock	15	—
Initial discount and issuance costs related to preferred stock	—	—
Amortization of preferred stock issuance costs	—	1,586
Issuance of preferred PIK dividend	—	14,407
Balance at September 30, 2019	210	$	192,596

Schedule of stock-based compensation

The following table summarizes stock-based compensation expense related to all of the Company’s stock awards included by operating expense categories, as follows:



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Cost of revenues	$	804	$	1,035	$	2,147	$	3,447
Research and development	1,117		1,340		3,231		4,682
Selling, general and administrative	4,079		4,841		11,650		13,911
Total stock-based compensation expense	$	6,000	$	7,216	$	17,028	$	22,040

The following table summarizes stock-based compensation expense related to all of the Company’s stock awards included by award types, as follows:



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Stock options	$	2,147	$	1,940	$	5,640	$	5,680
Restricted stock awards	3,840		5,276		11,164		16,340
Employee Stock Purchase Plan	—		—		—		—
Performance Based Cash Units	13		—		224		20
Total stock-based compensation before taxes	$	6,000	$	7,216	17,028		22,040
Tax benefit	$	862	$	1,402	$	2,700	$	4,356

Schedule of fair value assumptions

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



	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Expected stock price volatility	69.8		%	66.0		%	69.6		%	65.2		%
Risk-free interest rate	1.6		%	2.7		%	1.9		%	2.6		%
Expected life of options (in years)	4.36			4.29			4.34			4.11
Expected dividend yield	0.0		%	0.0		%	0.0		%	0.0		%
Weighted-average fair value (grant date) of the options	$	4.42		$	3.33		$	3.84		$	5.04

Schedule of information about stock options outstanding

The following table summarizes information about stock options outstanding as of September 30, 2019:



Options	Number of Options		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Outstanding at December 31, 2018	4,254		$	17.93
Options Granted	1,229		7.08
Options Exercised	(7	)	5.48
Options Cancelled	(549	)	23.96
Outstanding at September 30, 2019	4,927		$	14.57	5.03	$	8
Vested at September 30, 2019	1,667		$	24.24	3.73	$	2
Exercisable at September 30, 2019	1,667		$	24.24	3.73	$	2

Restricted stock awards

Stockholder's Equity

Summary of unvested restricted stock and performance shares activity

A summary of the Company’s unvested restricted stock at September 30, 2019, and changes during the nine months ended September 30, 2019, is presented below:



Unvested Restricted Stock	Number of Awards		Weighted- Average Grant Date Fair Value
Unvested at December 31, 2018	2,630		$	12.71
Granted	2,004		6.94
Vested	(999	)	18.63
Forfeited	(168	)	10.53
Unvested at September 30, 2019	3,467		$	8.96

Performance based cash units

Stockholder's Equity

Summary of unvested restricted stock and performance shares activity

A summary of the Company’s unvested performance-based cash units at September 30, 2019 and changes during the nine months ended September 30, 2019, is presented below:



Unvested Cash Units	Number of Awards		Weighted- Average Grant Date Fair Value
Unvested at December 31, 2018	70		$	6.14
Granted	236		—
Vested	—		—
Forfeited	(66	)	—
Unvested at September 30, 2019	240		$	5.40