Share Based Awards (Tables)

9 Months Ended

Sep. 30, 2019

Share Based Awards

Schedule of restricted stock unit activity

	Restricted Stock Units
		Weighted-
		Average
	Number of	Grant Date
	Shares	Fair Value
Unvested, December 31, 2018	12,303,913	$	4.63
Granted	9,738,871		5.45
Vested	(6,075,000)		4.75
Forfeitures	(2,161,696)		4.71
Unvested, September 30, 2019	13,806,088	$	5.14

Schedule of stock option activity under the 2008 Plan, 2014 Plan and 2015 Inducement Plan

		Options Outstanding
						Weighted-
	Number of					Average	Aggregate
	Shares		Weighted-			Remaining	Intrinsic
	Available	Number of	Average		Contractual		Value
	for Issuance	Shares	Exercise Price			Term (Years)	(In thousands)
Balance—December 31, 2018	2,337,545	4,496,557	$	5.02		4.98	$	2,446
Authorized	5,310,327	—
Stock options granted	(125,000)	125,000		4.52
Issuance of shares under Bonus Plans	(2,170,855)	—
Shares withheld from net settlement of restricted stock units	1,064,577
Restricted stock units granted	(7,568,016)	—
Exercised	—	(1,337,433)		4.10
Stock options canceled	355,029	(355,029)		6.99
Restricted stock units canceled	2,161,696	—
Balance—September 30, 2019	1,365,303	2,929,095	$	5.18		5.27	$	4,877
Vested and exercisable—September 30, 2019		2,374,402	$	5.36		4.48	$	3,703
Vested and expected to vest(1)—September 30, 2019		2,837,136	$	5.21		5.16	$	4,688

(1) Options expected to vest reflect an estimated forfeiture rate.

Schedule of stock-based compensation expense recognized

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2019		2018		2019		2018
Cost of revenue	$	1,052	$	1,223	$	3,859	$	3,672
Research and development		3,279		3,670		11,015		11,780
Sales and marketing		2,029		2,653		6,367		7,341
General and administrative		1,652		1,834		5,918		5,700
Total	$	8,012	$	9,380	$	27,159	$	28,493

Schedule of assumptions used to estimate fair value of stock options granted to employees

	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2019	2018	2019	2018
Expected dividend yield	n/a	—	—	—
Risk-free interest rate	n/a	2.8%	2.5%	2.7%
Expected volatility	n/a	50%	50%	52%
Expected life (in years)	n/a	6.1	6.1	6.1

Schedule of assumptions used to estimate the fair value of Employee Stock Purchase Plan awards

	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2019	2018	2019	2018
Expected dividend yield	—	—	—	—
Risk-free interest rate	1.7%	2.5%	2.1%	2.2%
Expected volatility	40%	43%	41%	47%
Expected life (in years)	1.3	1.3	1.3	1.3

Schedule of unrecognized stock-based compensation expense and its remaining weighted-average recognition period

	Unrecognized		Remaining
	Stock-based		Weighted-Average
	Compensation		Recognition
	Expense		Period
	(in millions)		(in years)
Stock options	$	0.9	2.7
Restricted stock units		52.3	2.9
ESPP		2.0	0.6
Total	$	55.2