Stock-Based Awards

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Awards

Note 5. Stock-Based Awards

Stock Options

The following table summarizes stock options activity for the nine months ended September 30, 2019 (in thousands):

	Number of Shares
Outstanding at December 31, 2018		3,603
Granted		558
Exercised		(424	)
Forfeited or expired		(362	)
Outstanding at September 30, 2019		3,375
Vested and exercisable at September 30, 2019		1,306

Restricted Stock Units

The following table summarizes activity for restricted stock units, or RSUs, and RSUs with performance conditions, or PSUs, for the nine months ended September 30, 2019 (in thousands):

	Number of Shares
	RSUs			PSUs
Outstanding at December 31, 2018		32			—
Granted		462			248
Vested		(40	)		—
Forfeited		(4	)		(12	)
Outstanding at September 30, 2019		450			236

PSUs granted during the nine months ended September 30, 2019 were primarily related to 234,000 PSUs associated with a PSU bonus program that replaced what has historically been our annual cash-bonus program for our senior executives and other bonus-eligible employees. The number of PSUs that ultimately vest will depend on the extent to which we achieve certain 2019 financial metrics: 134,000 PSUs will vest at 100% achievement of these financial metrics and 234,000 PSUs at 175% achievement. We record compensation expense each period based on our estimate of the most probable number of PSUs that will vest and recognize such expense over the related service period. Stock-based compensation expense recognized for the PSUs was $600,000 and $1.2 million for the three and nine months ended September 30, 2019, respectively.

Stock-Based Compensation Expense

The following table presents the effects of stock-based compensation in our condensed consolidated statements of operations for the periods presented (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Cost of revenue	$	192	$	144	$	495	$	325
Research and development expense		1,717		1,039		4,028		2,620
Sales and marketing expense		1,622		1,188		4,028		2,876
General and administrative expense		1,262		964		3,262		2,192
Total stock-based compensation expense	$	4,793	$	3,335	$	11,813	$	8,013