Stock-Based Compensation

3 Months Ended

Mar. 31, 2019

Stock Incentive Plans

We maintain stock incentive plans to attract and retain officers, directors, employees, consultants and advisors. Stock awards under these plans may include both performance-based and non-performance based stock incentives. We granted stock options and other incentive awards to our employees and nonemployee directors to acquire 4,676 and 5,150 shares of our Class A common stock during the three months ended March 31, 2019 and 2018, respectively.

Stock-Based Compensation

Total noncash, stock-based compensation expense for all of our employees is shown in the following table for the three months ended March 31, 2019 and 2018, respectively, and was assigned to the same expense categories as the base compensation for such employees:



	For the three months ended March 31,
	2019		2018
	(In thousands)
Research and development expenses	$	161	$	191
Selling, general and administrative expenses	2,467		2,574
Total stock-based compensation	$	2,628	$	2,765

As of March 31, 2019, total unrecognized stock-based compensation cost, net of estimated forfeitures, related to our unvested stock awards was $12 million.