Stock-Based Compensation

3 Months Ended

Mar. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based CompensationWe have issued stock-based awards from various equity incentive and stock purchase plans, as more fully described in the consolidated financial statements and related notes included in our 2018 Annual Report on Form 10-K.

Under our 2010 Equity Incentive Award Plan, which was amended in June 2012 (2010 Plan), the aggregate number of shares of our common stock that may be issued as stock-based awards may not exceed 7,500,000 shares. At December 31, 2018, 1,550,351 shares were available for grant under the 2010 Plan. Pursuant to its evergreen provision, the number of shares reserved for issuance under the 2010 Plan automatically increases on January 1 of each year, commencing on January 1, 2013, and on each January 1 through and including January 1, 2020, in an amount equal to 4% of the total number of shares of common stock outstanding on December 31 of the preceding year, or a lesser number of shares as determined by our board of directors. On January 1, 2019, the increase in shares reserved for issuance pursuant to the evergreen provision was limited to 589,619 shares as the 2010 Plan’s maximum 7,500,000 shares reserved for issuance was reached. As of March 31, 2019, 1,298,107 shares were available for grant under the 2010 Plan.

In 2013, our board of directors adopted the Inducement Plan, which allows us to grant equity awards only to new employees as an inducement material to join us. Effective March 27, 2019, our board of directors approved an increase to the share reserve under the Inducement Plan by 100,000 shares resulting in the aggregate number of shares of our common stock that may be issued as stock-based awards to 737,500 shares. As of March 31, 2019, there were 124,925 shares available for grant under the Inducement Plan.

Stock Options

The following is a summary of stock option activity for the three months ended March 31, 2019 (in thousands, except per share data):


	Shares	Weighted- Average Exercise Price per Share
Outstanding at December 31, 2018	3,744	$	20.69
Granted	770	51.86
Exercised	(349)	15.17
Canceled	(10)	29.94
Outstanding at March 31, 2019	4,155	$	26.91

Restricted Stock Units

The following is a summary of restricted stock unit activity for the three months ended March 31, 2019 (in thousands, except per share data):


	Shares	Weighted- Average Fair Value per Share at Grant Date
Outstanding at December 31, 2018	289	$	25.56
Granted	167	52.66
Vested	(31)	42.65
Canceled	(7)	18.81
Outstanding at March 31, 2019	418	$	35.27

Stock-Based Compensation Expense

The following table summarizes the components of total stock-based compensation expense included in the condensed consolidated statements of operations (in thousands):


	Three Months Ended March 31,
	2019		2018
Research and development	$	1,435	$	681
Selling, general and administrative	2,788		1,231
Total	$	4,223	$	1,912