Stock-Based Compensation and Compensation Plans

The Company adopted its 2007 Stock Incentive Plan (the "2007 Plan") for employees, non-employee directors and consultants for the purpose of advancing the interests of the Company's stockholders by enhancing its ability to attract, retain and motivate persons who are expected to make important contributions to the Company. The 2007 Plan provided for the granting of stock option awards, RSUs, and other stock-based and cash-based awards. Following the effectiveness of the 2013 Stock Incentive Plan described below in connection with the closing of the Company's initial public offering, the Company is no longer granting additional awards under the 2007 Plan.

In August 2013, the Company's board of directors adopted, and the Company's stockholders approved, the 2013 Stock Incentive Plan (the "2013 Plan"), which became effective immediately prior to the closing of the Company's initial public offering. In June 2015, the Company’s board of directors adopted a first amendment to the 2013 Plan. The 2013 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, RSUs, restricted stock awards and other stock-based awards. Upon the effectiveness of the 2013 Plan, the number of shares of the Company's common stock that were reserved for issuance under the 2013 Plan was the sum of (1) a number of shares (up to a maximum of approximately 3,359,641 shares) that is equal to the sum of 739,317 shares (the number of shares of the Company's common stock then available for issuance under the 2007 Plan), and such number of shares of the Company's common stock that are subject to outstanding awards under the 2007 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right, plus (2) an annual increase, to be added the first business day of each fiscal year, beginning with the fiscal year ending December 31, 2014 and continuing until, and including, the fiscal year ending December 31, 2023, equal to the lowest of 2,542,372 shares of the Company's common stock, 4% of the number of shares of the Company's common stock outstanding on the first day of the fiscal year and an amount determined by its board of directors. The Company's employees, officers, directors, consultants and advisors are eligible to receive awards under the 2013 Plan. However, incentive stock options may only be granted to employees of the Company.

Annual increases under the evergreen provisions of the 2013 Plan have resulted in the addition of an aggregate of approximately 10,539,000 additional shares to the 2013 Plan, including for 2020, an increase of approximately 1,985,000 shares, or 4% of the total number of shares of the Company's common stock outstanding as of January 1, 2020. As of December 31, 2019, the Company had approximately 732,000 shares available for grant under the 2013 Plan.

In October 2019, the Company's board of directors adopted the 2019 Inducement Stock Incentive Plan (the “2019 Inducement Plan”) to reserve 1,000,000 shares of its common stock to be used exclusively for grants of awards to individuals that were not previously employees or directors of the Company as a material inducement to such individuals’ entry into employment with the Company within the meaning of Rule 5635(c)(4) of the Nasdaq Listing Rules. The terms and conditions of the 2019 Inducement Plan are substantially similar to those of the 2013 Plan. As of December 31, 2019, the Company had approximately 650,000 shares available for grant under the 2019 Inducement Plan.

In April 2016, the board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of common stock. The ESPP was approved by the Company’s stockholders in June 2016. The ESPP allows eligible employees to purchase common stock at a price per share equal to 85% of the lower of the fair market value of the common stock at the beginning or end of each six month offering period during the term of the ESPP. The first offering period began in September 2016.

A summary of the stock option activity, weighted average exercise prices, options outstanding and exercisable as of December 31, 2019, 2018 and 2017 is as follows (in thousands except weighted average exercise price):



	Years ended December 31,
	2019				2018				2017
	Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price
Outstanding, December 31, 2018	5,903		$	13.72	5,284		$	19.58	3,359		$	39.92
Granted	1,610		$	4.26	1,293		$	1.67	3,024		$	3.50
Exercised	(80	)	$	2.66	—		$	—	(20	)	$	1.64
Expired or forfeited	(653	)	$	21.16	(674	)	$	36.54	(1,079	)	$	38.17
Outstanding, December 31, 2019	6,780		$	10.89	5,903		$	13.72	5,284		$	19.58



	Years ended December 31,
	2019		2018		2017
Options exercisable at December 31, 2019	3,317		2,709		1,954
Weighted average grant date fair value (per share) of options granted during the period	$	3.37	$	1.20	$	2.45

As of December 31, 2019, there were approximately 6,468,000 options outstanding, net of estimated forfeitures, that had vested or are expected to vest. The weighted-average exercise price of these options was $11.24 per option; the weighted-average remaining contractual life of these options was 7.7 years; and the aggregate intrinsic value of these options was approximately $10.6 million. A summary of the stock options outstanding and exercisable as of December 31, 2019 is as follows (in thousands except exercise prices and weighted average exercise price):



			December 31, 2019
			Options Outstanding			Options Exercisable
Range of Exercise Prices	Total Options Outstanding		Weighted Average Remaining Life (Years)	Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$1.13-$2.79	1,350		8.8	$	1.59	433		$	1.76
$2.80-$2.96	1,725		7.9	$	2.93	876		$	2.93
$2.97-$4.87	1,444		8.1	$	4.18	648		$	4.48
$4.88-$31.09	1,090		8.7	$	7.13	216		$	14.89
$31.10-$73.22	1,171		5.1	$	45.14	1,144		$	45.01
	6,780		7.8	$	10.89	3,317		$	18.38

Aggregate Intrinsic Value	$	28,475				$	10,557

Cash proceeds from, and the aggregate intrinsic value of, stock options exercised during the years ended December 31, 2019, 2018 and 2017, respectively, were as follows:



	Years ended December 31,
	2019		2018		2017
Cash proceeds from options exercised	$	192	$	—	$	33
Aggregate intrinsic value of options exercised	$	135	$	—	$	43

In connection with stock option awards granted to employees, the Company recognized approximately $5.9 million, $7.6 million and $13.1 million in share-based compensation expense during the years ended December 31, 2019, 2018 and 2017, respectively, net of expected forfeitures. As of December 31, 2019, there were approximately $8.0 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards granted to employees, which are expected to be recognized over a remaining weighted average period of 3.1 years.

In connection with stock option awards granted to consultants, the Company recognized approximately $0.3 million, $0.2 million and $0.3 million in share-based compensation expense during the years ended December 31, 2019, 2018 and 2017, respectively, net of expected forfeitures. As of December 31, 2019, there were approximately $0.2 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards granted to consultants, which are expected to be recognized over a remaining weighted average period of 3.6 years.

The following table presents a summary of the Company's outstanding RSU awards granted as of December 31, 2019 (in thousands except weighted average grant-date fair value):



	Restricted Stock Units		Weighted Average Grant-Date Fair Value
Outstanding, December 31, 2018	679		$	15.61
Awarded	1,090		$	4.57
Vested	(255	)	$	13.94
Forfeited	(33	)	$	16.35
Outstanding, December 31, 2019	1,481		$	7.79

As of December 31, 2019, there were approximately 1,287,000 RSUs outstanding, net of estimated forfeitures, that are expected to vest. The weighted-average fair value of these RSUs was $5.39 per share; and the aggregate intrinsic value of these RSUs was approximately $11.0 million.

In connection with RSUs granted to employees, the Company recognized approximately $3.0 million, $3.3 million and $4.4 million in share-based compensation expense during the years ended December 31, 2019, 2018 and 2017, respectively, net of expected forfeitures. As of December 31, 2019, there was approximately $5.0 million of unrecognized compensation costs, net of estimated forfeitures, related to RSUs granted to employees, which are expected to be recognized over a remaining weighted average period of 2.7 years. The total fair value of the RSUs that vested during the year ended December 31, 2019 was $3.6 million.

In connection with RSUs granted to consultants, the Company recognized a de minimis amount in share-based compensation expense during the year ended December 31, 2019, net of expected forfeitures. In connection with RSUs granted to consultants, the Company recognized approximately $0.1 million in share-based compensation expense during the year ended December 31, 2018. As of December 31, 2019, there were approximately $0.1 million of unrecognized compensation costs, net of estimated forfeitures, related to RSUs granted to consultants, which are expected to be recognized over a remaining weighted average period of 3.4 years.

In connection with the ESPP made available to employees, the Company recognized approximately $0.1 million and a de minimis amount of share-based compensation expense during the years ended December 31, 2019 and December 31, 2018, respectively, net of expected forfeitures. As of December 31, 2019, there was a de minimis amount of unrecognized compensation costs, net of estimated forfeitures, related to the ESPP, which are expected to be recognized over 0.3 years. There were 70,466 shares of common stock issued under the ESPP during the year ended December 31, 2019. Cash proceeds from ESPP purchases were approximately $81 thousand during the year ended December 31, 2019. There were 31,413 shares of common stock issued under the ESPP during the year ended December 31, 2018. As of December 31, 2019, 881,763 shares were available for future purchases under the ESPP.