Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Based Compensation Expenses Included on Operations Statement

The following table presents all stock-based compensation as included on the condensed consolidated statements of operations (in thousands):

	Three Months Ended June 30,					Six Months Ended June 30,
	2020			2019		2020		2019
	(Unaudited)					(Unaudited)
Stock-based compensation expense:
Employee stock options	$	192		$	104	$	297	$	1,101
Employee RSUs		83			313		373		563
Non-employee RSUs		41			105		91		209
	$	316		$	522	$	761	$	1,873
Stock-based compensation expense in operating expenses:
Research and development	$	(55	)	$	150	$	73	$	261
Selling, general and administrative		371			372		688		1,612
	$	316		$	522	$	761	$	1,873

Summarizes Stock Option Activity Under Equity Intensive Plan

The following table summarizes stock option activity under all equity incentive plans for the six months ended June 30, 2020:

	Number of Shares			Weighted- Average Exercise Price		Aggregate Intrinsic Value (in thousands)		Weighted- Average Remaining Contractual Life (in years)
Outstanding at December 31, 2019		4,506,950		$	9.37	$	5,710		5.8
Options granted		400,000		$	6.21
Options exercised		(259,017	)	$	2.18
Options forfeited		(116,667	)	$	3.07
Outstanding at June 30, 2020		4,531,266		$	9.67	$	30,354		5.7
Vested and Exercisable at June 30, 2020		3,806,264		$	10.59	$	24,933		5.0

Weighted Average of Fair Value of Options Under Black-Scholes Option-Pricing Model

The company uses a Black-Scholes option-pricing model to determine the fair value of stock-based compensation under U.S. GAAP. The assumptions used for employee stock options granted during the periods presented in these condensed consolidated financial statements are presented in the table below for the three and six months ended June 30, 2020 (Unaudited):

Expected term (in years)		5.5
Risk-free interest rate		0.4	%
Expected volatility		96.8	%
Dividend yield		0.0	%
Weighted-average measurement date fair value	$	4.64

Restricted Stock Units (RSUs) Activity

The following table summarizes the restricted stock units, or RSUs, activity under the 2015 Plan for the six months ended June 30, 2020:

	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested balance at December 31, 2019		1,139,428		$	2.23
Granted		33,500		$	6.43
Vested		(558,976	)	$	1.79
Forfeited		(48,150	)	$	4.86
Unvested balance at June 30, 2020		565,802		$	2.70