Stock Options (Tables)

9 Months Ended

Sep. 30, 2019

Stock Options

Schedule of assumptions used for estimating the fair value of stock options granted

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2019			2018			2019			2018
Expected dividend yield		—	%		—	%		—	%		—	%
Risk-free interest rate		1.44% - 1.85	%		2.91% - 3.01	%		1.44% - 2.54	%		2.67% - 3.01	%
Volatility		83% - 85	%		79	%		83% - 85	%		78% - 79	%
Expected life		5.83	years		6.25	years		6.04	years		6.25	years
Weighted-average fair value per share	$	3.51		$	8.33		$	8.35		$	8.33

Schedule of stock option activity

			Weighted
	Shares		Average
	Available	Options	Exercise
	for Issuance	Outstanding	Price
Outstanding at December 31, 2018	1,193,329	1,658,112	$	8.76
Shares reserved for future issuance for 2018 Plan	620,779	—
Options granted	(667,108)	667,108	$	11.88
Exercised	—	(32,325)	$	4.37
Cancelled/expired from 2004 Plan	—	—	$	—
Cancelled/expired from 2016 Plan	—	(137,734)	$	9.35
Cancelled/expired from 2018 Plan	165,112	(118,158)	$	14.15
Outstanding at September 30, 2019	1,312,112	2,037,003	$	9.49

Schedule of stock options vested and expected to vest

		Weighted
		Average
		Remaining	Weighted
	Number	Contractual	Average
	of	Life	Exercise
	Options	(In Years)	Price
Outstanding and expected to vest	1,807,947	7.89	$	9.29
Vested and exercisable	788,572	6.44	$	7.05