Stock based compensation

9 Months Ended

Sep. 30, 2020

Share-based Payment Arrangement [Abstract]

Stock Based Compensation

The following table summarizes stock option activity as of September 30, 2020, and changes during the nine months ended September 30, 2020:


	Nine months ended September 30, 2020	Weighted average exercise price
Outstanding at January 1, 2020	4,644,835	$	1.80
Granted	6,070,557	$	3.32

Lapsed / surrendered	(4,562,049)	$	2.39
Number of outstanding options	6,153,343	$	2.31
Exercisable at September 30, 2020	679,600	$	2.00

The following table summarizes restricted stock units ("RSUs") granted in the form of a nominal-cost options as of September 30, 2020 and changes during the nine months ended September 30, 2020:


	Nine months ended September 30, 2020	Weighted average exercise price
Outstanding at January 1	138,461	$	0.07
Exercised during the period	(53,846)	$	0.07
Number of outstanding RSUs	84,615	$	0.07

The total intrinsic value of all outstanding options and exercisable options at September 30, 2020 was $3.8 million and $1.0 million, respectively.

The following table summarizes consultant warrant activity as of September 30, 2020, and changes during the nine months ended September 30, 2020:


	Nine months ended September 30, 2020	Weighted average exercise price
Outstanding at January 1	3,358,732	$	1.44
Lapsed / surrendered	(2,798,944)	$	1.44
Number of outstanding warrants	559,788	$	1.44

The total intrinsic value of all outstanding warrants which are all exercisable at September 30, 2020 was $1.1 million.

The following table summarizes stock-based compensation expense reflected in the consolidated statements of operations:


	Three months ended				Nine months ended
	September 30,				September 30,
	2020		2019		2020		2019
	(in thousands)
Research and development	$	275	$	135	$	638	$	561
General and administrative	86		109		550		287
	$	361	$	244	$	1,188	$	848