Stock based compensation and warrants

6 Months Ended

Jun. 30, 2021

Share-based Payment Arrangement [Abstract]

The following table summarizes stock option activity as of June 30, 2021, and changes during the six months ended June 30, 2021:


	Six Months Ended June 30, 2021	Weighted average exercise price
Outstanding at December 31, 2020	3,672,968	$	2.90
Granted	2,646,350	5.02

Forfeited	(649,385)	3.64
Exercised	(436,836)	2.60
Number of outstanding options at June 30, 2021	5,233,097	3.90
Exercisable at June 30, 2021	878,568	$	2.51

In addition to the stock options outstanding above, as of June 30, 2021, the Company had granted 7,520,886 stock options subject to performance based conditions. As of June 30, 2021, the performance conditions relating to those stock options had not been agreed and communicated and therefore a grant date for accounting purposes had not been established. As such, these performance based stock options have been excluded from the summary of stock option activity above and no expense has been recorded in the consolidated statement of comprehensive loss.

The total intrinsic value of all outstanding and exercisable stock options at June 30, 2021 was $18.6 million and $4.3 million, respectively.

The following table summarizes restricted stock units ("RSUs") granted in the form of nominal-cost options as of June 30, 2021 and changes during the six months ended June 30, 2021:


	Six Months Ended June 30, 2021	Weighted average exercise price
Outstanding at December 31, 2020	26,932	$	0.07
Exercised during the period	(26,932)	0.07
Number of outstanding RSUs at June 30, 2021	—	$	—

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


	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
	(in thousands)
Research and development	$	1,591	$	380	$	1,914	$	464
General and administrative	2,080		150		2,626		363
Total stock-based compensation expense	$	3,671	$	530	$	4,540	$	827

The Company also had outstanding and exercisable warrants of 5,821,137 as of June 30, 2021 (December 31, 2020: 5,821,137) with weighted average exercise price of $1.56.