Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Summary of Fair Value Assumptions of Stock Option Awards Estimated on Grant Date

The fair value of stock option awards is estimated on the grant date using the Black-Scholes option pricing model with the following assumptions:

	THREE MONTHS ENDED MARCH 31,
	2022			2021
Fair value of underlying common stock	$	9.15		$	0.82
Weighted average risk-free interest rate		2.56	%	0.27% - 1.55%
Expected term (in years)		6.00		5.00 - 6.00
Expected volatility		56.28	%	69.49% - 70.36%
Expected dividend yield		—			—

Summary of Stock Options Activity

The following table summarizes the activity of the Company’s stock options under the Plan for the three months ended March 31, 2022:

						AVERAGE		AGGREGATE
				WEIGHTED-		REMAINING		INTRINSIC
				AVERAGE		CONTRACTUAL		VALUE
	SHARES (1)			EXERCISE PRICE (1)		TERM (in years)		(in thousands)
Outstanding at December 31, 2021		18,101,548		$	1.14		8.0	$	139,505
Granted		555,000			9.15		—		—
Exercised		(79,055	)		0.32		—		594
Cancelled or forfeited		(72,127	)		0.27		—		—
Outstanding at March 31, 2022		18,505,366			0.71		7.8		141,869
Vested and expected to vest at March 31, 2022		18,505,366			0.71		7.8		141,869
Exercisable at March 31, 2022		8,337,001		$	0.54		6.3	$	69,248

(1) Number of options and weighted average exercise price has been adjusted to reflect the exchange of Legacy GreenLight's stock options for New GreenLight stock options at an exchange ratio of approximately 0.665 as a result of the Business Combination. See Note 3 for further information.

Summary of Restricted Stock Activity

A summary of the Company’s restricted stock activity during the three months ended March 31, 2022 is presented below:

	SHARES			WEIGHTED AVERAGE GRANT DATE FAIR VALUE
Unvested shares as of December 31, 2021		4,231		$	0.76
Vested		(1,567	)		0.23
Unvested shares as of March 31, 2022		2,664		$	0.22

Summary of Stock-Based Compensation Expense

Stock-based compensation expense recorded as research and development and general and administrative expenses, for employees, directors and non-employees during the three months ended March 31, 2022 and 2021 is as follows:

	THREE MONTHS ENDED MARCH 31,
	2022		2021
Research and development	$	504	$	131
General and administrative		1,683		217
Total stock-based compensation expense	$	2,187	$	348