Stock-Based Compensation

3 Months Ended

Mar. 31, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-based compensation

11. Stock-based compensation

Equity incentive plans

In February 2021, the Company adopted the 2021 Incentive Award Plan (2021 Plan) and the 2021 Employee Stock Purchase Plan (2021 ESPP), both of which became effective on the completion of the Company’s IPO. The 2021 Plan provides for a variety of stock-based compensation awards, including stock options, restricted stock awards (RSAs), and restricted stock units (RSUs). The 2021 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their earnings, subject to plan limitations. Unless otherwise determined by the Company’s board of directors, employees may purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first date of an offering period or on the purchase date. As of March 31, 2022, 14.2 million shares and 3.8 million shares were available for future issuance under the 2021 Plan and the 2021 ESPP, respectively.

Stock-based compensation expense

Stock-based compensation expense is recognized in the condensed consolidated statements of operations as follows:

		Three Months Ended March 31,
		2022		2021
	(in thousands)
Research and development		$	5,712	$	2,668
General and administrative			2,043		1,490
Total stock-based compensation expense		$	7,755	$	4,158

Unrecognized stock-based compensation costs related to unvested awards and the weighted-average period over which the costs are expected to be recognized as of March 31, 2022 are as follows:

	Stock Options		RSAs		RSUs
Unrecognized stock-based compensation expense (in thousands)	$	103,144	$	1,509	$	4,900
Weighted-average period costs expected to be recognized (in years)		3.2		1.3		3.2

Stock options

A summary of the Company’s stock option activity is as follows:

	Stock Options (in thousands)			Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2021		17,337		$	8.96		8.7	$	141,718
Granted		8,045			5.98
Exercised		(284	)		2.26
Forfeited/Cancelled		(270	)		13.98
Outstanding as of March 31, 2022		24,828		$	8.02		8.9	$	62,772
Exercisable as of March 31, 2022		5,139		$	5.35		8.1	$	20,355

The fair value of stock options granted to employees, directors, and consultants was estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions:

	Three Months Ended March 31,
Assumptions	2022	2021
Risk free interest rate	1.56% - 2.41%	0.64% - 1.11%
Expected volatility	70%	70%
Expected term (years)	6.25	5.50 - 6.25
Expected dividend	0%	0%

The following table summarizes additional information related to stock option activity:

	Three Months Ended March 31,
	2022		2021
Weighted average grant date fair value per share for options granted	$	3.83	$	16.75
Aggregate intrinsic value of stock options exercised (in thousands)	$	2,642	$	3,764

Restricted stock awards

A summary of the Company’s RSA activity is as follows:

	RSAs (in thousands)			RSAs Weighted-Average Grant Date Fair Value per Share		RSUs (in thousands)			RSUs Weighted-Average Grant Date Fair Value per Share
Unvested shares as of December 31, 2021		4,365		$	0.43		141		$	9.43
Granted		-			-		685			5.89
Vested		(1,406	)		0.24		(14	)		1.44
Forfeited		-			-		(2	)		5.70
Unvested shares as of March 31, 2022		2,959		$	0.52		810		$	6.58

The fair value of RSAs and RSUs vested during the three months ended March 31, 2022 and 2021 was $0.3 million and $0.1 million, respectively, and $0.4 million and $0, respectively.