Stock-Based Compensation Plan

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Stock-based compensation plan

13.Stock-based compensation plan

Stock Options

The following table shows stock option activity during the periods indicated (in thousands except share and per share data):

	Number of options outstanding			Weighted-average exercise price		Weighted-average remaining contractual term (in years)		Aggregate intrinsic value
Balance as of December 31, 2019		5,219,930		$	0.38		8.04	$	2,825
Options granted		1,748,320		$	1.37
Options exercised		(756,416	)	$	0.26
Options forfeited		(37,056	)	$	0.92
Balance as of December 31, 2020		6,174,778		$	0.67		7.79	$	11,405
Options granted		4,344,187			12.99
Options exercised		(1,289,652	)		0.51
Options forfeited		(417,797	)		5.05
Options expired		(5,666	)		1.39
Balance as of December 31, 2021		8,805,850		$	6.56		8.03	$	147,623
Options unvested as of December 31, 2021		5,621,169		$	9.96		9.11	$	74,986
Options exercisable as of December 31, 2021		3,184,681		$	0.56		6.11	$	72,637

The weighted-average grant date fair value of options granted during the year ended December 31, 2021 and 2020 was $10.42 and $0.97 per share, respectively.

The total fair value of options vested during each of the year ended December 31, 2021 and 2020 was $1.0 million and $0.5 million, respectively.

There was $39.1 million of unrecognized stock-based compensation expense related to unvested stock options as of December 31, 2021. The unrecognized stock-based compensation expense is estimated to be recognized over a period of 3.03 years as of December 31, 2021.

The Company currently uses authorized and unissued shares to satisfy option exercises.

The aggregate intrinsic value is calculated as the difference between the exercise price and the estimated fair value of the Company’s common stock as of December 31, 2021.

RSU Awards

The following table shows RSU awards activity during the year ended December 31, 2021:

	Shares		Weighted-average grant date fair value per share
Unvested balance at December 31, 2020		-	$	-
Granted		104,876	$	21.10
Vested		-	$	-
Forfeited		-	$	-
Unvested balance at December 31, 2021		104,876	$	21.10

There was $2.1 million of unrecognized stock-based compensation expense related to unvested RSU awards as of December 31, 2021. The unrecognized stock-based compensation expense is estimated to be recognized over a period of 3.77 years as of December 31, 2021.

Stock-based compensation expense

The following table shows the allocation of stock-based compensation expense related to the Company’s stock-based awards (in thousands):

	Year ended December 31,
	2021		2020
Cost of sales	$	1,508	$	232
Research and development		1,877		109
Sales and marketing		1,375		183
General and administrative		1,826		87
Total stock-based compensation	$	6,586	$	611

The Company uses the Black-Scholes option pricing model to determine the fair value of stock options. The valuation model for stock compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation including the expected term (weighted-average period of time that the options granted are expected to be outstanding), volatility of the Company’s common stock and an assumed-risk free interest rate. The following table shows the weighted-average valuation assumptions used in determining the fair value of employee stock options:

	Year ended December 31,
	2021			2020
Expected term (in years)		6.05			5.96
Expected volatility		90	%		83	%
Risk-free interest rate		1	%		1	%
Dividend yield	—			—

Total stock-based compensation recorded for the ESPP was $58,000 for the year ended December 31, 2021.
The following table summarizes the weighted-average assumptions used in estimating the fair value of the ESPP for the initial offering period using the Black-Scholes option-pricing model:

Year ended December 31,
	2021
Expected term (in years)		0.5
Expected volatility		75	%
Risk-free interest rate		1	%
Dividend yield	—