The Company maintains three equity incentive plans: the 2018 Equity Incentive Plan ("2018 Plan"), the 2019 Employee, Director and Consultant Equity Incentive Plan ("2019 Plan") and the 2020 Employee, Director, and Consultant Equity Incentive Plan ("2020 Plan" and collectively, "Incentive Plans"). The 2020 Plan serves as the successor to the 2019 Plan and 2018 Plan and provides for the issuance of incentive stock options ("ISOs"), stock grants and stock-based awards to employees, directors, and consultants of the Company. No further awards will be issued under the 2018 Plan and 2019 Plan. As of December 31, 2023, a total of 1,400,453 shares were available for grant under the 2020 Plan.

The Incentive Plans are administered by the Company's Board of Directors. Notwithstanding the foregoing, the Board of Directors may delegate concurrent responsibility for administering each plan, including with respect to designated classes of persons eligible to receive an award under each plan, to a committee or committees (which term shall include subcommittees) consisting of one or more members of the Board of Directors (collectively, the "Plan Administrator"), subject to such limitations as the Board of Directors deems appropriate.

In November 2020, the Board of Directors and stockholders approved the 2020 Plan and reserved an aggregate of 2,284,053 shares of common stock for issuance under the 2020 Plan. Pursuant to the 2020 Plan, the number of shares available for issuance under the 2020 Plan may be increased on January 1 of each year, beginning on January 1, 2021, and ending on January 2, 2030, in an amount equal to the lesser of (i) 4% of the outstanding shares of the Company’s common stock on such date or (ii) such number of shares determined by the Plan Administrator.

•The Plan Administrator may grant options designated as incentive stock options or nonqualified stock options. Options shall be granted with an exercise price per share not less than 100% of the fair market value of the common stock on the grant date, subject to certain limitations and exceptions as described in the plan agreements. Generally, the maximum term of an option shall be 10 years from the grant date. The Plan Administrator shall establish and set forth

•The Plan Administrator may grant stock grants and stock-based awards, including securities convertible into shares, stock appreciation rights, phantom stock awards or stock units on such terms and conditions which may be based on continuous service with the Company or related company or the achievement of any performance goals, as the Plan Administrator shall determine in its sole discretion, which terms, conditions and restrictions shall be set forth in the instrument evidencing the award.

RSUs granted to certain executives, employees and members of the Board of Directors expire 10 years after the grant date. The awards generally have a time-based vesting requirement (based on continuous employment). Upon vesting, the RSUs convert into shares of the Company's common stock. The stock-based compensation expense related to service-based awards is recorded over the requisite service period. During the first quarter of 2023, the Company granted RSU awards that are expected to vest with two equal vesting tranches; one tranche vested on October 31, 2023, and the second one is scheduled to vest on October 31, 2024. During the second quarter of 2023, the Company granted RSU awards to members of the Board of Directors that are expected to vest on the one year anniversary of the grant date. During the third quarter of 2023, the Company granted RSU awards that are expected to vest with three equal vesting tranches, annually on the anniversary of the grant date.

The award granted to a former member of the Board (the "former Board member") in July 2020, and modified in November 2020, contained a market-based vesting condition based on the traded value of shares of the Company’s common stock following the Company's initial public offering ("IPO") over a specific time frame. For this award, the market condition was factored into its fair value. The fair value of the award, at the modification date, was $3,180, all of which was recorded as stock-based compensation expense upon the IPO. In July 2021, the market-based vesting condition for this award was satisfied and 148,315 RSUs of the former Board member vested. The remaining 111,236 unvested RSUs met the time-based vesting conditions during the year ended December 31, 2022, and vested at that time. No additional awards with market-based conditions have been granted.

The following table summarizes the activity related to the Company's RSUs for the year ended December 31, 2023. For purposes of this table, vested RSUs represent the shares for which the service condition had been fulfilled during the year ended December 31, 2023:


	Number of RSUs	Weighted average grant date fair value
Balance, December 31, 2022	992,633	$	8.57
Granted	1,091,726	$	1.19
Vested	(779,412)	$	6.82
Forfeited	(62,737)	$	11.05
Balance, December 31, 2023	1,242,210	$	3.06

As of December 31, 2023, total unamortized stock-based compensation cost related to unvested RSUs was $2,021 and the weighted-average period over which the compensation is expected to be recognized is 1.09 years. As of December 31, 2023, there were 6,357 RSUs which had vested, but were not yet issued due to the recipients' elections to defer the awards.

The Company recognized $4,502, and $7,638, of total stock-based compensation expense for RSUs for the years ended December 31, 2023, and 2022, respectively. For the year ended December 31, 2023, the Company withheld 203,756, of the 779,412, of common stock issued upon vesting of RSUs to meet employees' payroll tax withholding requirements. The tax

During the year ended December 31, 2023, the Company granted PSU awards that are subject to a one-year vesting requirement (based on continuous employment) and contain performance conditions based on certain performance metrics. The following table summarizes the activity related to the Company's PSUs for the year ended December 31, 2023:


	Number of PSUs	Weighted average grant date fair value
Balance, December 31, 2022	96,246	$	15.74
Granted	1,141,543	$	1.77
Vested	(25,894)	$	15.74
Forfeited	(290,713)	$	5.15
Balance, December 31, 2023	921,182	$	1.77

During the year ended December 31, 2023, the PSU forfeitures were due to employee terminations and performance conditions that were not satisfied, while PSU vests were from awards granted in prior periods. The Company anticipates that a majority of the PSUs outstanding as of December 31, 2023 will forfeit in 2024 as a result of not meeting certain performance conditions.

As of December 31, 2023, total unamortized stock-based compensation cost related to unvested PSUs was $72 and the weighted-average period over which the compensation is expected to be recognized is less than one-year.

For the years ended December 31, 2023, and 2022, respectively, the Company recognized $300, and $355, of total stock-based compensation expense for PSUs. For the year ended December 31, 2023, the Company withheld 8,909, of the 25,894, of common stock issued upon vesting of PSUs to meet employees' payroll tax withholding requirements. The tax withholding payments of $15 were made in 2023.


	Number	Weighted average exercise price		Weighted average grant date fair value		Weighted average remaining contractual term (years)
Outstanding as of December 31, 2022	670,026	$	9.50	$	2.05	5.25
Cancelled	(91,443)	$	9.44	$	2.19
Forfeited	(7,224)	$	12.28	$	7.69
Outstanding as of December 31, 2023	571,359	$	9.47	$	2.01	3.69
Options exercisable as of December 31, 2023	554,685	$	9.16	$	1.71	3.59
Vested and expected to vest as of December 31, 2023	571,359	$	9.47	$	2.01	3.69

Since stock options represent equity awards of the Company, such awards are fair valued as of the grant date for the purposes of measurement and recognition under U.S. GAAP. To measure the fair value of an option, the Black-Scholes valuation model was utilized. The valuation model requires the input of subjective assumptions. For inputs into the Black-Scholes model, the expected volatility is based on historical implied volatility from recent stock option transactions at the time of grant. The risk-free interest rate for the expected term of the option is based on the U.S. Treasury implied yield at the date of grant. The Company has elected to use the "simplified method" to determine the expected term which is the midpoint between the vesting date and the end of the contractual term because it has insufficient history upon which to base an assumption about the term. The expected dividend yield is 0.0% as the Company has not paid and does not anticipate paying dividends on its common stock. Inputs to the model were as follows for the period indicated:

As of December 31, 2023, the total compensation cost related to unvested options not yet recognized was $113 and the weighted-average period over which the compensation is expected to be recognized is less than one-year. For the years ended December 31, 2023, and 2022, respectively, the Company recognized $273 and $361, of total stock-based compensation expense for stock options. The total intrinsic value of options exercised was $82 for the year ended December 31, 2022.