In July 2012, the Company’s stockholders approved the 2012 Share Incentive Plan covering a total of 750,000 shares of common stock issuable upon exercise of options to be granted under the plan. At December 31, 2023, options are no longer able to be granted from of this plan.

In July 2015, the Company’s stockholders approved the 2015 Executive and Employee Stock Option Plan covering a total of 2,000,000 shares of common stock issuable upon exercise of options to be granted under the plan. At December 31, 2023, approximately 70,000 are available to be issued in this plan.

In August 2017, the Company’s stockholders approved the 2017 Executive and Employee Stock Option Plan covering a total of 3,000,000 shares of common stock issuable upon exercise of options to be granted under the plan. At December 31, 2023, approximately 10,000 are available to be issued in this plan.

In August 2019, the Company’s stockholders approved the 2019 Share Incentive Plan covering a total of 2,000,000 shares of common stock issuable upon exercise of options to be granted under the plan. At December 31, 2023, approximately 360,000 are available to be issued in this plan.

In August 2021, the Company’s stockholders approved the 2021 Share Incentive Plan covering a total of 1,375,000 shares of common stock issuable upon exercise of options to be granted under the plan. At December 31, 2023, approximately 250,000 are available to be issued in this plan.

In August 2023, the Company’s stockholders approved the 2023 Share Incentive Plan covering a total of 1,600,000 shares of common stock issuable upon exercise of options to be granted under the plan. At December 31, 2023, all 1,600,000 are available to be issued in this plan.

On January 10, 2024, the Company granted employees approximately 1,400,000 options to purchase common shares of the Company's stock at an exercise price of $2.42. All options granted were pursuant to the plans noted above. The options vest over a period of three years.


	Number of options	Weighted average exercise price












Outstanding at December 31, 2021	5,397,691	$	5.95
Granted	1,692,417	10.64
Exercised	(316,506)	3.96
Canceled and forfeited	(253,158)	9.59
Outstanding at December 31, 2022	6,520,444	$	7.12
Granted	1,527,865	2.63
Exercised	(57,000)	2.65
Canceled and forfeited	(648,426)	6.18
Outstanding at December 31, 2023	7,342,883	$	6.31


	Number of options	Weighted average grant date fair value
Non-vested at December 31, 2022	2,227,608	$	6.27
Granted	1,527,865	1.95
Vested	(1,195,115)	5.78
Forfeited	(504,577)	4.00
Non-vested at December 31, 2023	2,055,781	$	3.90

Common shares required to be issued upon the exercise of stock options would be issued from authorized and unissued shares. Options are valued using the Black-Scholes model. For employee grants, the Company calculates expected life via the simplified method as it does not have sufficient history to determine actual expected life. For non-employee grants, the Company calculates expected life using a combination of past exercise behavior, the contractual term and expected remaining exercise behavior. Inputs used in the valuation models are as follows:


	2023 Grants			2022 Grants
Exercise price	$2.50	-	$4.21	$5.10	-	$10.96
Risk-free rate	3.6%	-	4.3%	1.6%	-	3.9%
Expected dividend yield	—%			—%
Expected volatility	85.8%	-	88.4%	69.6%	-	78.5%
Expected term (in years)	6			5	-	6

The Company recognized approximately $5,114,000 and $6,697,000 in stock-based compensation expense during the years ended December 31, 2023 and 2022, respectively.

The intrinsic value of each option share is the difference between the fair value of our common stock and the exercise price of such option share to the extent it is “in-the-money”. Aggregate intrinsic value represents the value that would have been received by the holders of in-the-money options had they exercised their options on the last trading day of the year and sold the underlying shares at the closing stock price on such day. The intrinsic value calculation at December 31, 2023 is based on the $2.62 closing stock price of the Company's common stock on December 29, 2023, the last trading day of 2023.

As of December 31, 2023, there were 6,931,726 stock options outstanding and expected to vest with an aggregate intrinsic value of approximately $140,000. These options have a weighted average exercise price of $6.33 and a weighted average remaining contractual term of approximately 6 years.

As of December 31, 2023, there were 5,287,102 stock options outstanding and exercisable with an aggregate intrinsic value of approximately $140,000. These options have a weighted average exercise price of $6.43 and a weighted average remaining contractual term of approximately 6 years.

The total intrinsic value of in the money options exercised during the years ended December 31, 2023 and 2022, was approximately $210,000 and $900,000, respectively. Intrinsic value of exercised shares is the fair value of such shares on the date of exercise less the exercise price of the option on the exercise date.

The total fair value of options granted during the years ended December 31, 2023 and 2022, was approximately $2,980,000 and $11,350,000, respectively. The weighted average fair value of options granted during the years ended December 31, 2023 and 2022, was $1.95 and $6.71, respectively. The total fair value of options vested during the years ended December 31, 2023 and 2022, was approximately $6,900,000 and $5,260,000, respectively.

The Company allows employees to exercise stock-based awards by surrendering stock-based awards with an intrinsic value equal to the cumulative exercise price of the stock-based awards being exercised, referred to as net settlements. These surrenders are included in stock options exercised in the options rollforward above. During the years ended December 31, 2023 and 2022, the Company received 10,967 and 125,596 options as payment in the exercise of 11,033 and 81,737 options, respectively.

As of December 31, 2023, there was approximately $4,280,000 of total unrecognized stock-based compensation expense, related to unvested stock options granted under the plans above. This expense is expected to be recognized over a weighted-average period of approximately 1 year.