Note 12. Stock-Based Compensation Plans

The Company maintains the 2021 Equity Incentive Plan, or the 2021 Plan, which provides for the granting of stock awards to employees, directors and consultants. Options granted under the 2021 Plan may be either incentive stock options or nonqualified stock options. Options granted under the 2021 Plan expire no later than 10 years from the date of grant. Options and restricted stock awards, or RSAs, under the 2021 Plan generally vest over four years. Restricted stock units, or RSUs, granted under the 2021 Plan generally vest in two years. As of December 31, 2024, there were 0.1 million shares of common stock available for issuance under the 2021 Plan.

The Company maintains the 2021 Employee Stock Purchase Plan, or the ESPP, which allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to plan limitations. An offering period under the ESPP consists of four six-month purchase periods, unless otherwise determined by the Company. The eligible employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the purchase day. As of December 31, 2024, there were approximately 20,000 shares of common stock available for issuance under the ESPP.

Stock Options

A summary of stock option activity is set forth below (shares in thousands):

 

 

Options Outstanding

 

 

 

 

 

 

Weighted

 

 

Average

 

 

Aggregate

 

 

 

 

 

 

Average

 

 

Remaining

 

 

Intrinsic

 

 

 

Number of

 

 

Exercise

 

 

Contractual Life

 

 

Value

 

 

 

Options

 

 

Price

 

 

(In years)

 

 

(In thousands)

 

Outstanding – December 31, 2023

 

 

311

 

 

$

27.70

 

 

 

7.99

 

 

 

 

Granted

 

 

258

 

 

 

9.64

 

 

 

 

 

 

 

Exercised

 

 

(4

)

 

 

9.20

 

 

 

 

 

 

 

Forfeited

 

 

(19

)

 

 

18.76

 

 

 

 

 

 

 

Expired

 

 

(10

)

 

 

29.16

 

 

 

 

 

 

 

Outstanding – December 31, 2024

 

 

536

 

 

 

19.45

 

 

 

8.00

 

 

$

1,514

 

Exercisable – December 31, 2024

 

 

262

 

 

 

25.33

 

 

 

7.01

 

 

 

487

 

 

The aggregate intrinsic value of options outstanding and exercisable are the difference between the exercise price of the options and the fair value of the Company’s common stock at December 31, 2024.

The intrinsic value of options exercised during the years ended December 31, 2024 and 2023 was de minimis in both periods.

During the years ended December 31, 2024 and 2023, the Company granted options with a weighted-average grant-date fair value of $7.45 per share and $9.47 per share, respectively.

 

Fair Value of Options

The fair value of options is estimated at the grant date using the Black-Scholes option-pricing model with the following weighted-average assumptions:

 

 

 

 

Year Ended December 31,

 

 

 

 

 

 

 

2024

 

 

2023

 

Expected term (in years)

 

 

 

 

 

 

6.00

 

 

 

5.85

 

Expected volatility

 

 

 

 

 

 

91.59

%

 

 

85.86

%

Risk-free rate

 

 

 

 

 

 

4.63

%

 

 

3.89

%

Dividend yield

 

 

 

 

 

 

 

 

 

 

 

Restricted Stock Units

The following table summarizes the Company’s RSUs activity (shares in thousands):

 

 

 

 

 

Weighted

 

 

 

 

 

 

Average

 

 

 

Number of

 

 

Grant Date

 

 

 

Shares

 

 

Fair Value

 

RSUs, unvested at December 31, 2023

 

 

90

 

 

$

7.73

 

Granted

 

 

40

 

 

 

9.17

 

Vested

 

 

(88

)

 

 

7.73

 

Canceled

 

 

(4

)

 

 

8.43

 

RSUs, unvested at December 31, 2024

 

 

38

 

 

 

9.16

 

 

 

 

 

 

 

 

 

The fair value of RSUs vested during the years ended December 31, 2024 and 2023 was $0.7 million and zero, respectively.

 

Stock-Based Compensation

Total stock-based compensation expense recorded in the consolidated statements of operations and comprehensive loss was as follows (in thousands):

 

 

 

 

Year Ended December 31,

 

 

 

 

 

 

 

2024

 

 

2023

 

Research and development

 

 

 

 

 

$

1,165

 

 

$

1,272

 

General and administrative

 

 

 

 

 

 

2,949

 

 

 

3,100

 

Total stock-based compensation expense

 

 

 

 

 

$

4,114

 

 

$

4,372

 

As of December 31, 2024, there was approximately $3.4 million of stock-based compensation expense to be recognized over a weighted-average period of approximately 2.04 years.

About Stock Compensation Disclosures

Stock-based compensation disclosures detail the equity awards granted to employees and executives — including stock options, restricted stock units (RSUs), and performance shares — along with the valuation methods and assumptions used to expense them. This section reveals the true cost of talent retention and the alignment between management incentives and shareholder interests.

Key signals: total unrecognized compensation expense and its expected recognition period signal future earnings headwinds from already-granted awards. For stock options, examine Black-Scholes assumptions — expected volatility, risk-free rate, and expected term — as understating any of these reduces reported compensation expense. Compare stock compensation expense as a percentage of revenue against peers to assess dilution cost. Watch vesting schedules for acceleration clauses tied to change-of-control events. Performance-based awards with undemanding targets may indicate weak governance. Add back stock compensation to operating cash flow to calculate a more conservative free cash flow figure.