NOTE 4  STOCK-BASED COMPENSATION AWARDS

Equity Incentive Plans

In March 2021, the Company’s board of directors adopted, and its stockholders approved, the Company’s 2021 Equity Incentive Plan (2021 Plan), which became effective in March 2021 in connection with the IPO. Upon adoption of the 2021 Plan, the Company restricted the grant of future equity awards under its 2017 Equity Incentive Plan, as amended and restated (2017 Plan).

The 2021 Plan provides for the grant of incentive stock options, within the meaning of Section 422 of the Internal Revenue Code, to the Company’s employees and any of its parent and subsidiary corporations’ employees, and for the grant of nonstatutory stock options, restricted stock, restricted stock units (RSUs), stock appreciation rights, performance units, and performance shares to its employees, directors, and consultants and its subsidiary corporations’ employees and consultants.

The vesting of stock options is stated in each individual grant agreement, which is generally four years. Options granted expire 10 years after the date of grant. An RSU represents the right to receive one share of common stock upon vesting of the RSU. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant and generally vest over 2 to 4 years. A total of 5,040,000 shares of the Company’s common stock were initially reserved for issuance pursuant to the 2021 Plan. The 2021 Plan share reserve increases by the number of shares under the 2017 Plan that are repurchased, forfeited, expired or cancelled after the effective date of the 2021 Plan up to the limit under the 2021 Plan. The number of shares available for issuance under the 2021 Plan increases annually on the first day of each fiscal year beginning with the Company’s 2022 fiscal year, equal to the least of (1) 5,040,000 shares, (2) five percent (5%) of the outstanding shares of its common stock as of the last day of the immediately preceding fiscal year; or (3) such other amount as the Company’s board of directors may determine. As of December 31, 2025, there were 2,599,220 shares available for future issuance under the 2021 Plan.

Inducement Equity Incentive Plan

Effective August 10, 2024, the Company’s board of directors adopted the Company’s 2024 Inducement Equity Incentive Plan (Inducement Plan) and, subject to the adjustment provisions of the Inducement Plan, reserved 2,000,000 shares of the Company’s common stock for issuance pursuant to equity awards granted under the Inducement Plan.

The Inducement Plan was adopted without stockholder approval pursuant to the applicable The Nasdaq Stock Market LLC’s (Nasdaq) Listing Rules. The Inducement Plan provides for the grant of equity-based awards, including nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units, and performance awards, and its terms are substantially similar to the 2021 Plan, including with respect to treatment of equity awards in the event of a “merger” or “change in control” as defined under the Inducement Plan, but with such other terms and conditions intended to comply with the Nasdaq inducement award exception or to comply with the Nasdaq acquisition and merger exception.

In accordance with the Nasdaq Listing Rules, awards under the Inducement Plan may only be made to individuals not previously employees or non-employee directors of the Company (or following such individuals’ bona fide period of non-employment with the Company), as an inducement material to the individuals’ entry into employment with the Company, or, to the extent permitted by the Nasdaq Listing Rules, in connection with a merger or acquisition. The

vesting of stock options is stated in each individual grant agreement, which is generally four years, and expires 10 years after the date of grant. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant and vests over 4 years. As of December 31, 2025, there were 1,009,750 shares available for future issuance under the Inducement Plan.

Stock Options

Stock option activity for the year ended December 31, 2025 is as follows:

Weighted

Average

Weighted

Remaining

Average

Total Intrinsic

Contractual Life

  ​ ​ ​

Options

  ​ ​ ​

Exercise Price

  ​ ​ ​

Value (000's)

  ​ ​ ​

(Years)

Outstanding as of December 31, 2024

 

15,416,761

 

$

9.40

 

$

267,397

7.5

Granted

 

4,267,256

$

15.78

Exercised

 

(993,495)

$

8.45

Cancelled

(529,284)

$

12.79

Outstanding as of December 31, 2025

18,161,238

$

10.85

$

255,726

7.2

Options exercisable as of December 31, 2025

10,687,753

$

8.46

$

175,917

6.0

The vesting of stock options is stated in each individual grant agreement, which is generally four years. As of December 31, 2025, there was unrecognized stock-based compensation cost of $64.9 million, which is expected to be recognized over a weighted-average term of 2.8 years. The aggregate intrinsic value of options exercised during the years ended December 31, 2025, 2024 and 2023 was $12.9 million, $30.3 million, and $1.0 million, respectively. For options granted during the years ended December 31, 2025, 2024 and 2023, the weighted-average grant date fair value was $10.92, $12.73, and $5.25 per share, respectively. The Company did not have any material awards modified during the years ended December 31, 2025, 2024 and 2023. In previous years, there were additional options issued outside of this plan as discussed under Founder Stock Options.

Fair Value Assumptions

The fair value of option grants is estimated on the date of grant using the Black-Scholes option-pricing model, which requires the use of the following assumptions:

Year ended December 31, 

  ​ ​ ​

2025

  ​ ​ ​

2024

  ​ ​ ​

2023

Expected term (Years)

0.36 - 6.85

5.10 - 6.85

5.44 - 6.85

Expected volatility

69.23% - 81.21%

78.67% - 83.21%

80.68% - 85.68%

Risk-free interest rate

3.51% - 4.41%

3.59% - 4.66%

3.47% - 4.80%

Expected dividend rate

-

-

-

Fair value common stock

$13.11 - $28.02

$16.33 - $33.57

$5.73 - $10.29

The expected term is based on the “simplified method” described in the U.S. Securities and Exchange Commission’s Staff Accounting Bulletin Topic 14 which is determined as the midpoint between the vesting date and the contractual end of the option grant. Stock price volatility was estimated based on the estimated stock price volatility of a peer group of publicly traded companies over a similar term. The risk-free interest rate for periods within the contractual life of the option is based on the U.S. Treasury yield in effect at the time of grant. The dividend yield was zero as the Company has never declared or paid dividends and has no plans to do so in the foreseeable future.

Founder Stock Options

On September 19, 2017, the Company granted one of its founders the option to purchase 1,795,880 shares of the Company’s common stock at an exercise price of $0.18 per share which vested monthly over a four-year period that expires 15 years after the date of grant. This grant is separate from the Company’s equity incentive plans discussed above.

As of December 31, 2025, 1,147,365 options were both outstanding and exercisable and there was no unrecognized stock-based compensation expense. During the years ended December 31, 2025 and 2024, 209,415 options with intrinsic value of $3.8 million and 175,000 options with intrinsic value of $4.6 million were exercised, respectively. There were no options exercised during the year ended December 31, 2023. As of December 31, 2025, the intrinsic value of options outstanding and exercisable was $28.3 million with a weighted-average remaining contractual life of 6.5 years.

Restricted Stock Units

A RSU represents the right to receive one share of common stock upon vesting of the RSU. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant and generally vest over 3 or 4 years.

RSU activity for the year ended December 31, 2025 is as follows:

Weighted Average

Grant Date

  ​ ​ ​

RSUs

  ​ ​ ​

Fair Value

Issued and unvested as of December 31, 2024

 

639,516

 

$

15.86

Granted

 

908,723

$

14.48

Vested

 

(213,411)

$

13.68

Cancelled

(59,876)

$

15.87

Issued and unvested as of December 31, 2025

1,274,952

$

15.24

As of December 31, 2025, there was unrecognized stock-based compensation cost of $15.5 million, which is expected to be recognized over a weighted-average term of 3.2 years. The total fair value of RSUs vested during the years ended December 31, 2025, 2024 and 2023 was $3.1 million, $0.7 million, and $0.7 million, respectively.

2021 Employee Stock Purchase Plan

The 2021 Employee Stock Purchase Plan (2021 ESPP) enables eligible employees of the Company to purchase shares of common stock at a discount. A total of 504,000 shares of the Company’s common stock were initially reserved for issuance pursuant to the 2021 ESPP. The number of shares available for issuance under the 2021 ESPP increases annually on the first day of each fiscal year beginning with the Company’s 2022 fiscal year, equal to the least of (1) 1,008,000 shares, (2) one percent (1%) of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (3) such other amount as the Company’s board of directors may determine. As of December 31, 2025, the Company has reserved for issuance 2,900,630 shares of common stock pursuant to the 2021 ESPP.

The 2021 ESPP provides for two offering periods of approximately twelve months’ duration, with purchase periods commencing on the first trading day on or after May 15 and November 15 and terminating on the last trading day on or before November 15 of the same year and May 15 of the following year, respectively. Contributions under the 2021 ESPP are limited to 15% of an employee’s eligible compensation, IRS limitations, and a maximum of 6,000 shares of common stock during each offering period. 2021 ESPP participants will purchase shares of common stock at a price per share equal to 85% of the lesser of (1) the fair market value per share of the common stock on the first trading day of the offering period or (2) the fair market value of the common stock on the purchase date. Additionally, during the years ended December 31, 2025, 2024 and 2023, a total of 75,161, 147,086, and 95,259 shares of common stock were issued under the ESPP at a weighted-average per share price of $12.28, $6.03, and $6.26, respectively.

Total stock-based compensation expense related to all equity plans, including Founder Stock Options was allocated as follows (in thousands):

Year ended December 31, 

  ​ ​ ​

2025

  ​ ​ ​

2024

  ​ ​ ​

2023

Research and development

 

$

19,647

 

$

13,956

 

$

10,029

General and administrative

 

15,105

 

10,755

 

7,531

Total stock-based compensation expense

$

34,752

$

24,711

$

17,560

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.