11. Stock-based compensation

2020 Stock incentive plan

The Company’s 2020 Stock Option and Grant Plan, or the 2020 Plan, provided for the Company to grant stock options, restricted stock and other stock awards, to employees, non-employee directors, and consultants. Upon the effectiveness of the 2021 Plan (as defined below), no further issuances were made under the 2020 Plan.

2021 Stock Option and Incentive Plan

The Company’s 2021 Stock Option and Incentive Plan, or the 2021 Plan, was approved by the Company’s board of directors on May 28, 2021 and the Company’s stockholders on June 17, 2021 and became effective on the date immediately prior to the date on which the registration statement for the Company’s initial public offering, or IPO, was declared effective. The 2021 Plan provides for the grant of incentive stock options; non-qualified stock options; stock appreciation rights; restricted stock units, or RSUs; restricted stock awards; unrestricted stock awards; cash-based awards and dividend equivalent rights to the Company’s officers, employees, directors and consultants. The number of shares initially reserved for issuance under the 2021 Plan was 4,903,145. Under the evergreen provision of the 2021 Plan, the shares available for issuance under the 2021 Plan will be automatically increased each January 1st by 5% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31st or such lesser number of shares as may be determined by the Company’s compensation, nomination and corporate governance committee. Effective January 1, 2026 the number of shares available under the 2021 Plan automatically increased by 3,277,186 shares pursuant to the evergreen provision of the 2021 Plan. As of June 30, 2026, 2,241,117 shares were available for issuance under the 2021 Plan.

2021 Employee Stock Purchase Plan

The Company’s 2021 Employee Stock Purchase Plan, or the 2021 ESPP, was approved by the Company’s board of directors on May 28, 2021 and the Company’s stockholders on June 17, 2021 and became effective on the date immediately prior to the date on which the registration statement for the Company’s IPO was declared effective. A total of 439,849 shares of the Company’s common stock were initially reserved for issuance under the 2021 ESPP. The shares available for issuance under the 2021 ESPP will be automatically increased on each January 1st, through January 1, 2031, by the least of (i) 439,849 shares of the Company’s common stock, (ii) 1% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31st or (iii) such lesser number of shares of the Company’s common stock as determined by the plan administrator of the 2021 ESPP. Effective January 1, 2026 the number of shares available under the 2021 ESPP automatically increased by 439,849 shares pursuant to the evergreen provision of the 2021 ESPP. As of June 30, 2026, 2,078,644 shares were available for issuance under the 2021 ESPP.

2026 Inducement Plan

The Company’s 2026 Inducement Plan, or the 2026 Plan, was approved by the Company’s board of directors on March 16, 2026 and became effective on the same date. The 2026 Plan provides for the grant of non-qualified stock options, stock appreciation rights, RSUs, restricted stock awards, unrestricted stock awards, and dividend equivalent rights exclusively to individuals who were not previously employees or directors of the Company, as an inducement material to the individuals' entry into employment with the Company and in accordance with the requirements of Nasdaq Stock Market Rule 5635(c)(4). The number of shares reserved for issuance under the 2026 Plan was 1,500,000. As of June 30, 2026, 1,428,075 shares were available for issuance under the 2026 Plan.

Stock option activity

The Company has granted stock options to employees, non-employee directors, and others under the 2021 Plan and under the 2026 Plan.

The aggregate intrinsic value of options granted is calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock.

Restricted stock unit activity

The Company has granted RSUs to employees under the 2021 Plan and under the 2026 Plan. Each of the RSUs represents the right to receive one share of the Company’s common stock upon vesting. The RSUs will typically vest over two or four years provided the individual remains in continuous service of the Company. Accordingly, stock-based compensation expense for each RSU is recognized on a straight-line basis over the vesting term. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant.

The aggregate fair value of RSUs that vested during the six months ended June 30, 2026 and 2025 was $2.9 million and $0.5 million, respectively. The weighted average grant date fair value of RSUs that vested during the six months ended June 30, 2026 and 2025 was $7.03 and $7.55 per share, respectively.

Stock-based compensation expense

As of June 30, 2026 total unrecognized stock-based compensation cost related to unvested stock options and restricted stock units was $48.4 million and $11.6 million, respectively. The Company expects to recognize this remaining cost over a weighted average period of 2.6 years and 3.0 years, respectively.