10. Equity Incentive Plans

In January 2024, the Company’s board of directors adopted, and stockholders approved, the Company’s 2024 Equity Incentive Plan (the “2024 Plan”), which became effective on February 6, 2024. The 2024 Plan superseded the Company’s 2019 Equity Incentive Plan (the “2019 Plan”). No share awards can be granted under the 2019 Plan from the effective date of the 2024 Plan. Shares subject to outstanding equity awards granted under the 2019 Plan may be added to the 2024 Plan as such shares become available from time to time if awards terminate, expire, or lapse for any reason without the delivery of shares, or are reacquired or withheld (or not issued) to satisfy a tax withholding obligation or the purchase or exercise price.

The Company initially reserved 4,215,000 shares of common stock for future issuance under the 2024 Plan. In addition, up to 3,960,713 shares issued and outstanding under the 2019 Plan may be added to the 2024 Plan as such shares become available from time to time if awards terminate, expire, or lapse for any reason without the delivery of shares, or are reacquired or withheld (or not issued) to satisfy a tax withholding obligation or the purchase or exercise price. The 2024 Plan also provides that the number of shares reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2025 and ending on January 1, 2034, by an amount equal to the lesser of (i) 5% of the shares of common stock outstanding on the last day of the immediately preceding fiscal year, and (ii) such smaller number of shares of common stock as determined by the Company’s board of directors. In accordance with the foregoing, 2,160,745 and 3,019,494 shares of common stock were added to the shares reserved for future issuance under the 2024 Plan on January 1, 2025 and 2026, respectively. No more than 12,645,000 shares of common stock may be issued upon the exercise of incentive stock options under the 2024 Plan.

As of June 30, 2026, incentive stock options, nonstatutory stock options and restricted stock units had been granted under the 2024 Plan. As of June 30, 2026, 4,535,168 shares of the Company’s common stock remained available for future grant under the 2024 Plan.

In January 2024, the Company’s board of directors and stockholders adopted the Company’s 2024 Employee Stock Purchase Plan (the “ESPP”), which became effective on February 6, 2024. As of June 30, 2026, 1,266,000 shares of common stock were reserved for future issuance under the ESPP. The number of shares of common stock reserved for issuance under the ESPP may not exceed 844,000 shares of common stock, plus the number of shares of common stock that will be automatically increased each January 1, beginning on January 1, 2025 and ending on January 1, 2034 by an amount equal to the lesser of (i) 1.00% of the shares of common stock outstanding on December 31st of the immediately preceding calendar year and (ii) 422,000 shares of common stock. The ESPP allows an eligible employee to purchase shares of our common stock at a discount through payroll deductions of up to 15% of the employee’s eligible compensation. At the end of each purchase period, employees are able to purchase shares at 85% of the lower of the fair market value of our common stock at the beginning of the offering period or at the end of each applicable offering period.

In September 2024, the Company adopted the 2024 Inducement Equity Incentive Plan (as amended and restated in January 2026, the “Inducement Plan”). On January 29, 2026, the Company's compensation committee of the board of directors approved an increase of the maximum number of shares available for grant under the Inducement Plan by 1,000,000 shares to an aggregate of 5,000,000 shares of the Company's common stock. As of June 30, 2026, 4,989,259 shares were granted and 10,741 shares were available for future grant under the Inducement Plan.

Stock Options

Aggregate intrinsic value represents the difference between the fair value of the underlying common stock and the exercise price. The weighted-average grant date fair value of options granted for the three and six months ended June 30, 2026 was $6.53 and $6.58, respectively. The total fair value of options that vested during the three and six months ended June 30, 2026 was $3.9 million and $6.6 million, respectively. The total fair value of options that vested during the three and six months ended June 30, 2025 was $1.7 million and $4.6 million, respectively. The intrinsic value of options exercised during the three and six months ended June 30, 2026 was $2.5 million and $3.1 million, respectively, and is calculated as the difference between the exercise price and the fair value of common stock as of the exercise date. As of June 30, 2026, total unrecognized stock-based compensation expense related to issued options was $33.0 million, which is expected to be recognized over a weighted-average period of 2.9 years.

Restricted Stock Units

Issued restricted stock units (“RSUs”) vest over a four-year period. The estimated aggregate grant-date fair value of RSUs granted during the three and six months ended June 30, 2026 was $2.5 million and $9.4 million. As of June 30, 2026, total unrecognized compensation expense for RSUs was $10.9 million, which is expected to be recognized over a weighted-average period of 3.4 years.

Performance Restricted Stock Units

During the three and six months ended June 30, 2026, the Company granted performance restricted stock units (“PRSUs”) for zero and 24,301 shares with a weighted-average grant date fair value per share of zero and $8.12, respectively. These PRSU shares vest in two tranches upon the attainment of certain target closing prices per share of the Company’s common stock. The Company used a Monte Carlo simulation model to estimate the grant date fair value of the PRSUs with the following assumptions: common stock fair value of $8.23, which was the closing market price of the Company’s common stock at the grant date, volatility of 105.00%, risk free rate of 4.19%, and vesting term of 10 years. Total estimated fair value of $0.2 million will be recognized as stock-based compensation expense over the derived requisite service period of 0.7 years and 1.5 years from the grant date for each of the two tranches, respectively.

As of June 30, 2026, total unrecognized compensation expense for PRSUs was $0.1 million and is expected to be recognized over the weighted-average remaining term of 0.6 years.
 

Stock-Based Compensation Expense