8. STOCK-BASED COMPENSATION

Equity Plans

In 2011, Private Tempest adopted the 2011 Equity Incentive Plan (the “2011 Plan), and in 2017, Private Tempest adopted the 2017 Equity Incentive Plan (the “2017 Plan”), and together with the 2011 Plan, the “Tempest Prior Plans.” The Tempest Prior Plans have been terminated and no additional grants may be made under either plan. All stock awards granted under the Tempest Prior Plans will remain subject to the terms of the applicable prior plan. As a result of the merger with Millendo, the Tempest Prior Plans were assumed by the Company.

On April 29, 2019, the Board of Millendo adopted the 2019 Equity Incentive Plan (the “2019 Plan”), subject to approval by the Company’s stockholders, and became effective with such stockholder approval on June 11, 2019. On June 17, 2022, the Company’s stockholders approved the Amended and Restated 2019 Equity Incentive Plan (the “A&R 2019 Plan”), which amended and restated the 2019 Plan and was the successor to, and replacement of, the 2019 Plan.

The Board of Tempest adopted the Amended and Restated 2023 Equity Incentive Plan (the “2023 Plan”) on April 30, 2023, subject to approval by the Company’s stockholders. On June 15, 2023, the Company’s stockholders approved the 2023 Plan, which amended and restated the A&R 2019 Plan and will be a successor to, and replacement of, the A&R 2019 Plan. The number of shares of the Company's common stock reserved for issuance under the 2023 Plan will automatically increase on January 1st of each year, for a period of 10 years, from January 1, 2024 continuing through January 1, 2033, by 4% of the total number of shares of the Company's common stock outstanding on December 31st of the preceding calendar year, or a lesser number of shares as may be determined by the Board of Directors. Accordingly, on January 1, 2025, the common stock reserved for issuance was increased by 135,297 shares. As of June 30, 2025, there were 47,745 shares available for future grant under the 2023 Plan.

The 2023 Plan allows the Company to grant stock awards to employees, directors and consultants of the Company, including incentive stock options (“ISOs”), non-qualified stock options (“NSOs”), stock appreciation rights, restricted stock awards, restricted stock unit awards and other stock awards.

The Board of Tempest adopted the 2023 Inducement Plan (“2023 Inducement Plan”) on June 21, 2023, pursuant to which the Company reserved 88,461 shares of its common stock to be used exclusively for grants of awards to individuals who were not previously employees or directors of the Company, as an inducement material to the individual’s entry into employment with the Company within the meaning of Rule 5635(c)(4) of the Nasdaq Listing Rules. The 2023 Inducement Plan was approved by the Company’s Board of Directors without stockholder approval in accordance with such rule. As of June 30, 2025, there were 67,615 shares available for future grant under the 2023 Inducement Plan.

The Company measures employee and non-employee stock-based awards at grant date fair value and records compensation expense on a straight-line basis over the vesting period of the award.

Employee Stock Ownership Plan

The Millendo Board adopted the 2019 Employee Stock Purchase Plan on April 29, 2019, which became effective upon stockholder approval on June 11, 2019. On June 17, 2022, the Company’s stockholders approved the Amended and Restated 2019 Employee Stock Purchase Plan (the “2019 ESPP”). The 2019 ESPP enables employees to purchase shares of the Company's common stock through offerings of rights to purchase the Company's common stock to all eligible employees.

The 2019 ESPP provides that the number of shares of common stock reserved for issuance under the 2019 ESPP will automatically increase on January 1, 2023 and continuing through (and including) January 1, 2029, by the lesser of 1.5% of the total number of shares of Common Stock outstanding on December 31st of the preceding calendar year, (ii) 38,461 shares of Common Stock, or (iii) such lesser number of shares of Common Stock as determined by the Board of Directors (which may be zero). On January 1, 2025, the common stock reserved for issuance was increased by 38,461 shares.

As of June 30, 2025, 70,914 shares of common stock remained available for future issuance under the 2019 ESPP. During the three and six months ended June 30, 2025, 3,649 shares of common stock were issued under the 2019 ESPP.

Stock Options

Options to purchase the Company’s common stock may be granted at a price not less than the fair market value in the case of both NSOs and ISOs, except for an options holder who owns more than 10% of the voting power of all classes of stock of the Company, in which case the exercise price shall be no less than 110% of the fair market value per share on the grant date. Stock options granted under the Plans generally vest over four years and expire no later than ten (10) years from the date of grant. Vested options can be exercised at any time.

During the six months ended June 30, 2025 and 2024, the Company granted employees and non-employees stock options to purchase 130,091 and 57,551 shares of common stock, respectively, with a weighted-average grant date fair value of $11.20 and $57.85 per share, respectively. As of June 30, 2025 and 2024, total unrecognized compensation costs related to unvested employee stock options were $512 and $14,772, respectively. These costs are expected to be recognized over a weighted-average period of approximately 2.0 years and 3.1 years, respectively.

The Company estimated the fair value of stock options using the Black-Scholes option pricing valuation model. The fair value of employee and non-employee stock options is being amortized on the straight-line basis over the requisite service period of the awards. The fair value of employee and non-employee stock options was estimated using the following assumptions for the six months ended June 30, 2025 and 2024:

Expected Term—The expected term of options granted represents the period of time that the options are expected to be outstanding. Due to the lack of historical exercise history, the expected term of the Company’s employee stock options has been determined utilizing the simplified method for awards that qualify as plain-vanilla options.

Expected Volatility—The expected stock price volatility assumption was determined by examining the historical volatilities for industry peers, as the Company did not have any trading history for the Company’s common stock. The Company will continue to analyze the historical stock price volatility and expected term assumption as more historical data for the Company’s common stock becomes available.

Risk-Free Interest Rate—The risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the Company’s stock options.

Dividends—The Company has not paid any cash dividends on common stock since inception and does not anticipate paying any dividends in the foreseeable future. Consequently, an expected dividend yield of zero was used.

Stock-Based Compensation Expense