MiNK Therapeutics, Inc. Stock Compensation Disclosure

(8) Share-based Compensation Plans

The Company’s 2018 Equity Incentive Plan (the “2018 Plan”) provided for the grant of incentive stock options intended to qualify under Section 422 of the IRC, nonstatutory stock options, restricted stock, unrestricted stock and other equity-based awards, such as

stock appreciation rights, and stock units including restricted stock units for up to approximately 1.4 million shares of the Company’s common stock (subject to adjustment in the event of stock splits and other similar events). As of December 31, 2025, no shares remain available for issuance under the 2018 Plan.

In connection with the Company’s initial public offering (“IPO”), MiNK’s board of directors adopted the MiNK Therapeutics, Inc. 2021 Equity Incentive Plan (the “2021 Plan”). The 2021 Plan provides for the grant of incentive stock options intended to qualify under Section 422 of the Code, nonstatutory stock options, restricted stock, unrestricted stock and other equity-based awards, for an initial share pool of approximately 0.6 million shares of the Company’s common stock (subject to adjustment in the event of stock splits and other similar events). The initial share pool automatically increases on January 1st of each year from 2022 to 2031 by the lesser of (i) four percent of the number of shares of the Company’s common stock outstanding as of the close of business on the immediately preceding December 31st and (ii) the number of shares determined by the Company’s board of directors on or prior to such date for such year. The 2021 Plan share pool increased by approximately 159,000 and 140,000 shares in January 2025 and 2024, respectively. As of December 31, 2025, there were approximately 1.2 million shares reserved for issuance under the 2021 Plan.

In connection with the Company’s IPO, MiNK’s board of directors adopted the MiNK Therapeutics, Inc. 2021 Employee Stock Purchase Plan (the “ESPP”). The ESPP provides eligible employees the opportunity to acquire the Company’s common stock in a program designed to comply with Section 423 of the Code. There are approximately 175,000 shares reserved for issuance under the ESPP, plus an automatic annual increase on January 1st of each year from 2022 to 2031 equal to the lesser of (i) one percent of the number of shares of the Company’s common stock outstanding as of the close of business on the immediately preceding December 31st and (ii) the number of shares determined by the Company’s board of directors on or prior to such date for such year, up to a maximum of approximately 0.4 million shares in the aggregate.

On June 18, 2025, at the Company's annual meeting of stockholders, the Company’s stockholders approved a one-time exchange of options to purchase shares of the Company’s common stock issued under the 2021 Plan and the 2018 Plan that were held by the Company’s executive officers, other employees, consultants, and non-employee directors, for new options to purchase shares of the Company’s common stock (the “Option Exchange”). Pursuant to the Option Exchange, eligible options were cancelled in exchange for an equal number of new options to purchase shares of common stock with an exercise price equal to the fair market value of the Company’s common stock at the time of the Option Exchange and a term of the option that extends ten years from the date of grant. An eligible stock option generally included any outstanding stock option that had an exercise price equal to or greater than $8.50 per share and greater than the closing price of the Company’s common stock on the date of the Option Exchange, that vested based on continued service with the Company or based on the achievement of performance milestones and that was granted under the Equity Plans. The Option Exchange resulted in the re-pricing of 647,915 options to an exercise price of $7.43. The vesting conditions of the modified options remained the same and the modified awards have a 10-year term. Total expected incremental share-based compensation expense resulting from the modification was approximately $0.6 million, of which $0.4 million related to vested awards and was recognized immediately with $0.2 million being recognized over the remaining vesting period.

The Company primarily uses the Black-Scholes option pricing model to value options granted to employees and non-employees, as well as options granted to members of the Company’s Board of Directors. All stock option grants have 10-year terms, service conditions, and generally vest ratably over a 3 or 4-year period.

The expected term of stock options granted is based on historical data and other factors and represents the period of time that stock options are expected to be outstanding prior to exercise. The risk-free interest rate is based on U.S. Treasury strips with maturities that match the expected term on the date of grant.

The weighted average grant-date fair values of options granted during the years ended December 31, 2025 and 2024, was $10.04 and $6.86, respectively. During both 2025 and 2024, all options were granted with exercise prices equal to the market value of the underlying shares of common stock on the grant date except certain awards dated January 16, 2024. In January 2024, the Company's Board of Directors approved certain awards. However, the awards were not communicated to employees until May 2024. Accordingly, these awards have a grant date of May 2024, with an exercise price as of the date the Board of Directors approved the awards in January 2024.

The aggregate intrinsic value in the table above represents the difference between the Company's closing stock price on the last trading day of fiscal 2025 and the exercise price, multiplied by the number of in-the-money options that would have been received by the option holders had all option holders exercised their options on December 31, 2025 (the intrinsic value is considered to be zero if the exercise price is greater than the closing stock price). This amount changes based on the fair market value of the Company's stock. The total intrinsic value of options exercised during the year ended December 31, 2025, determined on the dates of exercise, was approximately $797,971.

As of December 31, 2025, there was $1.4 million of unrecognized share-based compensation expense related to stock options granted to employees, consultants and directors which, if all milestones are achieved on outstanding performance based awards, will be recognized over a weighted average period of 2.5 years. For awards with performance conditions, expense is recognized if the achievement of underlying performance conditions is deemed probable.

As of December 31, 2025, there was $0.6 million of unrecognized share-based compensation expense related to these non-vested shares which will be recognized over a weighted average period of 2.8 years. The total intrinsic value of shares vested during the year ended December 31, 2025 was $801,257.

The Company issues new shares upon option exercises the vesting of non-vested stock and purchases under the ESPP. During the years ended December 31, 2025 and 2024, 96,885 shares and 7,423 shares, respectively, were issued as a result of stock option exercises. During the years ended December 31, 2025 and 2024, 36,068 shares and 30,173 shares, respectively, were issued as a result of the vesting of non-vested stock. During the years ended December 31, 2025 and 2024, 209 shares and 1,539 shares, respectively, were issued under the ESPP. Additionally, during the year ended December 31, 2025, 35,412 shares were issued as payment for certain employee bonuses, with 11,286 of those shares being withheld to cover taxes, resulting in a net share issuance of 24,126 shares.

Stock based compensation expense also includes expense related to awards granted to employees of the Company from the Agenus 2019 Equity Incentive Plan. The impact on the Company’s results of operations from share-based compensation for the year ended December 31, 2025 and 2024, was as follows (in thousands):