(6) Share-based Compensation Plans

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 and generally vest ratably over a 3 or 4-year period.

The weighted average grant-date fair values of options granted during the six months ended June 30, 2026 and 2025 were $12.97 and $5.92, respectively.

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.

As of June 30, 2026, 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 2.3 years. For awards with performance conditions, expense is recognized if the underlying performance conditions are deemed probable of achievement.

As of June 30, 2026, 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 2.3 years.

During the six months ended June 30, 2026, 19,142 shares were issued as the result of stock option exercises and 37,157 shares were issued as a result of the vesting of non-vested stock. Additionally, 65,917 shares were issued as payment for certain employee bonuses, with 22,641 of those shares being withheld to cover taxes, resulting in a net share issuance of 43,276.

For the six months ended June 30, 2025, stock based compensation expense also includes expense related to awards 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 three and six months ended June 30, 2026 and 2025, was as follows (in thousands):