Theriva Biologics, Inc. Stock Compensation Disclosure

7. Stock-Based Compensation

Stock Incentive Plan

On November 2, 2010, the Company’s Board of Directors and stockholders adopted the 2010 Stock Incentive Plan (“2010 Stock Plan”) for the issuance of up to 343 shares of Common Stock to be granted through incentive stock options, nonqualified stock options, stock appreciation rights, dividend equivalent rights, restricted stock, restricted stock units and other stock-based awards to officers, other employees, directors and consultants of the Company and its subsidiaries. From time to time the number of shares authorized for awards was increased such that 16,000 shares were authorized as of September 5, 2019. The exercise price of stock options under the 2010 Stock Plan was determined by the compensation committee of the Board of Directors and could be equal to or greater than the fair market value of the Company’s Common Stock on the date the option was granted. Options become exercisable over various periods from the date of grant and expire between five and ten years after the grant date. As of December 31, 2025, there were 5,893 options issued and outstanding under the 2010 Stock Plan. There are no shares available to be issued under this plan. Only options were issued under the plan.

On September 17, 2020, the Company’s stockholders approved and adopted the 2020 Stock Incentive Plan (“2020 Stock Plan”) for the issuance of up to 16,000 shares of Common Stock to be granted through incentive stock options, nonqualified stock options, stock appreciation rights, dividend equivalent rights, restricted stock, restricted stock units and other stock-based awards to officers, other employees, directors and consultants of the Company and its subsidiaries. The number of shares authorized for awards under the 2020 Stock Plan was increased such that 4,500,000 shares were authorized as of December 31, 2025. As of December 31, 2025, there were 1,108,535 options issued and outstanding under the 2020 Stock Plan. Only options have been issued under the plan.

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7. Stock-Based Compensation – (continued)

In the event of an employee’s termination, the Company will cease to recognize compensation expense for that employee. Stock option forfeitures are recognized as incurred. The fair value of the stock-based payment is recognized over the stated vesting period.

The Company has applied fair value accounting for all stock-based payment awards since inception. The fair value of each option granted is estimated on the date of grant using the Black-Scholes option pricing model. The assumptions used for the years ended December 31, 2025 and 2024 are as follows:

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Expected dividends —The Company has never declared or paid dividends on its Common Stock and has no plans to do so in the foreseeable future.

Expected volatility—Volatility is a measure of the amount by which a financial variable such as a share price has fluctuated (historical volatility) or is expected to fluctuate (expected volatility) during a period. The expected volatility assumption is derived from the historical volatility of the Company’s Common Stock over a period approximately equal to the expected term.

Risk-free interest rate—The assumed risk-free rate used is a zero coupon U.S. Treasury security with a maturity that approximates the expected term of the option.

Expected life of the option—The period of time that the options granted are expected to remain unexercised. Options granted during the years ended 2025 and 2024 have a maximum term of seven years. The Company estimates the expected life of the option term based on the weighted average life between the dates that options become fully vested and the maximum life of options granted.

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7. Stock-Based Compensation – (continued)

The Company records stock-based compensation based upon the stated vesting provisions in the related agreements. The vesting provisions for these agreements have various terms as follows:

During the years ended December 31, 2025 and 2024, the Company granted 951,500 and 420, respectively, options to purchase shares of Common Stock to employees and directors having an approximate fair value of $1.0 million and $1,500, respectively, based upon the Black-Scholes option pricing model, respectively.

Stock-based compensation expense included in general and administrative expenses and research and development expenses relating to stock options issued to employees for the years ended December 31, 2025 and 2024 was $517,000 and $462,000, respectively. Stock-based compensation expense included in general and administrative expenses and research and development expenses relating to stock options issued to consultants for the years ended December 31, 2025 and 2024 was $137,000 and $209,000, respectively.

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7. Stock-Based Compensation – (continued)

A summary of stock option activity for the years ended December 31, 2025 and 2024 is as follows:

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The options outstanding and exercisable at December 31, 2025 are as follows:

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7. Stock-Based Compensation – (continued)

As of December 31, 2025, total unrecognized stock-based compensation expense related to stock options was $694,000 which is expected to be expensed through January 2028.

The FASB’s guidance for stock-based payments requires cash flows from excess tax benefits to be classified as a part of cash flows from operating activities. Excess tax benefits are realized tax benefits from tax deductions for exercised options in excess of the deferred tax asset attributable to stock compensation costs for such options. The Company did not record any excess tax benefits in 2025 or 2024. Cash received from option exercises under the Company’s stock-based compensation plans for the years ended December 31, 2025 and 2024 was zero.