8. Stock-Based Compensation

2021 Equity Incentive Plan

In January 2022, the Board of Directors and the Company’s stockholders adopted the 2021 Equity Incentive Plan (the “2021 Plan”). The 2021 Plan is administered by the Board of Directors. The 2021 Plan covers any option, restricted stock award, restricted stock unit, non-employee director or consultant award, or other stock-based award, in each case granted to an eligible participant pursuant to the 2021 Plan. Vesting periods and other restrictions for grants under the 2021 Plan are determined at the discretion of the Board of Directors. Grants to employees, officers, directors, advisors, and consultants of the Company typically vest immediately, or within periods from one to four years, with vesting based on the continued service of eligible participants, and in some cases based on the earlier of a service condition or market condition occurring. In addition, the number of shares of stock available for issuance under the 2021 Plan will be automatically increased on the first day of each quarter by 10% of the increase in the aggregate number of fully diluted shares of our common stock from the first day of the preceding quarter to the first day of the current quarter, or such lesser number as determined by our board of directors (the “Evergreen”). As of September 30, 2026, the number of shares of common stock approved for issuance under the 2021 Plan is 185,624 shares.

Under the 2021 Plan, stock options and stock appreciation rights are granted at exercise prices determined by the Board of Directors which cannot be less than 100% of the estimated fair market value of the common stock on the grant date. Incentive stock options granted to any stockholders holding 10% or more of the Company’s equity cannot be granted with an exercise price of less than 110% of the estimated fair market value of the common stock on the grant date and such options shall not be exercisable after five years from the grant date.

2026 Equity Inducement Plan

In April 2026, the Board of Directors of the Company adopted the Revelation Biosciences, Inc. 2026 Equity Inducement Plan (the “Inducement Plan”). The Inducement Plan provides for the grant of stock options, restricted stock awards, restricted stock units, and other stock-based awards. The Inducement Plan is intended to be used exclusively for grants of equity awards to new employees as an inducement to entering into employment with the Company. The maximum number of shares of common stock reserved for issuance under the Inducement Plan is 107,143 shares of common stock.

Restricted Stock Units

On January 8, 2026, there were an aggregate of 35,686 restricted stock units (“RSUs”) granted to employees and members of the Board of Directors. The RSUs were granted from shares available under the 2021 Plan and either vest quarterly over one year from the grant date or vest quarterly over two years from the grant date. The awards had a fair value of $0.9 million, based on the Company’s stock price on the date of grant.

In addition, on January 8, 2026, the Company issued an inducement grant to a new non-executive employee of 3,215 RSUs. This inducement award was granted outside of the 2021 Plan. These RSUs vest over two years in equal quarterly installments subject to the employee’s continued service. These RSUs had a fair value of $0.1 million, based on the Company’s stock price on the date of grant.

On July 15, 2026, there were an aggregate of 15,430 inducement RSUs granted to new employees under the Inducement Plan. These RSUs, which had a fair value of $0.1 million, based on the Company’s stock price on the date of grant, vest quarterly over two years from the date of grant.

Restricted Stock Awards

On February 11, 2025, there were 699 restricted stock awards (“RSAs”) granted to employees and members of the Board of Directors, which had a fair value of $0.2 million based on the Company’s stock price on the date of grant. The awards were granted from shares available under the 2021 Plan, with 688 shares fully vested on the date of grant and the remaining 11 shares vested on February 11, 2026.

On October 28, 2025, there were 35,445 RSAs granted to employees, the Board of Directors, and a consultant, which had a fair value of $1.3 million based on the Company’s stock price on the date of grant. The awards were granted from shares available under the 2021 Plan, with 6,984 shares that vest over one quarter and 28,461 shares that vest quarterly over one year.

On August 17, 2026, there were 114,333 RSAs granted to employees, the Board of Directors, and a consultant, which had a fair value of $0.9 million based on the Company’s stock price on the date of grant. The awards were granted from shares available under the 2021 Plan, and vest in four equal tranches on the 2nd or 4th anniversaries from the date of grant, depending on the tranche, or earlier if specified market capitalization thresholds are reached. The grant date fair value is recognized over the derived service period of the awards, using the accelerated attribution method. The derived service period represents the expected time to reach the market capitalization threshold, which was estimated using a Monte Carlo Simulation. The awards have a derived service period of between 1.2 and 2.9 years, depending on the tranche.

Stock-Based Compensation Expense

As of September 30, 2026, there was approximately $0.7 million of unrecognized stock-based compensation expense related to RSU grants, which is expected to be recognized over approximately 1.3 years, and approximately $0.9 million of unrecognized stock-based compensation expense related to RSA grants, which is expected to be recognized over approximately 1.65 years.