13. Stock-Based Compensation

Equity Plans

At the closing of the Merger, the Company assumed the 2019 Plan.

In connection with the Merger, AlloVir’s stockholders approved an amendment to AlloVir's 2020 Stock Option and Grant Plan (as amended, the “2020 Plan” and together with the 2019 Plan, the “Equity Plans”) to increase the number of shares reserved for future issuance under the 2020 Plan, which is subject to an annual increase on January 1 of each year from 2026 and thereafter, such that the number of shares of common stock reserved and available for issuance under the 2020 Plan is cumulatively increased by 5% of the number of shares of common stock issued and outstanding on the immediately preceding December 31, or such lesser number of shares as approved by the plan administrator; to establish the maximum aggregate number of shares of stock that may be issued in the form of incentive stock options (“ISOs”) shall not exceed 15,250,000 and to extend the term of the 2020 Plan to the tenth anniversary of the closing of the Merger.

Under the Equity Plans, the Company may grant ISOs, nonqualified stock options (“NSO”), restricted stock awards (“RSAs”), restricted stock unit awards and other stock awards to the Company’s employees, officers, non-employee directors, consultants, and advisors. Options to purchase common stock may be granted at a price not less than the fair market value as established by the board of directors in the case of both NSOs and ISOs. Stock option grants under the Equity Plans generally vest over four years. All options expire no later than ten years from the date of grant. The exercise price of ISOs granted to an employee who owns more than 10% of the voting power of all classes of stock of the Company shall be no less than 110% of the estimated fair market value of the underlying common stock on the grant date, and the contractual term is no longer than five years.

As of March 31, 2026, 1,588,703 shares of common stock had been authorized for issuance and 396,646 shares were available for future grants under the 2019 Plan and 3,414,594 shares of common stock had been authorized for issuance and 1,265,892 shares were available for future grants under the 2020 Plan.

Stock Options

The Company has granted stock options with service-based vesting conditions. Stock options typically vest over four years and have a maximum term of ten years. The Company typically grants stock options to employees and non-employees at exercise prices deemed to be equal to the fair value of the common stock at the time of grant.

The Black-Scholes option pricing model, used to estimate the fair value of stock-based awards, requires the use of the following assumptions:

Aggregate intrinsic value represents the difference between the fair value of the underlying common stock and the exercise price as of March 31, 2026. 89,873 shares were exercised during the three months ended March 31, 2026, and no shares were exercised during the three months ended March 31, 2025. The weighted-average fair value per share of options exercised during three months

ended March 31, 2026 and 2025 was $2.90 and immaterial, respectively. The aggregate intrinsic value of options exercised during the three months ended March 31, 2026 and 2025 was $0.5 million and immaterial, respectively.

The total fair value of options that vested during the three months ended March 31, 2026 and 2025 was $1.1 million and $0.5 million, respectively. No options were granted during the three months ended March 31, 2025. As of March 31, 2026 the total unrecognized stock-based compensation expense was $10.1 million, which is expected to be recognized over a weighted-average period of 3.2 years.

RSAs

In February 2022, the Company issued RSAs to its former president for 203,670 shares and a consultant for 13,577 shares, in each case, at a purchase price of $0.005 per share under the 2019 Plan. The shares related to the former president’s award vest monthly over four years starting from January 2021, while the shares related to the consultant’s award vest monthly over six years starting from January 2020. If and when an RSA vests, the Company will issue one share of common stock for each whole RSA that has vested, subject to satisfaction of the employee's tax withholding obligations. The unvested RSAs are subject to the Company’s right of repurchase upon termination of services at a repurchase price equal to their original purchase price. Shares purchased pursuant to these awards participate in dividends and voting, are legally outstanding, and are presented as outstanding shares; however, for accounting purposes, shares purchased by employees pursuant to RSAs are not considered issued until they vest according to their respective vesting schedules. Unvested awards are excluded from the calculation of net loss attributable to common stockholders as these are considered contingently issuable shares and require services to be performed as these shares continue to vest. Proceeds received from the issuance of RSAs are recorded as a share repurchase liability within accrued expenses and other current liabilities on the condensed consolidated balance sheet and reclassified to additional paid-in capital as such awards vest.

2020 Employee Stock Purchase Plan

The Company can issue common stock shares to its employees under the 2020 Employee Stock Purchase Plan (the “2020 ESPP”). The number of shares of common stock reserved and available for issuance under the 2020 ESPP is cumulatively increased on each January 1 by the lesser of (i) 53,161 shares of common stock, (ii) 1% of the number of shares of common stock issued and outstanding on the immediately preceding December 31, and (iii) such number of shares of common stock as determined by the plan administrator. On March 31, 2026, there was an aggregate of 172,487 shares reserved for future issuance under the 2020 ESPP.

The ESPP allows eligible employees to authorize payroll deductions of up to 15% of their base salary or wages up to $25,000 annually to be applied toward the purchase of shares of the Company's common stock on the last trading day of the offering period. Participating employees will purchase shares of the Company's common stock at a discount of up to 15% on the lesser of the closing price of the Company's common stock on the Nasdaq Global Market (i) on the first trading day of the offering period or (ii) the last day of any offering period. The Company utilizes the Black Scholes option pricing model to compute the fair market value of the shares and stock-based compensation expense is recognized over the offering period. Six-month offering periods commence each January 1 and July 1 during the term of the plan, with the plan administrator having the right to establish different offering periods.

The Company did not issue shares of common stock under the 2020 ESPP during the three months ended March 31, 2026.

Stock-Based Compensation Expense