ENANTA PHARMACEUTICALS INC Stock Compensation Disclosure

11. Stock-Based Awards

The Company grants stock-based awards, including stock options, restricted stock units and other unit awards under its 2019 Equity Incentive Plan (the “2019 Plan”), which was approved by its stockholders on February 28, 2019 and amended in March 2021, March 2022, March 2023, March 2024 and March 2025 and its 2024 Inducement Stock Incentive Plan (“2024 Inducement Plan”). The Company also has outstanding stock option awards under its 2012 Equity Incentive Plan (the “2012 Plan”), but is no longer granting awards under this plan. The Company’s 2019 Plan permits the Company to sell or issue awards of common stock or restricted common stock or to grant awards of incentive stock options or nonqualified stock options for the purchase of common stock, restricted stock units, performance units, stock appreciation rights or other cash incentive awards, to employees, members of the board of directors and consultants of the Company. The number of shares of common stock that may be issued under the 2019 Plan is subject to increase by the number of shares forfeited under any options forfeited and not exercised under the 2019 Plan or any predecessor plans such as the 2012 Plan. Pursuant to the Company's 2024 Inducement Plan, the Company may grant non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards to persons who (i) were not previously an employee or director of the Company or (ii) are commencing employment with the Company following a bona fide period of

non-employment, in either case as an inducement material to the individual’s entering into employment with the Company and in accordance with the requirements of Nasdaq Stock Market Rule 5635(c)(4). As of September 30, 2025, 1,985 shares remained available for future awards under the 2019 Plan and 2024 Inducement Plan.

Options granted to employees under the 2019 Plan and the 2024 Inducement Plan generally vest over four years and to non-employee directors over one year, and expire after ten years. As required under the equity plans, the exercise price for awards granted is not to be less than the fair value of common shares on the date of grant. Restricted stock units with service-based vesting conditions generally vest over four years.

Stock Option Valuation

The fair value of each stock option award is determined on the date of grant using the Black-Scholes option-pricing model. The volatility has been determined using the Company’s traded stock price to estimate expected volatility. The Company utilized historical data to determine the expected term of stock options granted. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is zero due to the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The relevant data used to determine the value of the stock option awards are as follows, presented on a weighted average basis:

Market and Performance-Based Stock Unit Awards

The Company awards both performance share units (“PSUs”) and relative total stockholder return units (“rTSRUs”) to its executive officers.

The PSUs vest and result in issuance, or settlement, of common shares for each recipient, based upon the recipient’s continued employment with the Company through the settlement date of the award and the Company’s achievement of specified research and development milestones. The requisite service period of the PSUs is generally two years. The fair value of PSUs is based on the fair

value of the stock on the date of grant, which is determined to be the closing price of the Company's common stock. Stock-based compensation expense for PSUs is recorded in the statements of operations over the service period, commencing when it is probable that the specified research and development milestone is achieved.

The rTSRUs vest and result in the issuance of common stock based upon the recipient’s continuing employment with the Company through the settlement date of the award and the relative ranking of the total stockholder return, or TSR, of the Company’s common stock in relation to the TSR of the component companies in the Nasdaq Biotech Index over two specified periods that are two years apart, based on a comparison of average closing stock prices in specified periods noted in the award agreement. The number of market-based rTSRUs awarded represents the target number of shares of common stock that may be earned; however, the actual number of shares that may be earned ranges from 0% to 150% of the target number, depending on the award agreement and the year of the award. The Company used a Monte Carlo model to estimate the grant-date fair value of the rTSRUs. Stock-based compensation expense for rTSRUs is recorded in the statements of operations over the service period regardless of whether the market condition is achieved.

Assumptions and estimates utilized in the calculation of the fair value of the rTSRUs include the risk-free interest rate, dividend yield, expected volatility based on the historical volatility of publicly traded peer companies and the remaining performance period of the award. The table below sets forth the weighted average grant date fair value assumptions used to value the rTSRUs:

The total fair value of PSUs and rTSRUs vested during the years ended September 30, 2025, 2024, and 2023 were $396, $307, and $8,103, respectively.

Restricted Stock Units

The total fair value of restricted stock units vested during the years ended September 30, 2025, 2024, and 2023 were $1,290, $1,228, and $2,590, respectively.

Stock-Based Compensation Expense

As of September 30, 2025, the Company had an aggregate of $18,839 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 1.8 years.