Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 268

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 268
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 group, (D) measured against the market as a whole, compared to applicable market indices and/or
(E) measured on a pre-tax or post-tax basis.

Each executive officer
who is selected to participate in the Bonus Plan will have a target bonus opportunity set for each performance period. The bonus formulas will be adopted in each performance period by the board of directors or the compensation committee, as
applicable, and communicated to each executive. The corporate performance goals will be measured at the end of each performance period at such time as the board of directors or the compensation committee determines. If the corporate performance
goals and individual performance objectives are met, payments will be made as soon as practicable following the end of each performance period, but not later than 2.5 months after the end of the calendar year in which such performance period ends.
Subject to the rights contained in any agreement between the executive officer and us, an executive officer shall be required to be employed by us on the bonus payment date to be eligible to receive a bonus payment under the Bonus Plan. The Bonus
Plan also permits the board of directors or the compensation committee to approve additional bonuses to executive officers in its sole discretion.

Equity Grants to Employees (Including NEOs)

In connection with this offering, our board of directors approved grants to certain employees of the
Company (including our NEOs) of options to purchase an aggregate of 1,758,504 shares of common stock (the “Employee IPO Grants”) under the 2025 Plan, with Mr. Cloonan, Ms. Ridloff and Dr. McKee being granted options to purchase 450,252,
157,820 and 148,536 shares of our common stock, respectively. The Employee IPO Grants were contingent and subject to the effectiveness of the registration statement of which this prospectus forms a part, which must occur no later than February 15,
2025, after which date these Employee IPO Grants shall be forfeited. The Employee IPO Grants each have an exercise price per share equal to $18.00, the per share “price to the public”, expire ten years from the date of grant and vest in 48
equal monthly installments following their applicable vesting start date, in each case subject to the applicable employee’s continued service relationship through each such vesting date. Vesting of the Employee IPO Grants for our NEOs commenced
on the date that the registration statement of which this prospectus forms a part became effective. Certain of our non-employee directors also received equity grants in