Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 260

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 260
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holders in the sale event multiplied by the number of shares of stock subject to such stock awards (payable at the time of the sale event or upon the later vesting of the
awards). In the event of the forfeiture of shares of restricted stock issued under our 2020 Plan, such shares of restricted stock shall be repurchased from the holder at a price per share equal to the original per share purchase price paid by the
recipient of such shares. Additionally, the board of directors may resolve, in its sole discretion, to subject any assumed options or payments in respect of options to any escrow, holdback, indemnification,
earn-out or similar provisions in the transaction agreements as such provisions apply to holders of our common stock. As of December 31, 2024, options to purchase up to 5,406,628 shares of common stock at
a weighted average exercise price of $4.01 per share and 110,984 shares of restricted stock were outstanding under the 2020 Plan.

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2025 Stock Option and Incentive Plan

Our 2025 Stock Option and Incentive Plan (the “2025 Plan”) was adopted by our board of directors on , adopted by
our stockholders on , and will become effective upon the date immediately preceding the date on which the registration statement of which this prospectus forms a part is declared effective by the SEC. The 2025 Plan will replace the 2020
Plan, as our board of directors has determined not to make additional awards under the 2020 Plan following the closing of this offering. However, the 2020 Plan will continue to govern outstanding equity awards granted thereunder. The 2025 Plan
allows us to make equity-based and cash-based incentive awards to our employees, non-employee directors and consultants. The following summary describes the material terms of the 2025 Plan. This summary is not
a complete description of all provisions of the 2025 Plan and is qualified in its entirety by reference to the 2025 Plan, which will be filed as an exhibit to the registration statement of which this prospectus forms a part.

We have initially reserved shares of our common stock for the issuance of awards under the 2025 Plan (the “Initial Limit”). The
2025 Plan provides that the number of shares reserved and available for issuance under the 2025 Plan will automatically be cumulatively increased on January 1, 2026 and each January 1 thereafter through January 1, 2034