Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 277

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 277
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 also contains provisions with respect to the elections of our board of directors and its composition. The rights under the voting agreement will terminate upon the completion of this offering.

Right of First Refusal and Co-SaleAgreement

In March 2024, we entered into a second amended and restated right of first refusal and co-sale agreement
(“right of first refusal and co-sale agreement”) with certain holders of more than 5% of our outstanding capital stock.

Our right of first refusal and co-sale agreement provides for rights of first refusal and co-sale rights in respect of sales by certain holders of our capital stock. The rights under the right of first refusal and co-sale agreement will terminate upon the
completion of this offering.

Indemnification Agreements

Our fifth amended and restated certificate of incorporation will contain provisions limiting the liability of directors and officers, and our amended and
restated bylaws will provide that we will indemnify each of our directors and officers to the fullest extent permitted under Delaware law. Our fifth amended and restated certificate of incorporation and amended and restated bylaws will also provide
our board of directors with discretion to indemnify our employees and other agents when determined appropriate by the board. In addition, we have entered into or intend to enter into an indemnification agreement with each of our directors and
executive officers, which will require us to indemnify them. For more information regarding these agreements, see the section titled “Management—Limitations on Liability and Indemnification.”

Policies and Procedures for Transactions with Related Persons

In connection with this offering, we adopted, effective upon the effectiveness of the registration statement of which this prospectus forms a part, a
written policy that our executive officers, directors, nominees for election as a director, beneficial owners of more than 5% of any series of our common stock and any members of the immediate family of any of the foregoing persons are not permitted
to enter into a related person transaction with us without the approval or ratification of our board of directors or our audit committee. Any request for us to enter into a transaction with an executive officer,

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director, nominee for election as a director, beneficial owner of more than 5% of any series of our common stock or any member of the immediate family of any of the foregoing persons, in which
the amount involved exceeds $120,000 (or, if less, 1% of the average of our total assets in a fiscal year) and such person would have a direct or indirect