Company: SION
Filing Date: 2025-02-07
Form Type: S-8
Source: 0001193125-25-022767
Chunk: 3

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: S-8
Chunk 3
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 amended and restated certificate of incorporation, which will become effective immediately prior to the completion of its initial public offering, and the amended and restated bylaws, which became effective upon the effectiveness of the Registration Statement on Form S-1for its initial public offering, that limit or eliminate the personal liability of the registrant’s directors and officers to the fullest extent permitted by the DGCL, as it now exists or may in the future be amended. Consequently, the registrant’s directors and officers will not be personally liable to it or its stockholders for monetary damages or breach of fiduciary duty as directors or officers, except for liability for:

| • |     | any breach of their duty of loyalty to the registrant or its stockholders; |

| • |     | any act or omission not in good faith or that involves intentional misconduct or a knowing violation of law; |

| • |     | for the registrant’s directors, any unlawful payments related to dividends or unlawful stock purchases, 
 redemptions or other distributions;                                                                     |

| • |     | any transaction from which they derived an improper personal benefit; or |

| • |     | for the registrant’s officers, any claim brought by or in the right of the corporation. |

These limitations of liability do not alter director and officer liability under the federal securities laws and do not affect the availability of equitable remedies such as an injunction or rescission. In addition, the registrant’s amended and restated bylaws provide that:

| • |     | it will indemnify our directors, officers and, in the discretion of its board of directors, certain employees to 
 the fullest extent permitted by the DGCL, as it now exists or may in the future be amended; and                  |

| • |     | it will advance reasonable expenses, including attorneys’ fees, to its directors and, in the discretion of                                                                                       
 our board of directors, to its officers and certain employees, in connection with legal proceedings relating to their service for or on behalf of the registrant, subject to limited exceptions. |

The registrant has entered into an indemnification agreement with each of its directors and executive officers. These agreements provide that the registrant will indemnify each of its directors, its executive officers and, at times, their affiliates to the fullest extent permitted by Delaware law. The registrant will advance expenses, including attorneys’ fees (but excluding judgments, fines and settlement amounts), to each indemnified director, executive officer or affiliate in connection with any proceeding in which indemnification is