Company: SION
Filing Date: 2025-04-29
Form Type: DEF 14A
Source: 0001193125-25-101830
Chunk: 33

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-04-29
Form: DEF 14A
Chunk 33
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2024, computed in accordance with Financial Accounting Standards Board Accounting Standards Codification Topic 718 (“FASB ASC Topic 718”). A discussion of the assumptions used in determining grant date fair value may be found in the “Management’s Discussion and Analysis of Financial Condition and Results of Operations” section of our 2024 Annual Report under heading “Critical Accounting Estimates.” Such grant date fair values do not take into account any estimated forfeitures related to service-based vesting. The amounts reported in this column reflect the accounting cost for the stock option award and do not correspond to the actual economic value that may be received by Mr. Clancy and Ms. Stelzer upon the vesting of the awards or any sale of the underlying securities. |

| (3) | As of December 31, 2024, Drs. Booth, Fleming, Iancovici, Resnick and Thompson did not hold any outstanding options or any unvested stock awards. |

| (4) | As of December 31, 2024, Mr. Clancy held outstanding options to purchase an aggregate of 185,485 shares of our common stock, and did not hold any other unvested stock awards. |

| (5) | As of December 31, 2024, Mr. Rosenberg did not hold any outstanding options to purchase shares of our common stock, and did not hold any other unvested stock awards. Mr. Rosenberg resigned from the board of directors as of June 13, 2024. |

| (6) | As of December 31, 2024, Ms. Stelzer held outstanding options to purchase an aggregate of 44,480 shares of our common stock, and did not hold any other unvested stock awards. Ms. Stelzer was appointed to the board of directors, effective November 12, 2024. |

Effective January 6, 2025, each of Marcella Ruddy and Joanne Viney joined our board of directors. Director Engagement Letters We previously entered into director engagement letters with each of Paul Clancy, Laurie Stelzer, Marcella Ruddy and Joanne Viney. These engagement letters were terminated on February 6, 2025, in connection with our initial public offering, and director compensation shall be governed by the non-employeedirector compensation policy thereafter, as further detailed below. 23

Paul Clancy, M.B.A.

In March 2022, we entered into a board of directors agreement with