Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 241

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 241
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 committee and a nominating and corporate governance committee. The composition and responsibilities of each of the committees of our board of directors are described below. Members serve on these committees until their resignation or until otherwise determined by our board of directors. Each committee intends to adopt a written charter that satisfies the application rules and regulation of the SEC and the Nasdaq Listing Rules, which we will post to our website at www.sionnatx.comupon the completion of this offering. Our board of directors may establish other committees as it deems necessary or appropriate from time to time. Audit Committee Our audit committee currently consists of Laurie Stelzer, M.B.A., the chair of our audit committee, Paul Clancy, M.B.A. and H. Edward Fleming, Jr., M.D. Our board of directors has determined that each member of the audit committee is independent under Nasdaq Listing Rules and Rule 10A-3(b)(1)of the Exchange Act and can read and understand fundamental financial statements in accordance with applicable requirements. Our board of directors has also determined that each of Mr. Clancy and Ms. Stelzer is an “audit committee financial expert” within the meaning of SEC regulations. In arriving at these determinations, our board of directors has examined each audit committee member’s scope of experience and the nature of their employment in the corporate finance sector. The primary purpose of the audit committee is to discharge the responsibilities of our board of directors with respect to our corporate accounting and financial reporting processes, systems of internal control and financial statement audits, and to oversee our independent registered public accounting firm. Specific responsibilities of our audit committee include:

| • |     | helping our board of directors oversee our corporate accounting and financial reporting processes; |

| • |     | managing the selection, engagement, qualifications, independence and performance of a qualified firm to serve as the 
 independent registered public accounting firm to audit our consolidated financial statements;                        |

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| • |     | discussing the scope and results of the audit with the independent registered public accounting firm, and reviewing, with 
 management and the independent accountants, our interim and year-end operating results;                                   |

| • |     | developing procedures for employees to submit concerns anonymously about questionable accounting or audit matters; |

| • |     | approving insurance coverage for our officers and directors; |

| • |     | preparing the audit committee report to be included in our annual proxy statement, reviewing with management our                                                                                                         
 consolidated financial statements to be included in our quarterly reports to be filed with the SEC and reviewing with