Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 16

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 16
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 shares (or    shares if the underwriters exercise their option to purchase additional shares of common stock in full). |

| Use of proceeds | We estimate that the net proceeds from the sale of our common stock in this offering will be approximately $  million (or approximately $  million if the underwriters exercise their option to purchase additional shares of                 
 common stock in full), based on the assumed initial public offering price of $  per share, which is the midpoint of the estimated offering price range set forth on the cover page of this prospectus, after deducting estimated underwriting 
 discounts and commissions and estimated offering expenses payable by us.                                                                                                                                                                      |

| We currently intend to use the net proceeds from this offering, together with our existing cash, cash equivalents and investments in marketable securities, (i) to complete our ongoing Phase 1 clinical trials,                                   
 our planned Phase 2a proof of concept trial, and certain preclinical and other early clinical activities to enable potential advancement of our selected dual combination of an NBD1 stabilizer and complementary modulator; (ii) to initiate and  
 progress a dual combination Phase 2b dose-ranging clinical trial of our selected NBD1 stabilizer and complementary modulator and to continue manufacturing scale-up to supply drug product for late stage clinical trials; (iii) on other research 
 and development activities; and (iv) to use the remainder for working capital and other general corporate purposes. See the section titled “Use of Proceeds” for additional information.                                                           |

| Risk factors | See the section titled “Risk Factors” for a discussion of factors you should carefully consider before deciding whether to invest in our common stock. |

| Proposed trading symbol on The Nasdaq Global Market | “SION” |

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The number of shares of our common stock that will be outstanding after this offering is based on 46,656,571 shares of our common stock (which includes 174,807 shares of restricted common stock) outstanding as of September 30, 2024 after giving effect to the automatic conversion of all outstanding shares of our Series Seed convertible preferred stock, par value $0.001 per share (the “Series Seed preferred stock”), Series A convertible preferred stock, par value $0.001 per share (the “Series A preferred stock”), Series B convertible preferred stock, par value $0.001 per share (the “Series B preferred stock”) and Series C convertible preferred stock, par value $0