Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 16

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 16
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 this offering | 42,520,700 shares (or 44,108,934 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 $173.0 million (or approximately $199.6 million if the underwriters exercise their option to purchase additional shares of common 
 stock in full), based on the initial public offering price of $18.00 per share, after deducting 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. |

| 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 31,932,467 shares of our common stock (which includes 119,639 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 $0.001 per share (the “Series C preferred stock” and, together with the Series Seed preferred stock,