Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 356

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 356
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 (iii) the tenth anniversary of the first commercial sale of a licensed product in such country.

In addition, the Company is
required to pay AbbVie up to $130.0 million in commercial and sales-based milestone payments, mid to high single-digit royalties on the licensed products, or other payments due to Galapagos pursuant to the Galapagos License Agreement, to the
extent such payments are triggered by the Company’s use of the licensed rights owned by Galapagos under the AbbVie License Agreement. As of September 30, 2024, none of such milestones under the AbbVie License Agreement and Galapagos
License Agreement have been achieved.

9. Convertible Preferred Stock

The Company has previously issued Series Seed convertible preferred stock (the “Series Seed Preferred Stock”), Series A convertible preferred
stock (the “Series A Preferred Stock”), and Series B convertible preferred stock (the “Series B Preferred Stock”). There have been no material changes to the previously issued convertible preferred stock during the nine months
ended September 30, 2024. For additional information, see Note 10, “Convertible Preferred Stock” in the audited consolidated annual financial statements for the years ended December 31, 2023 and 2022 included elsewhere in
this prospectus.

F-40

Series C In March 2024, the Company issued and sold 18,628,970 shares of Series C convertible preferred stock, par value $0.001 per share (“Series C Preferred Stock”) at a purchase price of $9.762 per share, for gross proceeds of $181.9 million (the “Series C Financing”). The Company incurred $0.5 million of issuance costs in connection with the Series C Financing. Upon the issuance of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock (the “Preferred Stock”), the Company assessed the embedded conversion and liquidation features of the shares and determined that the Company was not required to separately account for these features. Preferred Stock consists of the following (in thousands, except share amounts):

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