Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 95

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 95
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 Related to This Offering, Ownership of Our Common Stock and Our Status as a Public Company There has been no prior public market for our common stock. An active trading market for our common stock may not develop or be sustained. Prior to this offering, there has been no public market for our common stock. The initial public offering price for our common stock was determined through negotiations with the underwriters and may vary from the price of our common stock after the closing of this offering. An active trading market for our shares may never develop or, if it does develop, be sustained following this offering. If an active market for our common stock does not develop or is not sustained, the value of your shares may be impaired, and it may be difficult for you to sell shares you purchased in this offering at an attractive price or at all. An inactive market may also impair our ability to raise capital by selling shares, which in turn could materially adversely affect our business. Our operating results may fluctuate significantly, which makes our future operating results difficult to predict and could cause our operating results to fall below expectations. Our quarterly and annual operating results may fluctuate significantly, which makes it difficult for us to predict our future operating results. These fluctuations may occur due to a variety of factors, many of which are outside of our control, including:

| • |     | the timing and success or failure of clinical trials for our product candidates or competing product candidates or any 
 other change in the competitive landscape of our industry;                                                             |

| • |     | our ability to successfully recruit and retain subjects for clinical trials and any delays caused by difficulties in such 
 efforts;                                                                                                                  |

| • |     | the timing and cost of, and level of investment in, research, development, regulatory approvals and commercialization 
 activities relating to our product candidates, which may change from time to time;                                    |

| • |     | the cost of manufacturing our product candidates, which may vary depending on the quantity of production and the terms of 
 our agreements with manufacturers;                                                                                        |

| • |     | expenditures that we may incur to acquire, develop or commercialize additional product candidates; |

| • |     | the level of demand and the indication for any approved products, which may vary significantly; |

| • |     | the risk/benefit profile, cost, coverage, and reimbursement policies with respect to our product candidates, if approved, 
 and existing and potential future drugs that compete with our product candidates;                                         |

| • |     | the recruitment or departure of key personnel; |