Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 96

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 96
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| • |     | changes in the structure of healthcare payment systems; |

| • |     | the timing and amount of any milestone, royalty or other payments payable by us or due to us under any collaboration, 
 licensing or other similar agreement; and                                                                             |

| • |     | general market and economic conditions, including market conditions in the pharmaceutical and biotechnology sectors. |

The cumulative effects of these factors could result in large fluctuations and unpredictability in our quarterly and annual operating results. As a result, comparing our operating results on a period-to-periodbasis may not be meaningful. Investors should not rely on our past results as an indication of our future performance. 68

This variability and unpredictability could also result in our failing to meet the expectations of industry or financial analysts or investors for any period. If our revenue or operating results fall below the expectations of analysts or investors or below any forecasts we may provide to the market, or if the forecasts we provide to the market are below the expectations of analysts or investors, the price of our common stock could decline substantially. Such a stock price decline could occur even if we have met any previously publicly stated revenue or earnings guidance. The trading price of the shares of our common stock may be volatile, and purchasers of our common stock could lose all or part of their investment. The market price for our stock is likely to be highly volatile and could be subject to wide fluctuations in response to various factors, some of which we cannot control. The stock market in general and the market for biopharmaceutical companies in particular have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of particular companies. As a result of this volatility, investors may not be able to sell their common stock at or above the price paid for the shares. These factors include:

| • |     | the commencement, enrollment or results of our current or future clinical trials of our product candidates; |

| • |     | adverse results from, delays in, suspension or termination of current or future clinical trials or preclinical studies of 
 our product candidates, or any delay in advancing a clinical candidate;                                                   |

| • |     | the success of competitive products gaining approvals or announcements by current and future competitors of their product 
 development efforts;                                                                                                      |

| • |     | any delay in our regulatory filings for our product candidates or any other product candidate we may develop, and any              
 adverse development or perceived adverse development with respect to the applicable regulatory authority’s review of such filings; |

| • |