Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 120

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 120
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 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. Each $1.00 increase or decrease in the assumed initial public offering price of $ per share, which is the midpoint of the estimated offering range set forth on the cover of this prospectus, would increase or decrease, as applicable, the net proceeds to us from this offering by $ million, assuming the number of shares offered by us, as set forth on the cover page of this prospectus, remains the same, and after deducting underwriting discounts and commissions, placement agent fees and estimated offering expenses payable by us. Similarly, each increase or decrease of 1.0 million shares in the number of shares of common stock offered by us would increase or decrease, as applicable, the net proceeds to us from this offering by $ million, assuming the assumed initial public offering price of $ per share remains the same, and after deducting underwriting discounts and commissions, placement agent fees and estimated offering expenses payable by us. The information discussed above is illustrative only and will adjust based on the actual initial public offering price and other terms of this offering determined at pricing. The principal purposes of this offering are to create a public market for our common stock and thereby facilitate future access to the public equity markets, increase our visibility in the marketplace and obtain additional capital to support our operations. We currently intend to use the net proceeds from this offering, together with our existing cash, cash equivalents and investments in marketable securities, for the following:

| • |     | approximately $    million 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; |

| • |     | approximately $    million 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; |

| • |     | approximately $    million on other research and development activities; and |

| • |     | the remainder for working capital and other general corporate purposes, including the costs to operate our business, such 
 as our employee and facility costs and costs associated with being