Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 128

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 128
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 expenses payable by us. Each increase of 1.0 million shares in the number of shares of common stock offered by us would increase our pro forma as adjusted net tangible book value per share after this offering by $0.19 per share and decrease the dilution to investors participating in this offering by $0.19 per share, assuming that the assumed initial public offering price remains the same, and after deducting estimated underwriting discounts, placement agent fee and commissions and estimated offering expenses payable by us. Similarly, each decrease of 1.0 million shares in the number of shares of common stock offered by us would decrease our pro forma as adjusted net tangible book value per share after this offering by $0.20 per share and increase the dilution to investors participating in this offering by $0.20 per share, assuming that the assumed initial public offering price remains the same, and after deducting estimated underwriting discounts, placement agent fee and commissions and estimated offering expenses payable by us. If the underwriters exercise their option to purchase up to 1,323,529 additional shares of our common stock in full, the pro forma as adjusted net tangible book value after the offering would be $8.03 per share, the increase in pro forma as adjusted net tangible book value per share to existing stockholders would be $0.25 per share and the dilution per share to new investors would be $0.25 per share, in each case assuming an initial public offering price of $17.00 per share, which is the midpoint of the estimated offering range set forth on the cover page of this prospectus. The following table summarizes on the pro forma as adjusted basis described above, as of September 30, 2024, the differences between the number of shares of common stock purchased from us by our existing stockholders and common stock by new investors purchasing shares in this offering, the total consideration paid to us in cash and the average price per share paid by existing stockholders for shares of common stock issued prior to this offering and the price to be paid by new investors for shares of common stock in this offering. The calculation below is based on the assumed initial public offering price of $17.00 per share, which is the midpoint of the estimated offering price range set forth on the cover page of this prospectus, before deducting underwriting discounts, placement agent fees and commissions and estimated offering expenses payable by us.

|                                                  |     | Shares Purchased                                         
 Number                                                   
 (in thousands, except share, per share and percent