Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 100

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 100
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 stock on Nasdaq. If our common stock is listed on Nasdaq, we must meet certain financial and liquidity criteria to maintain such listing. If we violate Nasdaq’s listing requirements, our common stock may be delisted. If we fail to meet any of Nasdaq’s listing standards, our common stock may be delisted. In addition, our board of directors may determine that the cost of maintaining our listing on a national securities exchange outweighs the benefits of such listing. A delisting of our common stock from Nasdaq may materially impair our stockholders’ ability to buy and sell our common stock and could have an adverse effect on the market price of, and the efficiency of the trading market for, our common stock. The delisting of our common stock could significantly impair our ability to raise capital and the value of your investment. 70

If you purchase shares of our common stock in this offering, you will suffer immediate and substantial dilution of your investment.

The initial public offering price of our common stock is substantially higher than the net tangible book value per
share of our common stock immediately after the completion of this offering. Therefore, if you purchase shares of our common stock in this offering, you will pay a price per share that substantially exceeds our pro forma as adjusted net tangible
book value per share after this offering. Based on the initial public offering price of $17.00 per share, which is the midpoint of the price range set forth on the cover of this prospectus, you will experience immediate dilution of $9.22 per share,
representing the difference between our pro forma as adjusted net tangible book value per share as of September 30, 2024 and the initial public offering price. For a further description of the dilution that you will face immediately after this
offering, see “Dilution.”

A significant portion of our total outstanding shares are restricted from immediate resale but may be sold into the market in the near future. This could cause the market price of our common stock to drop significantly, even if our business is doing well.

Sales of a substantial number of shares of our common stock in the public market could occur at any time. If our stockholders sell, or the market
perceives that our stockholders intend to sell, substantial amounts of our common stock in the public market, the market price of our common stock could decline significantly and impair our ability to raise adequate capital through the sale of
additional equity or equity-linked securities.

Upon the closing of this offering, we will have