Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 101

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 101
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40,755,996 shares of common stock outstanding
(or 42,079,525 shares if the underwriters exercise their option to purchase additional shares from us in full), based on the number of shares outstanding as of September 30, 2024 and after giving effect to the automatic conversion of our redeemable
convertible preferred stock outstanding immediately prior to this offering into 27,149,206 shares of our common stock. Of these, the shares sold in this offering will be freely tradable immediately after this offering and substantially all of the
additional shares of common stock will be available for sale in the public market beginning 180 days after the date of this prospectus following the expiration of lock-up agreements between our directors,
officers, substantially all of our stockholders and the underwriters. The foregoing agreements are subject to certain limited exceptions, and Goldman Sachs & Co. LLC and TD Securities (USA) LLC may release these stockholders from their lock-up agreements with the underwriters at any time and without notice, which would allow for earlier sales of shares in the public market. See “Underwriting.”

In addition, promptly following the effectiveness of the registration statement of which this prospectus forms a part, we intend to file one or more
registration statements on Form S-8 under the Securities Act of 1933, as amended (the “Securities Act”), registering the issuance of 9,165,923 shares of common stock subject to options or other
equity awards issued or reserved for future issuance under our equity incentive plans. Shares registered under these registration statements on Form S-8 will be available for sale in the public market subject
to vesting arrangements and exercise of options, the lock-up agreements described above and the restrictions of Rule 144 in the case of our affiliates.

Additionally, after this offering, the holders of an aggregate of 27,149,206 shares of our common stock, or their transferees, will have rights, subject
to some conditions, to require us to file one or more registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders. If we were to register the resale of
these shares, they could be freely sold in the public market. If these additional shares are sold, or if it is perceived that they will be sold, in the public market, the trading price of our common stock could decline.

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Provisions in our corporate charter documents and under Delaware law may prevent or frustrate attempts by our stock