Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 292

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 292
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,700,335 shares of common stock were issuable upon the exercise of outstanding stock options under the 2020 Plan, at a
weighted-average exercise price of $5.87 per share and 5,060,000 shares of our common stock reserved for future issuance under the 2025 Plan, which will become effective once the registration statement of which this prospectus forms a part is
declared effective, as well as any future automatic annual increases in the number of shares of common stock reserved for issuance under the 2025 Plan and any shares underlying outstanding stock awards granted under the 2020 Plan, that expire or are
repurchased, forfeited, cancelled or withheld. For additional information regarding terms of our equity incentive plans, see the section titled “Executive Compensation—Employee Benefit and Equity Compensation Plans.”

Registration Rights

Upon the completion of this offering and
subject to the lock-up agreements entered into in connection with this offering and federal securities laws, certain holders of shares of our common stock, including those shares of our common stock that will
be issued upon the conversion of our preferred stock in connection with this offering, will initially be entitled to certain rights with respect to registration of such shares under the Securities Act. These shares are referred to as registrable
securities. The holders of these registrable securities possess registration rights pursuant to the terms of our third amended and restated investors’ rights agreement and are described in additional detail below. The registration of shares of
our common stock pursuant to the exercise of the registration rights described below would enable the holders to trade these shares without restriction under the Securities Act when the applicable registration statement is declared effective. We
will pay all registration expenses, other than underwriting discounts, selling commissions and stock transfer taxes, of the shares registered pursuant to the demand, piggyback and Form S-3 registrations
described below.

Generally, in an underwritten offering, the managing underwriter, if any, has the right, subject to specified conditions and
limitations, to limit the number of shares the holders may include. The demand, piggyback and Form S-3 registration rights described below will expire no later than four years after the completion of this
offering.

Form S-1Registration Rights

Upon the completion of this offering, certain holders of our common stock, including those issuable upon the conversion of shares of our preferred stock
upon completion of this offering, will be entitled to certain demand registration rights. At any time beginning 180 days after the completion of this offering,