Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 267

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 267
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 plan or when the employee ceases employment with us for any reason.

The ESPP may be terminated or amended by our board of directors at any time. An amendment that increases the number of shares of our common stock
authorized under the ESPP and certain other amendments require the approval of our stockholders.

Senior Executive Cash Incentive Bonus Plan

On December 12, 2024, our board of directors adopted the Senior Executive Cash Incentive Bonus Plan (the “Bonus Plan”), which became
effective on the date immediately preceding the date on which the registration statement of which this prospectus forms a part was declared effective by the SEC. The Bonus Plan provides for cash bonus payments based upon company and individual

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performance targets established by our compensation committee. The payment targets will be related to financial and operational measures or objectives with respect to our company, or the
corporate performance goals, as well as individual performance objectives. The following summary describes the material terms of the Bonus Plan. This summary is not a complete description of all provisions of the Bonus Plan and is qualified in its
entirety by reference to the Bonus Plan, which will be filed as an exhibit to the registration statement of which this prospectus forms a part.

Our
compensation committee may select corporate performance goals from among the following: research, preclinical, developmental, publication, clinical or regulatory milestones; cash flow (including, but not limited to, operating cash flow and free cash
flow); revenue; earnings before interest, taxes, depreciation and amortization; net income (loss) (either before or after interest, taxes, depreciation and/or amortization); changes in the market price of our common stock; economic value- added;
acquisitions, licenses, collaborations or strategic transactions; financing or other capital raising transactions; operating income (loss); return on capital, assets, equity or investment; stockholder returns; return on sales; total shareholder
return; gross or net profit levels; productivity; expense efficiency; margins; operating efficiency; working capital; earnings (loss) per share of our common stock; bookings, new bookings or renewals; sales or market shares; number of prescriptions
or prescribing physicians; coverage decisions; leadership development, employee retention and recruiting and other human resources matters; operating income and/or net annual recurring revenue, any of which may be (A) measured in absolute
terms, as compared to any incremental increase, (B) measured in terms of growth, (C) compared to another company or companies or the results of a peer