Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 256

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 256
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 pursuant to Section 280G of the Code and subject the NEO to an excise
tax under Section 4999 of the Code shall be reduced, but only if such reduction would result in the NEO retaining a larger portion of such payments and benefits on an after-tax basis than if no reduction
was made and the excises taxes had been paid (also known as a 280G modified cutback).

Severance and Change in Control Plan

On December 12, 2024, our board of directors adopted the New Severance and CIC Plan, subject to the effectiveness of the registration statement of
which this prospectus forms a part. Employees with the job title of vice president and above at the time of termination (or, if applicable, “change in control” (as defined in the New Severance and CIC Plan and which does not include this
offering)) and who have executed a participation agreement (each, an “Eligible Employee”), will be eligible to participate in the New Severance and CIC Plan.

The New Severance and CIC Plan will provide that, at any time outside of the period commencing upon a change in control (as defined in the New Severance
and CIC Plan) and ending 12 months after such change in control (the “change in control period”), upon a (i) termination by us for any reason other than due to “cause,” death or “disability” (as such terms are
defined in the New Severance and CIC Plan) or (ii) for Eligible Employees with a C-level position and who reports directly to our chief executive officer and/or has a job title of Executive Vice President
or above (each, an “Executive”), resignation for “good reason” (as defined in the New Severance and CIC Plan), an Eligible Employee or Executive will be entitled to receive, subject to the execution and delivery of an effective
and irrevocable release of claims in favor of the Company and continued compliance with all applicable restrictive covenants, (A) (x) 12 months of continued base salary for our chief executive officer and (y) nine months of continued base
salary for each of our Executives (which includes the NEOs other than the chief executive officer) and for each of our senior vice presidents, (B) a prorated “target bonus” (i.e., the higher of the target annual performance bonus for
the year in which the termination occurs or the target annual