Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 254

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 254
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 and (z) 0.75x the sum of
the base salary and the target bonus for our each of our vice presidents, (B) if the Eligible Employee elects to continue health and dental insurance coverage following such termination, an amount equal to the monthly employer contribution,
based on the premiums as of the date of termination, that we would have made to provide health insurance for the applicable executive if he or she had remained employed by us for (x) 18 months for our chief executive officer, (y) 12 months for each
of our Executives (which includes the NEOs other than the chief executive officer) and for each of our senior vice presidents and (z) nine months for each of our vice presidents, and (C) for all outstanding and unvested equity awards of
the Company that are subject to time-based vesting held by the eligible participant, full accelerated vesting of such awards; provided, that any equity awards with performance-based vesting will be treated as specified in the applicable award
agreement.

The payments and benefits provided under the New Severance and CIC Plan in connection with a change in control may not be eligible for a
federal income tax deduction by us pursuant to Section 280G of the Code. These payments and benefits may also subject an eligible participant, including the NEOs, to an excise tax under Section 4999 of the Code. If the payments or benefits
payable in connection with a change in control would be subject to the excise tax imposed under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after-tax benefit to the participant.

The New Severance and CIC Plan will fully supersede and replace all
previous severance and change in control plans, policies, arrangements, and agreements, except that if an Eligible Employee is party to a fully-executed offer letter, employment agreement, severance or change in control agreement with the Company
(each, an “Existing Employment Agreement”), e.g., the Severance and CIC Agreements described above, that, as of the New Severance and CIC Plan Effective Date, provides for more favorable terms or provisions than provided under such New
Severance and CIC Plan, then the more favorable definition, term or provision, or relevant combination thereof, will be applicable for the benefit of the eligible employee; provided, however, that there is no duplication of benefits and (i) a
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