Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 255

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 255
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 for any performance-based stock options and stock awards, treatment as set forth in the applicable
award agreement and (C) 12 months’ extension of any post- termination exercise period for options held by the NEO prior to the New Severance and CIC Plan Effective Date. The amounts payable under (i) through (iii) shall be paid out in
substantially equal installments in accordance with our payroll practice over 12 months commencing within 60 days after the date of termination.

Upon a terminating event within the change in control period, the Severance and CIC Agreements provide that the NEO will be entitled to receive, in lieu
of above, subject to the execution and delivery of an effective and irrevocable release of claims in favor of us and continued compliance with all applicable restrictive covenants, (i) 100% of the NEO’s annual base salary; (ii) earned but

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unpaid bonus for the year prior to the year of termination; (iii) 100% of the NEO’s annual target bonus for the year of termination; (iv) subject to the NEO’s timely COBRA
election, full health premium payments until the earlier of (A) the 18-month anniversary of the date of termination and (B) the date that the NEO obtains coverage under another health and dental
insurance plan; and (v) with respect to any equity grants held by the NEO, (A) full acceleration of vesting of any time-based stock option and stock awards; provided, that such options and awards were held by the NEO prior to the New
Severance and CIC Plan Effective Date, (B) for any performance-based stock options and stock awards, treatment as set forth in the applicable award agreement, and (C) 12 months’ extension of any post-termination exercise period for options held
by the NEO prior to the New Severance and CIC Plan Effective Date. The amounts payable under (i) through (iii) shall be paid out in a lump sum within 60 days after the date of termination. As of the New Severance and CIC Plan Effective Date,
prongs (i) and (iii) for Mr. Cloonan will be superseded by the New Severance and CIC Plan.

Pursuant to each of the Severance and CIC
Agreements, any payments and benefits provided to an NEO in connection with a change in control that would otherwise not be eligible for a federal income tax deduction for us