SEC Form 4 · accession 0002046433-26-000005
Sionna Therapeutics, Inc. · SION
Statement of changes in beneficial ownership, as filed. Original on EDGAR ↗
Reporting owner
Charlotte McKee
Officer — CMO and Head of R&D
Period of report
Sep 17, 2026
Accepted (ET)
Sep 18, 2026 · 4:58 pm EDT
Rule 10b5-1 plan
box not checked
Issuer CIK
0002036042
Table I — non-derivative securities
| Security | Date | Code | Shares | Price | A/D | Owned after | D/I | Nature of ownership |
|---|---|---|---|---|---|---|---|---|
| Common Stock | Sep 17, 2026 | A | 50,000 | $0.00 | A | 78,415 | D | |
| Common Stock | Sep 17, 2026 | A | 50,000 | $0.00 | A | 128,415 | D |
Table II — derivative securities
| Security | Conv. / exercise price | Date | Code | Shares | A/D | Exercisable | Expires | Underlying | Underlying shares | Owned after | D/I |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Non-Qualified Stock Option (right to buy)F4,F3,F5 | $7.18 | Sep 17, 2026 | A | 155,700 | A | — | Jan 1, 2036 | Common Stock | 155,700 | 155,700 | D |
| Non-Qualified Stock Option (right to buy)F4,F5 | $39.21 | Sep 17, 2026 | D | 155,700 | D | — | Jan 1, 2036 | Common Stock | 155,700 | 0 | D |
Explanation of responses
- F1Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of Common Stock of the Issuer. The RSUs will vest on June 17, 2027, subject to the Reporting Person's continued service with the Issuer as of the vesting date.
- F2Represents a grant of RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer. The RSUs will vest upon the achievement of a designated performance milestone, subject to the Reporting Person's continued service with the Issuer as of the vesting date.
- F3The exercise price of the option is $7.18 per share, representing the fair market value per share of the Issuer's Common Stock on September 17, 2026 (the "Repricing Date"). Unless otherwise provided by the Issuer's board of directors or its compensation committee, if the option is exercised before the applicable retention period ends, the exercise price will revert to its original exercise price. The retention period begins on the Repricing Date and ends on the earliest of (i) the 18-month anniversary of the Repricing Date (March 17, 2028), (ii) a Sale Event (as defined in the Sionna Therapeutics, Inc. 2025 Stock Option and Incentive Plan (the "2025 Plan")) or (iii) certain qualifying terminations of service.
- F4Effective on the Repricing Date, the Issuer's board of directors approved an option repricing. All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.
- F5This stock option award was issued pursuant to the 2025 Plan, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on the applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.