Charlotte McKee, Chief Medical Officer and Head of R&D at Sionna Therapeutics, Inc. (NASDAQ:SION), filed a Form 4 on September 18, 2026, disclosing two RSU grants, a post-repricing stock option acquisition, and the cancellation of a prior higher-priced option, all with a transaction date of September 17, 2026.

Key Highlights

  • Time-based RSU grant: McKee was awarded 50,000 restricted stock units vesting on June 17, 2027, subject to continued service, at a reported price of $0.0.
  • Performance-based RSU grant: A second award of 50,000 RSUs was granted, vesting upon achievement of a designated performance milestone, also subject to continued service, at a reported price of $0.0.
  • Option repricing: The board of directors approved a repricing of a 155,700-share non-qualified stock option from an exercise price of $39.21 to $7.18 per share, representing fair market value on September 17, 2026.
  • Repricing retention period: If the repriced option is exercised before the retention period ends, the exercise price reverts to the original $39.21; the retention period ends on the earliest of March 17, 2028, a Sale Event, or certain qualifying terminations.
  • Resulting beneficial ownership: Following the transactions, McKee directly holds 128,415 shares of common stock and 155,700 shares underlying the repriced non-qualified stock option.
  • Exemptions cited: The filing states the repricing transactions "were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable."

McKee RSU Awards and Option Repricing Details at Sionna Therapeutics

According to the filing, Charlotte McKee, serving as CMO and Head of R&D at Sionna Therapeutics, Inc., received two separate RSU grants on September 17, 2026. The first grant of 50,000 RSUs is time-based, with a vesting date of June 17, 2027, conditioned on McKee's continued service with the issuer. The second grant of 50,000 RSUs is performance-based, vesting upon the achievement of a designated performance milestone, also conditioned on continued service. Both grants were reported at a price of $0.0 and are held directly. Prior to these grants, McKee's directly held common stock stood at 78,415 shares, rising to 128,415 shares following both awards, as reported in the filing.

The filing also discloses that the Sionna Therapeutics board of directors approved an option repricing effective September 17, 2026. A non-qualified stock option covering 155,700 shares, previously carrying an exercise price of $39.21 per share, was repriced to $7.18 per share, which the filing describes as "the fair market value per share of the Issuer's Common Stock on September 17, 2026." The repriced option was reported as acquired at a price of $0.0, and the old option at $39.21 was simultaneously reported as disposed of. The filing notes that all other terms of the option remain unchanged, and the option expires January 1, 2036, pursuant to the Sionna Therapeutics, Inc. 2025 Stock Option and Incentive Plan.

The filing specifies a retention period tied to the repricing: if the option is exercised before the retention period concludes, the exercise price reverts to the original $39.21, unless otherwise provided by the board or compensation committee. The retention period runs from September 17, 2026, and ends on the earliest of March 17, 2028, a Sale Event as defined in the 2025 Plan, or certain qualifying terminations of service. The Form 4 was signed by Jennifer Fitzpatrick as attorney-in-fact on September 18, 2026.

What Was Disclosed

The Form 4 filed by Charlotte McKee covers two RSU grants totaling 100,000 units, a board-approved repricing of a 155,700-share stock option from $39.21 to $7.18 per share, and resulting direct beneficial ownership of 128,415 shares of common stock and 155,700 option shares.