SEC Form 3 · accession 0001193125-26-388123

Korsana Biosciences, Inc. · KRSA

Statement of changes in beneficial ownership, as filed. Original on EDGAR ↗

Reporting owner

Director

Period of report

Sep 8, 2026

Accepted (ET)

Sep 10, 2026 · 5:34 pm EDT

Rule 10b5-1 plan

unknown — predates the checkbox

Issuer CIK

0001755237

Table I — non-derivative securities

No Table I lines on this filing.

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	Owned after	D/I
Stock Option (Right to Buy)^F1,F2	$4.15	holding	—	—	—	—	Oct 26, 2035	Common Stock	28,805	—	D

F1Effective as of September 8, 2026 (the "Effective Time"), (i) Cariboos Merger Sub Corp., a wholly owned subsidiary of Cyclerion Therapeutics, Inc. ("Cyclerion"), merged with and into Korsana Biosciences, Inc. ("Pre-Merger Korsana"), with Pre-Merger Korsana continuing as a wholly owned subsidiary of Cyclerion and the surviving corporation of the merger (the "First Merger"), and (ii) immediately thereafter, Pre-Merger Korsana merged with and into Cariboos Merger Sub II, LLC, a second wholly owned subsidiary of Cyclerion ("Second Merger Sub"), with Second Merger Sub being the surviving entity of the merger under the name Korsana Biosciences Operating Company, LLC (the "Second Merger" and, together with the First Merger, the "Merger"). At the Effective Time, Cyclerion changed its name to "Korsana Biosciences, Inc." (hereinafter, the "Issuer").
F2Represents options to purchase shares of the Issuer's common stock received by the Reporting Person in the Merger in exchange for options of Pre-Merger Korsana held by the Reporting Person prior to the Merger. This option vested as to 25% on November 8, 2025 and vests in equal monthly installments thereafter through November 8, 2028, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

Exhibit 24 - Power of Attorney