X0607 3 2026-09-08 0 0001755237 Korsana Biosciences, Inc. KRSA 0001802528 Fairmount Funds Management LLC false 200 BARR HARBOR DRIVE, SUITE 400 WEST CONSHOHOCKEN PA 19428 true false true false 0001769651 Fairmount Healthcare Fund II L.P. false 200 BARR HARBOR DRIVE, SUITE 400 WEST CONSHOHOCKEN PA 19428 true false true false 0002124208 Fairmount Healthcare Co-Invest VI L.P. false 200 BARR HARBOR DRIVE, SUITE 400 WEST CONSHOHOCKEN PA 19428 true false true false 0001830177 Kiselak Tomas false 200 BARR HARBOR DRIVE, SUITE 400 WEST CONSHOHOCKEN PA 19428 true false true false 0001663607 Harwin Peter Evan false 200 BARR HARBOR DRIVE, SUITE 400 WEST CONSHOHOCKEN PA 19428 true false true false Common Stock 6911174 I By Fairmount Healthcare Fund II L.P. Common Stock 2192555 I By Fairmount Healthcare Co-Invest VI L.P. Series B Non-Voting Preferred Stock Common Stock 2074000 I By Fairmount Healthcare Fund II L.P. Pre-funded Warrant 0.0001 Common Stock 66436 I By Fairmount Healthcare Fund II L.P. Effective 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"). Represents the number of shares of the Issuer's common stock received by the Reporting Person in the Merger in exchange for the shares of Pre-Merger Korsana's common stock held by the Reporting Person prior to the Merger. Each share of Pre-Merger Korsana's common stock held at the Effective Time was exchanged for 0.2074 shares of the Issuer's common stock. Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. and Fairmount Healthcare Co-Invest VI L.P. Peter Harwin and Tomas Kiselak are the managers of Fairmount. Fairmount, Mr. Harwin and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein. Series B Non-Voting Convertible Preferred Stock of the Issuer, no par value per share (the "Issuer Preferred Stock"), has no expiration date and is convertible at any time and from time to time at the option of the holder thereof into a number of shares of the Issuer's common stock equal to the Conversion Ratio, initially 1,000 shares of common stock for each share of Issuer Preferred Stock, subject to adjustment. A holder may not convert Issuer Preferred Stock to the extent that, after giving effect to the conversion, the holder, together with its affiliates and any other persons whose beneficial ownership would be aggregated with the holder's for purposes of Section 13(d) or Section 16 of the Securities Exchange Act of 1934, including any group of which the holder is a member, would beneficially own shares of common stock in excess of the applicable beneficial ownership limitation, which the Reporting Person has designated as 19.99% of the shares of common stock outstanding. (Continued from footnote 4) A holder may reset that limitation to a lower percentage effective immediately, or to a higher percentage not exceeding 19.99% effective on the 61st day after written notice to the Issuer, and the limitation is automatically set at 9.99% at any time the holder's beneficial ownership is 9.00% or less of the outstanding common stock. Represents the number of shares of the Issuer's common stock underlying 2,074 shares of Issuer Preferred Stock received by the Reporting Person in the Merger in exchange for the shares of Pre-Merger Korsana's Series Seed Preferred Stock ("Korsana Series Seed Preferred Stock") held by the Reporting Person prior to the Merger. Each share of Korsana Series Seed Preferred Stock held at the Effective Time was exchanged for 0.0002074 shares of Issuer Preferred Stock. The pre-funded warrants to purchase shares of the Issuer's common stock (the "Issuer Pre-Funded Warrants") have no expiration date and are exercisable at any time and from time to time on or after the date of issuance. A holder may not exercise the Issuer Pre-Funded Warrants to the extent that, immediately prior to or following the exercise, the holder, together with its affiliates and any other persons whose beneficial ownership would be aggregated with the holder's for purposes of Section 13(d) of the Securities Exchange Act of 1934, would beneficially own shares of common stock in excess of the maximum percentage applicable to such holder, which the Reporting Person has elected to be 19.99% of the shares of common stock issued and outstanding following the exercise. (Continued from footnote 7) A holder may increase or decrease that maximum percentage by written notice to the Issuer, provided that it may not exceed 19.99% and that any increase is not effective until the 61st day after the notice is delivered to the Issuer. Represents the number of Issuer Pre-Funded Warrants received by the Reporting Person in the Merger in exchange for pre-funded warrants to purchase shares of Pre-Merger Korsana's common stock (the "Korsana Pre-Funded Warrants") held by the Reporting Person prior to the Merger. Each Korsana Pre-Funded Warrant held at the Effective Time was exchanged for 0.2074 Issuer Pre-Funded Warrants. Exhibit 24 - Power of Attorney Fairmount Funds Management LLC, Fairmount Healthcare Fund II L.P. and Fairmount Healthcare Co-Invest VI L.P. may each be deemed a director by deputization of the Issuer by virtue of the fact that Tomas Kiselak serves on the board of directors of the Issuer and is a manager of Fairmount Funds Management LLC. /s/ Peter Harwin, Managing Member of Fairmount Funds Management LLC 2026-09-10 /s/ Peter Harwin, Managing Member of Fairmount Healthcare Fund II L.P. 2026-09-10 /s/ Peter Harwin, Managing Member of Fairmount Healthcare Co-Invest VI L.P. 2026-09-10 /s/ Tomas Kiselak 2026-09-10 /s/ Peter Harwin 2026-09-10