Cyclerion Therapeutics Inc美股招股说明书(2026-07-24版)

To the Shareholders of Cyclerion Therapeutics, Inc. and Korsana Biosciences, Inc., Cyclerion Therapeutics, Inc., a Massachusetts corporation (“Cyclerion”), and Korsana Biosciences, Inc., a Delaware corporation (“Korsana”),entered into an Agreement and Plan of Merger and Reorganization on April1, 2026, which agreement was subsequently amended on April17, 2026 (asamended, the “Merger Agreement”), pursuant to which, among other matters, and subject to the satisfaction or waiver of the conditions set forth in theMerger Agreement, Cariboos Merger Sub Corp., a Delaware corporation (“First Merger Sub”), will merge with and into Korsana, with Korsanacontinuing as a wholly owned subsidiary of Cyclerion and the surviving corporation of the merger (the “First Merger”), and Korsana will merge withand into Cariboos Merger Sub II, LLC, a Delaware limited liability company (“Second Merger Sub” and together with First Merger Sub, “MergerSubs”), with Second Merger Sub being the surviving entity of the merger (the “Second Merger” and, together with the First Merger, the “Merger”). Afterthe completion of the Merger, Second Merger Sub will change its corporate name to “Korsana Biosciences Operating Company, LLC” and Cyclerionwill change its name to “Korsana Biosciences, Inc.” The term “Combined Company” when used in the accompanying proxy statement/prospectus refersto the post-Merger corporate structure including Korsana Biosciences, Inc. (f/k/a Cyclerion Therapeutics, Inc.) as the parent entity and KorsanaBiosciences Operating Company, LLC as its wholly-owned subsidiary. At the closing of the First Merger (the “First Effective Time”, and the date on which the closing of the Merger occurs, the “Closing Date”), uponthe terms and subject to the conditions set forth in the Merger Agreement: (i)each then-outstanding share of Korsana common stock, $0.0001 par valueper share, of Korsana (the “Korsana Common Stock”) and Korsana Series A Preferred Stock, $0.0001 par value per share (“Korsana Series A PreferredStock”) (including shares of Korsana Common Stock issued in the Korsana Pre-Closing Financing described below), excluding any shares to becancelled pursuant to the Merger Agreement and excluding dissenting shares, will be automatically converted solely into the right to receive a number ofshares of Cyclerion common stock, no par value per share (the “Cyclerion Common Stock”), equal to the exchange ratio as described in more detail inthe section titled “The Merger Agreement — Exchange Ratio” beginning on page169 of the accompanying proxy statement/prospectus (the “ExchangeRatio”); provided, that in the event the aggregate number of shares of Cyclerion Common Stock issuable to a holder of Korsana capital stock (whenaggregated with all of the shares of the Cyclerion Common Stock outstanding then beneficially owned by such person and its affiliates (as calculatedpursuant to Section13(d) of the Securities Exchange Act of 1934, as amended, and Rule13d-3promulgated thereunder) immediately after giving effectto the issuance of the merger consideration) would result in the issuance of shares of Cyclerion Common Stock to a holder in excess of a specifiedpercentage (initially set at a percentage up to 9.99%) of the total outstanding shares of Cyclerion Common Stock (such specified percentage, a“Beneficial Ownership Limitation”), then Cyclerion will issue to any such holder (x)shares of Cyclerion Common Stock up to such holder’s BeneficialOwnership Limitation and (y)in lieu of any shares in excess of such holder’s Beneficial Ownership Limitation, pre-funded warrants (“CyclerionPre-Funded Warrants”) to purchase a number of shares of Cyclerion Common Stock upon exercise of such Cyclerion Pre-Funded Warrants equal to suchexcess shares; (ii)each then-outstanding share of Korsana Series Seed Preferred Stock, $0.0001 par value per share (“Korsana Series Seed PreferredStock” and, together with the Korsana Series A Preferred Stock, the “Korsana Preferred Stock”), excluding any shares of Korsana Series Seed PreferredStock to be cancelled pursuant to the Merger Agreement and any dissenting shares, will be converted into the right to receive a number of shares ofCyclerion Series B non-voting convertible preferred stock, no par value per share (“Cyclerion Series B Preferred Stock”), equal to the Exchange Ratiodivided by 1,000; (iii) each then-outstanding option (a “Korsana Option”) to purchase shares of Korsana Common Stock will be converted into andbecome an option to purchase shares of Cyclerion Common Stock on the existing terms and conditions (including with respect to vesting andaccelerated vesting), Table of Contents subject to adjustment as set forth in the Merger Agreement and described in more detail in the section titled “The Merger Agreement — Treatment ofKorsana Options” beginning on page172 of the accompanying proxy statement/prospectus; (iv)each then-outstanding restricted stock unit (a “KorsanaRSU”) for shares of Korsana Common Stock