0001755237 2026-04-17 2026-04-17 0001755237 1 2026-04-17 2026-04-17 0001755237 2 2026-04-17 2026-04-17 0001755237 3 2026-04-17 2026-04-17 0001755237 4 2026-04-17 2026-04-17 iso4217:USD pure shares S-4 S-4 EX-FILING FEES 0001755237 Cyclerion Therapeutics, Inc. N/A N/A S-4 Cyclerion Therapeutics, Inc. false Equity Common Stock, no par value per share true 303313423 10110.45 0.0001381 1.40 false Equity Warrants to purchase Common Stock true 66084401 0.00 0.0001381 0.00 false Equity Options to purchase Common Stock true 12599027 0.00 0.0001381 0.00 false Equity Series B Preferred Stock, no par value per share true 22018 0.00 0.0001381 0.00 10110.45 1.40 0.00 0.00 1.40 (1) Relates to common stock, no par value per share, of Cyclerion Therapeutics, Inc., a Massachusetts corporation ("Cyclerion"), issuable to holders of common stock, $0.0001 par value per share, of Korsana Biosciences, Inc., a Delaware corporation ("Korsana"), and other Korsana security holders in the proposed merger of Cariboos Merger Sub Corp., a Delaware corporation and a direct, wholly owned subsidiary of Cyclerion, with and into Korsana, with Korsana surviving the merger, and as part of the same overall transaction, Korsana will merge with and into Cariboos Merger Sub II, LLC, a Delaware limited liability company and a wholly owned subsidiary of Cyclerion, with Cariboos Merger Sub II, LLC continuing as a wholly owned subsidiary of Cyclerion and the surviving corporation of the merger. The amount of common stock of Cyclerion to be registered includes the estimated maximum number of shares of common stock of Cyclerion that are expected to be issued (or become issuable) pursuant to the merger, without taking into account the effect of a reverse stock split of common stock of Cyclerion, assuming an estimated pre-split exchange ratio (which is subject to adjustment prior to the closing of the merger) of approximately 1.1009 shares of common stock of Cyclerion for each outstanding share of common stock of Korsana. The issuances of (i) all shares of Cyclerion Common Stock in exchange for each share of Korsana Common Stock and Korsana Series A Preferred Stock, (ii) all Cyclerion Warrants in exchange for Korsana Warrants (including Korsana Pre-Funded Warrants issued in the Korsana Pre-Closing Financing), (iii) all shares of Cyclerion Series B Preferred Stock in exchange for shares of Korsana Series Seed Preferred Stock, (iv) all options to purchase shares of Cyclerion Common Stock in exchange for options to purchase shares of Korsana Common Stock, (v) all Cyclerion RSUs in exchange for Korsana RSUs, (vi) all shares of Cyclerion Common Stock issuable upon exercise of Cyclerion Warrants issued in exchange for Korsana Warrants, (vii) all shares of Cyclerion Common Stock issuable upon conversion of Cyclerion Series B Preferred Stock issued in exchange for Korsana Series Seed Preferred Stock, (viii) all shares of Cyclerion Common Stock issuable upon exercise of options to purchase shares of Cyclerion Common Stock issued in exchange for Korsana Options, and (ix) all shares of Cyclerion Common Stock issuable upon settlement of Cyclerion RSUs issued in exchange for Korsana RSUs, are intended to be covered by this registration statement on Form S-4. In accordance with Rule 416 under the Securities Act of 1933, as amended (the "Securities Act"), this registration statement shall be deemed to cover any securities that may from time to time be offered or issued resulting from forward or reverse stock splits, stock dividends or similar transactions. (2) Estimated solely for purposes of calculating the registration fee in accordance with Rule 457(f)(2) of the Securities Act. Korsana is a private company, no market exists for its securities, and it has an accumulated capital deficit. Therefore, the proposed maximum aggregate offering price for the shares expected to be issued pursuant to the merger is one-third of the aggregate par value of the Korsana securities expected to be exchanged in the proposed merger. Consists of Cyclerion Warrants issued in the merger in exchange for Korsana Warrants, without taking into account the effect of a reverse stock split of common stock of Cyclerion, assuming an estimated pre-split exchange ratio (which is subject to adjustment prior to the closing of the merger) of approximately 1.1009 shares of common stock of Cyclerion for each outstanding share of common stock of Korsana. The registration fee with respect to the Cyclerion Warrants has been allocated to the underlying shares of Cyclerion Common Stock issuable upon exercise of such Cyclerion Warrants, as described in footnote (1). Consists of all options to purchase shares of Cyclerion Common Stock in exchange for Korsana Options, without taking into account the effect of a reverse stock split of common stock of Cyclerion, assuming an estimated pre-split exchange ratio (which is subject to adjustment prior to the closing of the merger) of approximately 1.1009 shares of common stock of Cyclerion for each outstanding share of common stock of Korsana. The registration fee with respect to the options to purchase shares of Cyclerion Common Stock has been allocated to the underlying shares of Cyclerion Common Stock issuable upon exercise of such options, as described in footnote (1). Consists of all shares of Cyclerion Series B Preferred Stock convertible into shares of Cyclerion Common Stock (at a ratio of 1,000 shares of Cyclerion Common Stock per one share of Cyclerion Series B Preferred Stock) issued in the merger in exchange for shares of Korsana Series Seed Preferred Stock, without taking into account the effect of a reverse stock split of common stock of Cyclerion, assuming an estimated pre-split exchange ratio (which is subject to adjustment prior to the closing of the merger) of approximately 1.1009 shares of common stock of Cyclerion for each outstanding share of common stock of Korsana. The registration fee with respect to the Cyclerion Series B Preferred Stock has been allocated to the underlying shares of Cyclerion Common Stock issuable upon exercise of such Cyclerion Series B Preferred Stock, as described in footnote (1).