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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

X0202 SCHEDULE 13D/A 0001478485 XXXXXXXX LIVE 8 Common Stock, no par value 07/16/2026 false 0001755237 23255M204 CYCLERION THERAPEUTICS, INC. 245 First Street 18th Floor Cambridge MA 02142 Peter M. Hecht (857) 338-3348 245 First Street, Riverview II 18th Floor Cambridge MA 02142 0001478485 N Peter M. Hecht b PF OO N X1 910240.00 0.00 910240.00 0.00 910240.00 N 19.4 IN Common Stock, no par value CYCLERION THERAPEUTICS, INC. 245 First Street 18th Floor Cambridge MA 02142 This Amendment No. 8 (the "Amendment") amends and supplements the beneficial ownership statement on Schedule 13D filed with the Securities and Exchange Commission by Peter M. Hecht (the "Reporting Person") on May 14, 2021, as amended by Amendment No. 1 filed June 7, 2021, Amendment No. 2 filed November 21, 2022, Amendment No. 3 filed March 31, 2023, Amendment No. 4 filed May 12, 2023, Amendment No. 5 filed May 23, 2023, Amendment No. 6 filed December 5, 2023 and Amendment No. 7 filed March 25, 2025 (the "Original Statement"). The Original Statement, as amended by this Amendment (the "Statement"), relates to the shares of Common Stock, no par value (the "Common Stock"), of Cyclerion Therapeutics, Inc., a Massachusetts corporation (the "Issuer"). This amendment is being filed to reflect the Reporting Person's forfeiture of options to purchase 110,984 shares of Common Stock and the conversion of 351,037 shares of non-voting Series A Convertible Preferred Stock of the Issuer ("Preferred Stock") into 351,037 shares of Common Stock. Capitalized terms used but not defined in this Amendment have the meanings ascribed to them in the Original Statement. This Amendment amends the Original Statement as specifically set forth herein. Except as set forth below, all previous Items in the Original Statement remain unchanged. Percentages in this Amendment are based on 4,681,351 shares of Common Stock outstanding, which consists of (a) 4,330,314 shares outstanding as of June 30, 2026, as reported in the Issuer's Registration Statement on Form S-4 filed with the Securities and Exchange Commission on July 10, 2026 and (b) the issuance of 351,037 shares of Common Stock on July 16, 2026 upon conversion of 351,037 shares of Preferred Stock at the election of the Reporting Person. Item 5 of the Original Statement is hereby amended and restated in its entirety to read as follows: As calculated in accordance with Rule 13d-3 under the Securities Exchange Act of 1934, as amended, the Reporting Person beneficially owns 910,240 shares of Common Stock. The information in Items 7 through 10 of the cover page is incorporated by reference into this Item 5(b). Except as described in this Statement, the Reporting Person has not effected any transactions in the Common Stock during the past 60 days. Not applicable. Not applicable. Peter M. Hecht /s/ Peter M. Hecht Peter M. Hecht 07/20/2026