X0306 4 2021-02-25 0001755237 Cyclerion Therapeutics, Inc. CYCN 0001838503 Wright Christopher I C/O CYCLERION THERAPEUTICS, INC. 245 FIRST STREET, 18TH FLOOR CAMBRIDGE MA 02142 true Chief Medical Officer Common Stock 2021-02-25 4 S 0 2637 3.99 D 42728 D This sale was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person. This sale was made to cover tax withholding obligations in connection with the vesting and settlement of approximately 25% of the reporting person's restricted stock units granted on April 1, 2019. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.80 to $4.00, inclusive. The reporting person will provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each price within the range set forth in this footnote. /s/ Gary J. Simon, Attorney-in-Fact 2021-03-01