Cyclerion Therapeutics Inc ownership filing shows FMR LLC beneficially owns 649,547 shares of common stock, representing 15.0% of the class as of 04/30/2026. The filing states portions of that interest are held on behalf of Fidelity Growth Company Commingled Pool (287,563 shares, 6.6%) and Fidelity Growth Company Fund (218,257 shares, 5.0%). The schedule is a passive institutional disclosure listing voting and dispositive powers and refers to an attached exhibit and a power of attorney.
Positive
None.
Negative
None.
Insights
FMR LLC reports a 15.0% passive stake in Cyclerion as of 04/30/2026.
FMR LLC is disclosed as beneficial owner of 649,547 shares with sole dispositive power. The filing identifies two Fidelity pools accounting for 287,563 and 218,257 shares respectively, each meeting or exceeding 5% thresholds.
Cash‑flow treatment is not stated; ownership is presented as institutional holdings with an attached Exhibit 99 and a referenced power of attorney. Subsequent SEC filings would reflect any changes to these positions.
Key Figures
FMR LLC beneficial ownership:649,547 sharesFMR LLC ownership percent:15.0%Fidelity Growth Company Commingled Pool:287,563 shares+1 more
4 metrics
FMR LLC beneficial ownership649,547 sharesAmount beneficially owned as of 04/30/2026
FMR LLC ownership percent15.0%Percent of class as of 04/30/2026
Fidelity Growth Company Commingled Pool287,563 sharesListed interest representing 6.6% as of 04/30/2026
Fidelity Growth Company Fund218,257 sharesListed interest representing 5.0% as of 04/30/2026
Key Terms
Schedule 13G, Beneficially owned, Sole dispositive power, Power of Attorney
4 terms
Schedule 13Gregulatory
"Item 1. (a) Name of issuer: CYCLERION THERAPEUTICS INC"
A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.
Beneficially ownedfinancial
"Item 4. Amount beneficially owned: 649547.00"
Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.
Sole dispositive powerregulatory
"Item 4. (iii) Sole power to dispose or to direct the disposition of: 649547.00"
Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.
Power of Attorneylegal
"Signed: Richard Bourgelas Duly authorized under Power of Attorney effective as of April 13, 2026"
A power of attorney is a legal document that allows one person to make decisions and act on behalf of another person, often in financial or legal matters. It’s like giving someone a trusted helper or agent the authority to handle important tasks if you are unable to do so yourself. This matters to investors because it can impact how their assets are managed or transferred if they become unable to oversee their affairs.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
CYCLERION THERAPEUTICS INC
(Name of Issuer)
COMMON STOCK
(Title of Class of Securities)
23255M204
(CUSIP Number)
04/30/2026
(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)
schemaVersion:
SCHEDULE 13G
CUSIP Number(s):
23255M204
1
Names of Reporting Persons
FMR LLC
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
649,547.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
649,547.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
649,547.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
15.0 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
CUSIP Number(s):
23255M204
1
Names of Reporting Persons
Abigail P. Johnson
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
649,547.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
649,547.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
15.0 %
12
Type of Reporting Person (See Instructions)
IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
CYCLERION THERAPEUTICS INC
(b)
Address of issuer's principal executive offices:
301 Binney Street,Cambridge,MA,USA,02142
Item 2.
(a)
Name of person filing:
FMR LLC
(b)
Address or principal business office or, if none, residence:
245 Summer Street, Boston, Massachusetts 02210
(c)
Citizenship:
Not applicable
(d)
Title of class of securities:
COMMON STOCK
(e)
CUSIP Number(s):
23255M204
Item 3.
If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)
Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)
An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)
An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)
A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)
A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)
A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
649547.00
(b)
Percent of class:
15.0 %
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
Please see the responses to Items 5 and 6 on the cover page.
(ii) Shared power to vote or to direct the vote:
0.00
(iii) Sole power to dispose or to direct the disposition of:
649547.00
(iv) Shared power to dispose or to direct the disposition of:
0.00
Item 5.
Ownership of 5 Percent or Less of a Class.
Not Applicable
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
One or more other persons are known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the COMMON STOCK of CYCLERION THERAPEUTICS INC. The interest of Fidelity Growth Company Commingled Pool, in the COMMON STOCK of CYCLERION THERAPEUTICS INC, amounted to 287563.00 shares or 6.6% of the total outstanding COMMON STOCK at 04/30/2026. The interest of Fidelity Growth Company Fund, in the COMMON STOCK of CYCLERION THERAPEUTICS INC, amounted to 218257.00 shares or 5.0% of the total outstanding COMMON STOCK at 04/30/2026.
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
See attached Exhibit 99.
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.
SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
FMR LLC
Signature:
Richard Bourgelas
Name/Title:
Duly authorized under Power of Attorney effective as of April 13, 2026, by and on behalf of FMR LLC and its direct and indirect subsidiaries*
Date:
05/06/2026
Abigail P. Johnson
Signature:
Richard Bourgelas
Name/Title:
Duly authorized under Power of Attorney effective as of April 13, 2026, by and on behalf of Abigail P. Johnson*
Date:
05/06/2026
Comments accompanying signature: *This power of attorney is incorporated herein by reference to Exhibit 24 to the Schedule 13G filed by FMR LLC on April 29,2026, accession number: 0000315066-26-000738.
What stake does FMR LLC hold in Cyclerion Therapeutics (CYCN)?
FMR LLC beneficially owns 649,547 shares, equal to 15.0% of Cyclerion's common stock as of 04/30/2026. This figure is reported on the Schedule 13G filing signed on 05/06/2026 and shows sole dispositive power.
Which Fidelity funds are reported as holding more than 5% of CYCN?
The filing lists two Fidelity interests: Fidelity Growth Company Commingled Pool with 287,563 shares (6.6%) and Fidelity Growth Company Fund with 218,257 shares (5.0%), both referenced as of 04/30/2026.
Does the Schedule 13G indicate voting power for FMR LLC over CYCN shares?
Yes; the cover responses show FMR LLC reports sole dispositive power over 649,547 shares and lists sole voting power for the same amount. Shared voting and dispositive powers are reported as 0 in the filing.
Was the FMR LLC filing executed under a power of attorney?
Yes; signatures state the filing was executed by Richard Bourgelas under a power of attorney effective April 13, 2026, incorporated by reference to an exhibit noted in the filing. The Schedule references Exhibit 99 for related agreements.
