Cyclerion holder updates 19.4% ownership stake

Peter M. Hecht has updated his beneficial ownership in Cyclerion Therapeutics, Inc. common stock.

Rhea-AI Filing Summary

Peter M. Hecht has updated his beneficial ownership in Cyclerion Therapeutics, Inc. common stock. He now beneficially owns 910,240 shares of Common Stock, representing 19.4% of the outstanding class, with sole voting and sole dispositive power over all of these shares.

The ownership change reflects the 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 into 351,037 shares of Common Stock. The 19.4% figure is based on 4,681,351 shares of Common Stock outstanding, consisting of 4,330,314 shares outstanding as of June 30, 2026 plus 351,037 shares issued on July 16, 2026 upon Hecht’s conversion election. Apart from the events described, he reports no other transactions in the company’s common stock during the past 60 days.

Filing Explained

The filing records an amendment to a major-holder ownership report; the July 16, 2026 conversion issued 351,037 common shares, increasing the share count and reducing existing holders’ percentage ownership absent offsetting changes.

Key Figures

Beneficial ownership: 910,240 shares of Common Stock Ownership percentage: 19.4% Shares outstanding basis: 4,681,351 shares of Common Stock +4 more

7 metrics

Beneficial ownership 910,240 shares of Common Stock Shares beneficially owned by Peter M. Hecht under Rule 13d-3

Ownership percentage 19.4% Percent of Cyclerion Common Stock class represented by 910,240 shares

Shares outstanding basis 4,681,351 shares of Common Stock Total shares outstanding used to calculate the 19.4% ownership

Common shares previously outstanding 4,330,314 shares of Common Stock Shares outstanding as of June 30, 2026 from the issuer’s Form S-4

New shares from conversion 351,037 shares of Common Stock Shares issued July 16, 2026 upon conversion of Preferred Stock

Preferred shares converted 351,037 shares of Preferred Stock Non-voting Series A Convertible Preferred Stock converted into Common Stock

Options forfeited 110,984 options Options to purchase 110,984 shares of Common Stock forfeited by the reporting person

Key Terms

beneficially owns, Rule 13d-3, non-voting Series A Convertible Preferred Stock, Sole Voting Power, +1 more

5 terms

beneficially owns financial

"As calculated in accordance with Rule 13d-3 , as amended, the Reporting Person beneficially owns 910,240"

Beneficially owns means a person or entity enjoys the economic benefits and control of a security even if the legal title or registration is held in another name. Think of it like having the keys and profits from a car that is registered to a friend: you use it, benefit from it, and make decisions about it even though the official paperwork lists someone else. For investors, this matters because it reveals who truly controls shares, affects voting power, potential conflicts of interest, and regulatory disclosure obligations.

Rule 13d-3 regulatory

"As calculated in accordance with Rule 13d-3 , as amended, the Reporting Person beneficially owns"

Rule 13d-3 defines who is treated as the beneficial owner of a company’s shares for U.S. securities disclosure rules — essentially anyone who has the power to vote or direct how shares are voted, or the power to buy or sell them, even if they don’t hold the certificates. For investors this matters because crossing certain ownership thresholds triggers public filing and disclosure obligations and signals potential control or influence, much like having the keys to a car implies you can drive it even if it’s registered to someone else.

non-voting Series A Convertible Preferred Stock financial

"conversion of 351,037 shares of non-voting Series A Convertible Preferred Stock of the Issuer"

Sole Voting Power financial

"Number of Shares Beneficially Owned by Each Reporting Person With: | 7 | Sole Voting Power 910,240.00"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

Sole Dispositive Power financial

"9 | Sole Dispositive Power 910,240.00 10 | Shared Dispositive Power 0.00"

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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many CYCN shares does Peter M. Hecht currently beneficially own?

Peter M. Hecht beneficially owns 910,240 shares of Cyclerion Therapeutics (CYCN) Common Stock. This figure is calculated under Rule 13d-3 and reflects his sole voting and dispositive power over the reported shares.

What percentage of Cyclerion Therapeutics (CYCN) does Peter M. Hecht own?

Peter M. Hecht’s beneficial ownership represents 19.4% of Cyclerion’s outstanding Common Stock. This percentage is based on 4,681,351 common shares outstanding, including new shares issued upon his preferred stock conversion.

What corporate actions changed Peter M. Hecht’s CYCN ownership in this amendment?

The update reflects two actions: the forfeiture of options to purchase 110,984 shares of Common Stock and the conversion of 351,037 non-voting Series A Convertible Preferred shares into 351,037 Common shares of Cyclerion Therapeutics (CYCN).

How many Cyclerion (CYCN) shares are used to calculate the 19.4% ownership?

The 19.4% beneficial ownership is calculated using 4,681,351 shares of Common Stock outstanding. This total includes 4,330,314 shares outstanding as of June 30, 2026 plus 351,037 shares issued on July 16, 2026 upon conversion.

Does Peter M. Hecht have sole voting power over his CYCN shares?

Yes. He reports sole voting power over 910,240 shares and no shared voting power in Cyclerion Therapeutics (CYCN). He also has sole dispositive power over the same number of shares, with no shared dispositive power.

Were there other recent CYCN stock transactions by Peter M. Hecht?

Apart from the option forfeiture and preferred stock conversion described in this amendment, Peter M. Hecht reports no additional transactions in Cyclerion Therapeutics (CYCN) Common Stock during the past 60 days.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 07/20/2026 - 07:51 PM Accepted by SEC EDGAR 07/20/2026 - 07:50 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 8)

CYCLERION THERAPEUTICS, INC.

(Name of Issuer)

Common Stock, no par value

(Title of Class of Securities)

23255M204

(CUSIP Number)

Peter M. Hecht
245 First Street, Riverview II, 18th Floor
Cambridge, MA, 02142
(857) 338-3348

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

07/16/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 23255M204

1

Name of reporting person

Peter M. Hecht

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

PF, OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 910,240.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 910,240.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

910,240.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

19.4 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, no par value
(b)	Name of Issuer: CYCLERION THERAPEUTICS, INC.
(c)	Address of Issuer's Principal Executive Offices: 245 First Street, 18th Floor, Cambridge, MASSACHUSETTS , 02142.
Item 1 Comment: 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.	Interest in Securities of the Issuer
(a)	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.
(b)	The information in Items 7 through 10 of the cover page is incorporated by reference into this Item 5(b).
(c)	Except as described in this Statement, the Reporting Person has not effected any transactions in the Common Stock during the past 60 days.
(d)	Not applicable.
(e)	Not applicable.

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.

Peter M. Hecht

Signature:	/s/ Peter M. Hecht
Name/Title:	Peter M. Hecht
Date:	07/20/2026