Cyclerion grants 48K-share option to Fairmount funds

An investment group associated with a director received a 48,445-share stock option grant in Cyclerion vesting monthly through 2029.

Rhea-AI Filing Summary

Cyclerion Therapeutics, Inc. (CYCN) reported that investment entities associated with Fairmount Funds Management LLC received a compensatory grant of stock options indirectly held through Tomas Kiselak. On September 9, 2026, an option for 48,445 shares of common stock was awarded at an exercise price of $26.20 per share, with no cash paid for the grant. The option vests in equal monthly installments through September 9, 2029, and expires on September 9, 2036. The filing states that Kiselak holds the option for one or more Fairmount-managed investment vehicles, and Fairmount, Peter Harwin, and Kiselak each disclaim beneficial ownership except to the extent of any pecuniary interest.

Insider Trade Summary

Grant/Award: 48,445 shares

Grant/Award 1 txn

Insider Fairmount Funds Management LLC, Fairmount Healthcare Fund II L.P., Fairmount Healthcare Co-Invest VI L.P., Kiselak Tomas, Harwin Peter Evan

Role Director, 10% Owner | Director, 10% Owner | Director, 10% Owner | Director, 10% Owner | Director, 10% Owner

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy) F1, F2	48,445	$0.00	$0.00

Holdings After Transaction: Stock Option (Right to Buy) — 48,445 contracts (Indirect, By: Tomas Kiselak)

Footnotes (2)

1. F1. This option represents a right to purchase 48,445 shares of the Issuer's common stock. This option will vest in equal monthly installments through September 9, 2029, subject to the Reporting Person's continued service to the Issuer on each such vesting date.
2. F2. Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. ("Fund II") and Fairmount Healthcare Co-Invest VI L.P. ("Co-Invest"). Peter Harwin and Tomas Kiselak are the managers of Fairmount. Under Mr. Kiselak's arrangement with Fairmount, Mr. Kiselak holds the option for one or more investment vehicles managed by Fairmount (each, a "Fairmount Fund"). Mr. Kiselak is obligated to turn over to Fairmount any net cash or stock received from the option for the benefit of such Fairmount Fund. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Key Figures

Option shares granted: 48,445 shares Exercise price: $26.20 per share Shares after transaction: 48,445 derivative shares +3 more

6 metrics

Option shares granted 48,445 shares Stock option grant reported for September 9, 2026

Exercise price $26.20 per share Conversion or exercise price of the stock option

Shares after transaction 48,445 derivative shares Total option shares indirectly held following the grant

Grant price paid $0.00 per option share Cost to acquire the option on grant date

Vesting end date September 9, 2029 Monthly vesting continues through this date, subject to continued service

Option expiration date September 9, 2036 Expiration date of the stock option

Key Terms

Stock Option (Right to Buy), vest in equal monthly installments, beneficial ownership, pecuniary interest, +1 more

5 terms

Stock Option (Right to Buy) financial

"security titled "Stock Option (Right to Buy)" linked to common stock"

vest in equal monthly installments financial

"option will vest in equal monthly installments through September 9, 2029"

beneficial ownership financial

"Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

pecuniary interest financial

"disclaim beneficial ownership of any reported securities, except to the extent of their pecuniary interest"

indirect ownership financial

"ownership nature described as indirect, by: Tomas Kiselak for Fairmount funds"

FAQ

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

What insider transaction in CYCN is disclosed in this Form 4?

The filing reports a grant of stock options for 48,445 shares of Cyclerion common stock on September 9, 2026, indirectly held through Tomas Kiselak for investment vehicles managed by Fairmount Funds Management LLC.

What is the exercise price and term of the new CYCN stock options?

The granted option covers 48,445 shares at an exercise price of $26.20 per share. It expires on September 9, 2036, giving the holder the right to buy Cyclerion common stock at that price before expiration.

How do the CYCN options granted on September 9, 2026 vest?

The option for 48,445 shares vests in equal monthly installments through September 9, 2029, and each vesting installment is subject to the reporting person’s continued service to Cyclerion on the applicable vesting date.

Who effectively holds the CYCN stock options reported in this Form 4?

The option is held by Tomas Kiselak for one or more investment vehicles managed by Fairmount Funds Management LLC. Kiselak must turn over any net cash or stock from the option to Fairmount for the benefit of the relevant Fairmount fund.

Do the reporting persons claim full beneficial ownership of the CYCN options?

No. Fairmount Funds Management LLC, Peter Harwin, and Tomas Kiselak each disclaim beneficial ownership of the reported securities, except to the extent of their pecuniary interest in those securities.

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

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Available on EDGAR 09/10/2026 - 05:45 PM Accepted by SEC EDGAR 09/10/2026 - 05:44 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Fairmount Funds Management LLC

(Last) (First) (Middle)

200 BARR HARBOR DRIVE, SUITE 400

(Street)

WEST CONSHOHOCKEN PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Korsana Biosciences, Inc. [ KRSA ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/09/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	$26.2	09/09/2026		A		48,445		(1)	09/09/2036	Common Stock	48,445	$0	48,445	I(2)	By: Tomas Kiselak

1. Name and Address of Reporting Person^*

Fairmount Funds Management LLC

(Last) (First) (Middle)

200 BARR HARBOR DRIVE, SUITE 400

(Street)

WEST CONSHOHOCKEN PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Fairmount Healthcare Fund II L.P.

(Last) (First) (Middle)

200 BARR HARBOR DRIVE, SUITE 400

(Street)

WEST CONSHOHOCKEN PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Fairmount Healthcare Co-Invest VI L.P.

(Last) (First) (Middle)

200 BARR HARBOR DRIVE, SUITE 400

(Street)

WEST CONSHOHOCKEN PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Kiselak Tomas

(Last) (First) (Middle)

200 BARR HARBOR DRIVE, SUITE 400

(Street)

WEST CONSHOHOCKEN PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Harwin Peter Evan

(Last) (First) (Middle)

200 BARR HARBOR DRIVE, SUITE 400

(Street)

WEST CONSHOHOCKEN PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. This option represents a right to purchase 48,445 shares of the Issuer's common stock. This option will vest in equal monthly installments through September 9, 2029, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

2. Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. ("Fund II") and Fairmount Healthcare Co-Invest VI L.P. ("Co-Invest"). Peter Harwin and Tomas Kiselak are the managers of Fairmount. Under Mr. Kiselak's arrangement with Fairmount, Mr. Kiselak holds the option for one or more investment vehicles managed by Fairmount (each, a "Fairmount Fund"). Mr. Kiselak is obligated to turn over to Fairmount any net cash or stock received from the option for the benefit of such Fairmount Fund. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Remarks:

Fairmount, Fund II and Co-Invest may each be deemed a director by deputization of the Issuer by virtue of the fact that Tomas Kiselak serves on the board of directors of the Issuer and is a manager of Fairmount.

	/s/ Peter Harwin, Managing Member of Fairmount Funds Management LLC	09/10/2026
	/s/ Peter Harwin, Managing Member of Fairmount Healthcare Fund II L.P.	09/10/2026
	/s/ Peter Harwin, Managing Member of Fairmount Healthcare Co-Invest VI L.P.	09/10/2026
	/s/ Tomas Kiselak	09/10/2026
	/s/ Peter Harwin	09/10/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)