SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* Fairmount Funds Management LLC (Last) (First) (Middle) 200 BARR HARBOR DRIVE, SUITE 400 (Street) WEST CONSHOHOCKEN PA 19428 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 09/11/2023	3. Issuer Name and Ticker or Trading Symbol Dianthus Therapeutics, Inc. /DE/ [ DNTH ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	1,819,579(1)(2)	I	See footnote(3)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* Fairmount Funds Management LLC (Last) (First) (Middle) 200 BARR HARBOR DRIVE, SUITE 400 (Street) WEST CONSHOHOCKEN PA 19428 (City) (State) (Zip) 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 PA 19428 (City) (State) (Zip) 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 PA 19428 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Effective as of September 11, 2023 (the "Effective Time"), a wholly-owned subsidiary of Magenta Therapeutics, Inc. ("Magenta"), merged (the "Merger") with and into Dianthus Therapeutics, Inc. ("Dianthus") resulting in, among other things, Dianthus becoming a wholly owned subsidiary of Magenta. At the Effective Time, Magenta effected a name change to "Dianthus Therapeutics, Inc." (hereinafter, the "Issuer").

2. Represents the number of shares of common stock of the Issuer received by the Reporting Persons in the Merger in exchange for the shares of Dianthus held by the Reporting Persons prior to the Merger. Each share of Dianthus common stock held at the Effective Time was exchanged for 0.2181 shares of the Issuer's common stock, which gives effect to the reverse stock split of common stock effected by the Issuer and the Merger exchange ratio.

3. Consists of (i) 58,129 shares of common stock held of record by Fairmount Healthcare Fund LP, (ii) 1,699,304 shares of common stock held of record by Fairmount Healthcare Fund II LP and (iii) 62,146 shares of common stock held of record by Fairmount SPV III, LLC. Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund LP and Fairmount Healthcare Fund II LP and is the Class A Member for Fairmount SPV III, LLC. The general partner of Fairmount is Fairmount Funds Management GP LLC ("Fairmount GP"), of which Peter Harwin and Tomas Kiselak are the managing members. Fairmount, Fairmount GP, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Remarks:

Exhibit 24 - Power of Attorney Fairmount, Fairmount Healthcare Fund LP, Fairmount Healthcare Fund II LP and Fairmount SPV III, LLC 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 Managing Member of Fairmount.

	/s/ Tomas Kiselak, Managing Member of Fairmount Funds Management LLC	09/13/2023
	/s/ Tomas Kiselak	09/13/2023
	/s/ Peter Harwin	09/13/2023
	** Signature of Reporting Person	Date
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