Sec Form 4 Filing - Meng Lei @ Dianthus Therapeutics, Inc. /DE/ - 2024-01-22

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

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Meng Lei 2. Issuer Name and Ticker or Trading Symbol Dianthus Therapeutics, Inc. /DE/ [ DNTH] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O DIANTHUS THERAPEUTICS, INC., 7 TIMES SQUARE, 43RD FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 01/22/2024 (Street) NEW YORK, NY10036 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 Common Stock 01/22/2024 A 1,500,000 ( 1 ) A $ 12 2,717,554 I See footnote ( 2 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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 Pre-Funded Warrants (Right to Buy) $ 0.001 01/22/2024 A 1,833,333 ( 3 ) ( 4 ) ( 4 ) Common Stock 1,833,333 $ 11.999 1,833,333 I See footnote ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Meng Lei C/O DIANTHUS THERAPEUTICS, INC. 7 TIMES SQUARE, 43RD FLOOR NEW YORK, NY10036 X Avidity Partners Management LP 2828 N HARWOOD STREET, SUITE 1220 DALLAS, TX75201 X Gregory Michael David C/O AVIDITY PARTNERS MANAGEMENT LP 2828 N HARWOOD STREET, SUITE 1220 DALLAS, TX75201 X Avidity Partners Management (GP) LLC 2828 N HARWOOD STREET, SUITE 1220 DALLAS, TX75201 X Witzke David Roy C/O AVIDITY PARTNERS MANAGEMENT LP 2828 N HARWOOD STREET, SUITE 1220 DALLAS, TX75201 X Signatures LEI MENG, /s/ Adam Veness, as attorney-in-fact for Lei Meng 01/24/2024 Signature of Reporting Person Date AVIDITY PARTNERS MANAGEMENT LP, By: Avidity Partners Management (GP) LLC, its general partner, /s/ David Witzke Managing Member, /s/ Michael Gregory Managing Member 01/24/2024 Signature of Reporting Person Date AVIDITY PARTNERS MANAGEMENT (GP) LLC, /s/ David Witzke Managing Member, /s/ Michael Gregory Managing Member 01/24/2024 Signature of Reporting Person Date DAVID WITZKE, /s/ David Witzke 01/24/2024 Signature of Reporting Person Date MICHAEL GREGORY, /s/ Michael Gregory 01/24/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Consists of an aggregate of 1,500,000 shares of common stock purchased by clients of Avidity Partners Management LP from the Issuer in a private placement, which transaction is exempt from Section 16(b) in accordance with Rule 16b-3(d)(1) promulgated under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). ( 2 )The reported securities are held by clients of Avidity Partners Management LP and may be deemed to beneficially owned by (i) Avidity Partners Management LP, (ii) Avidity Partners Management (GP) LLC, the general partner of Avidity Partners Management LP and (iii) each of David Witzke and Michael Gregory, the managing members of Avidity Partners Management (GP) LLC. Lei Meng, an employee of Avidity Partners Management LP, is a director of the Issuer. Avidity Partners Management LP, Avidity Partners Management (GP) LLC, Mr. Witzke and Mr. Gregory may be considered directors by deputization due to their affiliation with Ms. Meng. Each Reporting Person disclaims beneficial ownership of these shares except to the extent of its, his or her pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose. ( 3 )Consists of Pre-Funded Warrants to purchase up to an aggregate of 1,833,333 shares of common stock purchased by clients of Avidity Partners Management LP from the Issuer in a private placement, which transaction is exempt from Section 16(b) in accordance with Rule 16b-3(d)(1) promulgated under the Exchange Act. ( 4 )The Pre-Funded Warrants have no expiration date and are exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of shares of common stock outstanding immediately after giving effect to such exercise.

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).

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