Sec Form 4 Filing - MPM BioVentures 2014, L.P. @ Werewolf Therapeutics, Inc. - 2025-10-30

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 MPM BioVentures 2014, L.P. 2. Issuer Name and Ticker or Trading Symbol Werewolf Therapeutics, Inc. [ HOWL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O MPM BIOIMPACT LLC, 399 BOYLSTON STREET, SUITE 1100 3. Date of Earliest Transaction (MM/DD/YY) 10/30/2025 (Street) BOSTON, MA02116 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 10/30/2025 S( 1 ) 86,936 ( 2 ) ( 3 ) D $ 1.43 ( 4 ) 6,355,717 I See Footnote ( 5 ) Common Stock 10/31/2025 S( 1 ) 114,044 ( 6 ) D $ 1.28 ( 7 ) 6,241,673 I See Footnote ( 8 ) Common Stock 11/03/2025 S( 1 ) 94,063 ( 9 ) D $ 1.29 ( 10 ) 6,147,610 I See Footnote ( 11 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other MPM BioVentures 2014, L.P. C/O MPM BIOIMPACT LLC 399 BOYLSTON STREET, SUITE 1100 BOSTON, MA02116 X MPM BioVentures 2014 (B), L.P. C/O MPM BIOIMPACT 399 BOYLSTON STREET, SUITE 1100 BOSTON, MA02116 X MPM BioVentures 2014 LLC C/O MPM BIOIMPACT LLC 399 BOYLSTON STREET, SUITE 1100 BOSTON, MA02116 X MPM BioVentures 2014 GP LLC C/O MPM BIOIMPACT LLC 399 BOYLSTON STREET, SUITE 1100 BOSTON, MA02116 X MPM Asset Management Investors BV2014 LLC C/O MPM BIOIMPACT LLC 399 BOYLSTON STREET, SUITE 1100 BOSTON, MA02116 X Signatures /s/ Ansbert Gadicke, Managing Director of MPM BioVentures 2014 LLC 11/03/2025 Signature of Reporting Person Date /s/ Ansbert Gadicke, Managing Director of MPM BioVentures 2014 LLC, the manager of MPM Asset Management Investors BV2014 LLC 11/03/2025 Signature of Reporting Person Date /s/ Ansbert Gadicke, Managing Director of MPM BioVentures 2014 LLC, the Managing Member of MPM BioVentures 2014 GP LLC, the GP of MPM BioVentures 2014 (B), L.P. 11/03/2025 Signature of Reporting Person Date /s/ Ansbert Gadicke, Managing Director of MPM BioVentures 2014 LLC, the Managing Member of MPM BioVentures 2014 GP LLC, the GP of MPM BioVentures 2014, L.P. 11/03/2025 Signature of Reporting Person Date /s/ Ansbert Gadicke, Managing Director of MPM BioVentures 2014 LLC, the Managing Member of MPM BioVentures 2014 GP LLC 11/03/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 dated September 24, 2025. ( 2 )The shares were sold as follows: 5,969 by MPM Asset Management LLC ("AM LLC"), 37,709 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,515 by MPM BioVentures 2014(B), L.P. (BV 2014(B), 1,298 MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 8,304 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 31,141 by UBS Oncology Impact Fund L.P. ("UBS Oncology"). MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). BV LLC is the manager of AM BV2014. MPM Oncology Innovations Fund GP LLC ("MPM OIF GP") is the general partner of MPM OIF. Ansbert Gadicke is a member of AM LLC, a managing director of BV LLC and a manager of MPM OIF GP. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein. ( 3 )MPM BioImpact LLC ("BioImpact") is the General Partner of Oncology Impact Fund (Cayman) Management L.P., the General Partner of UBS Oncology. Ansbert Gadicke is the managing partner of BioImpact. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein. ( 4 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $1.365 to $1.55 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. ( 5 )The shares are held as follows: 436,489 by AM LLC, 2,756,691 by BV 2014, 183,866 by BV 2014(B), 94,885 by AM BV2014, 604,989 by MPM OIF and 2,278,797 by UBS Oncology. ( 6 )The shares were sold as follows: 7,830 by AM LLC, 49,467 by BV 2014, 3,299 by BV 2014(B), 1,702 by AM BV2014, 10,894 by MPM OIF and 40,852 by UBS Oncology. ( 7 ). The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $1.205 to $1.415 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. ( 8 )The shares are held as follows: 428,659 by AM LLC, 2,707,224 by BV 2014, 180,567 by BV 2014(B), 93,183 by AM BV2014, 594,095 by MPM OIF and 2,237,945 by UBS Oncology. ( 9 )The shares were sold as follows: 6,458 by AM LLC, 40,800 by BV 2014, 2,721 by BV 2014(B), 1,405 by AM BV2014, 8,985 by MPM OIF and 33,694 by UBS Oncology. ( 10 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $1.245 to $1.33 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. ( 11 )The shares are held as follows: 422,201 by AM LLC, 2,666,424 by BV 2014, 177,846 by BV 2014(B), 91,778 by AM BV2014, 585,110 by MPM OIF and 2,204,251 by UBS Oncology.

Remarks: This filing is 1 of 2 identical filings due to limitations on number of Reporting Persons. See Form 4 filed by Ansbert Gadicke.

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).

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