Sec Form 4 Filing - MPM BioVentures 2014, L.P. @ Werewolf Therapeutics, Inc. - 2021-05-04

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 CAPITAL, 450 KENDALL STREET 3. Date of Earliest Transaction (MM/DD/YY) 05/04/2021 (Street) CAMBRIDGE, MA02142 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 05/04/2021 C 2,298,430 A 2,298,430 I See Footnote ( 2 ) Common Stock 05/04/2021 C 763,809 A 3,062,239 I See Footnote ( 3 ) Common Stock 05/04/2021 P 125,759 ( 4 ) A $ 16 3,187,998 I See Footnote ( 5 )

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 Series A Preferred Stock ( 1 ) 05/04/2021 C 19,925,321 ( 1 ) ( 1 ) Common Stock 2,298,430 ( 6 ) $ 0 0 I See Footnote ( 7 ) Series B Preferred Stock ( 1 ) 05/04/2021 C 6,621,546 ( 1 ) ( 1 ) Common Stock 763,809 ( 8 ) $ 0 0 I See Footnote ( 7 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other MPM BioVentures 2014, L.P. C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA02142 X MPM BioVentures 2014 (B), L.P. C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA02142 X MPM BioVentures 2014 LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA02142 X MPM BioVentures 2014 GP LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA02142 X Foley Todd C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA02142 X MPM Asset Management Investors BV2014 LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA02142 X Signatures /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC, the general partner of MPM BioVentures 2014, L.P. 05/06/2021 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 general partner of MPM BioVentures 2014 (B), L.P. 05/06/2021 Signature of Reporting Person Date /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC 05/06/2021 Signature of Reporting Person Date /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC 05/06/2021 Signature of Reporting Person Date /s/ Todd Foley 05/06/2021 Signature of Reporting Person Date /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the manager of MPM Asset Management Investors BV2014 LLC 05/06/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of Series A Preferred Stock and Series B Preferred Stock converted into common stock on a 8.6691-for-1 basis into the number of shares of common stock shown in Column 7 without payment of further consideration upon closing of the initial public offering of the Issuer's common stock. The shares had no expiration date. ( 2 )The shares are held as follows: 2,087,358 by MPM BioVentures 2014, L.P. ("BV 2014"), 139,224 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)") and 71,848 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"). 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. Todd Foley is a Managing Director of BV LLC. Each Reporting Persons disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein. ( 3 )The shares are held as follows: 2,781,025 by BV 2014, 185,490 by BV 2014(B) and 95,724 by AM BV2014. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein. ( 4 )The shares were purchased as follows: 114,210 by BV 2014, 7,618 by BV 2014(B) and 3,931 by AM BV2014. ( 5 )The shares are held as follows: 2,895,235 by BV 2014, 193,108 by BV 2014(B) and 99,655 by AM BV2014. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein. ( 6 )The shares were held as follows: 2,087,358 by BV 2014, 139,224 by BV 2014(B) and 71,848 by AM BV2014. ( 7 )No securities held by the Reporting Persons. ( 8 )The shares were held as follows: 693,667 by BV 2014, 46,266 by BV 2014(B) and 23,876 by AM BV2014.

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