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[Form 4] Werewolf Therapeutics, Inc. Insider Trading Activity

Filing Impact
(Moderate)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

Werewolf Therapeutics, Inc. (HOWL) reported insider activity by MPM-affiliated entities on a Form 4. Investment vehicles associated with MPM BioImpact and related funds, which are reported as a director and 10% owner group, sold Werewolf Therapeutics common stock on three days under a pre-arranged Rule 10b5-1 trading plan dated September 24, 2025.

The group sold 52,627 shares on November 18, 2025 at a weighted average price of $0.93, 66,324 shares on November 19, 2025 at a weighted average price of $0.94, and 41,152 shares on November 20, 2025 at a weighted average price of $0.89. After these sales, they reported indirect beneficial ownership of 5,321,436 shares held across several MPM-managed entities, including MPM Asset Management LLC, MPM BioVentures 2014 funds, MPM Oncology Innovations Fund and UBS Oncology Impact Fund, with each reporting person disclaiming beneficial ownership beyond its pecuniary interest.

Positive

  • None.

Negative

  • None.
Insider MPM BioVentures 2014, L.P., MPM BioVentures 2014 (B), L.P., MPM BioVentures 2014 LLC, MPM BioVentures 2014 GP LLC, MPM Asset Management Investors BV2014 LLC
Role 10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner
Sold 160,103 shs ($148K)
Type Security Shares Price Value
Sale Common Stock 41,152 $0.89 $37K
Sale Common Stock 66,324 $0.94 $62K
Sale Common Stock 52,627 $0.93 $49K
Holdings After Transaction: Common Stock — 5,321,436 shares (Indirect, See Footnotes)
Footnotes (1)
  1. Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 dated September 24, 2025. The shares were sold as follows: 3,613 by MPM Asset Management LLC ("AM LLC"), 22,827 by MPM BioVentures 2014, L.P. ("BV 2014"), 1,523 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 786 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 5,027 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 18,851 by UBS Oncology Impact Fund L.P. ("UBS Oncology"). The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.8902 to $0.9601 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. 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. 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 a member of AM LLC, a managing director of BV LLC, a manager of MPM OIF GP and 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. The shares are held as follows: 372,858 by AM LLC, 2,354,688 by BV 2014, 157,054 by BV 2014(B), 81,046 by AM BV2014, 516,458 by MPM OIF and 1,946,808 by UBS Oncology. The shares were sold as follows: 4,554 by AM LLC, 28,768 by BV 2014, 1,919 by BV 2014(B), 990 by AM BV2014, 6,335 by MPM OIF and 23,758 by UBS Oncology. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.901 to $0.9806 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. The shares are held as follows: 368,304 by AM LLC, 2,325,920 by BV 2014, 155,135 by BV 2014(B), 80,056 by AM BV2014, 510,123 by MPM OIF and 1,923,050 by UBS Oncology. The shares were sold as follows: 2,825 by AM LLC, 17,850 by BV 2014, 1,191 by BV 2014(B), 614 by AM BV2014, 3,931 by MPM OIF and 14,741 by UBS Oncology. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.8506 to $0.9556 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. The shares are held as follows: 365,479 by AM LLC, 2,308,070 by BV 2014, 153,944 by BV 2014(B), 79,442 by AM BV2014, 506,192 by MPM OIF and 1,908,309 by UBS Oncology.
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Form 4 Insider Transactions: What Each Field Means →
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).
X
 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*
MPM BioVentures 2014, L.P.
(Last) (First) (Middle)
C/O MPM BIOIMPACT LLC
399 BOYLSTON STREET, SUITE 1100
(Street)
BOSTON MA 02116
(City) (State) (Zip)
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)
3. Date of Earliest Transaction (Month/Day/Year)
11/18/2025
4. 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 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
Common Stock 11/18/2025 S(1) 52,627(2) D $0.93(3) 5,428,912 I See Footnotes(4)(5)
Common Stock 11/19/2025 S(1) 66,324(6) D $0.94(7) 5,362,588 I See Footnotes(4)(8)
Common Stock 11/20/2025 S(1) 41,152(9) D $0.89(10) 5,321,436 I See Footnotes(4)(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 (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
1. Name and Address of Reporting Person*
MPM BioVentures 2014, L.P.
(Last) (First) (Middle)
C/O MPM BIOIMPACT LLC
399 BOYLSTON STREET, SUITE 1100
(Street)
BOSTON MA 02116
(City) (State) (Zip)
Relationship of Reporting Person(s) to Issuer
Director X 10% Owner
Officer (give title below) Other (specify below)
1. Name and Address of Reporting Person*
MPM BioVentures 2014 (B), L.P.
(Last) (First) (Middle)
C/O MPM BIOIMPACT
399 BOYLSTON STREET, SUITE 1100
(Street)
BOSTON MA 02116
(City) (State) (Zip)
Relationship of Reporting Person(s) to Issuer
Director X 10% Owner
Officer (give title below) Other (specify below)
1. Name and Address of Reporting Person*
MPM BioVentures 2014 LLC
(Last) (First) (Middle)
C/O MPM BIOIMPACT LLC
399 BOYLSTON STREET, SUITE 1100
(Street)
BOSTON MA 02116
(City) (State) (Zip)
Relationship of Reporting Person(s) to Issuer
Director X 10% Owner
Officer (give title below) Other (specify below)
1. Name and Address of Reporting Person*
MPM BioVentures 2014 GP LLC
(Last) (First) (Middle)
C/O MPM BIOIMPACT LLC
399 BOYLSTON STREET, SUITE 1100
(Street)
BOSTON MA 02116
(City) (State) (Zip)
Relationship of Reporting Person(s) to Issuer
Director X 10% Owner
Officer (give title below) Other (specify below)
1. Name and Address of Reporting Person*
MPM Asset Management Investors BV2014 LLC
(Last) (First) (Middle)
C/O MPM BIOIMPACT LLC
399 BOYLSTON STREET, SUITE 1100
(Street)
BOSTON MA 02116
(City) (State) (Zip)
Relationship of Reporting Person(s) to Issuer
Director X 10% Owner
Officer (give title below) Other (specify below)
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: 3,613 by MPM Asset Management LLC ("AM LLC"), 22,827 by MPM BioVentures 2014, L.P. ("BV 2014"), 1,523 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 786 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 5,027 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 18,851 by UBS Oncology Impact Fund L.P. ("UBS Oncology").
3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.8902 to $0.9601 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.
4. 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. 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 a member of AM LLC, a managing director of BV LLC, a manager of MPM OIF GP and 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.
5. The shares are held as follows: 372,858 by AM LLC, 2,354,688 by BV 2014, 157,054 by BV 2014(B), 81,046 by AM BV2014, 516,458 by MPM OIF and 1,946,808 by UBS Oncology.
6. The shares were sold as follows: 4,554 by AM LLC, 28,768 by BV 2014, 1,919 by BV 2014(B), 990 by AM BV2014, 6,335 by MPM OIF and 23,758 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 $0.901 to $0.9806 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: 368,304 by AM LLC, 2,325,920 by BV 2014, 155,135 by BV 2014(B), 80,056 by AM BV2014, 510,123 by MPM OIF and 1,923,050 by UBS Oncology.
9. The shares were sold as follows: 2,825 by AM LLC, 17,850 by BV 2014, 1,191 by BV 2014(B), 614 by AM BV2014, 3,931 by MPM OIF and 14,741 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 $0.8506 to $0.9556 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: 365,479 by AM LLC, 2,308,070 by BV 2014, 153,944 by BV 2014(B), 79,442 by AM BV2014, 506,192 by MPM OIF and 1,908,309 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.
/s/ Ansbert Gadicke, Managing Director of MPM BioVentures 2014 LLC 11/20/2025
/s/ Ansbert Gadicke, Managing Director of MPM BioVentures 2014 LLC, the manager of MPM Asset Management Investors BV2014 LLC 11/20/2025
/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. 11/20/2025
/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. 11/20/2025
/s/ Ansbert Gadicke, Managing Director of MPM BioVentures 2014 LLC, the Managing Member of MPM BioVentures 2014 GP LLC 11/20/2025
** 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.

Source: View Original Filing on SEC EDGAR

FAQ

What insider transactions did HOWL report in this Form 4?

The Form 4 reports that MPM-affiliated entities sold Werewolf Therapeutics common stock on three dates in November 2025, totaling several tens of thousands of shares, with each sale reported at a weighted average price and tied to specific MPM investment vehicles.

What prices were received for the HOWL shares sold by the MPM entities?

The sales were reported at weighted average prices: $0.93 on November 18, 2025, $0.94 on November 19, 2025, and $0.89 on November 20, 2025, with underlying trades executed within disclosed price ranges.

How many HOWL shares do the MPM-affiliated entities report owning after these transactions?

Following the reported transactions, the MPM-affiliated reporting persons disclosed 5,321,436 shares of Werewolf Therapeutics common stock beneficially owned indirectly through various MPM-managed funds and entities.

Were the HOWL insider sales made under a Rule 10b5-1 trading plan?

Yes. The filing states that the transactions were effected pursuant to a trading plan established under Rule 10b5-1 dated September 24, 2025, which pre-arranged the sale of shares.

Which entities are involved in the reported HOWL insider holdings and sales?

The shares and sales are allocated among entities including MPM Asset Management LLC, MPM BioVentures 2014, L.P., MPM BioVentures 2014(B), L.P., MPM Asset Management Investors BV2014 LLC, MPM Oncology Innovations Fund, L.P., and UBS Oncology Impact Fund L.P., with related general partners and managers identified.