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

HOWL insider 10b5-1 stock sales reported, 5.48M shares remain

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

Rhea-AI Filing Summary

Werewolf Therapeutics, Inc. (HOWL) director and 10% owner affiliated with MPM BioImpact reported planned insider stock sales. The filing covers three open‑market sales of Werewolf common stock executed under a Rule 10b5-1 trading plan dated September 24, 2025.

On November 13, 2025, the reporting group sold 90,951 shares at a weighted average price of $0.98. On November 14, 2025, they sold 61,640 shares at a weighted average price of $0.93, and on November 17, 2025, they sold 57,061 shares at a weighted average price of $0.95. Each day’s trades occurred across multiple prices within disclosed ranges.

After these transactions, the group reports indirect beneficial ownership of 5,481,539 Werewolf shares held through several affiliated investment vehicles, including MPM Asset Management LLC, MPM BioVentures 2014 funds, MPM Oncology Innovations Fund, and UBS Oncology Impact Fund.

Positive

  • None.

Negative

  • None.
Insider GADICKE ANSBERT, MPM ONCOLOGY INNOVATIONS FUND LP, UBS Oncology Impact Fund L.P., Oncology Impact Fund (Cayman) Management L.P., MPM BioImpact LLC, MPM Oncology Innovations Fund GP LLC, MPM ASSET MANAGEMENT LLC
Role 10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner
Sold 209,652 shs ($201K)
Type Security Shares Price Value
Sale Common Stock 57,061 $0.95 $54K
Sale Common Stock 61,640 $0.93 $57K
Sale Common Stock 90,951 $0.98 $89K
Holdings After Transaction: Common Stock — 5,481,539 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: 6,244 by MPM Asset Management LLC ("AM LLC"), 39,450 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,631 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 1,359 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 8,688 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 32,579 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 $0.918 to $1.07 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: 384,621 by AM LLC, 2,429,001 by BV 2014, 162,011 by BV 2014(B), 83,604 by AM BV2014, 532,824 by MPM OIF and 2,008,179 by UBS Oncology. The shares were sold as follows: 4,232 by AM LLC, 26,736 by BV 2014, 1,783 by BV 2014(B), 921 by AM BV2014, 5,888 by MPM OIF and 22,080 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 $0.895 to $0.9551 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: 380,389 by AM LLC, 2,402,265 by BV 2014, 160,228 by BV 2014(B), 82,683 by AM BV2014, 526,936 by MPM OIF and 1,986,099 by UBS Oncology. The shares were sold as follows: 3,918 by AM LLC, 24,750 by BV 2014, 1,651 by BV 2014(B), 851 by AM BV2014, 5,451 by MPM OIF and 20,440 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 $0.9183 to $0.99 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: 376,471 by AM LLC, 2,377,515 by BV 2014, 158,577 by BV 2014(B), 81,832 by AM BV2014, 521,485 by MPM OIF and 1,965,659 by UBS Oncology.
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*
GADICKE ANSBERT
(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)
11/13/2025
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 11/13/2025 S(1) 90,951(2) D $0.98(3) 5,600,240 I See Footnotes(4)(5)
Common Stock 11/14/2025 S(1) 61,640(6) D $0.93(7) 5,538,600 I See Footnotes(4)(8)
Common Stock 11/17/2025 S(1) 57,061(9) D $0.95(10) 5,481,539 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*
GADICKE ANSBERT
(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 ONCOLOGY INNOVATIONS FUND LP
(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*
UBS Oncology Impact Fund 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*
Oncology Impact Fund (Cayman) Management 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 BioImpact 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 Oncology Innovations Fund 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 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: 6,244 by MPM Asset Management LLC ("AM LLC"), 39,450 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,631 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 1,359 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 8,688 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 32,579 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 $0.918 to $1.07 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: 384,621 by AM LLC, 2,429,001 by BV 2014, 162,011 by BV 2014(B), 83,604 by AM BV2014, 532,824 by MPM OIF and 2,008,179 by UBS Oncology.
6. The shares were sold as follows: 4,232 by AM LLC, 26,736 by BV 2014, 1,783 by BV 2014(B), 921 by AM BV2014, 5,888 by MPM OIF and 22,080 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 $0.895 to $0.9551 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: 380,389 by AM LLC, 2,402,265 by BV 2014, 160,228 by BV 2014(B), 82,683 by AM BV2014, 526,936 by MPM OIF and 1,986,099 by UBS Oncology.
9. The shares were sold as follows: 3,918 by AM LLC, 24,750 by BV 2014, 1,651 by BV 2014(B), 851 by AM BV2014, 5,451 by MPM OIF and 20,440 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 $0.9183 to $0.99 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: 376,471 by AM LLC, 2,377,515 by BV 2014, 158,577 by BV 2014(B), 81,832 by AM BV2014, 521,485 by MPM OIF and 1,965,659 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 MPM BioVentures 2014, L.P.
/s/ Ansbert Gadicke, Manager of MPM Oncology Innovations Fund GP LLC, the GP of MPM Oncology Innovations Fund, L.P. 11/17/2025
/s/ Ansbert Gadicke, Manager of MPM Oncology Innovations Fund GP LLC 11/17/2025
/s/ Ansbert Gadicke, Managing Partner of MPM BioImpact LLC 11/17/2025
/s/ Ansbert Gadicke, member of MPM Asset Management LLC 11/17/2025
/s/ Ansbert Gadicke 11/17/2025
/s/ Ansbert Gadicke, Managing Partner of MPM BioImpact LLC, the GP of Oncology Impact Fund (Cayman) Management L.P., the GP of UBS Oncology Impact Fund, L.P. 11/17/2025
/s/ Ansbert Gadicke, Managing Partner of MPM BioImpact LLC, the GP of Oncology Impact Fund (Cayman) Management L.P. 11/17/2025
** 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 did the HOWL insider report in this Form 4 filing?

The filing reports that an insider group associated with MPM BioImpact, which includes a director and 10% owner of Werewolf Therapeutics (HOWL), sold shares of the company’s common stock in several open-market transactions and updated its remaining indirect beneficial ownership.

How many Werewolf Therapeutics (HOWL) shares were sold and on which dates?

The group sold 90,951 shares of common stock on November 13, 2025, 61,640 shares on November 14, 2025, and 57,061 shares on November 17, 2025, all reported as open‑market sales coded as transaction type S.

What prices did the HOWL insider receive for the shares sold?

The reported weighted average sale prices were $0.98 on November 13, $0.93 on November 14, and $0.95 on November 17. Each set of trades occurred in multiple individual transactions within stated price ranges on those days.

How many Werewolf Therapeutics (HOWL) shares does the reporting group still own after these sales?

Following the reported transactions, the filing shows 5,481,539 Werewolf Therapeutics common shares beneficially owned indirectly through various affiliated entities, including MPM Asset Management LLC, MPM BioVentures 2014 funds, MPM Oncology Innovations Fund, and UBS Oncology Impact Fund.

What is a Rule 10b5-1 trading plan and how does it relate to this HOWL filing?

The filing states that the transactions were effected under a Rule 10b5-1 plan dated September 24, 2025. A Rule 10b5-1 plan is a pre-arranged trading program that allows insiders to systematically buy or sell shares according to set instructions, helping them trade while managing concerns about possessing material nonpublic information.

Were any derivative securities reported in this HOWL Form 4?

The section for derivative securities in this Form 4 does not list any acquired, disposed, or outstanding derivative instruments such as options, warrants, or convertible securities for the reporting group in the provided content.

Who is the key individual signing this Werewolf Therapeutics (HOWL) Form 4?

The Form 4 is signed multiple times by Ansbert Gadicke in various capacities, including as Managing Partner of MPM BioImpact LLC and manager or representative of several general partners for the investment funds that hold Werewolf Therapeutics shares.