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HOWL insider MPM BioImpact sells shares, still holds 5.13M

Werewolf Therapeutics, Inc. (HOWL) insider filing shows planned share sales by MPM-affiliated funds.

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

Rhea-AI Filing Summary

Werewolf Therapeutics, Inc. (HOWL) insider filing shows planned share sales by MPM-affiliated funds. A reporting group connected to MPM BioImpact and related investment vehicles sold 64,331 shares of common stock on 11/21/2025 at a weighted average price of $0.83, 88,802 shares on 11/24/2025 at $0.98, and 42,533 shares on 11/25/2025 at $0.92.

The sales were executed under a Rule 10b5-1 trading plan dated September 24, 2025, which is designed to pre-arrange trades. After these transactions, the reporting persons collectively report indirect beneficial ownership of 5,125,770 HOWL shares through several affiliated funds.

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 195,666 shs ($180K)
Type Security Shares Price Value
Sale Common Stock 42,533 $0.92 $39K
Sale Common Stock 88,802 $0.98 $87K
Sale Common Stock 64,331 $0.83 $53K
Holdings After Transaction: Common Stock — 5,125,770 shares (Indirect, See Footnotes)
Footnotes (11)
  1. F1. Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 dated September 24, 2025.
  2. F2. The shares were sold as follows: 4,417 by MPM Asset Management LLC ("AM LLC"), 27,904 by MPM BioVentures 2014, L.P. ("BV 2014"), 1,861 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 960 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 6,145 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 23,044 by UBS Oncology Impact Fund L.P. ("UBS Oncology").
  3. F3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.80 to $0.8861 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. F4. 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. F5. The shares are held as follows: 361,062 by AM LLC, 2,280,166 by BV 2014, 152,083 by BV 2014(B), 78,482 by AM BV2014, 500,047 by MPM OIF and 1,885,265 by UBS Oncology.
  6. F6. The shares were sold as follows: 6,097 by AM LLC, 38,518 by BV 2014, 2,569 by BV 2014(B), 1,325 by AM BV2014, 8,483 by MPM OIF and 31,810 by UBS Oncology.
  7. F7. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.8733 to $1.03 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. F8. The shares are held as follows: 354,965 by AM LLC, 2,241,648 by BV 2014, 149,514 by BV 2014(B), 77,157 by AM BV2014, 491,564 by MPM OIF and 1,853,455 by UBS Oncology.
  9. F9. The shares were sold as follows: 2,920 by AM LLC, 18,449 by BV 2014, 1,230 by BV 2014(B), 635 by AM BV2014, 4,063 by MPM OIF and 15,236 by UBS Oncology.
  10. F10. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.90 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. F11. The shares are held as follows: 352,045 by AM LLC, 2,223,199 by BV 2014, 148,284 by BV 2014(B), 76,522 by AM BV2014, 487,501 by MPM OIF and 1,838,219 by UBS Oncology.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does the latest Form 4 for Werewolf Therapeutics (HOWL) report?
The Form 4 reports that investment entities affiliated with MPM BioImpact and related funds sold shares of Werewolf Therapeutics, Inc. (HOWL) common stock over three days in November 2025 and continue to hold a large indirect position.

How many HOWL shares were sold by the MPM-affiliated group in November 2025?
The reporting persons sold 64,331 shares on 11/21/2025, 88,802 shares on 11/24/2025, and 42,533 shares on 11/25/2025, all reported as dispositions of common stock.

What prices were received for the HOWL share sales disclosed in this Form 4?
The filing reports weighted average prices of $0.83 per share on 11/21/2025, $0.98 per share on 11/24/2025, and $0.92 per share on 11/25/2025, with each reflecting multiple trades within stated price ranges.

How many Werewolf Therapeutics (HOWL) shares do the reporting persons still beneficially own?
After the reported transactions, the group reports indirect beneficial ownership of 5,125,770 HOWL common shares held across several funds, including AM LLC, MPM BioVentures 2014 entities, MPM Oncology Innovations Fund, and UBS Oncology Impact Fund.

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 Rule 10b5-1 trading plan dated September 24, 2025, which pre-establishes trading instructions for the securities.

Who is signing the Form 4 for the MPM-affiliated reporting persons in HOWL?
The Form 4 is signed by Ansbert Gadicke in various capacities, including as managing partner or manager of the general partners and management entities that control the reporting investment funds.

How are the remaining HOWL shares distributed among the MPM-affiliated funds?
According to the footnotes, the remaining 5,125,770 shares are held as 352,045 by AM LLC, 2,223,199 by MPM BioVentures 2014, L.P., 148,284 by MPM BioVentures 2014(B), L.P., 76,522 by MPM Asset Management Investors BV2014 LLC, 487,501 by MPM Oncology Innovations Fund, L.P., and 1,838,219 by UBS Oncology Impact Fund L.P.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 4 Insider Transactions: What Each Field Means →
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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)
11/21/2025
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 11/21/2025 S(1) 64,331(2) D $0.83(3) 5,257,105 I See Footnotes(4)(5)
Common Stock 11/24/2025 S(1) 88,802(6) D $0.98(7) 5,168,303 I See Footnotes(4)(8)
Common Stock 11/25/2025 S(1) 42,533(9) D $0.92(10) 5,125,770 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: 4,417 by MPM Asset Management LLC ("AM LLC"), 27,904 by MPM BioVentures 2014, L.P. ("BV 2014"), 1,861 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 960 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 6,145 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 23,044 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 $0.80 to $0.8861 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: 361,062 by AM LLC, 2,280,166 by BV 2014, 152,083 by BV 2014(B), 78,482 by AM BV2014, 500,047 by MPM OIF and 1,885,265 by UBS Oncology.
6. The shares were sold as follows: 6,097 by AM LLC, 38,518 by BV 2014, 2,569 by BV 2014(B), 1,325 by AM BV2014, 8,483 by MPM OIF and 31,810 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 $0.8733 to $1.03 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: 354,965 by AM LLC, 2,241,648 by BV 2014, 149,514 by BV 2014(B), 77,157 by AM BV2014, 491,564 by MPM OIF and 1,853,455 by UBS Oncology.
9. The shares were sold as follows: 2,920 by AM LLC, 18,449 by BV 2014, 1,230 by BV 2014(B), 635 by AM BV2014, 4,063 by MPM OIF and 15,236 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 $0.90 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: 352,045 by AM LLC, 2,223,199 by BV 2014, 148,284 by BV 2014(B), 76,522 by AM BV2014, 487,501 by MPM OIF and 1,838,219 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. 11/25/2025
/s/ Ansbert Gadicke, Manager of MPM Oncology Innovations Fund GP LLC 11/25/2025
/s/ Ansbert Gadicke, Managing Partner of MPM BioImpact LLC 11/25/2025
/s/ Ansbert Gadicke, member of MPM Asset Management LLC 11/25/2025
/s/ Ansbert Gadicke 11/25/2025
/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. 11/18/2025
/s/ Ansbert Gadicke, Managing Partner of MPM BioImpact LLC, the GP of Oncology Impact Fund (Cayman) Management L.P. 11/25/2025
** 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

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