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HOWL Form 4: 10% holder sells under Rule 10b5-1 plan

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

Rhea-AI Filing Summary

Werewolf Therapeutics (HOWL): Insider Form 4 filing reports sales by entities affiliated with MPM/UBS Oncology, identified as a director and 10% owner. The transactions were made pursuant to a Rule 10b5-1 plan dated September 24, 2025.

On October 27, 2025, 72,709 shares were sold at a weighted average price of $1.72 (range $1.675–$1.82), leaving 6,645,961 shares beneficially owned. On October 28, 2025, 69,068 shares were sold at a weighted average price of $1.64 (range $1.605–$1.70), leaving 6,576,893 shares beneficially owned. On October 29, 2025, 134,240 shares were sold at a weighted average price of $1.55 (range $1.51–$1.62), leaving 6,442,653 shares beneficially owned.

The filing attributes sales and post-transaction holdings across several affiliated funds and managers and notes that each reporting person disclaims beneficial ownership beyond their pecuniary interest.

Positive

  • None.

Negative

  • None.

Insights

Routine 10b5-1 insider sales; neutral signal.

Entities affiliated with a director and 10% owner reported open-market sales under a pre-established Rule 10b5-1 plan. The filing lists three trading days with weighted-average prices and detailed selling allocations across affiliated funds.

Because these sales were executed under a 10b5-1 plan, timing was pre-set rather than discretionary. The filing discloses remaining indirect beneficial ownership of 6,442,653 shares after the October 29 activity, with standard disclaimers about pecuniary interest.

There is no change to corporate operations indicated here. Actual market impact depends on trading volume and holder decisions, and the filing provides price ranges for transparency.

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 276,017 shs ($446K)
Type Security Shares Price Value
Sale Common Stock 134,240 $1.55 $208K
Sale Common Stock 69,068 $1.64 $113K
Sale Common Stock 72,709 $1.72 $125K
Holdings After Transaction: Common Stock — 6,442,653 shares (Indirect, See Footnote)
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: 4,992 by MPM Asset Management LLC ("AM LLC"), 31,538 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,104 by MPM BioVentures 2014(B), L.P. (BV 2014(B), 1,085 MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 6,945 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 26,045 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. 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. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $1.675 to $1.82 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: 456,416 by AM LLC, 2,882,585 by BV 2014, 192,263 by BV 2014(B), 99,218 by AM BV2014, 632,714 by MPM OIF and 2,382,765 by UBS Oncology. The shares were sold as follows: 4,742 by AM LLC, 29,958 by BV 2014, 1,998 by BV 2014(B), 1,031 by AM BV2014, 6,598 by MPM OIF and 24,741 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 $1.605 to $1.70 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: 451,674 by AM LLC, 2,852,627 by BV 2014, 190,265 by BV 2014(B), 98,187 by AM BV2014, 626,116 by MPM OIF and 2,358,024 by UBS Oncology. The shares were sold as follows: 9,216 by AM LLC, 58,227 by BV 2014, 3,884 by BV 2014(B), 2,004 by AM BV2014, 12,823 by MPM OIF and 48,086 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 $1.51 to $1.62 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: 442,458 by AM LLC, 2,794,400 by BV 2014, 186,381 by BV 2014(B), 96,183 by AM BV2014, 613,293 by MPM OIF and 2,309,938 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)
10/27/2025
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 10/27/2025 S(1) 72,709(2)(3) D $1.72(4) 6,645,961 I See Footnote(5)
Common Stock 10/28/2025 S(1) 69,068(6) D $1.64(7) 6,576,893 I See Footnote(8)
Common Stock 10/29/2025 S(1) 134,240(9) D $1.55(10) 6,442,653 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 (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: 4,992 by MPM Asset Management LLC ("AM LLC"), 31,538 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,104 by MPM BioVentures 2014(B), L.P. (BV 2014(B), 1,085 MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 6,945 by MPM Oncology Innovations Fund, L.P. ("MPM OIF") and 26,045 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 $1.675 to $1.82 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: 456,416 by AM LLC, 2,882,585 by BV 2014, 192,263 by BV 2014(B), 99,218 by AM BV2014, 632,714 by MPM OIF and 2,382,765 by UBS Oncology.
6. The shares were sold as follows: 4,742 by AM LLC, 29,958 by BV 2014, 1,998 by BV 2014(B), 1,031 by AM BV2014, 6,598 by MPM OIF and 24,741 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 $1.605 to $1.70 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: 451,674 by AM LLC, 2,852,627 by BV 2014, 190,265 by BV 2014(B), 98,187 by AM BV2014, 626,116 by MPM OIF and 2,358,024 by UBS Oncology.
9. The shares were sold as follows: 9,216 by AM LLC, 58,227 by BV 2014, 3,884 by BV 2014(B), 2,004 by AM BV2014, 12,823 by MPM OIF and 48,086 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 $1.51 to $1.62 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: 442,458 by AM LLC, 2,794,400 by BV 2014, 186,381 by BV 2014(B), 96,183 by AM BV2014, 613,293 by MPM OIF and 2,309,938 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 10/29/2025
/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. 10/29/2025
/s/ Ansbert Gadicke, Managing Partner of MPM BioImpact LLC, the GP of Oncology Impact Fund (Cayman) Management L.P. 10/29/2025
/s/ Ansbert Gadicke, Manager of MPM Oncology Innovations Fund GP LLC, the GP of MPM Oncology Innovations Fund, L.P. 10/29/2025
/s/ Ansbert Gadicke, Manager of MPM Oncology Innovations Fund GP LLC 10/29/2025
/s/ Ansbert Gadicke, Managing Partner of MPM BioImpact LLC 10/29/2025
/s/ Ansbert Gadicke, member of MPM Asset Management LLC 10/29/2025
** 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 Werewolf Therapeutics (HOWL) disclose in this Form 4?

Affiliated entities of a director and 10% owner reported open‑market sales executed under a Rule 10b5-1 plan across three days in October 2025.

How many HOWL shares were sold and at what prices?

Sales were 72,709 shares at a weighted average $1.72 (range $1.675–$1.82), 69,068 shares at $1.64 (range $1.605–$1.70), and 134,240 shares at $1.55 (range $1.51–$1.62).

Were the transactions under a Rule 10b5-1 plan?

Yes. The filing states the sales were effected pursuant to a Rule 10b5-1 plan dated September 24, 2025.

What is the reporting group’s remaining beneficial ownership after these sales?

After the October 29, 2025 transactions, the filing reports 6,442,653 shares beneficially owned indirectly.

Which entities were involved in the sales and holdings?

Allocations and holdings are attributed across AM LLC, MPM BioVentures 2014, L.P., MPM BioVentures 2014(B), L.P., AM BV2014, MPM Oncology Innovations Fund, L.P., and UBS Oncology Impact Fund L.P.

Do the prices reflect single trades or ranges?

Weighted average prices are provided, with each day’s trades executed across price ranges; the filer offers to supply detailed breakdowns upon request.