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MPM group cuts Werewolf Therapeutics (HOWL) holdings in May stock sales

Filing Impact
(Moderate)
Filing Sentiment
(Neutral)
Form Type
SCHEDULE 13D/A

Rhea-AI Filing Summary

Werewolf Therapeutics’ major MPM-affiliated investors filed Amendment No. 7 to Schedule 13D updating their ownership in the company’s common stock. The filing shows various MPM funds and related entities holding individual stakes ranging from 0.1% to 3.8% of outstanding shares.

As of May 1, 2026, the ownership percentages are calculated against 48,596,817 shares of Werewolf Therapeutics common stock. The reporting group sold blocks of shares in open-market transactions between May 6 and May 12, 2026 at average prices generally around $0.63–$0.70 per share.

Positive

  • None.

Negative

  • None.
Shares Outstanding 48,596,817 shares Common stock outstanding as of May 1, 2026
BV 2014 Stake 792,254 shares (1.6%) Held by MPM BioVentures 2014, L.P. with sole voting and dispositive power
UBS Oncology Stake 655,471 shares (1.3%) Held by UBS Oncology Impact Fund L.P. with sole voting and dispositive power
Ansbert Gadicke Ownership 1,826,646 shares (3.8%) Aggregate beneficial ownership with shared voting and dispositive power
MPM OIF Stake 173,334 shares (0.4%) Held by MPM Oncology Innovations Fund L.P. with sole voting and dispositive power
Sample Sale on May 8, 2026 $0.70 average price Open-market sales on 05/08/26 within $0.6183–$0.7668 range
Sample Sale on May 7, 2026 $0.63 average price Open-market sales on 05/07/26 within $0.62–$0.667 range
beneficially own financial
"may be deemed to beneficially own the shares held by BV 2014 and BV 2014(B)"
Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.
aggregate amount beneficially owned financial
"11Aggregate amount beneficially owned by each reporting person 792,254.00"
sole voting power financial
"7 | Sole Voting Power 792,254.00"
Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.
shared dispositive power financial
"10 | Shared Dispositive Power 1,826,646.00"
open market financial
"The Reporting Persons sold the following Common Stock in the open market since Amendment No. 6"
An open market is a system where buying and selling of goods, services, or financial assets happen freely without restrictions or special controls. For investors, it means they can trade assets easily and quickly, which helps determine fair prices based on supply and demand. This environment encourages transparency and competition, making it easier to buy or sell with confidence.





95075A107

(CUSIP Number)
Ansbert Gadicke
c/o MPM BioImpact LLC, 339 Boylston Street, Suite 1100
Boston, MA, 02116
617-425-9200

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)
05/08/2026

(Date of Event Which Requires Filing of This Statement)


If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).




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SCHEDULE 13D


MPM BioVentures 2014, L.P.
Signature:/s/ Ansbert Gadicke
Name/Title: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.
Date:05/12/2026
MPM BioVentures 2014 (B), L.P.
Signature:/s/ Ansbert Gadicke
Name/Title:Managing Director of MPM BioVentures 2014 LLC, Managing Member of MPM BioVentures 2014 GP LLC, the General Partner of MPM BioVentures 2014 (B), L.P.
Date:05/12/2026
MPM Asset Management Investors BV2014 LLC
Signature:/s/ Ansbert Gadicke
Name/Title:Managing Director of MPM BioVentures 2014 LLC, the manager of MPM Asset Management Investors BV2014 LLC
Date:05/12/2026
UBS Oncology Impact Fund L.P.
Signature:/s/ Ansbert Gadicke
Name/Title: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.
Date:05/12/2026
MPM BioVentures 2014 GP LLC
Signature:/s/ Ansbert Gadicke
Name/Title:Managing Director of MPM BioVentures 2014 LLC, the Managing Member of MPM BioVentures 2014 GP LLC
Date:05/12/2026
MPM BioVentures 2014 LLC
Signature:/s/ Ansbert Gadicke
Name/Title:Managing Director
Date:05/12/2026
Oncology Impact Fund (Cayman) Management L.P.
Signature:/s/ Ansbert Gadicke
Name/Title:Managing Partner of MPM BioImpact LLC, the General Partner of Oncology Impact Fund (Cayman) Management L.P.
Date:05/12/2026
MPM BioImpact LLC
Signature:/s/ Ansbert Gadicke
Name/Title:Managing Partner
Date:05/12/2026
ANSBERT GADICKE
Signature:/s/ Ansbert Gadicke
Name/Title:Ansbert Gadicke
Date:05/12/2026
LUKE EVNIN
Signature:/s/ Luke Evnin
Name/Title:Luke Evnin
Date:05/12/2026
Todd Foley
Signature:/s/ Todd Foley
Name/Title:Todd Foley
Date:05/12/2026
MPM ASSET MANAGEMENT LLC
Signature:/s/ Ansbert Gadicke
Name/Title:Member
Date:05/12/2026
MPM ONCOLOGY INNOVATIONS FUND LP
Signature:/s/ Ansbert Gadicke
Name/Title:Manager of MPM Oncology Innovations Fund GP LLC, the General Partner of MPM Oncology Innovations Fund, L.P.
Date:05/12/2026
MPM Oncology Innovations Fund GP LLC
Signature:/s/ Ansbert Gadicke
Name/Title:Manager
Date:05/12/2026

FAQ

What does the Werewolf Therapeutics (HOWL) Schedule 13D/A filing show about MPM ownership?

The filing shows several MPM-affiliated funds and individuals reporting updated beneficial ownership in Werewolf Therapeutics common stock, with individual positions ranging from about 0.1% up to 3.8% of outstanding shares, calculated against 48,596,817 shares as of May 1, 2026.

How many Werewolf Therapeutics (HOWL) shares does Ansbert Gadicke report owning?

Ansbert Gadicke reports beneficial ownership of 1,826,646 Werewolf Therapeutics common shares, representing about 3.8% of the class. These shares are held indirectly through various MPM-related investment entities over which he has management roles, as described in the ownership footnotes.

What stake in Werewolf Therapeutics (HOWL) is reported for UBS Oncology Impact Fund L.P.?

UBS Oncology Impact Fund L.P. reports beneficial ownership of 655,471 Werewolf Therapeutics common shares, representing about 1.3% of the outstanding stock. Control is attributed through BioImpact and Oncology Cayman as direct and indirect general partners of UBS Oncology Impact Fund L.P.

What Werewolf Therapeutics (HOWL) share sales are disclosed in the May 2026 Schedule 13D/A amendment?

The reporting persons disclose open-market sales of common stock between May 6 and May 12, 2026, with various MPM funds selling shares at average prices around $0.63–$0.70 per share. Each fund’s daily share amounts and price ranges are itemized in the transaction table.

How many Werewolf Therapeutics (HOWL) shares does MPM BioVentures 2014, L.P. hold?

MPM BioVentures 2014, L.P. reports holding 792,254 Werewolf Therapeutics common shares, equal to about 1.6% of the class. The partnership has sole voting and dispositive power over these shares, according to the ownership table in the amendment.

What is the reported total share count used for ownership percentages in the Werewolf Therapeutics (HOWL) filing?

Ownership percentages are calculated using 48,596,817 Werewolf Therapeutics common shares outstanding as of May 1, 2026. That share count comes from the company’s Form 10-Q filed on May 7, 2026, which the reporting group cites as its basis.