Werewolf Therapeutics (HOWL) stake trimmed by MPM entities in planned sales

Filing Impact

(Moderate)

Filing Sentiment

(Negative)

Form Type

Rhea-AI Filing Summary

Entities associated with director Luke Evnin sold Werewolf Therapeutics, Inc. stock over three days under a pre-arranged plan. Investment vehicles including MPM Asset Management LLC, MPM BioVentures 2014 funds, MPM Asset Management Investors BV2014 LLC and MPM Oncology Innovations Fund, L.P. sold a total of 205,911 shares of Common Stock in open-market transactions on April 27, 28 and 29, 2026 at weighted average prices of $0.85, $0.73 and $0.69 per share, respectively.

After these indirect sales, the affiliated entities together held 1,953,949 shares. The filing notes the transactions were effected pursuant to a Rule 10b5-1 trading plan dated March 26, 2026 and that Evnin disclaims beneficial ownership beyond his pecuniary interest.

Insider Trade Summary 10b5-1

Net Seller: 205,911 shares ($154,525)

Net Sell 3 txns

Insider EVNIN LUKE

Role null

Sold 205,911 shs ($155K)

Type	Security	Shares	Price	Value
Sale	Common Stock	56,559	$0.69	$39K
Sale	Common Stock	95,412	$0.73	$70K
Sale	Common Stock	53,940	$0.85	$46K

Holdings After Transaction: Common Stock — 1,953,949 shares (Indirect, See Footnotes)

Footnotes (1)

Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 dated March 26, 2026. The shares were sold as follows: 5,779 by MPM Asset Management LLC ("AM LLC"), 36,488 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,434 by MPM BIoVentures 2014(B), L.P. ("BV 2014(B)"), 1,256 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 7,983 by MPM Oncology Innovations Fund, L.P. ("MPM OIF"). The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.818 to $0.8788 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. Luke Evnin is a member of AM LLC, a Managing Director of BV LLC and a manager of MPM OIF GP. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. The shares are held as follows: 225,629 by AM LLC, 1,424,566 by BV 2014, 95,016 by BV 2014(B), 49,033 by AM BV2014 and 311,676 by MPM OIF. The shares were sold as follows: 10,223 by AM LLC, 64,541 by BV 2014, 4,305 by BV 2014(B), 2,222 by AM BV2014 and 14,121 by MPM OIF. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.673 to $0.82 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: 215,406 by AM LLC, 1,360,025 by BV 2014, 90,711 by BV 2014(B), 46,811 by AM BV2014 and 297,555 by MPM OIF. The shares were sold as follows: 6,060 by AM LLC, 38,259 by BV 2014, 2,552 by BV 2014(B), 1,317 by AM BV2014 and 8,371 by MPM OIF. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.68 to $0.75 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: 209,346 by AM LLC, 1,321,766 by BV 2014, 88,159 by BV 2014(B), 45,494 by AM BV2014 and 289,184 by MPM OIF.

Key Figures

Total shares sold: 205,911 shares Shares sold April 27, 2026: 53,940 shares at $0.85/share Shares sold April 28, 2026: 95,412 shares at $0.73/share +5 more

8 metrics

Total shares sold 205,911 shares Aggregate indirect open-market sales on April 27–29, 2026

Shares sold April 27, 2026 53,940 shares at $0.85/share Indirect open-market sale of Common Stock

Shares sold April 28, 2026 95,412 shares at $0.73/share Indirect open-market sale of Common Stock

Shares sold April 29, 2026 56,559 shares at $0.69/share Indirect open-market sale of Common Stock

Shares held after transactions 1,953,949 shares Indirect holdings by affiliated entities following April 29, 2026 sale

Price range April 27 $0.818–$0.8788 Multiple sale transactions; weighted average price reported

Price range April 28 $0.673–$0.82 Multiple sale transactions; weighted average price reported

Price range April 29 $0.68–$0.75 Multiple sale transactions; weighted average price reported

Key Terms

Rule 10b5-1, weighted average price, pecuniary interest, beneficial ownership, +1 more

5 terms

Rule 10b5-1 regulatory

"Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 dated March 26, 2026."

Rule 10b5-1 is a regulation that allows company insiders to buy or sell their shares at predetermined times, even if they have access to non-public information. It acts like setting a schedule in advance for transactions, helping prevent accusations of unfair trading. This rule provides a way for insiders to plan trades transparently, giving investors confidence that these transactions are not based on hidden information.

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

pecuniary interest financial

"The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein."

beneficial ownership financial

"The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein."

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

indirect financial

"total_shares_following_transaction": "1953949.0000", "direct_or_indirect": "I""

Form 4 Insider Transactions: What Each Field Means →

04/29/2026 - 07:16 PM

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).

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^*

EVNIN LUKE

(Last)

(First)

(Middle)

C/O MPM BIOIMPACT LLC

399 BOYLSTON STREET, SUITE 1100

(Street)

BOSTON

MASSACHUSETTS

02116

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Werewolf Therapeutics, Inc. [ HOWL ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/27/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	04/27/2026		S⁽¹⁾		53,940⁽²⁾	D	$0.85⁽³⁾	2,105,920	I	See Footnotes⁽⁴⁾⁽⁵⁾
Common Stock	04/28/2026		S⁽¹⁾		95,412⁽⁶⁾	D	$0.73⁽⁷⁾	2,010,508	I	See Footnotes⁽⁴⁾⁽⁸⁾
Common Stock	04/29/2026		S⁽¹⁾		56,559⁽⁹⁾	D	$0.69⁽¹⁰⁾	1,953,949	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 dated March 26, 2026.

2. The shares were sold as follows: 5,779 by MPM Asset Management LLC ("AM LLC"), 36,488 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,434 by MPM BIoVentures 2014(B), L.P. ("BV 2014(B)"), 1,256 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 7,983 by MPM Oncology Innovations Fund, L.P. ("MPM OIF").

3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.818 to $0.8788 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. Luke Evnin is a member of AM LLC, a Managing Director of BV LLC and a manager of MPM OIF GP. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein.

5. The shares are held as follows: 225,629 by AM LLC, 1,424,566 by BV 2014, 95,016 by BV 2014(B), 49,033 by AM BV2014 and 311,676 by MPM OIF.

6. The shares were sold as follows: 10,223 by AM LLC, 64,541 by BV 2014, 4,305 by BV 2014(B), 2,222 by AM BV2014 and 14,121 by MPM OIF.

7. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.673 to $0.82 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.

8. The shares are held as follows: 215,406 by AM LLC, 1,360,025 by BV 2014, 90,711 by BV 2014(B), 46,811 by AM BV2014 and 297,555 by MPM OIF.

9. The shares were sold as follows: 6,060 by AM LLC, 38,259 by BV 2014, 2,552 by BV 2014(B), 1,317 by AM BV2014 and 8,371 by MPM OIF.

10. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.68 to $0.75 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: 209,346 by AM LLC, 1,321,766 by BV 2014, 88,159 by BV 2014(B), 45,494 by AM BV2014 and 289,184 by MPM OIF.

	/s/ Luke Evnin	04/29/2026
	** 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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What insider transactions did HOWL director Luke Evnin report in this Form 4?

Luke Evnin reported indirect open-market sales totaling 205,911 shares of Werewolf Therapeutics Common Stock. These sales occurred on April 27, 28 and 29, 2026 at weighted average prices of $0.85, $0.73 and $0.69 per share through affiliated investment entities.

Which entities actually sold Werewolf Therapeutics (HOWL) shares in this filing?

Shares were sold by affiliated vehicles including MPM Asset Management LLC, MPM BioVentures 2014, L.P., MPM BioVentures 2014(B), L.P., MPM Asset Management Investors BV2014 LLC and MPM Oncology Innovations Fund, L.P. The filing attributes holdings and sales among these entities in detailed footnotes.

How many HOWL shares do Evnin’s affiliated entities hold after these sales?

After the reported transactions, entities associated with Luke Evnin collectively hold 1,953,949 shares of Werewolf Therapeutics Common Stock. Footnotes break this down across AM LLC, BV 2014, BV 2014(B), AM BV2014 and MPM Oncology Innovations Fund, with each entity’s updated balance listed.

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

Yes. A footnote states the transactions were effected pursuant to a plan established under Rule 10b5-1 dated March 26, 2026. Such pre-arranged plans allow insiders to schedule trades in advance, providing structure around timing of sales disclosed here.

At what prices were the Werewolf Therapeutics (HOWL) shares sold?

The Form 4 reports weighted average prices of $0.85, $0.73 and $0.69 per share for the three sale dates. Footnotes explain each day’s sales occurred in multiple transactions within specified price ranges and offer to provide exact breakdowns on request.

Does Luke Evnin claim full beneficial ownership of the HOWL shares in this filing?

No. A footnote explains that Evnin is affiliated with the MPM entities holding the shares but disclaims beneficial ownership of the securities except to the extent of his pecuniary interest. This clarifies his economic exposure versus formal ownership control.