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

Werewolf Therapeutics (NASDAQ: HOWL) entities sell 274K shares

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

Rhea-AI Filing Summary

Werewolf Therapeutics, Inc. director-related investment entities completed open-market sales of a total of 274,619 shares of common stock associated with Luke Evnin. The trades occurred on April 30, May 1 and May 4 at weighted average prices around $0.72–$0.73 per share.

The sales were executed by MPM Asset Management LLC and several MPM BioVentures and MPM Oncology Innovations funds pursuant to a Rule 10b5-1 trading plan dated March 26, 2026. After these transactions, the entities collectively hold 1,679,330 shares, which Evnin reports indirectly and for which he disclaims beneficial ownership beyond his pecuniary interest.

Positive

  • None.

Negative

  • None.
Insider EVNIN LUKE
Role null
Sold 274,619 shs ($198K)
Type Security Shares Price Value
Sale Common Stock 47,963 $0.72 $35K
Sale Common Stock 58,394 $0.73 $43K
Sale Common Stock 168,262 $0.72 $121K
Holdings After Transaction: Common Stock — 1,679,330 shares (Indirect, See Footnotes)
Footnotes (1)
  1. Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 dated March 26, 2026. The shares were sold as follows: 18,028 by MPM Asset Management LLC ("AM LLC"), 113,821 by MPM BioVentures 2014, L.P. ("BV 2014"), 7,592 by MPM BIoVentures 2014(B), L.P. ("BV 2014(B)"), 3,918 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 24,903 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 $0.688 to $0.7458 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: 191,318 by AM LLC, 1,207,945 by BV 2014, 80,567 by BV 2014(B), 41,576 by AM BV2014 and 264,281 by MPM OIF. The shares were sold as follows: 6,256 by AM LLC, 39,501 by BV 2014, 2,635 by BV 2014(B), 1,360 by AM BV2014 and 8,642 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 $0.7011 to $0.74 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: 185,062 by AM LLC, 1,168,444 by BV 2014, 77,932 by BV 2014(B), 40,216 by AM BV2014 and 255,639 by MPM OIF. The shares were sold as follows: 5,139 by AM LLC, 32,445 by BV 2014, 2,164 by BV 2014(B), 1,117 by AM BV2014 and 7,098 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 $0.69 to $0.7497 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: 179,923 by AM LLC, 1,135,999 by BV 2014, 75,768 by BV 2014(B), 39,099 by AM BV2014 and 248,541 by MPM OIF.
Total shares sold 274,619 shares Open-market sales across April 30, May 1 and May 4
Sale on April 30, 2026 168,262 shares at $0.72/share Common Stock, indirect open-market sale
Sale on May 1, 2026 58,394 shares at $0.73/share Common Stock, indirect open-market sale
Sale on May 4, 2026 47,963 shares at $0.72/share Common Stock, indirect open-market sale
Shares held after transactions 1,679,330 shares Indirectly held across multiple MPM-managed entities
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.
open-market sale financial
"transaction_action": "open-market sale""
An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.
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.
Form 4 Insider Transactions: What Each Field Means →
SEC Form 4
FORM 4UNITED 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*
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)
XDirector10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
04/30/2026		6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock04/30/2026S(1)168,262(2)D$0.72(3)1,785,687ISee Footnotes(4)(5)
Common Stock05/01/2026S(1)58,394(6)D$0.73(7)1,727,293ISee Footnotes(4)(8)
Common Stock05/04/2026S(1)47,963(9)D$0.72(10)1,679,330ISee 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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
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: 18,028 by MPM Asset Management LLC ("AM LLC"), 113,821 by MPM BioVentures 2014, L.P. ("BV 2014"), 7,592 by MPM BIoVentures 2014(B), L.P. ("BV 2014(B)"), 3,918 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 24,903 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 $0.688 to $0.7458 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: 191,318 by AM LLC, 1,207,945 by BV 2014, 80,567 by BV 2014(B), 41,576 by AM BV2014 and 264,281 by MPM OIF.
6. The shares were sold as follows: 6,256 by AM LLC, 39,501 by BV 2014, 2,635 by BV 2014(B), 1,360 by AM BV2014 and 8,642 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 $0.7011 to $0.74 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: 185,062 by AM LLC, 1,168,444 by BV 2014, 77,932 by BV 2014(B), 40,216 by AM BV2014 and 255,639 by MPM OIF.
9. The shares were sold as follows: 5,139 by AM LLC, 32,445 by BV 2014, 2,164 by BV 2014(B), 1,117 by AM BV2014 and 7,098 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 $0.69 to $0.7497 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: 179,923 by AM LLC, 1,135,999 by BV 2014, 75,768 by BV 2014(B), 39,099 by AM BV2014 and 248,541 by MPM OIF.
/s/ Luke Evnin05/04/2026
** Signature of Reporting PersonDate
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 activity did Werewolf Therapeutics (HOWL) report in this Form 4?

Werewolf Therapeutics reported that investment entities associated with director Luke Evnin sold 274,619 shares of common stock in three open-market transactions. The trades occurred between April 30 and May 4 at weighted average prices near $0.72–$0.73 per share.

At what prices were the HOWL shares sold by entities linked to Luke Evnin?

The entities sold Werewolf Therapeutics shares at weighted average prices of $0.72 and $0.73 per share. Footnotes specify that individual trades occurred in ranges between $0.688 and $0.7497 per share across the three reported trading days.

How many Werewolf Therapeutics (HOWL) shares were sold on each reported date?

The entities sold 168,262 shares on April 30 at $0.72, 58,394 shares on May 1 at $0.73, and 47,963 shares on May 4 at $0.72. Together, these open-market sales totaled 274,619 shares of Werewolf Therapeutics common stock.

How many HOWL shares remain held by the entities after these Form 4 sales?

After the reported transactions, the entities collectively hold 1,679,330 Werewolf Therapeutics shares. These are spread across several MPM-managed entities, and Luke Evnin reports them as indirect holdings while disclaiming beneficial ownership beyond his pecuniary interest.

Were the HOWL insider sales by Luke Evnin’s associated entities pre-planned?

Yes. A footnote states the transactions were effected pursuant to a Rule 10b5-1 trading plan dated March 26, 2026. Such plans are pre-arranged trading programs, meaning the timing of these sales was determined in advance rather than decided opportunistically.

Which entities sold Werewolf Therapeutics (HOWL) shares in this Form 4?

The shares were sold by 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. These entities are associated with director Luke Evnin through various management roles.