Director-linked MPM funds trim Werewolf Therapeutics (HOWL) stake under 10b5-1 plan

Filing Impact

(Moderate)

Filing Sentiment

(Negative)

Form Type

Rhea-AI Filing Summary

Werewolf Therapeutics, Inc. director-associated investment entities reported open-market sales of an aggregate 407,574 shares of Common Stock in three transactions. The sales occurred on May 8, May 11, and May 12 at weighted average prices of $0.70, $0.67, and $0.64 per share, respectively. After these transactions, entities associated with Luke Evnin collectively held 1,171,175 shares indirectly. The filing notes the trades were effected under a pre-established Rule 10b5-1 trading plan, indicating they were pre-planned rather than discretionary.

Insights

Pre-planned fund sales reduce but do not exit an indirect HOWL stake.

Investment entities associated with director Luke Evnin executed three open-market sales totaling 407,574 Werewolf Therapeutics shares at prices between $0.6183 and $0.7668. These are reported as indirect holdings, reflecting venture funds and LLCs rather than Evnin’s personal account.

The filing states the transactions were carried out under a Rule 10b5-1 plan dated March 26, 2026. Such plans are pre-arranged and can signal routine portfolio management rather than an active timing decision. Following the sales, the associated entities still hold 1,171,175 shares, so the position remains sizable.

Footnotes detail allocation of both the sales and remaining holdings across multiple MPM vehicles, and Evnin disclaims beneficial ownership beyond his pecuniary interest. Subsequent ownership updates in future Forms 4 will show whether these planned dispositions continue or taper as the trading plan progresses.

Insider Trade Summary 10b5-1

Net Seller: 407,574 shares ($280,210)

Net Sell 3 txns

Insider EVNIN LUKE

Role null

Sold 407,574 shs ($280K)

Type	Security	Shares	Price	Value
Sale	Common Stock	67,885	$0.64	$43K
Sale	Common Stock	33,948	$0.67	$23K
Sale	Common Stock	305,741	$0.70	$214K

Holdings After Transaction: Common Stock — 1,171,175 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: 32,757 by MPM Asset Management LLC ("AM LLC"), 206,820 by MPM BioVentures 2014, L.P. ("BV 2014"), 13,795 by MPM BIoVentures 2014(B), L.P. ("BV 2014(B)"), 7,119 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 45,250 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 $0.6183 to $0.7668 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: 136,390 by AM LLC, 861,140 by BV 2014, 57,435 by BV 2014(B), 29,638 by AM BV2014 and 188,405 by MPM OIF. The shares were sold as follows: 3,637 by AM LLC, 22,965 by BV 2014, 1,532 by BV 2014(B), 790 by AM BV2014 and 5,024 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 $0.66 to $0.7002 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: 132,753 by AM LLC, 838,175 by BV 2014, 55,903 by BV 2014(B), 28,848 by AM BV2014 and 183,381 by MPM OIF. The shares were sold as follows: 7,273 by AM LLC, 45,921 by BV 2014, 3,063 by BV 2014(B), 1,581 by AM BV2014 and 10,047 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 $0.6286 to $0.66 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: 125,480 by AM LLC, 792,254 by BV 2014, 52,840 by BV 2014(B), 27,267 by AM BV2014 and 173,334 by MPM OIF.

Key Figures

Total shares sold: 407,574 shares Shares sold on May 8: 305,741 shares at $0.70 Shares sold on May 11: 33,948 shares at $0.67 +4 more

7 metrics

Total shares sold 407,574 shares Aggregate open-market sales reported in this Form 4

Shares sold on May 8 305,741 shares at $0.70 Common Stock open-market sale on 2026-05-08

Shares sold on May 11 33,948 shares at $0.67 Common Stock open-market sale on 2026-05-11

Shares sold on May 12 67,885 shares at $0.64 Common Stock open-market sale on 2026-05-12

Post-transaction holdings 1,171,175 shares Indirect ownership after the latest reported sale

Price range (May 8 block) $0.6183–$0.7668 Weighted-average sale price range noted in footnote

Price range (later trades) $0.6286–$0.7002 Additional weighted-average sale price ranges from footnotes

Key Terms

Rule 10b5-1, weighted average price, beneficial ownership, pecuniary interest, +2 more

6 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.

beneficial ownership regulatory

"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.

pecuniary interest financial

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

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.

indirect ownership financial

""ownership_type": "indirect""

Form 4 Insider Transactions: What Each Field Means →

05/12/2026 - 07:47 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)
05/08/2026

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	05/08/2026		S⁽¹⁾		305,741⁽²⁾	D	$0.7⁽³⁾	1,273,008	I	See Footnotes⁽⁴⁾⁽⁵⁾
Common Stock	05/11/2026		S⁽¹⁾		33,948⁽⁶⁾	D	$0.67⁽⁷⁾	1,239,060	I	See Footnotes⁽⁴⁾⁽⁸⁾
Common Stock	05/12/2026		S⁽¹⁾		67,885⁽⁹⁾	D	$0.64⁽¹⁰⁾	1,171,175	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: 32,757 by MPM Asset Management LLC ("AM LLC"), 206,820 by MPM BioVentures 2014, L.P. ("BV 2014"), 13,795 by MPM BIoVentures 2014(B), L.P. ("BV 2014(B)"), 7,119 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 45,250 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 $0.6183 to $0.7668 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: 136,390 by AM LLC, 861,140 by BV 2014, 57,435 by BV 2014(B), 29,638 by AM BV2014 and 188,405 by MPM OIF.

6. The shares were sold as follows: 3,637 by AM LLC, 22,965 by BV 2014, 1,532 by BV 2014(B), 790 by AM BV2014 and 5,024 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 $0.66 to $0.7002 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: 132,753 by AM LLC, 838,175 by BV 2014, 55,903 by BV 2014(B), 28,848 by AM BV2014 and 183,381 by MPM OIF.

9. The shares were sold as follows: 7,273 by AM LLC, 45,921 by BV 2014, 3,063 by BV 2014(B), 1,581 by AM BV2014 and 10,047 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 $0.6286 to $0.66 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: 125,480 by AM LLC, 792,254 by BV 2014, 52,840 by BV 2014(B), 27,267 by AM BV2014 and 173,334 by MPM OIF.

	/s/ Luke Evnin	05/12/2026
	** 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 did the latest Form 4 for Werewolf Therapeutics (HOWL) report?

The Form 4 reports that investment entities associated with director Luke Evnin sold 407,574 shares of Werewolf Therapeutics Common Stock in three open-market transactions, while continuing to hold 1,171,175 shares indirectly after the trades, according to the disclosed post-transaction ownership figure.

How many HOWL shares were sold in the recent insider transactions?

The filing shows total sales of 407,574 Werewolf Therapeutics shares. These occurred in three tranches: 305,741 shares, 33,948 shares, and 67,885 shares, each reported as open-market transactions executed by venture and fund entities associated with director Luke Evnin.

At what prices were Werewolf Therapeutics (HOWL) shares sold in the Form 4?

Reported weighted average prices were $0.70, $0.67, and $0.64 per share. Footnotes note that individual trades occurred over ranges from $0.6183 to $0.7668, with the reporting person offering to provide detailed price breakdowns on request to investors or regulators.

Were the HOWL insider sales by Luke Evnin discretionary or pre-planned?

The Form 4 states the transactions were effected pursuant to a Rule 10b5-1 plan dated March 26, 2026. Rule 10b5-1 trading plans are pre-established arrangements, indicating these sales were scheduled in advance rather than timed in response to short-term market developments.

How many Werewolf Therapeutics (HOWL) shares remain held after the reported sales?

After the reported transactions, entities associated with Luke Evnin collectively hold 1,171,175 shares of Werewolf Therapeutics Common Stock indirectly. Footnotes allocate these shares among several MPM-related funds and LLCs, and Evnin disclaims beneficial ownership beyond his pecuniary interest.

Who actually holds the HOWL shares mentioned in Luke Evnin’s Form 4?

The shares are held by several MPM-related entities, including MPM Asset Management LLC, MPM BioVentures 2014, L.P., related partnerships and LLCs, and MPM Oncology Innovations Fund, L.P. The filing notes Evnin’s roles in these entities and his disclaimer of full beneficial ownership.