Evnin-linked entities sell 44,679 HOWL shares

Werewolf Therapeutics director-affiliated entities reported an open-market sale of company stock.

Rhea-AI Filing Summary

Werewolf Therapeutics director-affiliated entities reported an open-market sale of company stock. Entities associated with Luke Evnin sold 44,679 shares of Werewolf Therapeutics common stock at a weighted average price of $0.54 per share in an open-market transaction. The sale was executed on May 13, 2026 under a pre-arranged Rule 10b5-1 trading plan dated March 26, 2026. After this transaction, these entities collectively held 1,126,496 shares indirectly, allocated among several MPM investment vehicles. Evnin disclaims beneficial ownership of these securities except to the extent of his pecuniary interest.

Insider Trade Summary 10b5-1

Net Seller: 44,679 shares

Net Sell 1 txn

Insider EVNIN LUKE

Role Director

Sold 44,679 shs ($24K)

Type	Security	Shares	Price	Value
Sale	Common Stock	44,679	$0.54	$24K

Holdings After Transaction: Common Stock — 1,126,496 shares (Indirect, See Footnotes)

Footnotes (5)

1. F1. Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 dated March 26, 2026.
2. F2. The shares were sold as follows: 4,787 by MPM Asset Management LLC ("AM LLC"), 30,223 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,016 by MPM BIoVentures 2014(B), L.P. ("BV 2014(B)"), 1,040 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 6,613 by MPM Oncology Innovations Fund, L.P. ("MPM OIF").
3. F3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.5077 to $0.61 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. F4. 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. F5. The shares are held as follows: 120,693 by AM LLC, 762,031 by BV 2014, 50,824 by BV 2014(B), 26,227 by AM BV2014 and 166,721 by MPM OIF.

Key Figures

Shares sold: 44,679 shares Weighted average sale price: $0.54 per share Post-transaction holdings: 1,126,496 shares +3 more

6 metrics

Shares sold 44,679 shares Open-market sale on May 13, 2026

Weighted average sale price $0.54 per share Common stock sale

Post-transaction holdings 1,126,496 shares Indirectly held by associated entities after sale

Sale price range $0.5077–$0.61 per share Range of execution prices for sold shares

Shares held by BV 2014 762,031 shares Indirect holding after transaction

Shares held by MPM OIF 166,721 shares Indirect holding after transaction

Key Terms

Rule 10b5-1, weighted average price, pecuniary interest, open-market sale, +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."

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 financial

"direct_or_indirect: I, nature_of_ownership: See Footnotes"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did HOWL disclose for Luke Evnin?

Werewolf Therapeutics reported that entities associated with director Luke Evnin sold 44,679 shares of common stock in an open-market transaction. The sale was conducted at a weighted average price of $0.54 per share, with prices ranging from $0.5077 to $0.61.

At what price were the 44,679 HOWL shares sold in this Form 4?

The 44,679 Werewolf Therapeutics shares were sold at a weighted average price of $0.54 per share. Individual trades occurred in a range from $0.5077 to $0.61, and detailed price breakdowns are available on request from the company or regulators.

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

Yes. The sales reported for entities associated with Luke Evnin were executed under a Rule 10b5-1 trading plan dated March 26, 2026. Such plans pre-schedule trades, making their timing more routine rather than discretionary or opportunistic.

How many HOWL shares do Evnin-linked entities hold after the sale?

Following the transaction, entities associated with Luke Evnin collectively held 1,126,496 shares of Werewolf Therapeutics common stock indirectly. These holdings are spread across several MPM investment vehicles, and Evnin disclaims beneficial ownership beyond his pecuniary interest.

Which entities sold HOWL shares in the reported insider transaction?

The 44,679 Werewolf Therapeutics 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., according to the Form 4 footnotes.

How are the remaining HOWL shares allocated among Evnin-related entities?

After the sale, 1,126,496 Werewolf Therapeutics shares were held as 120,693 by MPM Asset Management LLC, 762,031 by MPM BioVentures 2014, L.P., 50,824 by MPM BioVentures 2014(B), L.P., 26,227 by MPM Asset Management Investors BV2014 LLC, and 166,721 by MPM Oncology Innovations Fund, L.P.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/13/2026 - 04:06 PM Learn about SEC filing dates

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^*

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)
05/13/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/13/2026		S(1)		44,679(2)	D	$0.54(3)	1,126,496	I	See Footnotes(4)(5)

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

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: 4,787 by MPM Asset Management LLC ("AM LLC"), 30,223 by MPM BioVentures 2014, L.P. ("BV 2014"), 2,016 by MPM BIoVentures 2014(B), L.P. ("BV 2014(B)"), 1,040 by MPM Asset Management Investors BV2014 LLC ("AM BV2014") and 6,613 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 $0.5077 to $0.61 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: 120,693 by AM LLC, 762,031 by BV 2014, 50,824 by BV 2014(B), 26,227 by AM BV2014 and 166,721 by MPM OIF.

	/s/ Luke Evnin	05/13/2026
	** 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)