Zenas BioPharma (ZBIO): 316,219 Shares Bought, Now 2.21M

Zenas BioPharma insiders and affiliated entities reported an insider purchase on 10/07/2025.

Accepted by SEC EDGAR 10/09/2025 - 04:15 PM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Zenas BioPharma insiders and affiliated entities reported an insider purchase on 10/07/2025. Fairmount Healthcare Fund II L.P. purchased 316,219 shares of common stock at a price of $19 per share, bringing the fund's indirect beneficial ownership to 2,209,025 shares following the transaction. The Form 4 lists Fairmount Funds Management LLC as investment manager and names Tomas Kiselak and Peter Harwin as managers; Kiselak serves on the issuer's board. Signatures on the filing are dated 10/09/2025.

Positive

• 316,219 shares acquired at $19 demonstrates continued capital commitment
• Post-transaction indirect ownership of 2,209,025 shares increases the affiliated group’s stake

Negative

• None.

Insights

Corporate Governance Analyst

Insiders increased an indirect stake via a fund purchase on 10/07/2025.

The transaction shows Fairmount Healthcare Fund II L.P. acquired 316,219 shares at $19, producing an indirect holding of 2,209,025 shares. The filing clarifies that Fairmount Funds Management LLC is the fund's manager and that Tomas Kiselak and Peter Harwin are the managers; Mr. Kiselak also serves on the company's board.

This structure means the purchase was made through an affiliated investment vehicle rather than as a direct personal purchase by the named directors. Monitor periodic Section 16 filings for any subsequent purchases or sales and any changes in ownership percentages in upcoming filings.

Insider Trade Summary

Net Buyer: 316,219 shares

Net Buy 1 txn

Insider Fairmount Funds Management LLC, Fairmount Healthcare Fund II L.P., Kiselak Tomas, Harwin Peter Evan

Role Director | Director | Director | Director

Bought 316,219 shs ($6.01M)

Type	Security	Shares	Price	Value
Purchase	Common Stock	316,219	$19.00	$6.01M

Holdings After Transaction: Common Stock — 2,209,025 shares (Indirect, By Fairmount Healthcare Fund II L.P.)

Footnotes (1)

1. F1. Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. The managers of Fairmount are Peter Harwin and Tomas Kiselak. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

FAQ

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

What did insiders buy in Zenas BioPharma (ZBIO)?

Fairmount Healthcare Fund II L.P. acquired 316,219 shares of Zenas BioPharma common stock at $19 per share on 10/07/2025.

How many ZBIO shares are owned after the reported transaction?

The filing reports an indirect beneficial ownership total of 2,209,025 shares following the transaction.

Who filed the Form 4 reporting the ZBIO transaction?

The Form 4 lists Fairmount Funds Management LLC, Fairmount Healthcare Fund II L.P., Tomas Kiselak, and Peter Harwin as reporting persons, with signatures dated 10/09/2025.

Was the purchase made directly by the directors of Zenas BioPharma?

No. The purchase was made by an affiliated fund (Fairmount Healthcare Fund II L.P.) and is reported as indirect ownership; Tomas Kiselak and Peter Harwin are managers of the investment adviser.

What is the reported price per share for the ZBIO transaction?

The reported price per share is $19.

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

Form 4 Insider Transactions: What Each Field Means →

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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^*

Fairmount Funds Management LLC

(Last) (First) (Middle)

200 BARR HARBOR DRIVE

SUITE 400

(Street)

WEST CONSHOHOCKEN PA 19428

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Zenas BioPharma, Inc. [ ZBIO ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
10/07/2025

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

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

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

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	10/07/2025		P		316,219	A	$19	2,209,025	I	By Fairmount Healthcare Fund II L.P.(1)

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

1. Name and Address of Reporting Person^*

Fairmount Funds Management LLC

(Last) (First) (Middle)

200 BARR HARBOR DRIVE

SUITE 400

(Street)

WEST CONSHOHOCKEN PA 19428

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Fairmount Healthcare Fund II L.P.

(Last) (First) (Middle)

200 BARR HARBOR DRIVE

SUITE 400

(Street)

WEST CONSHOHOCKEN PA 19428

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Kiselak Tomas

(Last) (First) (Middle)

200 BARR HARBOR DRIVE

SUITE 400

(Street)

WEST CONSHOHOCKEN PA 19428

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Harwin Peter Evan

(Last) (First) (Middle)

200 BARR HARBOR DRIVE

SUITE 400

(Street)

WEST CONSHOHOCKEN PA 19428

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. The managers of Fairmount are Peter Harwin and Tomas Kiselak. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Remarks:

Fairmount may be deemed a director by deputization of Issuer by virtue of the fact that Tomas Kiselak serves on the board of directors of the Issuer and is also a Managing Member of Fairmount.

	/s/ Tomas Kiselak, Managing Member of Fairmount Funds Management LLC	10/09/2025
	/s/ Tomas Kiselak, Managing Member of Fairmount Healthcare Fund II, L.P.	10/09/2025
	/s/ Tomas Kiselak	10/09/2025
	/s/ Peter Harwin	10/09/2025
	** 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.