Jade Biosciences grants 34,843-share option to director

Jade Biosciences, Inc. reported a compensation-related insider transaction involving a stock option grant.

Rhea-AI Filing Summary

Jade Biosciences, Inc. reported a compensation-related insider transaction involving a stock option grant. Director Tomas Kiselak received an option covering 34,843 shares of common stock at an exercise price of $15.22 per share, with no cash paid for the grant itself.

The option vests in full on the earlier of June 9, 2027 or the date of the next annual meeting of stockholders, subject to Kiselak’s continued service to the company. The option expires on June 8, 2036, giving a long-dated right to purchase shares once vested.

A footnote explains that Kiselak holds this option for one or more investment vehicles managed by Fairmount Funds Management LLC, and he must turn over any net cash or stock from the option to Fairmount for the benefit of the relevant Fairmount fund. Fairmount, Peter Harwin, and Kiselak each disclaim beneficial ownership of the securities except to the extent of any pecuniary interest.

Insider Trade Summary

Grant/Award: 34,843 shares

Grant/Award 1 txn

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

Role Director, 10% Owner | Director, 10% Owner | Director, 10% Owner | Director, 10% Owner | Director, 10% Owner

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	34,843	$0.00	$0.00

Holdings After Transaction: Stock Option (Right to Buy) — 34,843 contracts (Direct)

Footnotes (2)

1. F1. This option represents a right to purchase shares of the Issuer's common stock, which vests in full on the earlier of (i) June 9, 2027 or (ii) the date of the next annual meeting of the Issuer's stockholders, in each case, subject to Tomas Kiselak's continued service to the Issuer.
2. F2. Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II LP ("Fund II") and Fairmount Healthcare Co-Invest IV L.P. ("Co-Invest"). Peter Harwin and Tomas Kiselak are the managers of Fairmount. Under Mr. Kiselak's arrangement with Fairmount, Mr. Kiselak holds the option for one or more investment vehicles managed by Fairmount (each, a "Fairmount Fund"). Mr. Kiselak is obligated to turn over to Fairmount any net cash or stock received from the option for the benefit of such Fairmount Fund. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Key Figures

Option shares granted: 34,843 shares Exercise price: $15.22 per share Option expiration: June 8, 2036 +3 more

6 metrics

Option shares granted 34,843 shares Stock Option (Right to Buy) granted to Tomas Kiselak

Exercise price $15.22 per share Conversion or exercise price of the stock option

Option expiration June 8, 2036 Expiration date of the stock option

Vesting date trigger June 9, 2027 Vests on earlier of this date or next annual meeting

Grant price paid $0.00 per option Transaction price per option share on grant

Options held after grant 34,843 options Total shares following transaction in derivative position

Key Terms

Stock Option (Right to Buy), vests in full, investment manager, pecuniary interest, +1 more

5 terms

Stock Option (Right to Buy) financial

"This option represents a right to purchase shares of the Issuer's common stock"

vests in full financial

"which vests in full on the earlier of (i) June 9, 2027 or (ii) the date of the next annual meeting"

investment manager financial

"Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II LP"

pecuniary interest financial

"disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein"

beneficial ownership financial

"disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest"

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.

FAQ

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

What insider transaction did Jade Biosciences (JBIO) report on this Form 4?

Jade Biosciences reported a stock option grant to director Tomas Kiselak for 34,843 shares of common stock. The option is a compensation award, not an open-market trade, and gives a right to buy shares at a fixed exercise price.

How many Jade Biosciences (JBIO) shares are covered by the new option grant?

The option grant covers 34,843 shares of Jade Biosciences common stock. This represents the total number of underlying shares tied to the award and equals Kiselak’s total option holdings following the reported transaction in this filing.

What is the exercise price and expiration date of the JBIO option granted to Tomas Kiselak?

The option has an exercise price of $15.22 per share and expires on June 8, 2036. This long-term option lets the holder buy Jade Biosciences shares at that fixed price once the award is fully vested.

When does the new Jade Biosciences (JBIO) stock option to Tomas Kiselak vest?

The option vests in full on the earlier of June 9, 2027 or the date of Jade Biosciences’ next annual stockholder meeting. Vesting in both cases is conditioned on Tomas Kiselak’s continued service to the company through that vesting date.

Who ultimately benefits from the JBIO option granted to Tomas Kiselak?

According to the filing, Kiselak holds the option for one or more Fairmount-managed investment vehicles. He must turn over any net cash or stock from the option to Fairmount for the benefit of the relevant Fairmount fund, subject to pecuniary interest.

Do Fairmount and the managers claim beneficial ownership of the new Jade Biosciences option?

Fairmount Funds Management, Peter Harwin, and Tomas Kiselak each disclaim beneficial ownership of the reported securities, except to the extent of their pecuniary interest. This clarifies that economic exposure is limited to any actual financial stake they may hold.

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

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Accepted by SEC EDGAR 06/11/2026 - 04:37 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).

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 PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Jade Biosciences, Inc. [ JBIO ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/09/2026

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

	Form filed by One Reporting Person
X	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

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
Stock Option (Right to Buy)	$15.22	06/09/2026		A		34,843		(1)	06/08/2036	Common Stock	34,843	$0	34,843	D(2)

1. Name and Address of Reporting Person^*

Fairmount Funds Management LLC

(Last) (First) (Middle)

200 BARR HARBOR DRIVE, SUITE 400

(Street)

WEST CONSHOHOCKEN PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	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 PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Fairmount Healthcare Co-Invest IV L.P.

(Last) (First) (Middle)

200 BARR HARBOR DRIVE, SUITE 400

(Street)

WEST CONSHOHOCKEN PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	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 PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	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 PENNSYLVANIA 19428

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. This option represents a right to purchase shares of the Issuer's common stock, which vests in full on the earlier of (i) June 9, 2027 or (ii) the date of the next annual meeting of the Issuer's stockholders, in each case, subject to Tomas Kiselak's continued service to the Issuer.

2. Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II LP ("Fund II") and Fairmount Healthcare Co-Invest IV L.P. ("Co-Invest"). Peter Harwin and Tomas Kiselak are the managers of Fairmount. Under Mr. Kiselak's arrangement with Fairmount, Mr. Kiselak holds the option for one or more investment vehicles managed by Fairmount (each, a "Fairmount Fund"). Mr. Kiselak is obligated to turn over to Fairmount any net cash or stock received from the option for the benefit of such Fairmount Fund. 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, Fairmount Healthcare Fund II L.P. and Fairmount Healthcare Co-Invest IV L.P. may each be deemed a director by deputization of the 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	06/11/2026
	/s/ Tomas Kiselak, Managing Member of Fairmount Healthcare Fund II L.P.	06/11/2026
	/s/ Tomas Kiselak, Managing Member of Fairmount Healthcare Co-Invest IV L.P.	06/11/2026
	/s/ Tomas Kiselak	06/11/2026
	/s/ Peter Harwin	06/11/2026
	** 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)