Fairmount Funds Management LLC - Oct 6, 2025 Form 4 Insider Report for Jade Biosciences, Inc. (JBIO)

Signature
/s/ Tomas Kiselak, Managing Member of Fairmount Funds Management LLC
Stock symbol
JBIO
Transactions as of
Oct 6, 2025
Transactions value $
$19,999,816
Form type
4
Date filed
10/8/2025, 04:15 PM
Previous filing
Sep 19, 2025
Next filing
Oct 9, 2025

Reporting Owners (5)

Name Relationship Address Signature Signature date CIK
Fairmount Funds Management LLC Director, 10%+ Owner 200 BARR HARBOR DRIVE, SUITE 400, WEST CONSHOHOCKEN /s/ Tomas Kiselak, Managing Member of Fairmount Funds Management LLC 2025-10-08 0001802528
Fairmount Healthcare Fund II L.P. Director, 10%+ Owner 200 BARR HARBOR DRIVE, SUITE 400, WEST CONSHOHOCKEN /s/ Tomas Kiselak, Managing Member of Fairmount Healthcare Fund II, L.P. 2025-10-08 0001769651
Fairmount Healthcare Co-Invest IV L.P. Director, 10%+ Owner 200 BARR HARBOR DRIVE, SUITE 400, WEST CONSHOHOCKEN /s/ Tomas Kiselak, Managing Member of Fairmount Healthcare Co-Invest IV, L.P. 2025-10-08 0002042283
Kiselak Tomas Director, 10%+ Owner 200 BARR HARBOR DRIVE, SUITE 400, WEST CONSHOHOCKEN /s/ Tomas Kiselak 2025-10-08 0001830177
Harwin Peter Evan Director, 10%+ Owner 200 BARR HARBOR DRIVE, SUITE 400, WEST CONSHOHOCKEN /s/ Peter Harwin 2025-10-08 0001663607

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction JBIO Common Stock Award $12.2M +1.33M +236.14% $9.14 1.9M Oct 6, 2025 By Fairmount Healthcare Fund II L.P. F1, F2
holding JBIO Common Stock 2.66M Oct 6, 2025 By Fairmount Healthcare Co-Invest IV L.P. F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction JBIO Pre-Funded Warrant (Right to Buy) Award $7.82M +855K $9.14 855K Oct 6, 2025 Common Stock 855K $0.00 By Fairmount Healthcare Fund II L.P. F1, F2, F3
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 The shares of Common Stock and Pre-Funded Warrants were purchased from the Issuer in a private placement, which transaction is exempt from Section 16(b) in accordance with Rule 16b-3(d)(1) promulgated under the Securities Exchange Act of 1934, as amended.
F2 Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. and Fairmount Healthcare Co-Invest IV 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.
F3 The Pre-Funded Warrants have no expiration date and are exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of outstanding shares of common stock of the Issuer immediately after giving effect to such exercise.

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.