RA CAPITAL MANAGEMENT, L.P. - 28 Apr 2025 Form 4 Insider Report for Jade Biosciences, Inc. (JBIO)

Footnote F1

On April 28, 2025, the Issuer completed the transactions contemplated by the Agreement and Plan of Merger, dated October 30, 2024, by and among the Issuer, Caribbean Merger Sub I, Inc. ("Merger Sub I"), Caribbean Merger Sub II, LLC ("Merger Sub II") and Jade Biosciences, Inc. (" Old Jade"), pursuant to which, Merger Sub I merged with and into Old Jade, with Old Jade surviving the merger as the surviving corporation (the "First Merger"), and as part of the same overall transaction, Old Jade merged with and into Merger Sub II, with Merger Sub II continuing as a wholly owned subsidiary of the Issuer and the surviving corporation of the merger (the "Second Merger"). At the effective time of the First Merger, each share of Old Jade common stock was converted based on an exchange ratio (after giving effect to the Reverse Stock Split, as defined below) of 0.6311 shares of the Issuer's common stock for each share of Old Jade common stock.

Footnote F2

On April 28, 2025, the Issuer effected a 1-for-35 reverse stock split of its common stock stock (the "Reverse Stock Split"). The share counts herein reflect the reverse stock split.

Footnote F3

Held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

Footnote F4

RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, the Fund, the Nexus Fund, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Footnote F5

Held directly by the Nexus Fund.

Footnote F6

Held directly by the Account.