RA CAPITAL MANAGEMENT, L.P. - 10 Feb 2025 Form 4 Insider Report for Sionna Therapeutics, Inc. (SION)

Footnote F1

Each share of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock (collectively the "Preferred Stock") converted into shares of Common Stock of the Issuer on a one-for-1.4611 basis upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date.

Footnote F2

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

Footnote F3

RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III"), 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, he Nexus Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Footnote F4

Held directly by the Nexus Fund.

Footnote F5

Held directly by Nexus Fund III.

Footnote F6

Held directly by the Account.