ORBIMED ADVISORS LLC - 15 Oct 2024 Form 4 Insider Report for Upstream Bio, Inc. (UPB)

Footnote F1

Each share of Series A redeemable convertible preferred stock and Series B redeemable convertible preferred stock automatically converted into shares of the Issuer's common stock on a one-for-1.049 basis immediately prior to the closing of the Issuer's initial public offering and have no expiration date.

Footnote F2

These securities are held of record by OrbiMed Israel Partners II, L.P. ("OIP II"). OrbiMed Israel GP II, L.P. ("Israel GP") is the general partner of OIP II, and OrbiMed Advisors Israel II Limited ("Advisors II") is the general partner of Israel GP. By virtue of such relationships, Israel GP and Advisors II may be deemed to have voting and investment power over the securities held by OIP II and, as a result, may be deemed to have beneficial ownership over such securities. Advisors II exercises voting and investment power through an investment committee comprised of Carl L. Gordon, David P. Bonita, and Erez Chimovits ("Chimovits"), each of whom disclaims beneficial ownership of the securities held by OIP II.

Footnote F3

These securities are held of record by OrbiMed Private Investments VIII, LP ("OPI VIII"). OrbiMed Capital GP VIII LLC ("GP VIII") is the general partner of OPI VIII, and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VIII. By virtue of such relationships, GP VIII and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VIII and, as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the securities held by OPI VIII.

Footnote F4

Each of Advisors II, Israel GP, OrbiMed Advisors, and GP VIII disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors, GP VIII. Advisors II, and Israel GP have designated a representative, Chimovits, an employee of OrbiMed Advisors and a director of Advisors II, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such person or entity is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.