Upstream Bio (UPB) Proxy filing summary

Executive summary

• The annual meeting will be held virtually on June 9, 2026, with shareholders able to vote online or by proxy.

• Shareholders will vote on electing two class II directors and ratifying the appointment of PwC as the independent auditor for 2026.

• The company uses online proxy materials to reduce costs and environmental impact.

• Only common stockholders as of April 13, 2026, are entitled to vote; each share equals one vote.

Voting matters and shareholder proposals

• Proposal 1: Elect two class II directors (H. Edward Fleming, Jr., M.D. and Liam Ratcliffe, M.B.Ch.B., Ph.D.) for three-year terms expiring in 2029.

• Proposal 2: Ratify PwC as independent registered public accounting firm for fiscal year ending December 31, 2026.

• Shareholders may submit proposals for the 2027 meeting by December 17, 2026, or nominate directors with advance notice.

Board of directors and corporate governance

• The board is divided into three classes with staggered three-year terms; currently seven members.

• All directors except the CEO are considered independent under Nasdaq and SEC rules.

• Board committees include audit, compensation, and nominating/governance, each with defined charters and responsibilities.

• The chairperson and CEO roles are separated to enhance governance.

• Directors are expected to attend at least 75% of meetings and the annual meeting.