Sionna Therapeutics (SION) Proxy filing summary

Executive summary

• The 2026 annual meeting will be held virtually on June 17, 2026, with shareholders able to vote online or by phone or mail, using a 16-digit control number for access and voting.

• Shareholders of record as of April 21, 2026, are entitled to vote on the election of four class II directors and the ratification of Deloitte & Touche LLP as the independent auditor for 2026.

• The company uses the SEC's "Notice and Access" rule to provide proxy materials online, reducing costs and environmental impact.

• The board recommends voting FOR all director nominees and FOR the auditor ratification.

Voting matters and shareholder proposals

• Shareholders will vote on electing four class II directors for three-year terms and ratifying Deloitte & Touche LLP as auditor for 2026.

• Shareholders may submit proposals for the 2027 meeting by December 28, 2026, and must follow advance notice procedures for nominations or other business.

• Universal proxy rules apply for shareholders nominating directors, requiring notice by the same deadline.

Board of directors and corporate governance

• The board is divided into three classes with staggered terms; class II nominees are H. Edward Fleming, Jr., Marcella Kuhlman Ruddy, Peter A. Thompson, and Joanne Louise Viney.

• Most directors are independent under NASDAQ and SEC rules, except the CEO.

• The board has audit, compensation, and nominating/governance committees, each with independent members and written charters.

• The board chair and CEO roles are separated to enhance governance.

• Directors are expected to attend meetings and the annual meeting; most attended at least 75% of meetings in 2025.