Alan S. Armstrong resigned from The Williams Companies Inc. (NYSE: WMB) board of directors on March 23, 2026, to accept an appointment as United States Senator representing Oklahoma, according to a company statement.

Armstrong was sworn in as senator on March 24, 2026, after being appointed by Oklahoma Governor Kevin Stitt. He fills the Senate seat previously held by Markwayne Mullin, who was appointed by President Donald Trump and confirmed by the Senate to serve as Secretary of the Department of Homeland Security.

Armstrong served as executive board chair at Williams and was a member of the board's Environmental, Health and Safety Committee before his resignation took effect at the end of March 23, 2026.