First reported by Cable News Networks’ (C.N.N. Business; New York) Senior Business Writer Chris Isidore: https://www.cnn.com/2021/06/03/investing/united-supersonic-flights/index.html
Below verbatim quotes are from the C.N.N. article referenced herein.
“United is buying the supersonic jet from Boom Supersonic, a privately held upstart aircraft maker based in Denver. The plane, dubbed the “Overture,” is slated to be completed by 2025, start test flights by 2026 and carry passengers by 2029. United has agreed to buy 15 of the jets, with options for 35 more.”