The story
Founded by Frederick Rentschler and William Boeing on Feb 1, 1929.1
The holding company controlled the stock of several aviation manufacturing companies, including the Boeing Airplane Company, Northrop Aircraft Corporation, Chance Vought Corporation, Hamilton Aero Manufacturing Company, Pratt & Whitney Aircraft Company, Sikorsky Aviation Corporation, and Stearman Aircraft Company. At its founding, the company initially controlled three airlines, Boeing Air Transport, Pacific Air Transport, and Stout Air Services. Other United Operations included the Boeing School of Aeronautics, United Aircraft Exports, United Airports Company of California, which built Burbank Airport, and the United Airports of Connecticut, which built factories in East Hartford for Pratt & Whitney and Chance Vought. The first annual report lists William Boeing as chairman, Frederick Rentschler as president, and Chance M. Vought, Philip G. Johnson, and George Wheat as vice presidents.
The Standard Steel Propeller Company were added to United's portfolio shortly thereafter, followed by two airlines in 1930, Varney Air Lines and National Air Transport. The airline interests were soon grouped under a new management company known as United Air Lines, Inc. However, the individual airlines (as well as the individual companies held by United) continued to operate under their own names.
From Wikipedia’s article on United Aircraft and Transport Corporation, shared under CC BY-SA 4.0.3