IMM was founded by shipping magnates Clement Griscom of the American Line and Red Star Line, Bernard N. Baker of the Atlantic Transport Line, J. Bruce Ismay of the White Star Line, and John Ellerman of the Leyland Line. The Dominion Line was also amalgamated. The project was bankrolled by J.P. Morgan & Co., led by financier J. P. Morgan. The company also had working profit-sharing relationships with the German Hamburg-Amerika and the North German Lloyd lines. The trust caused great concern in the British shipping industry and led directly to the British government's subsidy of the Cunard Line's new ships RMS "Lusitania" and RMS "Mauretania" in an effort to compete.