Continental Airlines jets at the gate at Liberty International Airport in Newark, New Jersey. United Airlines and Continental Airlines announced they had completed their merger that creates the world’s biggest carrier. The new firm begins trading on the New York Stock Exchange as United Continental Holdings, with the symbol UAL. “This is a true merger of equals, bringing together two strong companies and positioning us to succeed in a dynamic and highly-competitive global aviation industry,” said Glenn Tilton, the United Airlines chief who is the non-executive chairman of the new firm.