United Airlines Holdings, Inc. is a publicly traded airline holding company headquartered in the Willis Tower in Chicago. UAH owns and operates United Airlines, Inc. UAL Corporation agreed to change its name to United Continental Holdings in 2010, when an agreement was reached between United and Continental Airlines where the two airlines merged in an $8.5 billion all-stock merger of equals on October 1, 2010. To effect the acquisition, Continental shareholders received 1.05 shares of UAL stock for each Continental share; at the time of closing, it was estimated that United shareholders owned 55% of the merged entity and Continental shareholders owned 45%. The company or its subsidiary airlines also have several other subsidiaries. Once completely combined, United became the world's largest airline, as measured by revenue passenger miles. United is a founding member of the Star Alliance. UAH has major operations at Chicago–O'Hare, Denver, Guam, Houston–Intercontinental, Los Angeles, New York/Newark, San Francisco, and Washington–Dulles. Additionally, UAH's United is the largest U.S. carrier to the People's Republic of China and maintains a large operation throughout Asia. Wikipedia