RCA was formed in 1919 when the U.S. Navy discovered that the British Marconi Company was about to purchase the Alexanderson alternator from General Electric, thus leaving the expansion of the new medium of radio under the control of a foreign company. The U.S. Navy pressured General Electric, AT&T - and later Westinghouse and the United Fruit Company to pool their patents in a cartel. British Marconi sold its U.S. radio interests to RCA. David Sarnoff, who eventually became the president of RCA, pioneered the concept of linking radio receiver sales to organized broadcasts. The success of this concept enabled RCA to become the largest U.S. radio manufacturer. NBC was formed as a radio network in 1926 by Westinghouse, General Electric & RCA. During the 1930's, RCA spent millions on television research and patent buyouts. In 1939, their first line of consumer televisions made its appearance at the New York World's Fair. Sarnoff reapplied his concept of linking broadcasts and set sales by simultaneously beginning regular television broadcasts through RCA's broadcasting wing, NBC.