Mexican billionaire Carlos Slim's telecommunications giant America Movil has agreed to sell its US subsidiary Tracfone to Verizon for $6.25 billion, the companies announced Monday. America Movil, one of the world's largest mobile network operators, said half of the payment would be in cash and half in Verizon shares. Verizon also stands to gain up to an additional $650 million in cash if certain performance-related targets are achieved, the two firms said. With around 21 million subscribers, Tracfone is a leading provider of pre-paid mobile services in the United States and a longtime partner of Verizon, the US giant said. America Movil, which operates across much of Latin America, the United States and in central and eastern Europe, has helped to make Slim one of the world's richest men. dr/sst