America Movil SAB from Mexico, Latin America’s largest wireless carrier, fell the most in 10 months after announcing plans to take over its sister fixed-line companies in a deal valued at more than $20 billion.

The company, controlled by Mexican billionaire Carlos Slim, said yesterday that it would offer stock worth about 215 billion pesos ($17 billion) for a holding company that controls South American carrier Telmex Internacional SAB. America Movil would then offer as much as 82.5 billion pesos in cash, or less in stock, for the rest of Telmex, also controlled by Slim.

• Telmex Internacional operates phone and cable-TV networks in Brazil, Colombia, Argentina, Chile, Ecuador, Peru and Uruguay. The company’s revenue in Brazil, its biggest market, rose 7.6 percent in the third quarter to 2.7 billion reais ($1.53 billion), boosted by Internet and corporate sales.

• Telmex Internacional owns 98 percent of Embratel Participacoes SA, the former long-distance unit of the state-run phone utility that was split up and sold in 1998. Embratel has branched out into local phone, Internet and satellite TV service and holds a stake of about one-third in Net Servicos de Comunicacao SA, Brazil’s biggest pay-TV company, which also offers digital phone and Internet plans.

Brazil is America Movil’s second-largest unit, with 42.3 million subscribers at the end of September. Slim’s companies in the country compete with wireless and landline companies controlled by Madrid-based Telefonica SA, which also has mobile- phone operations in Mexico and throughout Latin America. Tele Norte Leste Participacoes SA, based in Rio de Janeiro, also has wireless and fixed-line phone businesses in Brazil.

“I’m not opposed to them becoming more exposed to Brazil,” Christopher King, an analyst at Stifel Nicolaus & Co., said yesterday in a phone interview from Baltimore. He advises buying America Movil shares. “It’s probably not a bad thing, given the state of the Brazilian economy.”