MEXICO CITY – Grupo Carso, which is owned by Mexican billionaire Carlos Slim, said Monday it acquired 60 percent of the Mexico subsidiary of U.S.-based Bronco Drilling Co. for $30 million. Carso said in a filing with Mexican securities regulators that it reached an agreement on Sept. 18 with Bronco Drilling Mexico, a firm involved in “the operation, leasing and maintenance of drilling rigs, and the repair of oil and gas wells in Mexico and Latin America.” “In addition, Grupo Carso ...