AT&T has been one of Mexico's biggest carriers for over a decade, but that's about to come to an end. The company has announced that it has reached an agreement to sell AT&T Mexico to Grupo Televisa and Fintech Holdings for $2 billion in cash at closing, "subject to certain adjustments", plus "additional contractual and contingent benefits".The buyer is a consortium owned 50/50 by Televisa and Fintech, which plans to pay with a combination of cash on hand and debt financing. What it's getting is Mexico's second-largest mobile operator, with about 24.7 million wireless subscribers at the...