The No. 2 U.S. wireless carrier AT&T Inc and the biggest satellite-TV provider DirecTV became the country’s largest pay-TV company on Friday, completing their $48.5 billion merger after receiving final regulatory approval. The newly expanded AT&T leapfrogs the biggest U.S. cable company Comcast Corp. The company said it will serve more than 26 million U.S. customers and more than 19 million in Latin America, making it the world’s biggest pay-TV company.