The retail giant is in talks to buy smart television-manufacturer Vizio for more than $2 billion, according to people familiar with the situation. The move would give Walmart more places where it can sell ads and pitch shoppers on goods. … Walmart gets most of its U.S. revenue from its grocery business, which typically has low profit margins. Executives see the Walmart Connect ad unit as a path to heftier profits and a way to generate cash beyond the company’s longtime engine of selling goods through stores.