A logo sits on a customer's shopping basket on the conveyor belt of a check-out desk inside an Asda supermarket. U.K. grocer J Sainsbury Plc is considering a purchase of rival Asda from Walmart Inc., in what could be a multibillion-pound deal creating Britain’s biggest supermarket operator, according to a person familiar with the situation. The companies have held preliminary discussions and could announce an agreement in the coming weeks, said the people, who asked not to be identified because deliberations are private. No final agreement has been reached and talks could still fall apart, they said.