Walmart has 28 million Facebook fans. "It's the biggest fan page in the United States," Kerry Lakin, a senior account manager for Facebook, told an audience of national retail executives and others in Tucson Friday at the University of Arizona's Global Retailing Conference. "That's more fans than Facebook has," Lakin said. Building relationships with customers through social-media platforms was a hot topic Friday at the retailing conference at Loews Ventana Canyon, where fashion designer Tory Burch also spoke.