Burger King Holdings (BKC) is in talks with private equity firm 3G Capital Management about a buyout, according to a person familiar with the matter. The No. 2 U.S. hamburger chain has struggled to repair relations with franchisees and differentiate itself from archrival McDonald's (MCD). Sales fell 1.4 percent, to $2.5 billion, for the year ended June 30. TPG, Bain Capital, and Goldman Sachs Group (GS) bought Burger King from Diageo (DEO) in 2002 and took the company public four years later. They still retain one third of the company.