Japan’s largest e-commerce firm Rakuten Inc (4755.T) said it was in talks to buy U.S. Shares of Rakuten fell 4.4 percent in mid-morning trade, underperforming the benchmark Nikkei (.N225), which was flat. Rakuten said in a statement it was in talks but that no final decision on the deal had been made yet. Ebates operates websites offering rebates and coupons from retailers including Amazon.com and Best Buy.