Samsung Electronics Co. on Tuesday estimated its fourth-quarter operating profit at 2.8 trillion won (US$2.1 billion), down 35 percent from a year earlier.Revenue decreased 4.9 percent to 67 trillion won. The data for net earnings was not available.The operating profit was 29.3 percent lower than the average estimate, according to a survey by Yonhap Infomax, the financial data firm of Yonhap News Agency.The company will release its final earnings report later.(END)Source: Yonhap News Agency