Tokyo-based Sumitomo Corp. posted its first annual loss in its 78-year history, hurt by the copper-trading scandal that rocked world commodity markets last year. The giant trading house, which was founded in 1919, said net losses totaled $1.3 billion for the year ended March 31, contrasted with a profit of $144 million a year earlier. Takashi Nomura, senior managing director, said Sumitomo plans "to tighten risk control for all commodities and financial trading." Sumitomo said last year that it lost $2.6 billion as a result of a decade of unauthorized copper trading by Yasuo Hamanaka, who was fired in June after the scandal broke. Hamanaka, for nearly 10 years the most influential trader in copper markets worldwide, has pleaded guilty to charges of fraud and forgery in connection with the scandal.