Sumitomo copper affair
The Sumitomo copper affair refers to a metal trading scandal in 1996 involving Yasuo Hamanaka, the chief copper trader of the Japanese trading house Sumitomo Corporation (Sumitomo). The scandal involves unauthorized trading over a 10-year period by Hamanaka, which led Sumitomo to announce US$1.8 billion in related losses in 1996 when Hamanaka's trading was discovered, and more related losses subsequently.