Yasuo Hamanaka was in charge of copper trading at Sumitomo Corporation. Seeking to recover the lossess his company suffered in the early 1980s, the trader developed and began to implement a grand plan to corner the world's copper markets and drive up the value of the metal. The the fraud was revealed 10 years later. Over this period, the copper price increased 1.5-2 times: up to $2,700-3,000 per ton.
As a result of the trader's efforts, his company began to control up to 5% of the world's copper reserves. The trader took control of another 3-4% illegally, using borrowed funds. At one point it was all over. In 1998, "Mr. Copper" was sentenced to eight years in jail. Sumitomo suffered $2.6 billion USD in losses from Hamanaka's trading activities.
