Yasuo Hamanaka

Who is Yasuo Hamanaka?

Yasuo Hamanaka is a man who formerly was the chief copper trader at Sumitomo Corporation, one of the largest trading companies in Japan, and was also known as "Mr. Copper" because of his aggressive trading style and "Mr. Five Percent" because that is how much of the world's yearly supply he controlled.

On June 13, 1996, Sumitomo Corporation reported a loss of 1.8 billion dollars in unauthorized copper trading by Hamanaka on the London Metal Exchange.

In September 1996, Sumitomo disclosed that the company's financial losses were much higher at 2.6 billion dollars.

Considering the size of the losses and the fact that they were accumulated over more than ten years, many believe that Hamanaka could not have been able to corner the copper market without some kind of knowledge or authorization from his supervisors.

Hamanaka was sentenced to eight years in prison in 1998 and was released in July 2005, one year early.