Who Is Mr. Copper: Unveiling the Rise and Fall of Yasuo Hamanaka

Who Is Mr. Copper: Unveiling the Rise and Fall of Yasuo Hamanaka

4 Min.

Yasuo Hamanaka, known as Mr. Copper, was the head of Sumitomo's metal trading division and gained infamy for cornering the world copper market. His manipulative strategies controlled 5% of the global copper supply, leading to $2.6 billion in losses for Sumitomo. This article explores how he achieved this feat and the consequences he faced.


In the annals of financial markets, Yasuo Hamanaka earned his moniker, Mr. Copper, through his remarkable ascent as the head of Sumitomo's metal-trading division. During the mid-1980s, Hamanaka's audacious and illicit investment tactics in copper futures and options propelled Sumitomo to become the world's largest copper trader. His influence was so vast that, at one point, he controlled a staggering 5% of the global copper supply, earning him another moniker: Mr. Five Percent, a name synonymous with the famed oil trader Calouste Gulbenkian. Hamanaka took immense pride in this title.

The Sumitomo Enigma

What made Hamanaka's achievement even more astonishing was that Sumitomo, the Japanese trading company he represented, had no copper mines of its own. Despite this, Hamanaka's copper market investment strategies elevated Sumitomo to a position of global leadership in the copper industry. His success was nothing short of a financial marvel.

Mr. Copper's Catastrophic End

However, Hamanaka's reign as Mr. Copper came to a crashing end when he was unmasked as the rogue trader responsible for colossal losses totaling $2.6 billion for Sumitomo. His once-admired copper market strategies turned out to be fraudulent and forged. In the wake of his exposure, Hamanaka faced legal consequences, receiving a seven-year prison sentence. Sumitomo, while denying any knowledge of his illicit activities, had to pay a substantial $150 million to settle claims with regulators.

Hamanaka’s Commodity Market Manipulations

Hamanaka's remarkable ability to manipulate the copper market stemmed from his strategic accumulation of futures contracts for Sumitomo, in addition to their substantial holdings of physical copper. Copper, being an illiquid commodity, meant that Sumitomo's 5% copper holdings effectively placed them in a dominant global position. This dominance granted them the power to exert control over the world copper price through the London Metal Exchange.

Hamanaka skillfully utilized his immense power to his advantage. He relied on cash reserves and maintained long positions in copper to deter investors attempting to short the commodity. While Hamanaka's market manipulations were an open secret among traders, the London Metal Exchange was not obligated to report on positions, concealing the extent of Hamanaka's control from public scrutiny.

Profits and Consequences

Additionally, Sumitomo profited substantially through commissions on transactions due to the artificially inflated price of copper over an extended period. This period of artificial price inflation persisted until market conditions shifted in 1995, resulting in an increase in copper supply that set the stage for a market correction.

Sumitomo's extensive long positions in copper at the time became a significant liability for the company. The year 1996 marked the revelation of Hamanaka's rogue trading activities and the subsequent unraveling of his copper empire.

The Aftermath and Regulatory Changes

In the aftermath of this market debacle, regulatory changes were instituted by the London Metal Exchange, effectively preventing the recurrence of such egregious commodities market cornering. These changes aimed to enhance transparency and oversight, ensuring that no individual could wield unchecked influence over vital global markets as Mr. Copper once did.


The enigmatic rise and catastrophic fall of Mr. Copper, Yasuo Hamanaka, stand as a cautionary tale in the world of finance. Hamanaka's manipulation of the copper market, his control of 5% of the global supply, and the subsequent $2.6 billion losses for Sumitomo serve as stark reminders of the potential consequences of unchecked power and unethical financial practices. His story has left an indelible mark on the history of commodities trading, leading to regulatory reforms that aim to prevent future market cornering of this magnitude.

Mr. Copper (Yasuo Hamanaka)
London Metal Exchange (LME)
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