1950s, United States onion farmers alleged that Sam Seigel and Vincent Kosuga, Chicago Mercantile Exchange traders, were attempting to corner the market on onions. Their complaints resulted in the passage of the Onion Futures Act, which banned trading in onion futures in the United States and remains in effect . 1970s: The Hunt brothers and the silver market Brothers Nelson Bunker Hunt and William Herbert Hunt attempted to corner the world silver markets in the late 1970s and early 1980s, at one stage holding the rights to more than half of the world's deliverable silver. During the Hunts' accumulation of the precious metal, silver prices rose from $11 an ounce in September 1979 to nearly $50 an ounce in January 1980. Silver prices ultimately collapsed to below $11 an ounce two months later, much of the fall occurring on a single day now known as Silver Thursday, due to changes made to exchange rules regarding the purchase of commodities on margin. 1990s: Hamanaka and the copper market Rogue trader Yasuo Hamanaka, Sumitomo Corporation's chief copper trader, attempted to corner the international copper market over a ten-year period leading up to 1996. As his scheme collapsed, Sumitomo was left with large positions in the copper market, ultimately losing US$2.6 billion. Hamanaka confessed in June 1996, and pleaded guilty to criminal charges stemming from his trading activity in 1997. A Tokyo court sentenced him to eight years in prison. 2008: Porsche and shares in Volkswagen During the financial crisis of 2007–2010, Porsche cornered the market in shares of Volkswagen, which briefly saw Volkswagen become the world's most valuable company. Porsche claimed that its actions were intended to gain control of Volkswagen rather than to manipulate the market: in this case, while cornering the market in Volkswagen shares, Porsche contracted with naked shorts—resulting in a short squeeze on them. It was ultimately unsuccessful, leading to the resignation of Porsche's chief executive and financial director and to the merger of Porsche into Volkswagen. One of the wealthiest men in Germany's industry, Adolf Merckle, committed suicide after shorting Volkswagen shares. 2010: Armajaro and the European cocoa market On July 17, 2010, Armajaro purchased 240,100 tonnes of cocoa. The buyout caused cocoa prices to rise to their highest level since 1977. The purchase was valued at £658 million and accounted for 7 percent of annual global cocoa production. The transaction, the largest single cocoa trade in