Kosuga was unable to leave trading behind permanently, however, and returned to the commodity market where he began trading onion futures. At the time, onions futures contracts were the most traded product on the
Chicago Mercantile Exchange, accounting for 20% of its trades in 1955. He soon began splitting his time between New York and Chicago, where he traded on the Chicago Mercantile Exchange several days a week. In Chicago, he was a very successful trader. He lavished expensive gifts upon his brokers, buying them each a new
Buick one year. One of his brokers eventually rose to the position of Chairman of the exchange.
Cornering the onion market With his partner Sam Siegel, a fellow onion trader and owner of a local produce company, Kosuga embarked upon a scheme to
corner the onion futures market. In the fall of 1955, Siegel and Kosuga bought enough onions and onion futures so that they controlled 98 percent of the available onions in Chicago. They soon changed course and convinced onion growers to begin purchasing their inventory by threatening to flood the market with onions if they did not. As the growers began buying onions, Siegel and Kosuga purchased
short positions on a large amount of onion contracts. Siegel and Kosuga made millions of dollars on the transaction due to their short position on onion futures. Many of the farmers had to pay to dispose of the large amounts of onions that they had purchased and grown. The abrupt change in prices gained the attention of the
Commodity Exchange Authority. ==Later life==