“In 1955, Onion Futures accounted for 20% of trades in the 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.[4] Millions of pounds (thousands of tonnes) of onions were shipped to Chicago to cover their purchases. By late 1955, they had stored 30,000,000 pounds (14,000 t) of onions in Chicago.[5] 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.”

~Onion Futures Act on Wikipedia: https://en.m.wikipedia.org/wiki/Onion_Futures_Act