Chicago grain plunged on Thursday, following other commodities markets, as prices came under pressure from heavy fund-selling, amid worsening fears that the euro zone\'s debt crisis is spreading quickly across the region. The most active corn contract for December delivery lost 28.25 cents, or 4.4 percent, to close at 6.145 U.S. dollars per bushel. December wheat trimmed 24.25 cent, or 3.9 percent, to 5.925 dollars per bushel. January soybean dropped 19.5 cents, or 1.6 percent, to close at 11.6825 dollars per bushel. On Thursday, Spain was forced to pay the highest rate to sell its 10-year debt since 1997, just shy of the 7-percent mark seen as unsustainable, stoking fears that Europe\'s debt problems are escalating. Meanwhile, the cost of insuring debt from France, Spain, Belgium and Italy all rose to record highs. Grain and other commodities market plunged in a volatile session on Thursday, as fund-traders and investors alike are liquidating risky assets like stocks and commodities in order to raise cash. A trader mentioned that a firm tone to the U.S. dollar and sharp break in crude oil price both helped set the negative tone for grain market. According to a report released by U.S. Department of Agriculture, last week\'s net weekly export sale for soybean reached 751,200 tons, beating market expectations and including 517,100 tons sold to China. USDA also confirmed that private exporters sold 420,000 tons of U.S. soybeans to China. Market participants mentioned that stronger-than-expected weekly sales plus long-waited confirmation of sales to China offered strong support to soybean price. As for corn, corn price suffered heavy pressure as USDA report showed last week\'s corn export sale was well below trade expectations, while more and more signs of fierce competition for feed grains on International export market also weighed on the price.