Chicago grain futures retreated on Monday, as a sharply stronger U.S. dollar and mounting concerns over potential bankruptcy of a major global financial derivatives broker both helped add to the long liquidation selling trend. The most active corn contract for December delivery trimmed 8 cents, or 1.2 percent, to close at 6.47 U.S. dollars per bushel. December wheat dropped 16.25 cent, or 2.5 percent, to 6.2825 dollars per bushel. January soybean dropped 8.75 cents, or 0.7 to close at 12.1725 dollars per bushel. MF Global Holdings, a futures broker, filed for Chapter 11 bankruptcy protection on Monday, triggering caution across the commodity markets. Bad investments linked to the European Union\'s financial crisis are being cited as the cause. The MF Global news reflects just how much the European Union\'s financial fragility is affecting the overall economy of the world, said Mike Daly, a market analyst with PFGbest here in Chicago. Market participants pointed out that volume was light in the commodities market, as investors appeared to be reluctant to jump in to the latest fire, after The CME Group has limited MF Global trading to liquidation only. Meanwhile, U.S. dollar leaped Monday morning after the Bank of Japan sold an undisclosed amount of yen in the foreign exchange market overnight, in order to drag the yen down from a post-World War II high against the dollar. The grain market also suffered the pressure, as a stronger dollar makes U.S. grain export less competitive in the international market. Besides, U.S. grain export also faces fierce competition from South America, as the nice weather for planting season in South America plus surge in supply of exportable surplus corn from the Black Sea region have made traders concerned with export demand for U.S grain. \"We have a forecast of the rains for Argentina within next 14 days, relieving any dryness down there, so that was a major bearish factor in the market. Overall the demand trends continue to be lackluster,\" said Mario Balletto, a grain analyst for CitiGroup Global Markets Inc. in Chicago.