Currencies in Asia tumbled and stocks in China fluctuated after China\'s central bank devalued its tightly controlled currency. The central bank\'s move sent the yuan down 1.6% against the U.S. dollar early Tuesday. The U.S. dollar rose to as high as 6.3299 Chinese yuan from its close 6.2136 late Monday. The move comes after disappointing Chinese trade data over the weekend cast doubt on the economic health of the world\'s no. two economy. It also follows the International Monetary Fund\'s recent announcement to delay its decision on whether to include the yuan in its basket of reserve currencies. The yuan\'s fixing against the U.S. dollar was lowered 1.9% Tuesday from the previous day, its biggest-ever move in a single day. The yuan is allowed to trade 2% above or below the People\'s Bank of China\'s daily reference rate against the U.S. dollar.