China's shock 2% devaluation of the yuan on Tuesday pushed the dollar higher and raised the prospect of a new round of currency wars, just as Greece reached a new deal to contain its debt crisis.
Stocks fell in Asia and Europe as investors worried about the implications of a move designed to support China's slowing economy and exports.
The stronger dollar hit commodity prices, driving crude oil down after Monday's hefty gains, though gold hit three-week highs as investors focused on the risks to the global economy.
China's move, which the central bank described as a "one-off depreciation" based on a new way of managing the exchange rate that better reflected market forces, triggered the yuan's biggest fall since 1994, pushing it to its weakest against the dollar in almost three years.