The dollar hovered close to 15-year lows versus the yen but rose against other currencies on August 10 as investors pared back risk exposure in the wake of steps announced by the Federal Reserve to boost the economy.
In early European trade, the dollar was up around one percent against the euro and the Australian dollar.
The Federal Reserve said it will use cash from maturing mortgage bonds it holds to buy more US government debt, marking a policy shift from a central bank which only a few months ago debated how to start exiting monetary stimulus.
US Treasury yields fell in response, reflecting expectations that US interest rates would stay at record low levels for some time to come, pushing the dollar close to the key 85.00 level against the yen.
Investors were also concerned by what the Fed's move said about a faltering economic recovery, driving global stocks lower along with perceived riskier currencies.
“If anything the Fed decision pushed back rate hike expectations in the US and the initial reaction was a jump in euro/dollar, but quickly US equities turned negative, pushing the dollar higher against most currencies except the yen,” said Niels Christensen, currency strategist at Nordea in Copenhagen.
“The dollar could fall below 85.00 yen at any moment,” said Shuichi Kanehira, head of FX spot trading at Mizuho Corporate Bank in Tokyo.