Global shares rose and the euro jumped against the dollar on Wednesday after the Federal Reserve ramped up its monetary stimulus and said it would keep benchmark US interest rates near zero until the jobless rate falls sharply.
But US stocks ended little changed, giving up most of the day's gains after Fed Chairman Ben Bernanke reiterated that monetary policy won't be enough to offset damage from the "fiscal cliff."
Treasury prices fell, with 30-year bonds slumping the most, as the central bank said it would shift more of its purchases to the five-year sector in a new easing program. Expectations the move would boost the economy and support riskier assets such as stocks also hurt safe-haven government debt.
The Fed, which cut its forecasts for economic growth and inflation next year, committed to monthly purchases of $45 billion in Treasuries on top of the $40 billion per month in mortgage-backed bonds it started buying in September, as expected.
It will likely keep official rates near zero for as long as unemployment remains above 6.5%, inflation is projected to be no more than 2.5% one or two years ahead and inflation expectations remain contained.
"It's another round of easing. It is good for stocks and risk more generally," said Quincy Krosby, market strategist at Prudential Financial in Newark, New Jersey. "And they came out with an economic data point as a guideline. That's very important, because it helps the market anticipate an exit strategy."
The MSCI global stock index advanced 0.3% to 337.93. The FTSEurofirst 300 closed up 0.1% at 1,139.65.
The Dow Jones industrial average dropped 2.99 points, or 0.02%, to end at 13,245.45. The Standard & Poor's 500 Index gained 0.64 points, or 0.04%, to close at 1,428.48. The Nasdaq Composite Index dropped 8.49 points, or 0.28%, to 3,013.81.
Bernanke "reiterated the fact that monetary policy has its hands tied as far as addressing the seriousness of going over the fiscal cliff," said Bucky Hellwig, senior vice president at BB&T Wealth Management in Birmingham, Alabama.
US House of Representatives Speaker John Boehner said on Wednesday "serious differences" remain with President Barack Obama in talks to avert the steep tax hikes and budget cuts set for the new year.
The euro rose 0.5% to $1.3066 after hitting a session peak of $1.3096 after the Fed announcement.
The euro had jumped sharply minutes before the Fed announcement. Traders attributed the move to comments from Silvio Berlusconi, who said he would withdraw as a candidate in Italy's coming election if outgoing Prime Minister Mario Monti ran as the head of a "moderate" coalition.
The dollar fell to multi-month lows against higher-yielding currencies such as the Australian and New Zealand dollars.
Omer Esiner, chief market analyst at Commonwealth Foreign Exchange in Washington, said the scope for further dollar losses may be somewhat limited, given investor concern about the US fiscal cliff, which could boost the safe-haven dollar.
"Uncertainty about the euro zone, concerns about Italy and the Japan election this weekend should also limit dollar losses," Esiner said.
The dollar rose to an eight-month high of 83.29 yen and was last up 0.8% at 83.18 on bets the Bank of Japan will implement more aggressive monetary easing after the election on Sunday, which is expected to yield a victory for the Liberal Democratic Party.
The benchmark 10-year US Treasury note was down 14/32 in price, the yield at 1.704%. Thirty-year bonds dropped 1-3/32 in price to yield 2.897%.
The new bond buying replaces the more modest "Operation Twist" program set to expire at the end of the month. The Fed will expand purchases to five-year notes from the current seven-, 10- and 30-year Treasuries.
"They are basically taking out the same amount of duration that they were in Twist, but they are buying less in the long end than they had been before," said Ira Jersey, an interest rate strategist at Credit Suisse in New York.
Oil prices rose. Brent crude futures gained $1.49 to settle at $109.50 a barrel. US crude rose 98 cents to settle at $86.77 a barrel.
Spot gold rose to $1,712 an ounce after the Fed decision bolstered bullion's inflation-hedge appeal.