"If the subsequent data remain broadly aligned with our current expectations for the economy, we will continue to reduce the pace of purchases in measured steps through the first half of next year, ending purchases around mid-year," he said.
For now, the Fed will continue to purchase mortgage-backed securities at a pace of US$40 billion per month and longer-term Treasury securities at a pace of US$45 billion per month.
The Fed said it will keep its key interest rate at between zero to 0.25 per cent as long as the unemployment rate remains above 6.5 per cent and as inflation is expected to remain below 2.5 per cent.
"If the economic growth we have is sustainable without the Fed, that's good news," Randy Bateman, chief investment officer of Huntington Asset Management in Columbus, Ohio, told Reuters. "But it is hard to wean the system off the easy money."
In late afternoon trading in New York, the Dow Jones Industrial Average fell 0.95 per cent, the Standard & Poor's 500 Index declined 0.53 per cent and the Nasdaq Composite Index slid 0.39 per cent.
US Treasuries also dropped, pushing yields on the 10-year note up to 2.31 per cent.
"The Fed's walking a tightrope here," George Rusnak, national managing director of fixed-income strategies for Wells Fargo Private Bank in Philadelphia, told Bloomberg News. "They're balancing preparing the markets that tapering is going to begin, but at the same time, comforting them that it's not going to be too dramatic and too quick to be disruptive. It's a fine line."
The greenback strengthened, gaining 0.8 per cent against the euro and increasing 1.6 per cent against the Japanese yen.
In Europe, the benchmark Stoxx 600 Index fell 0.2 per cent from the previous close. The UK's FTSE 100 closed 0.4 per cent lower, as did Germany's DAX. France's CAC 40 weakened 0.6 per cent.