The Fed specified 6.5 percent unemployment as the point at which it would consider changing its overnight bank-to-bank lending rate, which has been at zero to 0.25 percent since the recession.
Unemployment is currently at 7.7 percent.
The Fed kept its policy targets intact, holding to its historically low lending rate and announcing it would purchase additional mortgage-backed securities at the initial pace of $45 billion per month after its current asset rollover program is complete at the end of the year. It also said it would resume its rollover practice at auction in January.
By close of trading, despite the extended stimulus measures, the Dow Jones industrial average gave up 2.99 points or 0.02 percent to 13,245.45.
The tech-heavy Nasdaq index shed 8.49 points or 0.28 percent to 3,013.81. The Standard and Poor's 500 added 0.64 points or 0.04 percent to 1,428.48.
On the New York Stock Exchange, 1,481 stocks advanced and 1,580 declined on a volume of 3.6 billion shares traded.
The 10-year treasury note fell 13/32 to yield 1.704 percent.
The euro rose to $1.3064 from Tuesday's $1.3006. The dollar rose to 83.20 yen from 82.51 yen.
Japan's Nikkei 225 index rose 0.59 percent, 56.14 points, to 9,581.46.
Britain's FTSE 100 index added 0.35 percent, 20.88 points, to 5,945.85.