The U.S. dollar fell to a 3-1/2 week low against a basket of currencies on Wednesday as traders bet more major central banks would begin reducing monetary stimulus in 2018 due to faster global economic growth.
In the cryptocurrency arena, Bitcoin's rebound following its worst week since 2013 fizzled as it struggled to stay above $16,000 for a second day.
"The dollar has taken quite a beating against the majors in 2017," said Minh Trang, senior foreign currency trader at Silicon Valley Bank in Santa Clara, California.
In holiday-thinned trading, an index that tracks the U.S. dollar against six currencies was down 0.24 percent at 93.04 after slipping to its lowest since Dec. 1 earlier Wednesday.
The dollar index has fallen 9.0 percent this year, putting it on track for its steepest annual decline since 2003 when it posted a 14.7 percent drop.
Conversely, the euro would post its best year against the greenback since 2003. The single currency reached a 3-1/2 week high on Wednesday at $1.1904, Reuters data showed. The euro was last up 0.30 percent at 1.1894.
The greenback weakened versus the yen for a second straight year. It held steady on the day at 113.29 yen.