The dollar fell to its lowest in over three months against a basket of major currencies on Friday, on track for its steepest annual drop since 2003, on doubts over durability of a pickup in U.S. economic growth in wake of last week's tax overhaul.
One of the most dramatic market developments in 2017 was the breath-taking rise of bitcoin and other cryptocurrencies. While they have pulled back at year-end, many of these digital currencies have surged in value this year.
The greenback may lag further against its peers in 2018 as investors expected other major central banks to reduce their stimulus while the Federal Reserve has signaled it would raise interest rates further, analysts said.
"The dollar will face more headwinds in 2018," said Chris Gaffney, president of Everbank in St. Louis, Missouri. "The Fed won't be going at it alone in terms of taking off more gas from the stimulus pedal."