The dollar fell to a four-week low against a basket of currencies on Thursday on a less certain U.S. economic outlook after the passage of major tax cuts, while bitcoin succumbed to renewed selling, marking an over 30 percent drop in less than two weeks.
Commodity-linked currencies including the Australian and New Zealand dollars posted two-month highs with copper prices hitting a four-year high and oil holding at its strongest levels since mid-2015.
"The dollar had gained on expectations of tax reform. Now that it's here, we are seeing it sold off," said Sireen Harajli, currency strategist at Mizuho in New York.
Last week's passage of the biggest overhaul of the U.S. tax code in 30 years gave the dollar some support, but markets are not confident that the tax reform will feed through quickly into increased consumer confidence.