The dollar stumbled against the yen, euro and gold, with analysts pointing to U.S. President Donald Trump's failure to usher a Republican health-care reform bill through a seemingly friendly Congress.
Andy Brenner, head of international fixed income securities at National Alliance Securities, said in a note late Sunday U.S. time that this was markets' first chance to react to the health-care bill's failure.
"We sense the choppiness could lead to some very chunky swings," he said.
The dollar index, which measures the greenback against a basket of currencies, tumbled as low as 99.263 in early Asia trade on Monday, from as high as 100 on Friday.
The euro was fetching as much as $1.0849 early Monday, with the common currency marking its highest levels since early December. The yen also surged, with the dollar fetching as few as 110.23 yen, the greenback's lowest level since late November.
Gold also climbed, rising as high as $1,257.97 an ounce, the highest since late February and stocks around Asia tumbled.
That followed Trump lashing out at his party's conservative wing on Sunday after the stinging defeat of a Republican health care plan he backed.
Although the legislation was largely authored by House Speaker Paul Ryan, representatives from the right wing of the GOP, including the House Freedom Caucus, vigorously opposed the bill.
Vishnu Varathan, a senior economist at Mizuho Bank in Singapore, also pointed to the health-care bill's train wreck as driving the market selloff.
"It's just follow through on disappointment on the health-care bill and to doubts on whether Trump can push through his other policies," such as infrastructure and tax reforms, Varathan said.