The dollar tumbled by the most in three weeks after the Trump administration's unexpected bond buyback announcement reversed a Treasury market rout that had pushed long-dated yields to the highest since 2007.

The Bloomberg Dollar Spot Index dropped as much as 0.8% to the lowest since May 12. The decline in yields caused by the US Treasury's move drove the greenback down against all of its major counterparts, including the yen.

The Swiss franc and New Zealand dollar were among biggest gainers on Wednesday. The sudden policy intervention marked a significant shift in market dynamics, with investors reassessing fixed-income and currency positions.