Bitcoin slumped 7% to $48,176 in a third straight session of losses while Ether and XPR suffered double digit tumbles.
"The crypto currency came under fresh pressure on the Biden tax headlines," Deutsche Bank's Jim Reid wrote in a note to clients.
Bitcoin, the world's biggest cryptocurrency, is on track for a 15% loss on the week. However, the latest tumbles come in the wake of a sharp rally with Bitcoin still up 65% since the start of the year.
(Reporting by Karin Strohecker and Thyagaraju Adinarayan in London; Editing by Tommy Wilkes)