Bitcoin slid another 4.5% to $3,635 at midnight Sunday in New York, according to Bitstamp. It recouped most of the losses by 07:50 but remains in the red. It's lost 33% in the past week and 75% this year.
Cryptocurrencies just had their worst week ever, and Bitcoin is 82% below its high of $19 666 almost a year ago. Ripple declined 5.3% to 35 cents, and is about 90% below its peak.
After an epic rally last year that exceeded many of history's most notorious bubbles, digital currencies have become mired in an almost $700bn rout that shows few signs of abating. Many of the concerns that sparked the 2018 retreat - including increased regulatory scrutiny, community infighting and exchange snafus - have only intensified this week.
Even after the steep losses, Oanda Corporation's Stephen Innes has yet to see strong evidence of a capitulation that would signal a market bottom.
"There's still a lot of people in this game," Innes, head of trading for Asia Pacific at Oanda, said by phone from Singapore last week. "If we start to see a run down toward $3 000, this thing is going to be a monster. People will be running for the exits."
Innes said his base-case forecast is for Bitcoin, which turns 10 this year, to trade between $3 500 and $6 500 in the short term, with the potential to fall to $2 500 by January.