Bitcoin this week slumped to its lowest this year, tumbling as much as 10 percent to breach US$4300 and taking losses in the world's best-known digital coin to 25 percent within a week.
Other smaller coins also skidded sharply as a broader cryptocurrency sell-off, said by traders and market makers to be rooted in heavy selling at leveraged Asian exchanges, gathered steam.
The fall followed a sudden plunge last week that shook bitcoin out of a period of relative stability, where prices had hovered around the US$6500 mark for several months.
Bitcoin sunk as far as US$4327, its lowest since October 2017. By mid-afternoon, it was trading around US$4750 on the Bitstamp exchange.
"We'd been waiting for a break-out," said Mati Greenspan, senior market analyst at eToro. "When you have the price moving so steadily you had lots of stop-loss orders building up - and now you are seeing them being liquidated."
Ripple's XRP and Ethereum's ether, the second and third-largest coins, fell as much as 14 and 16 percent respectively before clawing back losses in US trading hours.
Tuesday's falls coincided with broader drops in financial markets. European shares fell as poor retail results and weakness in Apple dragged down Wall Street.
Bitcoin has plummeted over 75 percent this year from a peak of US$20,000 touched in December as retail investors piled into a one of the largest bubbles in history.
Traders and market makers blamed bitcoin's slide on heavy selling at leveraged exchanges in Asia such as Hong Kong-based OKEx and Bitmex. Few exchanges in the West lend bitcoin to traders, making the Asian venues popular with speculators.
"The presence of leverage makes day traders attracted to Asian markets," said Michael Moro, CEO of Genesis Global Trading in New York, one of the biggest over-the-counter trading desks.
"Folks who are risking 100X type of leverage, it’s really difficult to think of that as an investment – it’s a casino mentality."
Others blamed fears that last week's "hard fork" in bitcoin cash, where a software upgrade split the fourth-biggest coin into two separate currencies, could destabilise others.
The price of bitcoin tends to be sensitive to debates over how its underlying network evolves. Last year the suspension of hard fork planned by major developers and investors proved a major catalyst to its breakneck rise.
Mainstream investors have stayed clear of bitcoin, with concerns over scant regulatory oversight and undeveloped market infrastructure compounded by frequent swings in price.
That lack of involvement has seen bitcoin struggle to live up to its billing as something that will revolutionise world finance. Its usage as a payment currency has shrivelled this year.
At the same time, bitcoin's plunge in value has calmed the fears of regulators and central bankers that it could one day pose a risk to financial stability.
According to industry tracker Coinmarketcap.com, the total value of cryptocurrencies is now around US$154 billion, down from a peak of around US$800 billion in January.
Cryptocurrency advocates say bitcoin is still young and price volatility is to be expected. Many predict the need for virtual currencies that operate beyond mainstream banking will outlast any short-term price falls.
By late afternoon, XRP and ether were trading around US$0.45 and US$142 respectively on the Luxembourg-based Bitstamp exchange.
"The euphoria has died and prices have consolidated with lower lows and lower highs," said Fawad Razaqzada, an analyst at Forex.com. "A lot of people have lost interest."
(Reporting by Tom Wilson and Tommy Wilkes,; Editing by Saikat Chatterjee and Ed Osmond)