Billionaire investor Warren Buffett on Monday said buyers of bitcoin, which he has characterised as "rat poison squared," thrive on the hope they'll find other people who will pay more for it.
Police busted a crime ring based in Spain that used credit cards and cryptocurrencies to launder €8mn ($9.8mn) from drug traffickers, Europol said on Monday.
Bitcoin is a virtual currency created from computer code that allows anonymous transactions and its value has soared since it came into being in 2009.
Bitcoin extended its sharp tumble of the past 24 hours, skidding more than seven percent on Wednesday in a rapid downturn in fortunes as investors were spooked by fears regulators might clamp down on an asset whose value has skyrocketed in the past year.
A series of measures have failed to curb overheated virtual currency speculation in South Korea and Justice Minister Park Sang-Ki said it would be "devastating if the bubble bursts".
Bitcoin plunged by a quarter to below $12,000 on Friday as investors dumped the cryptocurrency in manic trading after its blistering ascent to a peak close to $20,000 prompted warnings by experts of a bubble.
Bitcoin futures jumped more than 20 percent in their eagerly anticipated US debut, which backers hope will encourage wider use and legitimacy for the world's largest cryptocurrency even as critics warn of the risk of a bubble and price collapse.
The newest way to bet on bitcoin, the cyptocurrency that has taken Wall Street by storm with its stratospheric price rise and wild daily gyrations, will arrive on Sunday when bitcoin futures start trading.
Bitcoin ploughed past $14,000 to a fresh record on Thursday as investors continued to pile in, triggering a warning the cryptocurrency was "like a charging train with no brakes" that would inevitably slip back.
Bitcoin slid to as low as $9,000 on Thursday, having lost more than a fifth of its value since hitting an all-time high of $11,395 on Wednesday.