Bitcoin, the world's biggest and best-known cryptocurrency, slipped below US$60,000 on Tuesday, taking losses from a record high of US$69,000 struck on Nov. 10 to more than 12 per cent.
Bitcoin was down five per cent at US$60,391.3 at 1253 GMT, after earlier falling as much as US$58,563, its lowest since Oct. 28, while Ether, the second-biggest cryptocurrency by market value, was down 6.8 per cent at US$4,253.08.
Cryptocurrency analysts could not identify any particular news driving the falls, which they said seemed to be driven by profit taking after a recent sharp run-up.
Bitcoin has more than doubled in value since June, driven by the mainstream adoption of cryptocurrencies and the launch in the United States of futures-based bitcoin exchange traded funds.
And on Sunday it went through a major upgrade, called Taproot, that enables its blockchain to execute more complex transactions, potentially widening the virtual currency's use cases and making it a little more competitive with ethereum for processing smart contracts.
"The fall below 60,000, puts (Bitcoin) below the 62,000 support level, slightly into the 'short term' bearish zone," said Sylvia Jablonski, chief investment officer at Defiance ETFs in New York.
"The next key support level is 58,000, but I think it gets bought up here, and demand driven prices will begin to play out to the upside."
Most investors expect bitcoin to remain between US$50,000 to US$75,000 in the next 12 months, according to BofA Securities' monthly fund manager survey, while 59 per cent believe bitcoin is in a bubble.
Jehan Chu, managing partner at Hong Kong blockchain venture capital firm Kenetic, said it could potentially break "the US$100k level before year's end."
Money pouring into bitcoin products and funds have hit a record US$9 billion so far this year, and totalled US$151 million last week in their 13th consecutive week of inflows, data from digital asset manager CoinShares showed on Monday.
Although flows have been positive recently, volumes have been subdued in the second half, averaging US$750 million daily versus US$960 million in the first, the CoinShares report said.
(Reporting by Tom Westbrook and Vidya Ranganathan in Singapore, Medha Singh in Bengaluru; Editing by Jacqueline Wong and Alexander Smith)