Bitcoin dropped to its lowest in more than two months.
The digital currency fell to a low of $5,947.40, its lowest since mid November, according to CoinDesk, whose bitcoin price index tracks prices from four major exchanges.
At a price of $6,088.02 at 8:56 a.m. London time, the cryptocurrency was down more than 11.9 percent on the day, according to CoinDesk. The site measures bitcoin based on Coordinated Universal Time — currently the same time zone as the U.K.
With that decline, bitcoin has now lost more than 50 percent for the year so far.
Bitcoin 12-month performance
Source: CoinDesk
The latest sell-off follows reports in the last week that have raised worries about increased regulation, hackers and potential price manipulation at a major cryptocurrency exchange. On Friday, J.P. Morgan Chase, Bank of America and Citigroup also said they have decided to ban cryptocurrency purchases by their credit card customers.
A report from China's Financial News on Sunday said authorities will increase efforts to restrict virtual currency trading platforms, especially those that may have moved overseas following Beijing's ban on initial coin offerings in September. The South China Morning Post first highlighted the report.
The heads of the U.S. Securities and Exchange Commission and Commodity Futures Trading Commission are also set to testify before the Senate Banking Committee on Tuesday.
In prepared remarks, SEC Chairman Jay Clayton said investors should remain cautious about investing in cryptocurrencies and gave an overview of the commission's efforts so far.
Bitcoin remains several hundred percent higher over the last 12 months, while ethereum and ripple are several thousands of percent higher.