Bitcoin is already having a bad year.

For the first time since 2015, the cryptocurrency began a new year by tumbling, extending its slide from a record $US19,511 reached on December 18.

The virtual coin traded at $US13,150 as of 12.58pm in New York, down 8.1 per cent from Friday, according to data compiled by Bloomberg. That's also a fall from the $US14,156 it hit on Sunday, according to coinmarketcap.com, which tracks daily prices.

Bitcoin got off to a much stronger start last year, and then kept that momentum going, eventually creating a global frenzy for cryptocurrencies.