Bitcoin tumbles 5.5% to $53,436

Bitcoin plunged 5.5% to $53,435.9 at 22:04 GMT on Friday, losing $3,112.06 from its previous close.

Bitcoin, the world's biggest and best-known cryptocurrency, is down 22.6% from the year's high of $69,000 on Nov. 10.

Ether, the coin linked to the ethereum blockchain network, dropped 6.81% to $4,208.68 on Friday, losing $307.35 from its previous close.