A visual representation of bitcoin with U.S. dollars.studioEAST | Getty ImagesBitcoin briefly climbed above the $16,000 mark on Thursday, hitting a level not seen since early January 2018.The cryptocurrency’s price rose as high as $16,019 just after 5 a.m. ET, according to data from industry site CoinDesk. It was last trading more than 1% higher at around $15,800.The last time bitcoin breached the $16,000 level was Jan. 8, 2018, according to CoinDesk data. The reason for the move higher on Thursday wasn’t immediately clear, but it comes as a number of companies appear to be warming to crypto.Last month, fintech giant PayPal announced it would add new features letting users trade bitcoin, ether, bitcoin cash and litecoin. By early 2021, the company also plans to let customers use crypto to shop with its network of 26 million retailers.Meanwhile, Square said last month that it had bought $50 million worth of bitcoin. The U.S. fintech firm, which is run by Twitter CEO Jack Dorsey, has long offered crypto services to users of its popular Cash app.Bitcoin, the world’s best-known and most valuable cryptocurrency, has more than doubled in price this year, a wild ascent that’s reminiscent of its monster rally in late 2017 that saw it narrow in on the $20,000 mark.Some crypto fans say it’s down to the unprecedented wave of stimulus from governments and central banks around the world aimed at tackling the coronavirus crisis. Such measures, they say, devalues fiat currencies, making bitcoin an attractive alternative.