To illustrate the massive growth another way: 10 days ago, the cryptocurrency market as a whole was worth $300 billion; now it's above $400 billion, per CoinMarketCap.com.
The quote of the day on the subject comes from Royal Bank of Scotland chair Sir Howard Davies, who called the whole situation "irrational exuberance" in comments to Bloomberg and warned, "All the authorities can do is put up the sign from Dante's Inferno: 'Abandon hope all ye who enter here.'"
As the AP earlier reported, the CME Group, which owns the Chicago Mercantile Exchange, got the OK on Friday to begin trading bitcoin futures on Dec. 18; CBOE Global Markets will do so as well.
But is it a bubble, and if so, when will it burst? The Verge reports some traders suspect the answer is soon, and are planning to short Bitcoin, "that is, make bets that its value will decrease in the future." Meanwhile, one unfortunate bitcoin headline today: The AP reports Slovenian bitcoin mining company NiceHash was hacked, and $70 million in bitcoin may have been stolen.
This article originally appeared on Newser: As Bitcoin Hits $15K, a Warning From Dante's Inferno