The virtual currency climbed suddenly at around 3:30 a.m. ET, adding $5,000 in the space of an hour to trade at $37,299. Musk added #bitcoin to his Twitter bio earlier Friday morning and sent out a cryptic tweet, saying: “In retrospect, it was inevitable.” It adds to the wild volatility in markets this week, as the stock prices of heavily-shorted companies like GameStop surged dramatically.