Bitcoin rallied more than 9 percent on Thursday, hitting $4,000 for the first time in more than two weeks after losing half its value in six weeks to mid-December. The world's most valuable cryptocurrency has been hit hard this year, falling around 80 percent from a record high last December on concerns of increased regulatory scrutiny.
On Thursday, bitcoin gained as much as 9 percent at $4,030.15, its highest since Dec. 4, before retreating slightly.