The No. 1 digital currency and its cohort continued to unravel Wednesday, extending a downturn that has seen the entire sector cough up a whopping $370 billion since Jan. 7, or more than 40% of their total value. Source: CoinMarketCap.com For its part, bitcoin BTCUSD, -4.58% has shed almost half its value since a single bitcoin traded at an all-time high just below $20,000 in late December. What’s dragging down a sector that had enjoyed stratospheric gains (bitcoin alone is up about 1,100% since last January) even compared against the Dow Jones Industrial Average DJIA, +1.25% the S&P 500 index SPX, +0.94% and the Nasdaq Composite Index COMP, +1.03% which boasts returns between 22% and 30% over the past 12 months?via