Bitcoin briefly plunged below $10,000 late Tuesday afternoon on Coinbase, after first topping the psychologically key level in late November.
Other major digital currencies also sold off sharply. Digital currency ethereum plunged 30 percent Tuesday, to below $1,000, while ripple fell below $1.
In fact, nearly every major cryptocurrency suffered massive losses during the day.
Ethereum traded at about $1,062 as of 8:12 p.m. ET. That represented a sizable rebound after hitting a low of $854 earlier in the afternoon. Coinbase is the leading U.S. marketplace for trading bitcoin, ethereum, litecoin and bitcoin cash.
But at around 10:50 p.m. ET, the price of ethereum fell below $1,000 again to trade at $973.
The declines followed comments from South Korean authorities that indicated tougher regulation on digital currency trading. However, there was no immediately apparent driver behind the late-afternoon decline.
Ethereum 24-hour performance
Bitcoin dropped 28 percent to a low of $9,969 on Coinbase, but quickly jumped back up to trade back above $11,000 as of 8:12 p.m., ET.
At about 10:50 p.m. ET, bitcoin prices slipped again to trade at $10,757.
Bitcoin has now nearly halved in price after topping $19,800 in mid-December. But the digital currency remains more than 1,100 percent higher over the last 12 months, according to Coinbase.
Bitcoin 1-hour performance
Ripple, the third-largest digital currency by market capitalization, traded near $1.05 after earlier plunging 46 percent to near 90 cents, according to CoinMarketCap. Last week, the site began excluding prices from some South Korean exchanges, where ripple trades about 20 cents higher.