Bitcoin plunged more than $1,000 in less than an hour Tuesday.
The digital currency fell from $17,929 to a low of $16,912 between 3:30 and 4:30 p.m. ET, according to Coinbase, the leading U.S. platform for buying and selling major cryptocurrencies. Bitcoin had traded near $19,800 on Sunday.
The slump came just around the close of the U.S. stock market.
Tuesday was a wild day for stock traders focused on cryptocurrencies as signs emerged bitcoin mania is getting a bit out of control. The U.S. Securities and Exchange Commission temporarily suspended trading in shares of The Crypto Company, partly on concerns of stock manipulation, while a tiny company called Future FinTech with no apparent connection to cryptocurrencies briefly soared more than 200 percent.
Bitcoin performance Tuesday afternoon
The CME bitcoin futures expiring in January settled 4.7 percent lower at $18,200 in their second day of trading ever. The Cboe bitcoin futures contract settled 7.9 percent lower at $17,555. Trading volume on both exchanges was roughly the same.
Bitcoin's rival offshoot, bitcoin cash, surged for a second day, up 24.5 percent to a record high of $2,735.58, according to CoinMarketCap. Bitcoin cash traded about 20 percent higher, near $2,625 as of 4:35 p.m. ET.
Bitcoin cash split off from bitcoin in August in a debate over how best to improve the digital currency's transaction efficiency.
The gains in bitcoin cash followed news in the last few days that bitcoin payments processor BitPay and major cryptocurrency storage company Blockchain added support for bitcoin cash. Coinbase is set to add support for bitcoin cash by January.
With Tuesday's price moves, bitcoin had roughly 48 percent of the total market cap of all cryptocurrencies, while bitcoin cash had about 7 percent, according to CoinMarketCap.