Former Fortress hedge fund manager Michael Novogratz predicted on CNBC’s “Fast Money” in October that bitcoin would reach $10,000 in the next six to 10 months. As bitcoin rose above $9,700 Monday, Novogratz said in another “Fast Money” segment that bitcoin could “easily” be at $40,000 at the end of 2018.

Bitcoin jumped above $9,000 over the weekend as about 300,000 users joined Coinbase, the leading U.S. platform for buying and selling bitcoin, around the Thanksgiving holiday, according to data compiled by Alistair Milne, co-founder and chief investment officer of Altana Digital Currency Fund.

Separately, the world’s largest bitcoin exchange, bitFlyer, announced Tuesday it is launching in the U.S.

U.S. dollar-bitcoin trading volume only makes up about 20 percent of the total, according to CryptoCompare. Japanese yen trading in bitcoin dominates at about 61 percent, while trading in South Korean won accounts for about 11 percent, according to CryptoCompare.

Digital currency ethereum also hit a record high Wednesday of $519.85, according to CoinMarketCap. The bitcoin offshoot, bitcoin cash, traded slightly higher near $1,619.36, well off its record high, according to CoinMarketCap.

Last Wednesday, Fundstrat’s Tom Lee raised his mid-2018 price target for bitcoin to $11,500 from $6,000. That followed a similar upgrade last Monday by Standpoint Research’s Ronnie Moas, who raised his 2018 price target for bitcoin to $14,000 from $11,000.

However, other market watchers remain highly critical of bitcoin. JPMorgan Chase CEO Jamie Dimon has called the digital currency a “fraud” and BlackRock CEO Larry Fink has said bitcoin is an “index of money laundering.” Aswath Damodaran, a professor of corporate finance and valuation at New York University’s Stern School of Business, has also noted that unless bitcoin can be used for ordinary transactions, “it could be just another fad.”