cryptocurrencies and bitcoin

Bitcoin is known to go through wild swings. In November, it tumbled almost 30 percent in four days from $7,888 to$5,555. In September, it fell 40 percent from $4,979 to$2,972.

"Trading in bitcoin is akin to gambling, so its movements don't follow logical patterns," said Takashi Hiroki, chief strategist at Monex Securities in Tokyo.

"Unlike equities and bonds, it is not possible to calculate expected returns on bitcoin, so buying it becomes a gamble rather than an investment."

While CME and its rival Cboe Global Markets move to list bitcoin futures has given the digital currency some perceived legitimacy, some policymakers remain skeptical.

South Korea's Financial Supervisory Service said on Tuesday it does not consider bitcoin and other cryptocurrencies to be currencies of any kind.

Japanese Finance Minister Taro Aso said on Tuesday that bitcoin had not been proven as a credible currency.

(Reporting by Shinichi Saoshiro; Additional reporting by Masayuki Kitano in Singapore; Editing by Sam Holmes)