The New York Times reported Wednesday that an increasing number of digital currency investors are worried the price of bitcoin and other digital currencies have been inflated by cryptocurrency exchange Bitfinex, which is included in CoinDesk's price index. Bloomberg reported Tuesday that in December, the U.S. Commodity Futures and Trading Commission subpoenaed Bitfinex and a cryptocurrency company called Tether, which is run by many of the same executives.
Representatives for Bitfinex and Tether did not immediately respond to a CNBC request for comment.
And last week, Japanese exchange Coincheck was compromised after hackers ran off with over $500 million worth of a cryptocurrency called NEM.
Key business leaders have poured cold water over the cryptocurrency world. Investing legend Warren Buffett told CNBC in a recent interview that the sector "will come to a bad ending."
Others still see the long-term potential of bitcoin and other coins.
Fundstrat's Tom Lee, the only major Wall Street strategist to issue formal price targets on bitcoin, said two weeks ago that $9,000 is a "major low" for bitcoin and "the biggest buying opportunity in 2018."
And Kay Van-Petersen, a Saxo Bank analyst who correctly predicted the cryptocurrency's rally at the start of last year told CNBC recently that bitcoin could hit between $50,000 and $100,000 this year.
Another buy low moment, or has the bubble finally popped? ---
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