Noted economist Nouriel Roubini thinks the price of bitcoin is going to zero.
The chairman of Roubini Macro Associates, also known as "Dr Doom" for his pessimistic economic outlooks, called the price crash on Twitter on Tuesday.
Roubini was referencing a Congressional hearing that will see Christopher Giancarlo, chairman of the Commodity Futures Trading Commission (CFTC), and Jay Clayton, chairman of the Securities and Exchange Commission (SEC), testify in front of lawmakers about cryptocurrencies.
The economist also used the term HODL, which stands for "hold on for dear life." It originated in an online forum when someone spelled the word "hold" wrong. It has now become a meme and is often used in times of extreme volatility in the cryptocurrency market for people holding rather than selling.
Roubini said that "HODL nuts" will hold bitcoin until it plummets to zero.
Dr Doom also said that traders will use wash trading to prop up the prices. Wash trading in the crypto world involves someone buying and selling their own order to manipulate markets. Some have feared that wash trading takes place on bitcoin exchanges.
Roubini asked if the authorities will look into this practice.
His tweets followed comments on Bloomberg last week in which he called bitcoin the "biggest bubble in human history."
Cryptocurrencies have seen a major sell-off in the last few days. Bitcoin fell below $6,000 for the first time since mid-November on Tuesday. Other major cryptocurrencies are all well off of their all-time highs.