Bitcoin was trading 1.4% lower on Friday morning.
The price was around $49,400 per coin, while rivals Ethereum and Dogecoin were trading around $3,800 and 29 cents per coin, respectively, according to Coindesk.
A man who participated in what prosecutors called a "textbook Ponzi scheme," pleaded guilty to defrauding cryptocurrency investors worldwide of more than $2 billion.
Prosecutors said Glenn Arcaro, of Los Angeles, sat atop the North American branch of the pyramid investment scheme BitConnect, the San Diego Union-Tribune reported.
Arcaro pleaded guilty in U.S. District Court to conspiracy to commit wire fraud and admitted in his plea agreement to earning "no less than $24 million from the BitConnect fraud conspiracy," the newspaper said.
As part of his plea, Arcaro must pay back that money to investors. He faces up to 20 years in prison.
He'll be sentenced Nov. 15.
"The BitConnect scheme is believed to be the largest cryptocurrency fraud ever charged criminally," the U.S. Attorney’s Office said in a statement.
"In truth, BitConnect operated a textbook Ponzi scheme by paying earlier BitConnect investors with money from later investors," prosecutors said.
In other cryptocurrency news, the majority of Salvadorans surveyed disagree with the government's decision to adopt bitcoin as legal tender, according to Reuters.
A poll by the Central American University showed many are unaware of how to use the digital currency and are distrustful of the project.
At least 67.9% of 1,281 people surveyed said they disagree or strongly disagree with the use of bitcoin as a legal tender.
The cryptocurrency will become legal tender in El Salvador on Sept. 7.
The survey also showed most Salvadorans think the main beneficiaries will be the wealthy, foreign investors, the government and business leaders.