Bitcoin is on a rollercoaster ride.

The cryptocurrency tumbled as much as 13% Tuesday. Bitcoin briefly fell below $6,000 for the first time in three months before recovering most of its earlier losses. It has lost nearly two-thirds of its value since it peaked above $19,000 in December.

On Tuesday, Switzerland-based Bank for International Settlements General Manager Agustin Carstens called bitcoin a "combination of a bubble, a Ponzi scheme and an environmental disaster.

framework for cryptocurrency trading was not designed with trading of the type we are witnessing in mind," Clayton said.

The SEC has already stepped up enforcement. Last week, it obtained a court order halting an initial coin offering from what claimed to be the world's first "decentralized bank.