Outgoing Federal Reserve Board Chair Janet Yellen said Wednesday that bitcoin is a "highly speculative asset," and downplayed its supposed role as a currency.
"Bitcoin at this time plays a very small role in the payment system," she said at her final press conference in Washington. "It is not a stable store of value, and it doesn't constitute legal tender."
"It is a highly speculative asset," she added.
Yellen's description of the trendy cryptocurrency came after the value of a single bitcoin has soared in value, and was approaching $20,000 this week. Some have called it a valuation bubble unlike anything seen since the tulip bulb mania in Holland centuries ago.