Asked if she agreed with Yellen's comments made last month that the cryptocurrency was a "speculative" asset, Warren did not give a direct answer, saying, "I think Janet's a really smart woman."
When pressed, she said, "'Speculative in nature and going to end badly' – I don't think Janet left a lot of room for ambiguity."
CNBC's host also clarified that Yellen had actually said bitcoin could "end badly for some."
The topic of bitcoin was brought up as a potential problem for a new "wealth tax" – proposed by Warren and Sen. Bernie Sanders (I-Vt.) on Monday – that would see rich individuals charged 2% annually on their net worth above $50 million and 3% above $1 billion.
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