Regarding high stock valuations amid high unemployment, Yellen said this was partly due to a very low interest rate environment that has chased money into stocks. “In a world of very low interest rates, price-earnings type multiples tend to be high,” she said, adding: “there are maybe sectors where we should be very careful.” Yellen also said the market for U.S. Treasury debt remains “robust” and that she sees no issues with the Treasury’s ability to finance the U.S. budget deficit. The Federal Reserve will buy whatever Treasury debt is appropriate for the central bank’s monetary policy goals, she added. Asked if she wanted to regulate cryptocurrencies such as bitcoin, Yellen called it “a high-risk, speculative investment” that has seen a recent surge in value. The top priority was to ensure that bitcoin is not used as a vehicle for illicit transactions and that investor protections are maintained, she said. Ensuring that firms dealing in bitcoin and other cryptocurrencies “adhere to their regulatory responsibilities I think is certainly important,” Yellen added.