Warren Buffett said the prospect of negative interest rates is a bit confusing.

“They puzzle me, but they don’t scare me,” Buffett said in a Yahoo Finance interview when asked if negative rates frighten him.

U.S. policy makers have been seeking to grapple with the economic fallout of the coronavirus pandemic, with the Federal Reserve on Sunday cutting its benchmark interest rate by a full percentage point to near zero. While Fed Chairman Jerome Powell said at the time that he did not think negative rates would be appropriate policy in the U.S., markets have seen the yield on the 10-year U.S. Treasury dip as low as 0.31 per cent earlier this month.

Buffett, the chairman and chief executive officer of Berkshire Hathaway Inc., said earlier this month the effects of the virus and an oil shock were “a big one-two punch.” He later announced that shareholders would be barred from attending his company’s annual meeting given the spread of the virus.

The billionaire investor has long favored investing in stocks over bonds, building up an equity portfolio that topped US$248 billion at the end of last year. Buffett said in his annual shareholder letter, released in February, that it was almost certain that equities would outperform long-term, fixed-rate debt instruments in the long run if current interest rates and low corporate taxes were to persist.

But he cautioned in the Yahoo Finance interview, conducted last week and released Wednesday, that he’s not an expert on forecasting the path of rates.

“I have never been able to predict interest rates,” Buffett said. “Interest rates are important, but we don’t think they’re knowable.”