"Potentially anything - including negative interest rates - would be on the table. But we would have to study carefully how they would work here in the U.S. context," Yellen told a House of Representatives committee.
This would happen if the economy were to "deteriorate in a significant way," she said, adding that she believed negative rates "would have some at least modest favorable effect on banks' incentives to lend." (Reporting by Jason Lange; Editing by James Dalgleish)