The Fed Chairwoman Janet Yellen testified before the Senate Banking Committee on Thursday. She said that the Fed and markets were surprised by oil price movements.

"We have been quite surprised by movements in oil prices. I think in part they reflect supply influences, but demand may also play a role," she said.

Yellen pointed out that it is too earlier to decide on monetary policy actions in March.

The Fed chairwoman noted that the Fed discussed negative rates in 2010, and it ready to implement negative rates if needed.

"We wouldn't take those [negative interest rates] off the table, but we have work to do to judge whether they would be workable here," Yellen said.