U.S. Treasury Secretary Janet Yellen said on Thursday that she and financial market regulators needed to "understand deeply" what happened in the trading frenzy involving GameStop Corp and other retail stocks in recent days before taking any action.

Yellen, who is convening a meeting of top market regulators on Thursday, told ABC's "Good Morning America": "We really need to make sure that our financial markets are functioning properly, efficiently and that investors are protected. ... We're going to discuss ... whether or not the recent events warrant further action."