The U.S. Federal Trade Commission said on Thursday it was investigating Equifax Inc.'s massive data breach, and a top Democrat suggested the credit-monitoring company's corporate leaders might need to resign.

Shares of Equifax fell 2.4 percent on Thursday and trading volume hit a record high. The shares have lost 32 percent since the company disclosed the hack on Sept. 7.

Senate Democratic leader Chuck Schumer compared Equifax to Enron, the U.S. energy company that filed for bankruptcy in 2001 after revelations of a widespread accounting fraud.