Shares of Equifax dove Friday after a newspaper said the credit rating company's data breach last year was worse than reported.
The stock traded down 4.5 percent in afternoon trading but recovered somewhat to close down 1.5 percent for the day. They are down 4.8 percent this year.
Equifax disclosed in September that personal information for 145.5 million consumers had been hacked from its computer systems over the summer, including names, Social Security numbers, birthdates and addresses.
The Wall Street Journal reported Friday that the company has submitted a document to the Senate Banking Committee saying cyberthieves also accessed tax identification numbers, email addresses and drivers' license information.
A statement from an Equifax spokeswoman said the information it disclosed to the public in September included details affecting the majority of the 145.5 million people but was not an exhaustive list. It added that the newspaper's account "was not new information."
"The Senate Banking Committee asked us a question about the extent of breach, and we provided them with a list of all of the elements we were analyzing as part of the forensic investigation," the Equifax spokeswoman said. "There were some additional data points affected. They were not the primary data points."