The U.S. credit monitoring company Equifax is facing a storm of criticism, lawsuits and investigations after a data breach that may have compromised personal data for about 143 million Americans.
"The Equifax breach has potentially exposed sensitive personal information of nearly everyone with a credit report, and my office intends to get to the bottom of how and why this massive hack occurred," Schneiderman said in a statement.
Illinois' attorney general also opened an investigation into the data breach, and more states are likely to follow suit.
Also Friday, U.S. Representative Jeb Hensarling, a Texas Republican who is chairman of the House Financial Services Committee, said he would call for congressional hearings on the Equifax breach.
Two proposed class-action lawsuits, one filed in Portland, Oregon, and another in Atlanta, Georgia, alleged that Equifax had been negligent in protecting consumer data.
Stock price slides
Investors were also showing their displeasure about the hack by dropping their stock in the company. Equifax's share price fell more than 13 percent in trading Friday, to $123.32. The decline equates to more than $2 billion in lost market value.
The Atlanta company said Thursday that the hackers had obtained names, Social Security numbers, birth dates and addresses of more than 40 percent of the U.S. population.
"Based on the company's investigation, the unauthorized access occurred from mid-May through July 2017," the company said in a statement.
The company said credit card numbers were also compromised for 209,000 U.S. consumers, as were credit dispute accounts for 182,000 people.
Equifax discovered the hack July 29 but waited until Thursday to warn consumers.
Although other cyberattacks have been bigger than this one, such as a data breach at Yahoo last year that affected more than 500 million accounts, this one could be the most damaging because of the type of data collected.
Equifax is one the largest credit-reporting companies in the United States.