Equifax Inc., the credit-reporting firm that suffered a massive data breach last year, said it will notify an additional 2.4 million U.S. consumers that they were affected by the hack.

The customers were among the 145.5 million people whose identities were stolen last year, but Equifax was unable to confirm who they were at the time because only partial driver's license information was taken, the Atlanta-based credit-reporting company said Thursday in a statement. The consumers will be notified and the firm will offer them free credit-monitoring and identity-protection services.

Equifax disclosed the cyberattack in September, resulting in Congressional hearings and the departure of then Chief Executive Officer Richard Smith. The stock also has taken a beating, slumping 21 percent since the disclosure. Paulino do Rego Barros Jr. was named interim CEO and the company hired Jamil Farshchi from Home Depot Inc. last month as chief information security officer in an effort to boost its oversight.