The personal details of about 106 million individuals across the US and Canada were stolen in a hack targeting Capital One systems, the company has revealed.
The announcement came after the alleged hacker was arrested on Monday.
According to Capital One, the data included names, addresses and phone numbers of people who applied for its credit card products.
But the hacker did not gain access to credit card account numbers, it said.
The statement added that 99% of social security numbers were not compromised.