The personal details of more than 100 million individuals across the US and Canada were stolen in a hack targeting financial services firm Capital One, the company has revealed.
According to Capital One, the data included names, addresses and phone numbers of people who applied for its credit card products.
The hacker did not gain access to credit card account numbers, it said.
The announcement came after the alleged hacker was arrested on Monday.
Paige A Thompson was charged with a single count of computer fraud and abuse.
Thompson made an initial appearance in the US district Court in Seattle and was ordered to remain in custody pending a detention hearing on Thursday.
Capital One is a major credit card issuer in the US and also operates retail banks.
The firm said in a statement released on Monday that the breach affected approximately 100 million individuals in the US and 6 million people in Canada.
The statement added that about 140,000 social security numbers and 80,000 linked bank account numbers were compromised in the US.
In Canada, about one million social insurance numbers belonging to Capital One credit card customers were also compromised.
Capital One, based in McLean, Virginia, said it found out about the vulnerability in its system on July 19 and immediately sought help from police to catch the perpetrator.
According to the FBI complaint, someone emailed the bank two days before that notifying it that leaked data had appeared on the web hosting site GitHub.
A month before that, the FBI said, a Twitter user who went by "erratic" sent Capital One direct messages warning about distributing the bank's data, including names, birth dates and social security numbers.
"Ive basically strapped myself with a bomb vest, (expletive) dropping capitol ones dox and admitting it," one said. "I wanna distribute those buckets i think first."
