Capital One Reports Data Breach Affecting 100 Million Customers, Applicants

Capital One Financial Corp. , the fifth-largest U.S. credit-card issuer, said Monday that a hacker accessed the personal information of approximately 106 million card customers and applicants, one of the largest-ever data breaches of a big bank.

Paige A. Thompson, 33 years old, was arrested in connection with the hack Monday by federal agents in Seattle, officials said. Ms. Thompson is accused of breaking through a Capital One firewall to access customer data that the bank had stored on Amazon.com Inc. ’s cloud service, according to a federal criminal complaint...