The letter expands on a fear Schneiderman has voiced before. Wrongdoing by insiders is the third-leading cause of unauthorised exposure of customer records in New York, he said in a report last year. From 2006 to 2013, more than 1.2 million customer records were exposed in 511 insider-caused security breaches, he said.
Tellers "frequently retrieved customer account numbers and Social Security numbers from bank databases, without authorisation or a legitimate business need," Schneiderman wrote. Purloined data was used to create phony documents, which tellers then used to impersonate account holders and withdraw money, he added.
"While we are reviewing the letter, protecting our customers' information is of critical importance to us," Citigroup spokeswoman Elizabeth Fogarty said in an emailed statement on Monday.
Michael Fusco, a JPMorgan spokesman, and Anne Pace, a Bank of America spokeswoman, declined to comment on the letter.
Earlier this year, an ex-JPMorgan employee was accused of trying to sell data for several accounts, including one containing $150,000, while he worked at a branch. Fusco said customers didn't lose any funds and were provided with free credit monitoring.
- Bloomberg