By Jonathan Spicer
The names and e-mails of customers of Citigroup Inc and other large U.S. companies, as well as College Board students, were exposed in a massive and growing data breach after a computer hacker penetrated online marketer Epsilon.
In what could be one of the biggest such breaches in U.S. history, a diverse swath of companies that did business with Epsilon stepped forward over the weekend to warn customers some of their electronic information could have been exposed.