Yahoo says hackers stole data from more than one billion user accounts. In a statement, Yahoo said it believes "an unauthorized third party, in August 2013, stole data associated with more than one billion user accounts," including names, email addresses, phone numbers, and possibly security questions and answers. The company says it believes bank-account information and payment-card data were not affected. Back in September, Yahoo announced that nearly 500 million accounts The new hack revelation raises questions about whether Verizon will try to change the terms of its $4.8 billion proposed acquisition of Yahoo.