Yahoo Inc. is evaluating whether an unidentified hacker has access to its user account data, following a 2014 hack that resulted in the theft of more than 500 million user account records.

In a regulatory filing Wednesday, Yahoo said law-enforcement authorities on Monday “began sharing certain data that they indicated was provided by a hacker who claimed the information was Yahoo user account data.” Yahoo said it would “analyze and investigate the hacker’s claim.”

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