Yahoo announced on Thursday that it believes information associated with at least 500 million user accounts was stolen by a "state-sponsored actor" at the end of 2014.
Cyber security experts believe that this was the largest-known breach of user accounts. Russian hackers are suspected as being behind the breach.
Since the announcement of the breach, two lawsuits have been filed against the company, both in California, alleging that it was negligent in securing users' personal information.
For more on the Yahoo security breach.