Yahoo Inc was sued on Friday by a user who accused it of gross negligence over a massive 2014 hacking in which information was stolen from at least 500 million accounts. The lawsuit was filed in the federal court in San Jose, California, one day after Yahoo disclosed the hacking, unprecedented in size, by what it believed was a “state-sponsored actor.” Ronald Schwartz, a New York resident, sued on behalf of all Yahoo users in the United States whose personal information was compromised. The lawsuit seeks class-action status and unspecified damages. A Yahoo spokeswoman said the Sunnyvale, California-based company does not discuss pending litigation. The attack could complicate Chief Executive Marissa Mayer’s effort to shore up the website’s flagging fortunes, two months after she agreed to a $4.8 billion sale of Yahoo’s Internet business to Verizon Communications Inc .