The $10B AI data training startup, Mercor, has been hit hard by a data breach following a major $350 million Series C that valued the company at $10 billion. Since March 31, a hacker group claimed to have obtained 4TB of stolen data from Mercor's systems, including candidate profiles, personally identifiable information, employer data, source code, and API keys. Mercor has not confirmed the authenticity of the data, but confirmed that it is investigating and will continue to communicate with customers and contractors as appropriate. Five of Mercor’s contractors have filed lawsuits over their alleged personal data exposure, with one claiming to have named LiteLLM and Delve as defendants. Other large model makers may also be considering their relationships with Mercor after the breach.