OpenAI co-founder John Schulman says in a Monday X post that he will leave the company to join rival Anthropic, saying he wants to ‘deepen my focus on AI alignment’ and return to hands-on technical work. Schulman, who was a co-leader of OpenAI’s post-training team that refined AI models for the ChatGPT chatbot and a programming interface for third-party developers, and later served as head of alignment science, becomes the latest high-profile researcher to depart. Earlier this year, superalignment team co-leaders Jan Leike and Ilya Sutskever also left, with Leike joining Anthropic as well.

In a separate announcement, OpenAI president and co-founder Greg Brockman said he is taking a sabbatical through the end of the year, his first extended break since co-founding the company nine years ago. The company also confirmed that product manager Peter Deng, who joined last year from Meta, has exited. With Schulman’s departure, only three of OpenAI’s original 11 founders remain: CEO Sam Altman, Brockman, and Wojciech Zaremba.

Schulman emphasized his decision was personal and not due to lack of support for alignment research at OpenAI, stating that company leaders are ‘very committed to investing in this area.’ Anthropic, founded by former OpenAI employees in 2021, has positioned itself as a rival focused on safety. The news caps a period of turmoil for OpenAI, which saw CEO Sam Altman briefly ousted and reinstated last November, and has since faced questions about its safety practices.