One of OpenAI's co-founders has left for rival Anthropic, itself formed from previously departed staffers.

Along with the exit of noted computer scientist John Schulman, OpenAI president and co-founder Greg Brockman plans to take an extended leave until the end of the year. Product leader Peter Deng has also left.

"I've made the difficult decision to leave OpenAI," Schulman said on Twitter/X. "This choice stems from my desire to deepen my focus on AI alignment, and to start a new chapter of my career where I can return to hands-on technical work. I've decided to pursue this goal at Anthropic, where I believe I can gain new perspectives and do research alongside people deeply engaged with the topics I'm most interested in."

He added: "To be clear, I'm not leaving due to lack of support for alignment research at OpenAI. On the contrary, company leaders have been very committed to investing in this area. My decision is a personal one, based on how I want to focus my efforts in the next phase of my career."

Schulman led OpenAI's reinforcement training organization and was instrumental in the development of ChatGPT.

Also on Twitter/X, Brockman said: "I’m taking a sabbatical through end of year. First time to relax since co-founding OpenAI nine years ago. The mission is far from complete; we still have a safe AGI to build."

Deng, a product manager who joined OpenAI last year after leading products at Meta, Uber, and Airtable, left earlier this year. His departure was first reported by The Information.

Late last year, company CEO Sam Altman was fired by the board for not being "consistently candid." After a brief fight, in which employees threatened to join Microsoft, he was reinstated.

The generative AI startup is believed to be bleeding money as it ramps up hiring, training, and inference spend, and will likely need to raise money to survive.