OpenAI's co-founder and chief scientist Simo closed his tenure, marking another leadership transition amid the company's scaling phase.

Fidji Simo's departure from OpenAI as the company's number two is now official. The announcement came as little surprise to those following the company's recent leadership shifts, particularly after Greg Brockman absorbed the majority of her responsibilities in mid-May on a permanent basis—a move that effectively signaled she would not return.

Simo will remain with OpenAI as an advisor while continuing to focus on her health recovery. Throughout her medical leave, she has maintained close contact with Brockman, communicating with him on an almost daily basis.

Sources indicate that Simo had initially anticipated her leave lasting only a month or two. However, the intensity of the artificial intelligence race prevented OpenAI from operating on autopilot during her absence. While some companies can sustain momentum when senior leaders step away temporarily, OpenAI proved unable to do so.