This marks the seventh co-founder exit from xAI since 2023.
Toby Pohlen is the latest co-founder to leave xAI, announcing his decision to resign just weeks after two others left.
The Elon Musk-owned xAI has lost three co-founders in the weeks since his space-tech company SpaceX bought xAI for a reported $250bn. The combined business is worth an estimated $1.25trn, with an initial public offering planned for later this year.
xAI had previously acquired X, the social media platform, last March.
In a post on X, Pohlen thanked Elon Musk for taking him on board. “I’ve learnt more about execution, speed and product perfectionism than I could ever have imagined. Thanks for everything,” he said. Musk responded: “Thanks for helping get xAI to where it is.”
Pohlen is the seventh co-founder to exit xAI in less than three years, following Jimmy Ba and Tony Wu, who left earlier this month. Kyle Kosic left in 2024, followed by Igor Babuschkin and Christian Szegedy in 2025.
Greg Yang, another co-founder, announced last month that he would be stepping down after being diagnosed with Lyme disease. Pohlen had worked in Google DeepMind as a research engineer for more than six years before co-founding xAI.
The flurry of exits leaves Musk, Manuel Kroiss, Zihang Dai, Guodong Zhang and Ross Nordeen at the company.
Earlier this month, Ireland’s data protection watchdog launched a “large-scale” inquiry into X following the Grok ‘nudification’ fiasco. This investigation followed separate similar inquiries launched by the European Commission and the UK government.
Meanwhile, a year-long inquiry by French authorities has expanded to probe Grok’s possible role in disseminating Holocaust denials and sexual deepfakes. The US state of California also launched a similar investigation into X and Grok’s parent company xAI last month.
Alongside this, the EU is continuing with a separate, years-long investigation into X to assess if the platform mitigated risks stemming from its recommender systems, including the impact of the recently announced switch to a Grok-based recommender system.
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