Noam Shazeer, co-author of a landmark AI paper and Google's Gemini co-lead, is leaving Google for OpenAI after a two-year return stint.

What happened: Noam Shazeer, who co-authored "Attention Is All You Need" and served as Vice President of Engineering at Google co-leading the Gemini models, is departing Google to join OpenAI. Shazeer had rejoined Google in 2024 as part of a $2.7 billion（約4300億円） deal that also brought back co-founder Daniel De Freitas and parts of the research team, specifically to improve Google's reasoning models.

Why it matters: Shazeer's departure signals continued talent movement at a time when Google is still working to catch up with OpenAI and Anthropic in reasoning capabilities — the very area he was brought back to strengthen. His exit, described as "the biggest AI talent story of the year so far," underscores competitive pressure among the leading AI labs for top researchers.

What to watch: Shazeer's move follows Andrej Karpathy's recent decision to join Anthropic, suggesting a broader pattern of senior AI talent shifting between major AI companies. His work on reasoning models at OpenAI will likely influence the competitive dynamics between the two organizations.