Shares of Alphabet fell as much as 7 percent after two prominent artificial intelligence researchers departed Google for rival AI firms, fueling investor concerns that the company may be losing ground in the race for top talent.

Among those leaving are Nobel Prize-winning researcher John Jumper, who joined Anthropic from Google DeepMind and Noam Shazeer, a co-lead of Google’s Gemini AI models, who moved to OpenAI. Analysts said the departures raised questions about Google’s ability to retain key personnel amid intensifying competition in the AI sector.

The selloff also reflected broader concerns about the enormous costs associated with artificial intelligence development. Alphabet has signaled plans to spend between $180 billion and $190 billion in fiscal 2026, much of it for AI infrastructure and data centers, as investors increasingly scrutinize whether technology giants can translate massive AI investments into sustainable returns.A