Google has unsettled investors by raising its capital spending forecast to as much as $205 billion, up from a previous top estimate of $190 billion, sparking concern that the company cannot accurately predict its AI-related costs. This matters because Google is spending more than it earns while facing pricing pressure from competitors and cheaper Chinese AI tools, and similar concerns are expected to surface when Meta, Amazon and Microsoft report earnings this week.

Other warning signs are adding to Wall Street's unease: SpaceX's valuation has nearly halved from its peak, investors are worried about Oracle's data-centre debt given its ties to OpenAI, and Nvidia is reportedly involved in deal talks worth a combined three-quarters of a trillion dollars, including guaranteeing $250 billion of OpenAI's debt. Analysts say such deals may signal funding strain rather than genuine demand, while a competitive new model from a Chinese start-up has renewed fears that firms are overbuilding data centres despite having less access to top-tier chips.