The Globe and Mail reports in its Friday edition that to understand the uncertainty around artificial intelligence spending, look no further than Celestica. The Globe's Joe Castaldo and Sean Silcoff write that Celestica had a fantastic year, driven by strong demand for its data-centre equipment. It exceeded analyst expectations in its fourth quarter earnings, raised its financial outlook and plans to increase capital expenditures to meet customer demand. Nevertheless, Celestica shares retreated $69.94 to close in Toronto Thursday at $394.94. The sell-off may reflect a change in how markets are thinking about AI spending. Investors are increasingly worried about whether record spending on AI is sustainable, or whether it amounts to a giant financial bubble. What may be causing investors concern is Celestica's plan to more than double its spending to $1-billion (U.S.) (or 6 per cent of 2026 revenue) to expand operations in response to intense customer demand. Previously, Celestica aimed to allot up to $400-million (U.S.). More spending can bring more risk, especially when the financial returns from AI are not entirely clear. Chief financial officer Mandeep Chawla says, "We have no hesitation in increasing our cap ex."