Amazon.com Inc. shares have largely climbed on the back of two trends: strength in its cloud business and a focus on costs. Now both could be in question.

The pressure is on Amazon.com to deliver on lofty expectations for cloud computing in its fourth-quarter results on Thursday, after Microsoft and Google's lackluster reports jolted investor faith in Big Tech's billion-dollar investments in AI.

Microsoft reported that its flagship cloud computing business experienced a slowdown in growth amid constraints on data center supply.

The results echoed the slowdown at Microsoft and Alphabet-owned Google, and highlighted how U.S. cloud-computing giants were struggling to scale AI as infrastructure bottlenecks cap growth, forcing them to invest billions in data centers with little short-term payoff.