Sundar Pichai, CEO, Google and Satya Nadella, CEO of Microsoft.

Denis Balibouse | Ruben Sprich | Reuters

The past few quarters of hyperscaler earnings have been marked by ever-increasing capital expenditure forecasts as tech giants race to build out artificial intelligence infrastructure to meet what they describe as insatiable demand.

At least for the moment, Microsoft and Alphabet are telling a slightly different story.

In their earnings reports Wednesday, both companies shared capex figures that came up shy of analysts' estimates. Microsoft reduced its capex forecast for the year to $170 billion from $175 billion, and Alphabet held its guidance at $195 billion to $205 billion.

The numbers suggest a slowdown is nowhere in sight, but they do represent another potential point of concern for the AI buildout.…