Microsoft and Alphabet reported capital expenditure figures below analyst expectations this week, signaling potential constraints in the AI infrastructure buildout both companies have bet their growth on.

Microsoft reduced its full-year capex forecast to $170 billion from $175 billion. CFO Amy Hood attributed the cut to delays from third-party GPU suppliers, which will push out available capacity until the first half of 2027. Alphabet maintained guidance at $195 billion to $205 billion, despite market expectations for an increase. Finance chief Anat Ashkenazi said outside computing power only became available at the end of the third quarter.

The revised forecasts spooked markets. Shares of neocloud providers CoreWeave, Nebius, and IREN all declined. Oracle also fell. Alphabet shares tumbled about 10 percent in extended trading after the company missed on earnings and revenue, reporting negative free cash flow of more than $9 billion.

Microsoft relies on firms like CoreWeave, IREN, and Nebius for supplemental computing capacity. Delays from these partners have occurred before, but they carry greater weight now as the neocloud sector faces a structural financing crunch. These companies need billions in outside capital to fund buildouts but lack investment-grade credit ratings. Lenders are withdrawing as interest rates rise and debt concerns mount.

Meta Platforms offered a contrasting signal last week, raising the low end of its full-year capex forecast to $135 billion to $145 billion, up from $130 billion. Meta shares sank anyway after reporting negative free cash flow, suggesting investors are skeptical that higher spending will translate to near-term returns.

The capacity constraints hit as AI developers lean harder on external infrastructure. Anthropic, which is preparing to go public, relies on computing from Amazon, Google, and Microsoft, supplemented by capacity from SpaceX, Lambda, and Nscale. Anthropic's Claude assistant has faced intermittent unavailability this year due to surging demand. OpenAI, which anticipates an IPO in 2027, also requires constant capacity expansion.

Nscale, which filed to go public in September, has not updated its prospectus in weeks—a sign of potential traction or stalled momentum.

Amazon's earnings report, due Thursday after market close, will provide the final read on hyperscaler capex trends for the quarter.