AI bubble / Circular financing

The hypothesis that AI capex ($500B+ Stargate, Hyperion, Prometheus) is creating a financial bubble through circular financing: NVIDIA invests in OpenAI, OpenAI buys from NVIDIA, Microsoft invests in OpenAI, which buys Azure. In 2025-26 this is becoming the central macro question: is it a dotcom-style bubble or a real transformation? The first clear test came in Q4 2025 with NVIDIA dropping ~25%.