Companies building the AI compute, data, and software layer that powers artificial intelligence. This index captures firms across the AI infrastructure stack: semiconductor companies designing GPUs and AI accelerators like NVIDIA and AMD, cloud infrastructure providers scaling AI workloads, networking specialists building high-bandwidth interconnects for data centers, and AI-native software platforms enabling machine learning operations. From chips to cloud to the applications reshaping every industry, these companies form the foundation layer that makes AI possible. The index focuses on US-listed companies deriving over 30% of revenue or strategic growth from AI infrastructure, excluding pure consumer AI applications and generic enterprise software with basic AI features.