OpenAI’s September 8, 2026 announcement of an AI-generated proof for the Navier-Stokes existence and smoothness problem, backed by a public Lean formalization that automatically verifies the singularity construction, underpins the 79.5% market-implied probability against retraction. The result, produced by an internal model coordinating roughly 10,000 agents over 88 hours, establishes specific Clay Millennium statements and differs from concurrent Euler-equation work by external researchers. While questions around training data and priority have surfaced, the machine-checked formalization and OpenAI’s decision not to claim the prize limit the scope for technical reversal. Upcoming community verification of the Lean repository and any Clay Institute response remain the main near-term catalysts that could shift sentiment before year-end.