OpenAI has established a rapid release cadence for major models, with GPT-5 expected in 2025 or 2026 and GPT-5.5 as a potential intermediate step. The company historically releases significant model iterations as new capabilities emerge, though timing often shifts from initial announcements. This market resolves positively if OpenAI officially announces and releases GPT-5.5 by April 30, 2026. The resolution is objective and verifiable: OpenAI must make an explicit public statement about the model release. The current 95% odds reflect strong market confidence that OpenAI will deliver an advanced iteration by the deadline, likely as a refinement between GPT-5 and successor models. This elevated probability suggests traders expect the company to maintain its pattern of releasing major model improvements within predictable timeframes. Odds have remained stable as April 2026 approaches, with minimal volatility indicating sustained conviction that a release event falls within this window.