OpenAI Ships GPT-5.5 With Full Base Retrain

OpenAI released GPT-5.5, its first fully retrained base model since GPT-4.5 – every 5.x release in between was post-training on the same foundation. It tops the Artificial Analysis Intelligence Index at 60, scores 82.7% on Terminal-Bench 2.0, and comes with a 1M context window. The pricing doubles to $5/$30 per million tokens, which is a bet that capability gains justify the cost. Strongest improvements land in agentic coding, computer use, and multi-step research tasks – the same surface area where Anthropic and Google have been concentrating. Available now for Plus, Pro, Business, and Enterprise ChatGPT users, with API access coming separately behind additional safeguards.