OpenAI launches GPT-5.5, its first fully retrained base model since GPT-4.5

The model, codenamed “Spud,” is designed to complete complex multi-step tasks with minimal human direction. It sets new benchmarks in agentic coding, computer use, and knowledge work, while matching GPT-5.4’s per-token latency. API access is delayed pending additional safety work.

For months, the AI industry’s open secret has been that Anthropic’s Claude is winning the enterprise market. OpenAI has been in what internal sources described as a “Code Red” state since at least December 2025, watching Anthropic’s ARR sprint from $9 billion to $30 billion while its own B2B positioning eroded.

On Thursday, OpenAI responded. GPT-5.5, the company’s first fully retrained base model since GPT-4.5, is rolling out to Plus, Pro, Business, and Enterprise users in ChatGPT and Codex. The model is designed to complete work with limited human direction, operating across email, spreadsheets, calendars, and other applications.

The core thesis ...