OpenAI replaced ChatGPT's default model with GPT-5.5 Instant on May 5, 2026. The upgrade delivers 52.5% fewer hallucinations and 30% more concise responses than GPT-5.3 Instant, with new memory source controls for personalization transparency.
OpenAI launched a limited preview of GPT-5.5-Cyber to vetted cybersecurity teams on May 7 via its Trusted Access for Cyber program — about a month after Anthropic's Mythos debut, despite OpenAI's earlier criticism of the restricted-access approach.
OpenAI launched GPT-5.5 Instant as ChatGPT's new default model, replacing GPT-5.3 Instant. The update delivers 52.5% fewer hallucinations on high-stakes topics like medicine, law, and finance, along with more concise responses and enhanced personalization using Gmail and past conversations.
The DoD cleared OpenAI, Google, Microsoft, AWS, Oracle, Nvidia, and SpaceX to deploy AI on classified Impact Level 6 and IL7 military networks. Anthropic was labeled a 'supply chain risk' after insisting on safety guardrails for wartime AI use.
GPT-5.5 Instant is now ChatGPT's default model, replacing GPT-5.3 Instant. The update cuts hallucinated claims by 52.5% on high-stakes medical, legal, and financial prompts, and adds Gmail-based personalization and memory-source transparency.
Anthropic announced a $1.5B joint venture with Blackstone, Goldman Sachs, and H&F to sell AI tools to enterprise; minutes later, OpenAI closed $4B+ for a rival Deployment Company. Both target PE-backed firms as the primary channel.
A Harvard Medical School trial found OpenAI's o1 reasoning model correctly diagnosed 67% of ER patients, beating human physicians at 50-55%. With more clinical data, o1 reached 82% accuracy and dominated long-term treatment planning at 89% versus doctors' 34%.
The U.S. Department of Defense struck agreements with seven tech companies to deploy AI on its highest-security networks on May 1. Anthropic, which insisted on safety guardrails against autonomous weapons, is conspicuously absent.
A peer-reviewed study published in Science tested OpenAI's o1 on 76 real ER triage cases and found it achieved exact or near-exact diagnoses 67% of the time, versus 55% and 50% for two attending physicians who received identical patient data.
Sam Altman announced OpenAI's updated partnership with Microsoft, ending exclusive cloud arrangements. Microsoft remains the primary cloud partner, but OpenAI can now deploy products on AWS, Google Cloud, and any other provider.
Sam Altman announced the rollout of GPT-5.5-Cyber, a frontier AI model purpose-built for cybersecurity. Initial access is limited to critical cyber defenders, with broader access to follow as trusted frameworks are established.
OpenAI CEO Sam Altman, who once funded a large-scale UBI study, says cash payments are no longer the right answer to AI-driven economic disruption.