A week ago Tuesday, OpenAI silently swapped the default ChatGPT model from GPT-5.3 Instant to GPT-5.5 Instant. Most enterprises did not notice. Their sensitive workflows ran on a different model at lunchtime than they did at breakfast — with a different hallucination profile on legal, medical, and financial outputs — and nobody at the C-level was told. Stephen reads the default swap as the cleanest test of where your company sits on a much larger divide: PwC's finding that 74 percent of AI's economic value is being captured by 20 percent of companies.

What's covered

• What actually changed on May 5 — GPT-5.5 Instant becomes default, GPT-5.3 phased out for paid users in 90 days, real benchmark improvements on hallucination in sensitive domains, and the parallel rollout of GPT-5.5-Cyber for vetted teams
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