OpenAI confirmed that GPT-5.5, internally codenamed Spud, finished pretraining on March 24 after what Greg Brockman called 'two years of research.' Sam Altman stated the model is only 'a few weeks' from release, with prediction markets and leaks pointing to a mid-to-late April launch. OpenAI has not confirmed whether the commercial name will be GPT-5.5 or GPT-6 — it depends on how significant the performance leap is versus GPT-5.4.