GPT-5.6 Pro LEAKED & Is Coming Soon Fact Check

As of June 15, 2026, there is exactly one verifiable thing about the GPT-5.6 leak: a model string that flashed through OpenAI's Codex rollout logs, spotted by a researcher who goes by Haider, and was gone within hours.

Leaked reports and prediction market data point to June 23, 2026, with Polymarket placing the probability of a release between June 22 and 28 at 83% as of June 15. Fable 5 is priced at $10 per million input tokens and $50 per million output tokens.

Android Authority reported on June ... on the model's release date, with 83% probability assigned to a launch window of June 22 through June 28....

The honest answer: probably late June 2026, but nobody outside OpenAI knows the date. Multiple leak roundups and model trackers converge on a “mid-to-late June 2026” window, with a fallback into July if it slips.

OpenAI will be releasing its new flagship language model GPT-5.6 on June 23rd, as per recently leaked documents in developer forums and prediction markets. The

Polymarket's « GPT-5.6 released by June 30 » contract sits at 80 to 89% probability, comparable to where the GPT-5.5 market stood in early April before that model shipped on schedule.

GPT-5.6 is rumored to launch next week with stronger reasoning, improved coding performance, and a larger 1.5 million token context window.

A model codename, a claimed backend leak, a test in a third-party arena, a prediction market price, and a viral post are not equal to a product announcement. They can be useful signals, especially when they cluster. They cannot establish availability, pricing, safety status, or benchmark performance. The practical rule is simple: treat GPT-5.6 as a likely topic, not as a launched product.

While GPT 5.6 still remains unreleased, Anthropic has already made progress. Anthropic released Claude 5 along with Mythos 5. According to 36KR, Claude 5 is the Mythos-class model that has been made publicly available.