OpenAI is set to release GPT-5.6 on June 23, aiming to rival Claude Fable 5

According to Cognizant Beating monitoring, leaks have revealed that OpenAI is planning to release a new flagship model codenamed GPT-5.6 on June 23. The new model will support a context window of 1.5 million tokens, show improvements in AI programming workflows, and offer an API price only one-third of Claude Fable 5's.

The timing of this release is closely tied to competitor Anthropic's developments. Anthropic launched the Claude Fable 5 model on June 9, but due to a security vulnerability, it was urgently taken down by the U.S. Department of Commerce on June 12. OpenAI's choice to release on June 23 is primarily to capitalize on the period when Fable's planned transition ends, and a large number of users are forced to switch to paid plans.

Amidst the release rumors, the probability in the prediction market regarding "OpenAI releasing GPT-5.6 between June 22 and June 28" has currently surged to 78%.