The Epoch Brief - October 23, 2026 epochai.substack.com

Epoch researchers found that six leading AI models could not reliably meet the quality standards for 11 tasks based on the organization’s work, though they performed best on coding and data analysis. The October 23 brief also reports that top models now win more than 90% of Slay the Spire runs, open-weight models trail closed models by about six to seven months in cybersecurity, and Google’s Gemini 4 Argon ties Claude Fable 5.1 on Epoch’s capabilities index.