Weekly briefs

The week's main stories in AI and why they matter.

• The week in AI, 5 to 11 October 2026
  5 to 11 October 2026 · this week
  Mistral AI opened a preview API for Mistral Large 4 on 6 October, a 1 trillion parameter multimodal model that it says will get open weights by the end of October.
• The week in AI, 28 September to 4 October 2026
  28 September to 4 October 2026
  Google released Gemini 4 Argon to vetted cyber defenders first, and Anthropic and OpenAI shipped Claude Sonnet 5.5 and GPT-6.1 Sol at $2/$10 per million tokens.
• The week in AI, 21 to 27 September 2026
  21 to 27 September 2026
  Anthropic released Claude Opus 5.5 on 22 September, cutting its price by 20% to $4 per million input tokens and reporting 66.4% on Terminal-Bench 4.0.