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Every major AI model launched from September to November 2026, explained in one page

GPT-6, Claude 5.5 and Fable 5.2, Gemini 4, DeepSeek V4.1 and Meta's open model: what each is for and what it costs.

In ten weeks, every major AI lab shipped a new generation. Here is what launched, what each model is meant for and what it costs per million tokens, from the labs' own announcements.

The short version

  • Hardest work (coding, research, security): Claude Fable 5.2, GPT-6 Astra and Gemini 4 Argon.
  • Everyday work at scale: Claude Sonnet 5.5 and Opus 5.5, GPT-6 Sol.
  • High volume, low cost: Claude Haiku 5.5, GPT-6 Luna, DeepSeek V4.1-Flash.
  • Open weights you can host yourself: DeepSeek V4.1-Flash (MIT licence) and Meta's Muse Spark Open.

The launches, in order

ReleasedLabModelPositioned forPrice per 1M tokens (input / output)
1 Sep 2026AnthropicClaude Fable 5.1Hardest technical workReplaced by Fable 5.2
3 Sep 2026OpenAIGPT-6 AstraMost capable OpenAI model; computer use, coding, science$10 / $50; 1.05M context
10 Sep 2026DeepSeekV4.1-FlashLow-cost coding and agents; open weights (MIT)Output $0.60 off-peak, double at peak
22 Sep 2026OpenAIGPT-6 Sol and GPT-6 LunaFaster, cheaper everyday modelsNot listed in the announcement
Sep 2026AnthropicClaude Opus 5.5 / Sonnet 5.5Everyday professional and coding work$4 / $20 and $2 / $10
30 Sep 2026GoogleGemini 4 ArgonCoding, enterprise knowledge work, cyber defence$2 / $10 introductory, then $4 / $20
Oct 2026AnthropicClaude Haiku 5.5High-volume, low-latency tasks$0.10 / $0.50 (prompts up to 100K tokens)
Oct 2026GoogleGemini 4 CarbonLong-horizon engineering and cyber defence; pre-release onlyNot publicly available
15 Oct 2026MetaMuse Spark OpenMeta's open-weights model; 1M contextHosted at about $1.25 / $4.25
9 Nov 2026AnthropicClaude Fable 5.2Anthropic's top model for the hardest technical work$8 / $40

Claude Fable 5.2 (Anthropic, 9 November 2026)

Anthropic's newest model, released alongside Mythos 5.2, a less restricted version of the same model that only verified cyber-security and life-sciences organisations can use. Anthropic says Fable 5.2 is a step above Opus 5.5 on almost every capability it measured and writes output up to 30% faster than Fable 5.1. Its published scores include 69.9% on FrontierSWE v2 (Opus 5.5: 62.3%) and 41.3% on the Remote Labor Index, roughly double Opus 5.5's 21.3%. Price: $8 input and $40 output per million tokens.

GPT-6 Astra, Sol and Luna (OpenAI, September 2026)

Astra arrived on 3 September as OpenAI's most capable model, with a 1.05 million token context window, 128,000 tokens of output and a knowledge cutoff of 30 April 2026. OpenAI claims state-of-the-art results in computer use, browsing, software engineering, cyber-security and science. It is also the most expensive model on this list at $10 / $50. Three weeks later OpenAI added Sol and Luna, cheaper models built on the same advances. OpenAI said their API prices are 50% below the earlier GPT-5.6 promotional prices.

Gemini 4 Argon and Carbon (Google, September–October 2026)

Argon is the first Gemini 4 model. Google positions it for real-world coding, legal and finance work, long-video understanding and finding and patching software vulnerabilities. Google reports 77.9% on DeepSWE v1.1 and 51.3% on Zapier's AutomationBench, and says Argon resists indirect prompt injection better than earlier models. After early safety testing it rolled out globally in October across AI Studio, the Gemini API, Google Cloud, Search and the Gemini app. Gemini 4 Carbon, announced about two weeks later, is in pre-release testing with the US government and selected cyber defenders only.

DeepSeek V4.1-Flash (10 September 2026)

The Chinese lab's smallest model in a new architecture family: 552 billion parameters in total, with only 8 to 16 billion active per token, and a 1 million token context. The weights are under the MIT licence, so any business can download and run it. DeepSeek retired its V4-Pro flagship at the same time and cut prices. Its own benchmark claims put it level with the best closed models on some coding tests but well behind on Humanity's Last Exam (36.8 against 56.3 for Claude Opus 5).

Meta Muse Spark Open (15 October 2026)

Meta's open-weights release in its Muse family, with a 1 million token context and text and image input. On the independent Vals Index it scores 48.6%, below the leading closed models, but it can be self-hosted for data-sensitive work.

What this means for an Indian business

  • Don't chase the top model for everything. The gap between the cheapest and most expensive model above is about 100 times on price. Most business tasks, such as sorting emails, drafting replies and extracting invoice data, run well on the cheaper tier.
  • Agents are getting real. The headline benchmarks have moved from quizzes to doing work: operating computers, running office automations and finishing paid freelance tasks. Even so, the best scores show these models completing about half of such tasks. Keep a human approval step.
  • Open weights are a serious option. DeepSeek and Meta both released large open models. If your data cannot leave your own servers, you no longer have to settle for a weak model.
  • Build so you can switch. A new model generation arrived roughly every month this quarter. Systems that let you swap the model underneath without rebuilding will save money every quarter.

Next: which model to use for which task, with worked cost maths, and why a custom AI agent differs from a ChatGPT subscription.

Sources

Checked on 10 November 2026. Model names, prices and availability change quickly; confirm on the provider's page before you budget.

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