Codex

Mythos

Opus

Azure

On November 1, the code of Anthropic’s Mythos web page carried a label, “Mythos 5.5,” that was hidden.
The find fed claims that some requests for Claude Opus 5.5 are hitting an unreleased model that users call Fable 5.5, which Anthropic has not announced.
<h3 id="span-style-font-weight-400-mythos-5-5-appeared-six-times-including-in-the-logo-s-alt-text-span">“Mythos 5.5” appeared six times, including in the logo’s alt text</h3>
An X user known as Chubby, Kim Isenberg, shared a screenshot of the page’s HTML on Nov. 1, citing an anonymous email tip. “Mythos 5.5 is already listed HTML source code of Anthropic’s official website,” Isenberg wrote.
<figure style="width: 100%" class="wp-caption alignnone"><img src="https://www.cryptopolitan.com/wp-content/uploads/2026/11/2026-11-03-hidden-mythos-5-5-tag-anthropic-fable-5-5-01.png" alt="Hidden &quot;Mythos 5.5&quot; tag on Anthropic site fuels Fable 5.5 talk." width="622" height="368">
 <figcaption>
 Chubby’s post showing “Claude Mythos 5.5” in the code of Anthropic’s Mythos page, posted by @kimmonismus on <a href="https://x.com/kimmonismus/status/2116914141017370972" rel="noopener noreferrer nofollow">X</a> on November 1, 2026.
 </figcaption>
</figure>
The X post has garnered over 3,600 likes. Pseudonymous leaker Chetaslua also noted that the label was mentioned six times in hidden code.
They were in an invisible headline and the alt text of the logo. The live page checked on November 2 only showed Mythos 5.1, the version that shipped with Fable 5.1 in September.
<a href="https://www.cryptopolitan.com/grok-4-7-beats-fable-5-1-harvey-legal-test/" rel="noopener noreferrer nofollow">Fable</a> is Anthropic’s flagship commercial Claude product, marketed for coding and office work. Mythos is a restricted AI model accessible to a select group of customers, like government and cybersecurity customers.
<h3 id="span-style-font-weight-400-unannounced-gpt-6-2-astra-took-19-8-of-one-account-s-usage-span">Unannounced gpt-6.2-astra took 19.8% of one account’s usage</h3>
The routing talk began on October 1. Users posted what looked like stronger than usual outputs from Claude, still tagged Fable 5.1.
“Claude Opus 5.5 is routing to a new model,” Chetaslua <a href="https://x.com/chetaslua/status/2109244702235275680" rel="noopener noreferrer nofollow">wrote</a> on October 11. The leaker said that the new model could be Fable 5.5 or a new Opus.
On October 13, a second hint was discovered. Following the general availability of “claude-fable-5-5” in Microsoft’s Azure catalog, the entry was automatically added to LiteLLM.
Builders use LiteLLM, an open-source tool, to connect with a variety of AI providers. Entry copied the limits and prices from Fable 5.1, but it was later removed.
Anthropic put out Fable 5 on June 9, but because of U.S. export controls, they had to take it offline for 18 days. Then came Fable 5.1 on September 1 and Opus 5.5 on September 22.
Anthropic says Opus 5.5 can do most of the same things as Fable 5.1 for a lot less money. “OpenAI is quietly A/B testing a new variant called GPT-6.2 Astra, and it’s already showing up in Codex usage analytics,” TokenGremlin <a href="https://x.com/TokenGremlin/status/2116834891744600291" rel="noopener noreferrer nofollow">wrote</a> on November 1 on X.
A Codex screenshot shared on X showed that gpt-6.2-astra accounted for 19.8% of one account’s usage and gpt-6-astra for 80%.
OpenAI has not announced a model named 6.2. OpenAI released GPT-6 Astra on September 3.
Isenberg forecast a GPT-6.2 Astra launch “very soon, in response to Fable 5.5 and Anthropic’s IPO.”
On October 26, the company made its IPO filing public, under the Nasdaq ticker ANT, <a href="https://www.cryptopolitan.com/openai-rival-anthropic-makes-its-ipo/" rel="noopener noreferrer nofollow">Cryptopolitan</a> reported.
Anthropic’s revenue for the first half of 2026 was $16.29 billion, up from $1.16 billion a year earlier.
If you're reading this, you’re already ahead. <a href="https://www.cryptopolitan.com/newsletters/?utm_source=cp&amp;utm_medium=web&amp;utm_campaign=inlineAds" rel="noopener noreferrer nofollow">Stay there with our newsletter</a>.

Anthropic web code shows "Mythos 5.5" as Fable 5.5 rumors grow

Table of Contents

Cryptopolitan_News

Other articles published on Nov 3, 2026

Join our free newsletter for daily crypto updates!