Anthropic Leaks Fable 5.5 and Next-Gen Opus Ahead of IPO: What We Know

Anthropic appears to be in full release mode ahead of its public offering. Two new Claude models have surfaced in early testing: Fable 5.5, a new image-capable model, and a next-generation Opus codenamed Obsidian 3, already spotted on benchmark platforms scoring above the current Opus 5.5.

The leaks emerged from X and Discord communities after an Azure model directory briefly listed an entry named claude-fable-5-5. The entry was quickly removed, but screenshots and leaked test images had already circulated. Sources familiar with the matter say both models could launch within one to two weeks.

Fable 5.5: Image Generation Leaks

The most widely shared test image is the classic pelican-on-a-bicycle prompt, a benchmark that has become a standard stress test for multimodal models. Leaked Fable 5.5 outputs show noticeably improved texture and lighting compared to current-generation models, with finer detail in the pelican's feathers, the bicycle's shadows on the sand, and even a small fish in the pelican's beak.

A second leaked test used the familiar game-controller prompt. The difference over Opus 5.5 was more subtle in that case, though observers noted Fable 5.5 produced more consistent surface detail and shadow layering.

The pelican prompt has effectively been saturated by training exposure, so community reactions are mixed on how much it actually demonstrates. The more telling signal is the texture resolution and the coherence of complex lighting, which several testers described as approaching dedicated image-generation models rather than a language model's built-in rendering.

Obsidian 3: The Next Opus

Beyond Fable 5.5, developers tracking benchmark platforms noticed an entry labeled Obsidian 3, reported to be the next Opus-tier model. Early results suggest a small but measurable score improvement over the currently shipping Opus 5.5.

No detailed benchmark breakdowns have been published, and the entry could be a pre-release checkpoint rather than a production candidate. The timing, however, is consistent with Anthropic's typical pattern: Opus 5.5 only recently displaced Google's top model on several leaderboards, and the company is already preparing a successor.

Why Anthropic Is Moving This Fast

The pace is not accidental. Earlier this week, Anthropic formally submitted its S-1 registration statement to the U.S. Securities and Exchange Commission, launching the IPO process. Market commentary has valued the company at between $1.5 trillion and $2 trillion, which would make it one of the largest public offerings in history.

In that context, two unannounced models in early testing serve a clear purpose: demonstrating that the company's technical momentum is ongoing, not a one-off result. The message to investors is that Anthropic can ship frontier improvements on a short cycle, not just maintain a lead.

Whether Fable 5.5 and Obsidian 3 launch before or after the listing remains unclear, but community sources expect the Fable 5.5 rollout to be the sooner of the two, potentially within the next week or two. The Opus successor may follow once Fable 5.5 has cleared the early-access phase.

What to Watch Next

• Official model card or API listing for Fable 5.5 and Obsidian 3.
• Independent benchmark comparisons against Opus 5.5 and Gemini's current top tier.
• Pricing: whether Fable 5.5 enters as a separate API tier or replaces an existing model.
• Any change to image generation policy or rate limits for Claude's multimodal endpoints.

Until Anthropic makes an official announcement, treat the leaked outputs as pre-release signals. Models in testing can change substantially before they ship, and screenshots without full prompts are notoriously difficult to evaluate fairly. The underlying fact—that Anthropic has more than one frontier model in the pipeline ahead of its IPO—is what matters most for developers planning their stack.