ByteDance Is Reportedly Training A 10 Trillion-Parameter AI Model to Rival Anthropic's Mythos

ByteDance, the Chinese technology group that owns TikTok, is training an artificial intelligence model with as many as 10 trillion parameters, a scale that could approach Anthropic's most advanced Mythos system, the FT reported, citing people familiar with the matter.

The report said it could not independently verify the details, and ByteDance had not immediately responded to a request for comment.

How the numbers stack up?

An AI model's parameter count refers to the numerical settings it learns from training data to recognise patterns, generate responses and carry out tasks, and is commonly used as a rough proxy for scale, though not necessarily for capability.

At 10 trillion parameters, ByteDance's model would be more than three times the size of Moonshot AI's Kimi K3, a 2.8 trillion-parameter model that is among the largest released by a Chinese AI lab so far.

According to the FT, industry estimates put Anthropic's Mythos 5 at around 8 trillion parameters, with its more widely available, guardrailed sibling Fable 5 estimated at about 5 trillion parameters. Anthropic does not officially disclose parameter counts for Mythos, Fable or any of its models, so these figures remain industry estimates rather than confirmed data, a caveat that also applies to parameter counts attributed to other US models such as OpenAI's GPT-5.5.

Still early days

The ByteDance model is currently in the pre-training phase, a process that typically takes three to six months, after which it would move to fine-tuning before any potential public release, the report said. The exact final parameter count has not been locked in and could change before training concludes.

The development comes days after ByteDance founder Zhang Yiming reportedly told employees to avoid relying on AI distillation techniques purely to chase short-term gains, following allegations from a senior US official that Moonshot AI had distilled Anthropic's Fable model while building Kimi K3.

The bigger picture

Mythos is Anthropic's frontier model class, positioned above its Opus tier, and has drawn attention for strong agentic coding, reasoning and cybersecurity capabilities. Access to Mythos has largely been restricted to trusted partners under Anthropic's Project Glasswing, given concerns about misuse in hacking and vulnerability exploitation, while Fable 5 is the safety-hardened version made more broadly available.

ByteDance's push comes as Chinese technology firms accelerate their model release cycles to keep pace with US rivals in an increasingly expensive race to build larger and more capable large language models, while also trying to keep the cost of running them from becoming prohibitive. Several Chinese labs are already working on models in the roughly 5 trillion-parameter range associated with Fable, with ByteDance now positioning itself as one of the most ambitious, aiming closer to Mythos-scale.