Tencent open-sources Hy4-preview, a 770B MoE with 1M-token context

Tencent's Hunyuan team released Hy4-preview on August 28, a 770-billion-parameter mixture-of-experts model with 49 billion activated per token and a context window exceeding one million tokens, TechNode reported. The weights ship under Apache 2.0.

The architecture: 78 layers, the first a standard dense feed-forward network, the remaining 77 running MoE with 256 routed experts and one shared expert.

API pricing on Tencent Cloud TokenHub is $0.834 per million input tokens and $2.501 per million output tokens, with a two-week free trial on WorkBuddy and CodeBuddy and additional API access via OpenRouter.

Tencent says the model helped tune its own stack. Per the release, "the model helped optimize parts of its own training and inference systems, increasing end-to-end throughput by 31.8% against a baseline." On an internal rubric graded by 163 experts across 203 engineering tasks, Hy4-preview scored 2.99 out of 4, ahead of GLM 5.3 at 2.92 and Kimi K3 at 2.94.

Those are self-reported numbers on a self-designed rubric; the TechNode write-up carries no GPQA, SWE-bench, or other public benchmark scores. Hy4-preview joins a steady run of Chinese open-weight releases we've tracked this quarter, one of more than 340 China AI stories in our tracker over the last 90 days.