Hy4 preview
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The gist
Tencent open-sourced Hy4 preview, a 770B-parameter AI model, on Aug 28. It targets productivity tasks and is free for two weeks on WorkBuddy and CodeBuddy.
Background
Tencent's Hunyuan lab released Hy4 preview on August 28, 2026, as an open-source model designed for productivity tasks like coding, office work, and scientific research. It uses a mixture-of-experts design with 770 billion total parameters but only 49 billion activated per request. The release follows Tencent's increased AI investment and the hiring of former OpenAI researcher Yao Shunyu to lead AI development.
How it unfolded
- Aug 28, 2026Tencent released and open-sourced Hy4 preview, with 770B total parameters and a 1M-token context window, available via WorkBuddy, CodeBuddy, Yuanbao, ima, and API through Tencent Cloud TokenHub and OpenRouter.
- Aug 28, 2026News of the release drove Tencent's stock up 1.65% to close at HKD 455.2, with an intraday high of HKD 462.2.
- Aug 29, 2026Early reviews highlighted strong coding performance (DeepSWE score 64.3 vs Hy3's 28.0) but noted potential flaws like over-verification and slower responses on complex tasks.
Who’s saying what
- Official
- Tencent says Hy4 preview is 'built for productivity' with significant improvements in software engineering, office analytics, game development, and scientific research.
- Analysts
- TechNode notes the model's 770B parameters and 1M-token context, positioning it as a top-tier open-source model for real-world tasks.
- Caution
- Reuters reports Tencent acknowledges the early-release model can sometimes take longer than necessary on complex questions and may over-verify its own answers.
Still unverified
Claims that Hy4 preview can 'outmanage Codex' and specific benchmark comparisons (e.g., DeepSWE 64.3) are from third-party reviews and not independently verified.