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Z.ai announced GLM-5.3-Flash on August 26, 2026 as the first natively multimodal model in the GLM-5 series, built from a newly trained base rather than a post-train of GLM-5.2. It is a 320-billion-parameter mixture-of-experts that activates only 18 billion parameters per token, and it introduces a hybrid architecture c For serving efficiency, the GLM-5.3-Flash design roughly halves both the activated parameter count (18B vs GLM-4.5's 32B) and the number of layers (45 vs 92) compared to the GLM-4.5 series, while using a hybrid attention scheme to minimize long-context attention costs. The post also notes that Z.ai's full flagship GLM-
