Elon Musk’s September 14 announcement that Grok 4.8, a 2.5-trillion-parameter model on xAI’s new C++ training stack, would finish pretraining that week and enter reinforcement learning remains the dominant factor shaping trader views. Grok 4.7 shipped September 21 and has since posted strong results on coding and cybersecurity benchmarks, yet 4.8 has not appeared in xAI’s app, API, or model list as of early October. Historical gaps between Musk’s training-complete posts and actual releases range from three to seven weeks, pointing to a late-October or early-November window for 4.8. Traders are watching for any follow-up statements on RL progress, multimodal fixes, or competitive positioning against models such as Claude Opus and Fable, as well as xAI’s pace of iteration on the broader 4.9-to-Grok-5 roadmap.