Musk says Grok 4.8 finished pre-training and will start a soft rollout later this week
Quick answer: On Nov 10, 2026, Elon Musk wrote on X that Grok 4.8’s pre-training is done, that the model is now in reinforcement learning (RL), and that “a soft rollout to Bot users” is planned “later this week.” He also said the team dumped JAX and SGLang and rewrote its RL and inference software in C/C++. There is still no Grok 4.8 post, model page, price, or score on the official site. The newest model announced there is Grok 4.7. (Musk on X; x.ai/news; xAI/SpaceXSI release notes)
What’s new
Musk was replying to someone who asked when to expect Grok 4.8. His full note, posted at 3:35 a.m. CT:
- He wrote that the team has “dumped JAX/SGLang and rewritten the entire RL and inference stack from scratch in C/C++, which took some extra time.” JAX and SGLang are widely used tools for training and serving AI models; C and C++ are lower-level programming languages. He is saying the company built that layer itself.
- “Training (aka pre-training) is done.” A “lot of cleanup was needed on the SFT data to get that mostly right.” SFT is supervised fine-tuning: training on curated example answers after the first, large pre-training pass.
- “Now, 4.8 is in RL and the evals are starting to climb.” RL is the later stage where a model is tuned against rewards. “Evals are starting to climb” is Musk’s claim; he published no scores.
- “We will do a soft rollout to Bot users later this week and see how it goes.” A soft rollout is a limited, gradual release. “Bot users” points to people using Grok Bot, the company’s always-on agent product, not necessarily everyone chatting with Grok on the web, the apps, or the API. He did not say how large the test is, who is included, or whether API customers will get it.
- “Grok 4.8 will bear no resemblance to 4.7 (thankfully). It is not yet incredible, but, this time, the foundations are built right, so I expect it to evolve to be something special.”
Those are Musk’s words, not independent tests. He gave no benchmarks, no parameter count in this post, no price, and no date more specific than “later this week.”
This update comes after earlier posts from him on the same model. On Sept 13, 2026 (8:24 p.m. CT), he wrote that Grok 4.8 “is a 2.5T model trained with our new C++ software stack” and “will finish training this week and start RL.” On Oct 30 he wrote that it had “taken longer than expected” but “will not be a disappointment,” and that the team is “not optimizing for benchmarks.” The Nov 10 note is the first time he has said pre-training is done, that 4.8 is in RL, and that a user-facing rollout has a timing (“later this week”). (Sept 13 post; Oct 30 post)
What has not been announced
The company’s news page at x.ai/news, which now brands the company as SpaceX Super Intelligence after SpaceX acquired xAI in April 2026, has no Grok 4.8 article. Its latest model announcement is Grok 4.7, listed on Sept 21, 2026. Developer release notes also introduce grok-4.7 on that date and do not mention Grok 4.8. A search of posts from @xai and @spacexsi since Sept 1, 2026 returned no posts mentioning 4.8.
So: Grok 4.8 is a real model Musk is talking about, but it is not a public launch. If you use Grok today, you are still on whatever the apps and API already offer, with Grok 4.7 as the newest model the company has formally shipped.
Why it matters
Most people will not rewrite an AI training stack, and most will not get 4.8 on day one. The useful takeaway is timing and scope. Musk said the first wave later this week is a soft rollout to Bot users, and he is openly saying the model “is not yet incredible.” The delay he describes is a software rewrite, not a dated launch event with scores you can check. Until the company publishes a model page, release notes, or results, treat claims about how much better 4.8 will be than 4.7 as his forecast.
Sources
- Elon Musk on X, reply on Grok 4.8 status (Nov 10, 2026, 3:35 a.m. CT / 09:35 UTC): https://x.com/elonmusk/status/2120088070443655190
- Elon Musk on X, Grok 4.8 described as a 2.5T model that would finish training that week (Sept 13, 2026, 8:24 p.m. CT / Sept 14, 01:24 UTC): https://x.com/elonmusk/status/2099308197802631191
- Elon Musk on X, “taken longer than expected” (Oct 30, 2026, 12:17 a.m. CT / 05:17 UTC): https://x.com/elonmusk/status/2116036703538606301
- SpaceXSI / xAI news index (no Grok 4.8 post; Grok 4.7 listed Sept 21, 2026; “xAI joins SpaceX” listed April 17, 2026): https://x.ai/news
- SpaceXSI, “Introducing Grok 4.7” (Sept 21, 2026): https://x.ai/news/grok-4-7
- SpaceXSI developer release notes (Grok 4.7 entry dated Sept 21, 2026; no Grok 4.8 entry as of Nov 10, 2026): https://docs.x.ai/developers/release-notes
— AltTab Dad