Grok 4.5 goes public today, July 9, the same day OpenAI opens GPT-5.6 Sol, Terra, and Luna to the public. It puts both companies' most advanced models in direct competition for the first time since Musk co-founded OpenAI in 2015.
Musk announced the public release on X, citing strong positive feedback from a private beta that began June 28 at SpaceX and Tesla. The model runs on xAI's new V9 foundation with 1.5 trillion parameters, roughly three times the size of the v8-small architecture behind Grok 4.3.
It includes supplemental training data from Cursor, the AI coding assistant SpaceXAI recently acquired.
"This is the first flagship under SpaceXAI since the merger, and the plan is a from-scratch foundation model shipping every month through the end of 2026," developer Tetsuo noted in an X post detailing the model's specs.
Musk described Grok 4.5 as "roughly comparable to Opus 4.7, but much faster." He previously called it an "Opus-class model" that is more token-efficient and lower cost. No system card or third-party benchmarks have been published to support those claims.
OpenAI secured Commerce Department approval to launch GPT-5.6 after the Trump administration lifted export controls that had also blocked Anthropic's Mythos 5 and Fable 5 from global markets. On Wednesday, OpenAI confirmed GPT-5.6 Sol alongside lower-cost variants Terra and Luna would launch publicly Thursday.
"We're expanding preview access globally now," OpenAI posted on X.
OpenAI also launched GPT-Live overnight, a new voice model for natural human-AI interaction, rolling it out to ChatGPT users on Go, Plus, and Pro plans. The release counters SpaceX's Voice Agent Builder, which launched a week ago and lets small businesses set up AI phone agents. The timing is no accident.
Musk co-founded OpenAI in 2015, left its board in 2018, and sued CEO Sam Altman in 2024 over the company's nonprofit pledge. A jury dismissed that lawsuit in May as untimely. The competing launches this week revive that rivalry in its most direct form yet.
SpaceX shares dropped 0.8% after the announcement, closing at $148.3. The stock remains 10% above the IPO price but roughly 34% below its post-offering high of $225.64.
xAI has stated it intends to release entirely new foundation models monthly through the end of 2026. The next model, already in training, will include Cursor data from the start of pre-training rather than supplemental fine-tuning.
