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xAI Unveils 1.5-Trillion-Parameter 'Grok 4.5' in Private Beta at SpaceX and Tesla

June 28, 2026 at 17:46 EDT

Foundation Models
Software Dev & Coding
AI Agents

Elon Musk announced xAI's new model 'Grok 4.5' on June 28, saying it is built on a 1.5-trillion-parameter V9 foundation model and has entered private beta at SpaceX and Tesla. Early evaluations reportedly show performance close to, or exceeding, Anthropic's Claude Opus.

June 28 · xAI

Grok 4.5 enters private beta at SpaceX & Tesla

Built on xAI's 1.5-trillion-parameter "V9" foundation model, early evaluations are said to match or exceed Anthropic's Claude Opus — trained partly on real rocket and automotive engineering feedback.

1.5T

parameters in the V9 foundation model

Monthly

new models planned through 2026, led by SpaceX

~$300

per month — prior Grok Build beta pricing tier

Scaling the Grok series

Foundation model size, in trillions of parameters

~1T

Grok 4 line

1.5T

Grok 4.5 (V9)

6–10T

Grok 5 (projected)

From ~1T to 1.5T in a short span — framed as a stepping stone toward a 6–10T Grok 5.

The differentiator

Rapid improvement from real operational data

SpaceX & Tesla

real rockets & automotive engineering

→

RL feedback

continuous reinforcement pipeline

→

Better model

Grok Build harness retested

Optimists say

"Opus-level" performance claim is a strong frontier signal
RL grounded in real-world environments stands out
Strong at agentic coding tasks

Skeptics caution

Cannot yet be independently verified
Inconsistent at long-running instructions; harness bugs noted
No public benchmarks or pricing released

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