What We Actually Know About Grok's Architecture
The only publicly documented Grok architecture is Mixture of 8 Experts — not 16 agents. Meanwhile, xAI's real story is nine departed co-founders and a paused agent project.
xAI has never publicly documented a multi-agent architecture for Grok. The only technical specifications the company has released describe Grok-1’s Mixture of 8 Experts — a neural network pattern, not an orchestration of distinct AI personas.
This matters because the distinction between “experts” in a model architecture and “agents” in a system is fundamental. Grok-1, which xAI open-sourced in March 2024 under Apache 2.0, runs 314 billion parameters across 64 layers. Its Mixture of Experts (MoE) design routes each token through two of eight specialized sub-networks. These “experts” are mathematical constructs within a single model, not separate agents with roles like “coordinator” or “contrarian.”
For Grok 4.20 0309, released in March 2026, xAI has disclosed no architectural details. What we know comes from third-party benchmarks: the model scores 48 on Artificial Analysis’s Intelligence Index, supports a 2-million-token context window, processes 159 tokens per second, and costs $2 per million input tokens. Strong numbers. No public documentation of internal structure.
The Real xAI Story
The more substantive news about xAI in 2026 concerns personnel, not architecture.
“xAI was not built right first time around, so is being rebuilt from the foundations up.” — Elon Musk, March 2026
Only two of the company’s 11 original co-founders remain as of March: Manuel Kroiss and Ross Nordeen. The departures accelerated through 2025 and into 2026 — Christian Szegedy left in February 2025, Igor Babuschkin departed for venture capital in August 2025, Greg Yang and Yuhuai (Tony) Wu exited in January and February 2026. Co-founders Zihang Dai and Guodong Zhang left after Musk reportedly complained that xAI’s coding tools couldn’t compete with Claude Code or Codex.
The coding-tool gap connects to a related development: xAI’s Macrohard project — an AI agent designed for white-collar computer work — is now paused. The project’s lead, Toby Pohlen, is among the departed.
SpaceX, Coding Tools, and What’s Next
SpaceX has acquired xAI, with an IPO anticipated. The company employs roughly 5,000 people, compared to OpenAI’s 7,500 and Anthropic’s 4,700. SpaceX and Tesla executives have reportedly been brought in to evaluate the workforce.
Claude Code and Codex have established themselves as the benchmarks for AI-assisted development. xAI’s offerings, by Musk’s own reported assessment, haven’t kept pace. The company recently hired Andrew Milich and Jason Ginsberg from Cursor, suggesting a renewed push.
Grok 4.20 0309 remains competitive on headline metrics. Its 2-million-token context window matches frontier offerings, and its pricing of $2 and $6 per million input and output tokens undercuts some competitors. The Intelligence Index score of 48 places it above average. But benchmarks don’t explain architectural decisions, and xAI hasn’t chosen to explain them publicly since open-sourcing Grok-1 two years ago.
What to Watch
The tension at xAI is between a model that benchmarks well and a company in visible disarray. Nine of 11 co-founders gone. A coding assistant that doesn’t compete with the leaders. An agent project on hold. A SpaceX parent expecting a return on its acquisition.
Whether Grok’s future involves multi-agent orchestration, more sophisticated MoE implementations, or something else — that information remains inside xAI. The next architecture disclosure, whenever it comes, will tell us more than any benchmark.