SpaceXAI Launches Grok 4.6: Ties GPT-5.6 Sol on Key Benchmark at a Fraction of the Price

SpaceXAI released Grok 4.6 on August 12, 2026, delivering benchmark performance that matches OpenAI's GPT-5.6 Sol at a significantly lower price point. The model scored 61 on the Artificial Analysis Intelligence Index, tying GPT-5.6 Sol Max and finishing just one point behind Anthropic's Claude Fable 5 Max (62) . Pricing remains unchanged from Grok 4.5 at $2 per million input tokens and $6 per million output tokens — roughly a fifth of GPT-5.6 Sol's $30 per million output tokens — making it one of the most cost-effective frontier models available .

Benchmark Performance

Grok 4.6 represents a significant leap over its predecessor, Grok 4.5, which scored 54 on the same index . The 5-point gain comes primarily from extended training and agent reinforcement learning, rather than a larger model: Grok 4.6 retains the same 1.5-trillion-parameter V9 foundation as Grok 4.5 .

Beyond the headline Intelligence Index score, SpaceXAI reports that Grok 4.6 outperforms Grok 4.5 across every evaluation listed, including CursorBench, FrontierCode, APEX-Agents, and Terminal-Bench . The model also ranks first on the GDPVal-AA v2 and AA-Briefcase leaderboards, and tops the Harvey benchmark .

Independent benchmarker Artificial Analysis highlighted the model's cost-effectiveness, noting that Grok 4.6 delivers "standout agentic performance at lower cost," with a cost per Intelligence Index task of approximately $0.84 — far below Claude Opus 5 and GPT-5.6 Sol .

Pricing Details

Grok 4.6's pricing structure is designed to compete aggressively on cost:

Pricing Tier	Standard Rate
Input tokens (below 200k prompt tokens)	$2 per million
Cached input tokens (below 200k prompt tokens)	$0.50 per million
Output tokens (below 200k prompt tokens)	$6 per million
Input tokens (200k+ prompt tokens)	$4 per million
Cached input tokens (200k+ prompt tokens)	$1 per million
Output tokens (200k+ prompt tokens)	$12 per million

Source: xAI Release Notes

A notable change from Grok 4.5 is the 67% increase in cached-input pricing, rising from $0.30 to $0.50 per million tokens for prompts under 200k tokens — a cost that affects long-running agents disproportionately .

For comparison, GPT-5.6 Sol charges $5 per million input tokens and $30 per million output tokens, while Claude Opus 5 charges $5/$25 , making Grok 4.6 roughly 60% cheaper than both on output and 80% cheaper than GPT-5.6 Sol.

Grok 4.6 also introduces an xhigh reasoning effort tier, and a faster version of the model is available at 2x pricing .

Availability and Platforms

Grok 4.6 launched on the same day across multiple platforms:

• xAI API (model ID grok-4.6) — with a 500,000-token context window, text and image inputs, and text-only output
• Cursor — with double usage quotas during the first week
• Grok Build — also with promotional double usage
• OpenRouter, Vercel, and Cloudflare

The model's knowledge cutoff date is February 1, 2026 .

Market Reaction and Stock Impact

SpaceX stock (SPCX) rose sharply on launch day. Real-time estimates showed the stock at approximately $147.92, an intraday gain of ~10.98–11% , significantly exceeding the "over 6%" figure initially reported in some outlets. The rally pushed the stock past $140 and extended SpaceX's August recovery to more than 30% from post-listing lows .[

The surge was amplified by two factors: a research note from Morgan Stanley arguing that public markets are "severely underestimating" SpaceX's AI enterprise platform, and comments from CEO Elon Musk teasing the upcoming Grok 4.7 model . The broader bullish sentiment was further supported by SpaceX reporting $2.56 billion in AI revenue during its first earnings call on August 5, 2026 .

Grok 4.7 and Future Roadmap

During SpaceX's earnings call on August 5, 2026, Elon Musk outlined an aggressive development timeline:

• Grok 4.6: Released on August 12, 2026
• Grok 4.7: Expected in three to four weeks (late August to early September 2026)
• Grok 5: Planned before year-end, trained on SpaceX's full historical data

Musk's teasing of Grok 4.7 on launch day contributed to the stock's positive movement, and Grok Bot — an always-on virtual assistant for executing complex workflows in cloud environments — launched alongside Grok 4.6 for SuperGrok Heavy, Cursor Ultra, and Cursor Teams Premium subscribers .

Key Takeaways

• Performance parity at a discount: Grok 4.6 ties GPT-5.6 Sol Max (61 AA Intelligence Index) at roughly a fifth of the output cost.
• Agentic strength: The model shows standout performance on agentic and coding benchmarks, with a cost per task ($0.84) that undercuts all major competitors.
• Immediate availability: Available across API, Cursor, Grok Build, and multiple third-party platforms on launch day.
• Stock market boost: SPCX rose approximately 11% intraday, extending a 30%+ August rebound.
• Rapid upgrade cycle: Grok 4.7 is expected within weeks, with Grok 5 targeting a year-end release.