Elon Musk announced that Grok 4.5, xAI's latest large language model, has entered internal testing at SpaceX and Tesla, with early evaluations suggesting performance comparable to Anthropic's Claude Opus. The model runs on a 1.5-trillion-parameter V9 foundation and incorporates training data from Cursor, an AI-powered code editor that SpaceX acquired for $60 billion earlier this year. However, these performance claims remain unverified by independent testing, and the timeline for public release remains unclear.

What Makes Grok 4.5 Different From Current AI Models?

Grok 4.5 represents xAI's attempt to close a significant performance gap with leading frontier AI models. Current production versions of Grok score in the 72 to 75 percent range on SWE-bench Verified, a widely used coding benchmark that measures how well AI systems can solve real software engineering problems. By contrast, Anthropic's Claude Opus 4.6 and Google's Gemini 3.1 Pro both score around 80 to 81 percent on the same benchmark.

Musk initially claimed that Grok 4.5 would perform "close to, perhaps exceeding Opus," but later tempered that statement, describing the V9 foundation model as "a solid workhorse in the same league as Opus" rather than something dramatically superior. This distinction matters because benchmark contamination has become a growing concern in AI evaluation, with researchers acknowledging that training data frequently leaks into benchmark tasks, potentially inflating performance scores.

How Is SpaceX Building a Faster AI Training System?

• Software Architecture Rewrite: SpaceX plans to rewrite Grok's entire training and inference stack in C/C++, a lower-level programming language that runs closer to hardware. This approach will replace higher-level frameworks like JAX, which add software overhead but provide more flexibility.
• Hardware Optimization: The rewrite is designed to map directly to NVIDIA's GB300 GPUs, which are liquid-cooled systems capable of 1,440 petaflops per rack. SpaceX operates approximately 550,000 of these chips inside Colossus 2, a supercomputing facility in Memphis, Tennessee that runs at roughly one gigawatt of power.
• Performance Targets: Musk estimates that the C/C++ rewrite will deliver "truly massive gains" within approximately three months, with SpaceX previously claiming the bare-metal approach could achieve speed improvements exceeding 10 times faster than Google's JAX framework.

This vertical integration approach mirrors SpaceX's broader engineering philosophy, which has led the company to build its own rocket engines and avionics rather than relying on external suppliers. No other AI laboratory operates a single training cluster with 550,000 GPUs at gigawatt-scale power consumption, giving SpaceX a potential infrastructure advantage if the software optimization succeeds.

Musk also announced that SpaceX plans to release "completely trained from scratch" new models every month for the remainder of 2026, a cadence that would be aggressive even by current AI development standards, where major labs typically ship new foundation models every few months.

Why Is SpaceX's IPO Creating Such Intense Trading Activity?

SpaceX's initial public offering on June 12, 2026, has dominated Wall Street trading activity in ways that surprised even seasoned market observers. The stock was priced at $135 per share and debuted at $150, closing its first day around $161. Within days, it rocketed to an intraday high of nearly $226 before experiencing significant volatility, hitting a low of $147 before recovering to $164 by June 29.

"I don't recall seeing one stock dominate our customers' activity in this manner," said Steve Sosnick, chief strategist at Interactive Brokers.

Steve Sosnick, Chief Strategist at Interactive Brokers

The trading frenzy reflects both the size of the IPO and the outsized investor interest in Elon Musk himself. Charles Schwab reported that SpaceX's IPO day ranked in the top five most active trading days in the company's 50-year history. At Citadel Securities, a major market maker, SpaceX's IPO generated the largest single day of net buying from retail investors in the firm's history, surpassing the previous record by 50 percent.

On Interactive Brokers, SpaceX has consistently ranked in the top two most traded stocks every day since its IPO, second only to Micron Technology, which has surged as part of the broader chipmaker boom. The stock's initial post-IPO surge briefly lifted SpaceX's market value above Amazon and Microsoft, and at its $150 debut price, SpaceX maintained a larger market value than either Meta or Tesla.

What Role Does Elon Musk's Reputation Play in SpaceX's Valuation?

Much of the investor enthusiasm for SpaceX reflects confidence in Musk himself rather than fundamental business metrics. Musk became the world's richest person after the SpaceX IPO, with his net worth exceeding $1 trillion, and investors are betting on his track record of building valuable companies.

"Most of the companies Elon runs are really not particularly valued on fundamentals, but rather on sentiment. People expect good things from the growth that Elon can potentially bring," said Howard Chan, founder and CEO at Kurv Investment Management.

Howard Chan, Founder and CEO at Kurv Investment Management

Luke Lango, a technology analyst and publisher of Innovation Investor, noted that while early investors who chased the first-week rally experienced losses when the stock fell 17 percent in its second week, the underlying business case remains compelling. "The underlying business, dominant launch monopoly, profitable Starlink, xAI embedded at the core, is a decade-long story, not a two-week story," Lango explained.

SpaceX's business portfolio spans rockets, satellites, internet service through Starlink, and now artificial intelligence through xAI. However, the company is burning cash on its AI businesses, and investors are making a bet that SpaceX will reach profitability in the future. Jay Ritters, professor emeritus at the University of Florida, noted that IPOs with the most volatility tend to be highly valued growth companies with rapid expansion but significant uncertainty about future profitability.

What Happens Next for SpaceX as a Public Company?

SpaceX will not join the S&P 500 for at least one year, but the company has already been added to the Russell 1000 index and is set to join the Nasdaq 100 in July. This means millions of Americans will own SpaceX stock indirectly through index funds in personal portfolios and retirement accounts.

Wall Street is building an entire ecosystem around SpaceX stock. Investment firms are launching new exchange-traded funds at a rapid pace to give investors additional ways to interact with the stock, including leveraged ETFs that aim to amplify SpaceX's performance by providing double the returns or losses. Options trading for SpaceX began last week and quickly saw a surge in interest, allowing investors to place more sophisticated bets on the stock's future direction.

The convergence of xAI's technical ambitions and SpaceX's public market debut creates a unique moment in AI development. If Grok 4.5 delivers on its performance claims and the C/C++ rewrite achieves the promised speed improvements, xAI could become a more serious competitor to OpenAI and Anthropic. But both the benchmark claims and the three-month rewrite timeline rest on Musk's own statements, and his public timelines for technical projects have historically been optimistic.