Key Takeaways
- Elon Musk called Anthropic’s Opus 5.5 “a masterpiece” on Tuesday and said Grok 5 should beat it, maybe within two or three months.
- SpaceX’s AI business made up 52% of its third-quarter revenue, and most of that business is computing power rented to labs like Anthropic.
- If Grok matched Anthropic’s best model, SpaceX could make money from its own model as well as from the compute it rents out.
- Anthropic now calls two other models its most powerful, and Musk’s timelines often slip, so SpaceX’s revenue estimates still depend on renting out compute.
Elon Musk just called a rival’s AI model “a masterpiece.” That rival also pays SpaceX (SPCX) more than a billion dollars a month to rent its computing power.
On Monday, Anthropic released Claude Fable 5.2 ahead of its IPO, which is expected later this month. It also cut the price to $8 per million input tokens and $40 per million output tokens, down from $10 and $50. On Tuesday, an X user asked Musk how Grok 4.8 compares with Anthropic’s Opus 5.5.
Musk’s answer: “Not as good. Opus 5.5 is a masterpiece. But Grok 5 should exceed Opus 5.5 and maybe that happens in 2 or 3 months, with continued acceleration thereafter.”
That’s humble, by Musk’s standards. For SpaceX shareholders, the deadline matters more than the compliment, since a better Grok would change how SpaceX makes money from AI.
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SpaceX makes its AI money as a landlord
SpaceX’s Super Intelligence segment brought in $7.56 billion in the third quarter. That’s 52% of the company’s $14.6 billion in revenue. Most of it came from renting computing power to other AI labs, and Anthropic is the biggest of them. Anthropic’s S-1 says its SpaceX deals will run about $3.1 billion a month once all the capacity is delivered, which it expects in December.
Analysts are counting on that growth. They expect SpaceX’s revenue to go from $48.9 billion this year to $181 billion in 2027 and $335 billion in 2028.
The catch is that rental revenue rises and falls with what compute rents for. Musk said so himself just days ago, when he wrote that if compute becomes “plentiful and cheap, SpaceX revenue will drop.”
A better Grok would let SpaceX earn on both ends
Right now, SpaceX gets paid for the compute, and Anthropic gets paid for the models that run on it. For Fable 5.2, Anthropic charges $40 per million output tokens. If Grok were as good as Anthropic’s best, SpaceX could sell its own model too, on data centers it already owns.
And it owns more of them every year. SpaceX’s capital spending more than doubled from 2023 to 2024, and nearly doubled again in 2025.
That was before this year’s buildout. Capex hit $48.1 billion in the first nine months of 2026, and management expects to spend another $35 billion to $40 billion in the fourth quarter.
On its recent earnings calls, management said about 10% of its compute goes to training Grok. It’s aiming for roughly a 50-50 split between its own use and rentals. Every gigawatt SpaceX moves from rentals to Grok has to earn more than the rent it gives up, and only a model that customers want to pay for can do that.
Anthropic has already moved the goalposts
Beating Opus 5.5 would be a real step for Grok. But Anthropic now calls Fable 5.2 and Mythos 5.2 its most powerful models, and it just cut Fable’s price by 20%. So Grok 5 would be catching a model that’s no longer Anthropic’s best, just as Anthropic is lowering its prices.
Musk hedged this one himself, with a “maybe.” His dates tend to slip. In August, he talked about Starship flying at least once a day within a year. By October, he was promising weekly flights in the first half of 2027.
There’s another risk. Every customer Grok wins from Claude is a customer Anthropic no longer needs SpaceX’s compute to serve. Either side can leave the Anthropic deal on 90 days’ notice, and Anthropic’s S-1 lists big compute commitments with other suppliers.
Grok 5 is a bonus on top of the rent
The way I see it, SpaceX should be judged on its rental business for now, with Grok 5 counted as a bonus. Analysts’ estimates are built mostly on renting out compute, and that business doesn’t need Grok to win. If Grok 5 does pass Opus 5.5 by early next year, SpaceX gets a second way to make money from its data centers. That second business would be worth far more if Grok can keep up with Anthropic’s newest models too.
Of course, Grok 5 isn’t out yet, and even a model that beats Opus 5.5 would still have Fable 5.2 and Mythos 5.2 to catch. SpaceX’s fourth-quarter results in early 2027 will show how much of the rental growth has actually arrived.
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