SpaceX IPO, Bezos tax pivot, Grok Build goes API — May 21

The biggest single-day signal in Musk's information circle on May 20 wasn't Starship on the pad. It was SpaceX's 308-page S-1 filing, and almost everyone in his follow network spent the afternoon parsing it.

SpaceX dropped its public IPO prospectus on May 20, targeting a Nasdaq listing under the ticker $SPCX. @SawyerMerritt's initial breakdown — viewed 1.2 million times — hit the key numbers first 1:

The structure: three businesses bolted together. Starlink (Connectivity) brought in $11.4B in 2025 revenue, $4.4B in operating income, growing nearly 50% year-over-year. The rocket launch segment ran close to breakeven. xAI — folded in after the SpaceX-xAI merger — posted a $6.4B operating loss in 2025, with $12.7B in AI CapEx that year. The consolidated net loss was $4.9B on $18.7B of revenue 2.

The headline Anthropic figure drew the most reaction. Tom Brown, Anthropic's Chief Compute Officer and co-founder, confirmed it publicly: Anthropic will pay $1.25B per month to rent Colossus 1 and Colossus 2 capacity through May 2029 — capacity currently ramping through June at a reduced rate 3.

Musk himself posted a broader frame: SpaceX is offering AI compute as a service at scale to Anthropic and is "in discussions with other companies to do the same." He specifically cited orbital data centers as the longer-term infrastructure path 4.

@SawyerMerritt calculated the figure differently: at ~$41M per day, Anthropic is paying more than the highest external estimate ($6B/year) by a factor of 2.5 5.

SpaceX cited asteroid mining, space tourism, Mars cargo, and orbital AI infrastructure as future market opportunities in the prospectus 6. Goldman Sachs, Morgan Stanley, Bank of America, Citigroup, and JPMorgan are named lead underwriters.

Starship V3 — Ship 39 stacked on Booster 19 — has been on the new Orbital Launch Pad 2 at Starbase since May 20, targeting today, May 21, at 5:30 PM CT / 6:30 PM ET for an ~90-minute window 7.

This is the first flight of the V3 design for both the Ship and the Booster. Key mission objectives include deploying 22 Starlink V3 expendable simulators via the new "Pez" dispenser, an in-space Raptor re-light demo, intentional missing heat shield tile testing, and a dynamic banking maneuver during re-entry. Booster 19 will attempt a controlled splashdown — no catch attempt — using three larger grid fins with Raptor V3 engines on the first flight 8.

The one-day delay from May 20 to May 21 was already confirmed; launch remains green as of the latest NOTAMs.

xAI quietly released grok-build-0.1 to its public API on May 20, priced at $1.00 per million input tokens / $2.00 per million output tokens 9. This is the same model that powers the Grok Build coding agent CLI. Separately, Vercel confirmed that Grok Build 0.1 is available via Vercel AI Gateway 10.

Grok Imagine also reached Paper (xAI's notebook product) the same day, with a new "Set as Project Cover" option in agent mode 11.

Jeff Bezos posted a series of tweets on May 20 advocating for eliminating federal income tax on the bottom half of US earners, calling it "only 3% of total tax revenue" but "very meaningful to that person." 12

Musk retweeted the follow-up ("Bravo @JeffBezos") — the tweet drew 97K likes and 13.8M views 13. Marc Andreessen also commented "Co-sign," which Musk retweeted separately 14. The policy alignment between Bezos, Musk, and Andreessen on the same afternoon is a notable convergence for the circle.

The most-viewed post in the 24-hour window wasn't about space or AI. @cb_doge's thread about 18-year-old Henry Nowak — an alleged stabbing victim who reportedly bled out while police restrained him on a UK street — reached 30.3 million views with 40,649 likes and 10,244 retweets 15.

Musk's own amplification in this cluster included retweets of @timburchett ("The UK has fallen") and @CCrowley100 and @kevinnbass on media coverage disparities in policing cases, all within a 90-minute window on May 20 afternoon 16.

Cursor CEO @mntruell added Gemini Flash 3.5 to CursorBench, the company's internal coding agent eval leaderboard 17. The eval URL is public at cursor.com/evals. No scores were released with the post, but the timing — one day after Composer 2.5 hit No. 1 in Cursor as the most-chosen model — means users will be watching the benchmark closely.

@teslaownersSV documented a Model S/X Signature Edition event at the Tesla Fremont Factory on May 20, with the first glimpses of the production Cybercab on-site alongside a new Tesla Semi 18. Tesla has confirmed production of the last Model S ever built — the original model that launched the EV era in 2012 is ending its run 19.

Musk retweeted a Neuralink video in which a patient described their first BCI-driven signature: "That first signature resembled my actual, physical handwriting." 20 No new device or trial announcements accompanied the post.