Six trading days. That's how long it took SpaceX to go from a $135 IPO price to a market cap large enough to leapfrog Microsoft. The company raised $86.2 billion in the largest IPO in history, greenshoe included, and by Monday's close the stock sat at $192.46, putting the market cap near $2.51 trillion — up roughly $740 billion from where it priced, in under a week. By Tuesday it had added another leg, briefly making SpaceX the fourth most valuable company in the United States. Then on Wednesday, the same day Kevin Warsh stripped the Fed's forward guidance and the market repriced for a hike, SPCX gave back almost 5%, closing at $191.82. None of that volatility changed the thing that actually matters here, which is what Musk did with the gain while it was sitting on the table.
In April, SpaceX signed an option giving it the right to acquire Cursor, the AI coding startup, for $60 billion in stock, or walk away for a $10 billion breakup fee plus compute. At the time, $60 billion for Cursor looked aggressive — the company had been quietly negotiating a $2 billion raise at a $50 billion valuation just months earlier, after a stretch where Silicon Valley had more or less started drafting its obituary, watching enterprise share slip from 41% to roughly 26% against Anthropic's Claude Code and OpenAI's Codex. By the time SpaceX actually exercised the option this week, the math had inverted entirely. Paying in SpaceX stock priced at post-IPO levels meant the $60 billion price tag represented only 3.4% dilution against the company's IPO valuation. The stock's run between Friday and Tuesday — that $740 billion of paper gains — covered the entire purchase price more than ten times over. Musk didn't spend money. He spent appreciation that hadn't existed three trading days earlier.
This is the part worth sitting with, because it's not really a story about Cursor, or even really about SpaceX. It's a demonstration of how a fresh, hype-saturated IPO functions as a kind of synthetic currency — one that lets an acquirer purchase real, cash-flowing businesses using equity whose price was set almost entirely by narrative and scarcity rather than by anything resembling discounted cash flow. Cursor is not a vanity asset. It's doing roughly $4 billion in annualized revenue, used by 67% of the Fortune 500, generating something like 150 million lines of enterprise code a day, with its enterprise segment tripling in a single quarter. That's a real company solving a real adoption curve. And it just got bought with stock that was worth 16 Cursors' worth of paper gains accumulated in ninety-six hours of trading. When the currency you're paying with can inflate that fast, due diligence stops being the binding constraint on what you can afford.
The vertical-integration logic Musk is selling — compute, satellites, energy, connectivity, and now a coding layer, all under one roof — is coherent enough on its own terms; it's the same playbook he ran at Tesla, batteries and chargers and insurance all bolted onto the car. What's different here is the speed at which the IPO pop converted directly into acquisition firepower, with no cooling-off period, no lockup-driven price discovery, nothing standing between "biggest IPO ever" and "biggest VC-backed acquisition ever" except five trading sessions. SpaceX told its own IPO investors it was chasing a combined $28 trillion addressable market, $26 trillion of it tied to AI ambitions the company has not yet built. Cursor is the first concrete brick in that wall, bought with money that, in a strict accounting sense, didn't exist when the option was signed.
There's a reflexive quality to this that should make index investors slightly uneasy, even if nobody's talking about it that way yet. A stock this large, this newly public, this momentum-driven, eventually pulls passive flows toward it almost mechanically as it works through index-inclusion thresholds — flows that have nothing to do with Cursor's revenue multiple or SpaceX's actual launch cadence and everything to do with float, weighting, and the unglamorous mechanics of fund rebalancing. That demand then further inflates the currency Musk is using to keep buying things, which mechanically inflates the company's footprint in the indices that will eventually have to hold more of it. It's not a Ponzi structure — Cursor's revenue is real, the satellites fly, the rockets land — but it rhymes with one in its sequencing: the valuation creates the means to justify the valuation.
The fragility sits exactly where you'd expect. The entire arrangement depends on the stock continuing to levitate, or at minimum holding its post-IPO altitude long enough for the deal to close in the third quarter at a price the market still respects. Wednesday's near-5% drawdown, arriving on the same day the Fed reset the risk-free rate conversation with a hawkish dot plot and a stripped-down statement, is a preview of what happens when two macro stories collide instead of running in parallel. Higher-for-longer rate expectations compress the multiple on every long-duration, narrative-heavy growth story, and SpaceX, whatever else it is, is currently trading as the most extreme version of that trade in the market. The day the multiple actually cracks — not a one-session wobble, but a real repricing — the $60 billion paid for Cursor stops looking like found money and starts looking like real, permanent dilution that happened to land on a chart at the worst possible moment. Musk built a currency that prints itself on the way up. Nobody's tested yet what it does on the way down.
