Jim Cramer warns SpaceX could soar to unsustainable levels after its debut

CNBC's Jim Cramer said Thursday he's worried that SpaceX's stock could soar too high, too quickly.

"Tomorrow at this time, if things really go awry, we may have a new champion, a new largest stock in the world: SpaceX," the "Mad Money" host said.

Elon Musk's rocket and artificial intelligence company is expected to begin trading Friday. It set a fixed sale price of $135 per share, equal to a valuation of $1.77 trillion. Demand for the IPO has been extraordinary, with the deal reportedly four times oversubscribed. While that level of interest is typically viewed as a positive, Cramer warned that excessive demand can create its own problems.

In his view, the best IPOs open modestly above their offering price and then trade in an orderly fashion. SpaceX, however, faces a unique mix of institutional demand, retail enthusiasm, and future index buying that could send shares sharply higher immediately after trading begins.

Cramer noted that he is particularly concerned about the wave of inexperienced investors placing market orders, rather than limit orders, potentially pushing the stock to unsustainable levels.

"These are new, unguided missiles who can't be controlled," Cramer said.

If enough buyers rush in at once, Cramer said SpaceX could briefly command a valuation that rivals or even exceeds the world's largest publicly traded companies. But he cautioned that those kinds of moves rarely end well.

"Can a $4 to $5 trillion stock really be at hand? For a few minutes perhaps, just as long as it takes to gaffe a marlin," he said. "That's a terrific catch, but if it isn't stuffed and mounted fast, it stinks to high heaven."

He pointed to recent IPOs such as Figma in July 2025 and Cerebras in May, which initially "continued to go higher and then they started the long descent."

Ultimately, Cramer said the goal should not be a spectacular first-day spike but a controlled debut that allows the stock to build value over time.

"We want the deals to be under control because otherwise it can be disastrous," he said.

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