Grantham: SpaceX’s $28.5T TAM Promise Is ‘Fabulous BS’ — Stock Drops 32%

Jeremy Grantham, the 87-year-old co-founder of institutional investment firm GMO and one of Wall Street’s most revered bubble historians, has delivered a blistering verdict on SpaceX (NASDAQ: SPCX) in an episode of Steven Bartlett’s “The Diary of a CEO” podcast aired over the June 27–28 weekend. Grantham called the company “such a fabulous BS story,” citing the narrative around mining asteroids and AI success as hallmarks of market euphoria. He went on to declare, “It’s the classic description of a market peak. It’s what you look for at the top of a terrific bubble.” His specific claim is not that SpaceX will cease operations, but that it will “fail to deliver anything like its promises in the prospectus,” a direct swipe at the $28.5 trillion total addressable market figure cited by New York University valuation professor Aswath Damodaran. This critique has landed with impact: SPCX closed on June 26 at $153.23, down a steep 32% from its all-time high of $225.64 on June 16, and extended its decline in early trading on June 29. Grantham’s intervention adds formidable weight to a growing chorus of skepticism. Prior bearish signals have included warnings from the former Nasdaq CEO about lockup expirations, Jim Cramer’s judgment that the stock “couldn’t sustain the walk-up,” a short thesis from Doug Kass, and even Michael Burry studying the trade before walking away. Grantham’s track record of calling market bubbles—predicting the dot-com crash, the 2008 housing collapse, and his current labeling of the AI bubble as the biggest in American history—makes his SpaceX criticism particularly resonant. His argument is not just about valuation; it is about the danger of investing in narratives that are disconnected from realistic revenue and profit delivery. For a company that just recently went public and captured the imagination of retail and institutional investors alike, the warning raises fundamental questions about whether the space sector’s most exciting story is another case of irrational exuberance. The immediate market reaction underscores the vulnerability: a 32% peak-to-trough drop in a matter of days signals that the air may already be leaking from the balloon. The broader context is a market already on edge about AI hype and the sustainability of high-growth, story-driven equities. Grantham’s framing of SpaceX as a symptom of a larger bubble—one he calls the greatest in American history—suggests that the pullback may not be contained to this one name. For space startups and the venture capital ecosystem that underpins them, the fallout could be significant: if the most celebrated commercial space venture is deemed a bubble, valuations across the sector may face a reassessment. On the other hand, SpaceX’s tangible achievements—Starlink revenue, reusable rockets, and government contracts—are not in dispute; the question is whether the market’s expectations have far outstripped what those operations can deliver. Grantham’s distinction between the company’s survival and its ability to meet prospectus promises is crucial: he is not betting on a going concern failure but rather on a dramatic repricing of the stock to align with fundamentals. Investors now face a classic market-peak dilemma: is this a buying opportunity in a genuinely transformative enterprise, or the early stage of a deflation cycle for one of the most richly priced stories in recent memory? The coming months, as lockup periods expire and insiders potentially sell, will test Grantham’s thesis in real time.