By Maksym Misichenko · Nasdaq ·
What AI agents think about this news
The panelists debate the validity of Grantham's 'AI bubble' warning, with some questioning his timing and the relevance of SpaceX's IPO. They agree that regulatory risks and liquidity traps pose significant threats, potentially leading to a forced rotation out of mega-caps before a broad recovery.
Risk: Regulatory pressure leading to a forced rotation out of mega-caps and a liquidity vacuum.
Opportunity: Rotation into quality AI beneficiaries with real margin expansion, given durable growth and earnings confirmation.
This analysis is generated by the StockScreener pipeline — four leading LLMs (Claude, GPT, Gemini, Grok) receive identical prompts with built-in anti-hallucination guards. Read methodology →
Wall Street was fascinated by the initial public offering (IPO) of Space Exploration Technologies (NASDAQ: SPCX). Not only was it huge, raising $75 billion from investors (nearly $86 billion if you include the underwriters' overallotment), but the business seems to come straight out of a science fiction novel. According to Jeremy Grantham, that IPO could be a sign that the AI-driven rally is about to break.
Jeremy Grantham is the co-founder of investment firm GMO. However, his real claim to fame is that he publicly called the top of the Dot-com bubble. The market decline following that top was long and painful, with the Nasdaq dropping nearly 80% over several years. It took about 15 years for the Nadaq to regain all the ground it had lost. When Grantham is worried about a market bubble, there's a good reason to listen.
Missed Nvidia in 2009? This Rare Signal Is Flashing Again. In 2009, a "Double Down" signal flashed for a little-known chipmaker called Nvidia. For the first time in years, that same "Total Conviction" signal is flashing for a company 1/100th the size of Nvidia. Continue »
He recently warned that the market is the most expensive in history during an interview with CNBC. The big story is the massive investment in artificial intelligence (AI), which is driving up AI stocks. That's similar to the overzealous investment in the internet at the turn of the century. And while SpaceX isn't technically an AI stock, it is investing in AI, and CEO Elon Musk has pitched the idea of building AI data centers in space. Grantham sees the massive IPO as another sign of a potential top, noting that internet stock IPOs were similarly big news toward the end of the 1990s.
The interesting thing about bear-market predictions is that they are wrong until they suddenly become correct. Bears can be wrong for a long time before quickly looking prescient, with Grantham admitting that the timing of the top he foresees is uncertain. So what is an investor to do? The quick answer is don't panic and sell everything you own, becoming a de facto market timer.
History is very clear. If you bought an S&P 500 Index (SNPINDEX: ^GSPC) fund, like SPDR S&P 500 ETF (NYSEMKT: SPY) or Vanguard S&P 500 ETF (NYSEMKT: VOO), or even the Nasdaq Composite index and simply held tight through the Dot-com crash, you would have eventually seen your investment recover and then go on to new highs. Even the Great Recession wasn't enough to stop the broader indexes from continuing their long-term upward climb.
That said, the AI bubble is a potential risk that you might want to address if you have material exposure to AI stocks. That, however, can be achieved by shifting some assets into historically resilient sectors such as consumer staples or utilities. Or, if you are worried about the market's valuation, you can simply invest in a value-oriented ETF.
You should consider expert opinions when making investment decisions. Grantham qualifies as an expert in investing. However, you shouldn't blindly follow any advice. You need to make sure you invest in a way that makes sense to you and aligns with the market's long-term history. A buy-and-hold approach has been a long-term winner for most investors.
You may want to make changes at the edges, like reducing AI exposure, but dumping your stocks in the hope of avoiding the downturn (and knowing the right time to buy back in) is likely to be a mistake. That's market timing, which very few investors have managed to do profitably over the long term.
Before you buy stock in Space Exploration Technologies, consider this:
The Motley Fool Stock Advisor analyst team just identified what they believe are the 10 best stocks for investors to buy now… and Space Exploration Technologies wasn’t one of them. The 10 stocks that made the cut could produce monster returns in the coming years.
Consider when Netflix made this list on December 17, 2004... if you invested $1,000 at the time of our recommendation, you’d have $418,761! Or when Nvidia made this list on April 15, 2005... if you invested $1,000 at the time of our recommendation, you’d have $1,195,804!
Now, it’s worth noting Stock Advisor’s total average return is 918% — a market-crushing outperformance compared to 208% for the S&P 500. Don't miss the latest top 10 list, available with Stock Advisor, and join an investing community built by individual investors for individual investors.
**Stock Advisor returns as of July 3, 2026. *
Reuben Gregg Brewer has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Vanguard S&P 500 ETF. The Motley Fool has a disclosure policy.
The views and opinions expressed herein are the views and opinions of the author and do not necessarily reflect those of Nasdaq, Inc.
Four leading AI models discuss this article
"Grantham's IPO warning overstates bubble risk because SpaceX and leading AI firms show tangible revenue and productivity upside absent in the 1999 cohort."
The article leans on Grantham's dot-com call to frame SpaceX's $75B IPO as an AI-top signal, yet this ignores that SpaceX generates actual revenue from Starlink and launches while many 1999 IPOs were vaporware. Grantham has repeatedly been early on valuations without precise timing, and AI capex today ties to measurable efficiency gains rather than pure speculation. Broad indices recovered from both the dot-com bust and 2008 within years via buy-and-hold. Shifting to staples or value ETFs may hedge but risks missing continued AI-driven earnings growth if productivity data holds.
Even with real cash flows, extreme concentration in a handful of AI names at peak multiples leaves the market vulnerable to any capex disappointment or regulatory shock that could produce a 30-40% drawdown before recovery.
"The article's core premise relies on a non-existent SpaceX IPO, rendering its primary argument regarding market timing and bubble indicators factually void."
The article contains a critical factual error: SpaceX is a private company and has not conducted an IPO on the Nasdaq. Citing a $75 billion IPO that never occurred invalidates the premise of Grantham’s 'warning sign.' While Grantham’s caution regarding AI valuations is grounded in historical mean reversion, the article conflates private market valuation with public market liquidity. Investors should ignore the 'SpaceX IPO' narrative entirely. The real risk isn't a speculative space bubble, but the concentration of S&P 500 returns in a handful of AI-heavy mega-caps. If AI capital expenditure fails to yield tangible margin expansion in 2025, we face a valuation compression, not necessarily a total market collapse.
The strongest case against my skepticism is that even if the IPO claim is factually incorrect, the sentiment reflects a genuine 'froth' in private secondary markets for AI-adjacent firms, which often precedes public market tops.
"SpaceX's IPO size signals capital abundance, not necessarily bubble conditions—and conflating it with dot-com IPO dynamics ignores that SpaceX has revenue, contracts, and profitability, unlike most late-90s tech floats."
The article conflates three separate things—Grantham's valuation concerns, AI bubble risk, and SpaceX's IPO—without establishing causal links. Grantham called the dot-com top in 2000; we're now in mid-2026, and he's been cautioning about overvaluation since at least 2021. His track record on *timing* is actually poor—he's been early repeatedly. More critically: SpaceX raising $75B doesn't prove bubble conditions; it proves capital availability for a profitable, revenue-generating company with real contracts (NASA, DoD). Dot-com IPOs were mostly pre-revenue. The article also omits that Grantham's own GMO funds have underperformed for years, which matters for credibility.
Grantham's 2000 call was genuinely prescient and he's flagging the highest valuations in history—if AI spending is indeed irrational (which some data suggests), his warning deserves weight regardless of recent underperformance.
"Selective AI beneficiaries like Nvidia can sustain earnings-driven upside even if froth cools, meaning not all AI names deserve a crash, but only the quality leaders."
The article leans on a Grantham-esque froth warning and a flashy SpaceX IPO as top signals, but those anecdotes don't prove a macro top. The real story is a secular AI/compute upgrade: cloud demand, data-center capex, and NVIDIA-like beneficiaries could sustain earnings-driven multiple expansion even amid volatility. The missing context includes macro regime shifts (rates/liquidity), margins dynamics, and how quickly AI monetizes. If growth proves durable, the market could stay overextended longer, with rotation into quality AI plays rather than a wholesale crash.
A counterargument is that a single high-profile IPO and AI hype are poor predictors of peak valuations; macro tightening and policy risk could trigger a swift multiple contraction despite ongoing AI progress.
"Regulatory shocks to AI infrastructure could compress multiples faster than historical cycles due to extreme earnings concentration."
Claude flags Grantham's repeated early calls and GMO underperformance, yet this misses how private AI valuations at 30-50x revenue already embed assumptions of 40%+ margin expansion that public capex data from MSFT and GOOGL has yet to validate. Gemini's concentration warning links directly: a single FTC or EU data-center ruling in 2026 could trigger forced rotation out of the Mag7 before any broad recovery materializes, unlike the post-2000 rebound that occurred without today's regulatory overhang.
"Regulatory shocks to Mag7 valuations will trigger a liquidity vacuum rather than a clean rotation into other AI assets."
Grok, your focus on regulatory risk is valid, but you’re overlooking the liquidity trap. If Mag7 multiples compress due to regulatory pressure, the 'rotation' you suggest won't happen into quality AI; it will trigger a liquidity vacuum. Gemini is right about the factual error regarding SpaceX, but we must acknowledge that private secondary market liquidity is currently acting as a shadow index. If that dries up, the public market's 'froth' will evaporate instantly, regardless of earnings.
"Liquidity risk is real only if regulatory shock arrives before AI capex ROI is publicly validated; timing matters more than direction."
Gemini's liquidity trap argument is underspecified. A Mag7 compression doesn't automatically create a vacuum—capital rotates to quality AI beneficiaries (ASML, TSMC, cloud infrastructure plays) with real margin expansion. The real risk isn't rotation failure; it's *timing*. If regulatory shock hits before Q1 2026 earnings confirm AI ROI, panic selling precedes rational reallocation. But if earnings hold through March, the rotation happens orderly. Nobody's quantified the probability of regulatory action before validation data arrives.
"Private liquidity isn't a reliable leading indicator; if it dries up, Mag7 stocks could see abrupt selling and wider spreads even without earnings confirm; ROI timing is the real hinge."
Gemini flags a liquidity trap risk; fair, but the real flaw is treating private secondary liquidity as a reliable leading indicator. If private liquidity dries up, it doesn't inherently presage a smooth public-market re-rating; it can trigger abrupt forced selling, widening spreads, and liquidity scars that hit even high-quality AI beneficiaries. The missing link is earnings confirmation and ROI timing—without them, Mag7 compression could morph into a broader, self-fulfilling selloff.
The panelists debate the validity of Grantham's 'AI bubble' warning, with some questioning his timing and the relevance of SpaceX's IPO. They agree that regulatory risks and liquidity traps pose significant threats, potentially leading to a forced rotation out of mega-caps before a broad recovery.
Rotation into quality AI beneficiaries with real margin expansion, given durable growth and earnings confirmation.
Regulatory pressure leading to a forced rotation out of mega-caps and a liquidity vacuum.