Legendary Investor Jeremy Grantham Warns of an Impending US Market Crash
New York, Friday, 26 June 2026.
Veteran investor Jeremy Grantham warns US stocks are more overpriced than during the 2000 dot-com peak, predicting a potential 70% crash driven by artificial intelligence hype.
The Anatomy of an Unprecedented Market Bubble
Jeremy Grantham, the co-founder and long-term investment strategist of Boston-based asset management firm GMO, made a striking appearance on CNBC’s ‘Squawk Box’ on June 26, 2026 [2]. Grantham, who also serves as GMO’s Head of Asset Allocation [4], sounded an urgent alarm on what he characterizes as the ‘biggest [market bubble] in American history’ [1]. The veteran investor, famous for predicting every major market crash over the past 25 years (spanning from 2001 to 2026) [3], warned that owning U.S. equities at their current valuations is akin to financial suicide [3].
Surpassing the Dot-Com Era Valuations
According to Grantham, the modern market’s irrational exuberance has surpassed even the notorious peaks of the late 1990s [3]. He asserts that U.S. stocks are now more overpriced than they were at the absolute peak of the dot-com bubble in 2000 [3]. The primary driver behind this modern-day valuation spike is the rapid rise of ‘artificial intelligence high flyers’ [1], which have ballooned corporate valuations to levels that Grantham believes are highly unsustainable [1][2].
The 70% Downside Risk and AI Hype
The potential consequences of this bubble bursting are severe. Grantham warns that a massive market correction is looming, with a potential decline of up to 70% in stock prices not to be ruled out [1]. This projected pullback would erase trillions of dollars in market value, deeply impacting retirement accounts and institutional portfolios globally [GPT]. Grantham advises investors to actively flee U.S. equities before this historic crash materializes [1], seeking safer asset classes or international markets that do not exhibit the same extreme valuation premiums [GPT].
An Analysis of Extreme Growth Expectations
To put the current market euphoria into perspective, analysts have highlighted the extraordinary growth expectations currently baked into stock prices. According to market data published on June 22, 2026, by analyst Tobias Carlisle, Wall Street analysts collectively project that S&P 500 earnings will compound at an astonishing rate of approximately 24% annually over the next five years [4]. This expected growth rate is exactly double the historical norm of roughly 12% [4], which can be represented as a factor of 2 [4]. It also comfortably eclipses the peak earnings growth expectations of approximately 19% observed during the dot-com era around 2000–2001 [4].
Historical Precedents and Economic Implications
This extreme divergence from historical averages is what makes veteran investors like Grantham highly skeptical. Grantham’s track record of calling historical market turns—including the 2000 dot-com bust, the 2008 global financial crisis, and subsequent market corrections up to 2026—lends significant weight to his current warnings [3]. While retail and institutional investors continue to pile capital into artificial intelligence and semiconductor sectors [4], Grantham highlights that the hype cycle often masks structural weaknesses in the broader economy [GPT].
The Impending Macroeconomic Fallout
The wider economic impact of a potential 70% market crash would be devastating [1][GPT]. Such a steep decline would likely trigger a severe contraction in consumer spending, freeze corporate capital expenditures, and potentially lead to widespread layoffs [GPT]. While tech proponents argue that artificial intelligence represents a permanent productivity paradigm shift that justifies these historic valuations, Grantham and other market bears warn that the current trajectory is unsustainable and that the status quo cannot last [4].