Jeremy Grantham warned that the current surge in artificial intelligence investment is an obvious bubble that could trigger a major market crash.
The caution from the GMO co-founder comes as global markets lean heavily on AI growth to sustain valuations. If the bubble bursts, Grantham suggests the resulting collapse could rival the Great Depression.
Speaking on the Bloomberg Television Odd Lots podcast on Jan. 19, 2026, Grantham said, "I think it's obviously a bubble, and I think it's quite a simple story." He said that AI investment is over-hyped and that multibillion-dollar funding [1] acts as a crutch that inflates valuations and creates systemic risk.
Grantham, who has spent more than four decades [3] warning about financial bubbles, noted that the current cycle is atypical. He said the advent of AI is unique in financial history because it is the only time a new technology emerged just in time to short-circuit a bear market immediately following the deflation of a previous bubble [2].
This funding, primarily driven by the "Mag 7" companies, provides the capital necessary to keep the market supercharged [1]. However, Grantham said this reliance on massive capital injections masks underlying vulnerabilities in the broader economy.
While AI offers genuine technological potential, the financial architecture surrounding it may be unsustainable. The strategist said the current trajectory creates a fragile environment where a sudden shift in sentiment could lead to a brutal correction.
“"I think it's obviously a bubble, and I think it's quite a simple story."”
Grantham's warning highlights a growing tension between fundamental economic value and speculative growth. By characterizing AI as a 'crutch' for the market, he suggests that the current bullish trend is not based on organic productivity gains but on a concentrated burst of capital from a few dominant firms. If these investments fail to yield expected returns, the systemic risk could extend beyond tech stocks to the wider global financial system.
