GMO co‑founder Jeremy Grantham told Bloomberg’s Odd Lots podcast that the valuation gap between legacy big‑tech firms and newer AI‑driven challengers has reached a “watershed moment.” He warned that Apple, Microsoft, Alphabet and Meta are trading at historically low price‑to‑earnings multiples, suggesting a material correction could follow a prolonged rally.

Grantham’s thesis builds on GMO’s 2024 research that flagged a 30 % earnings slowdown for the quartet over the next two years, while AI‑centric firms like Nvidia and OpenAI enjoy double‑digit growth. The disparity has investors reallocating capital, lifting Nvidia’s market cap past $1 trillion, a level the older giants have yet to match.

For portfolio managers, Grantham’s warning signals a shift from passive exposure to legacy platforms toward thematic bets on generative AI and cloud infrastructure. He cautioned that a sharp sell‑off in the big‑tech index could trigger broader market volatility, given its 15 % weighting in the S&P 500. Investors should therefore reassess risk balances ahead of the expected correction.

Grantham’s outlook arrives as regulators in the EU and U.S. intensify scrutiny of data practices, adding headwinds for the incumbents. Meanwhile, venture capital continues to pour into AI start‑ups, driving valuations that eclipse traditional tech multiples. The convergence of regulatory pressure and capital migration underscores why Grantham sees the current environment as a decisive inflection point.