Overview

• This year’s market gains are heavily concentrated in Nvidia, Microsoft, Alphabet, Amazon and Meta, with analysis saying these firms account for virtually all S&P 500 growth.
• Valuation gauges are flashing rare extremes, with the Shiller price-to-earnings ratio near 40 and global equities up about $28.6 trillion since April.
• AI infrastructure spending has surged to roughly $393 billion in 2025 versus about $60 billion in generative‑AI revenues, alongside reports of vendor financing and growing debt ties across the ecosystem.
• The IMF and Bank of England warn of dotcom-style risks and a potential sudden correction, Bank of America finds 54% of fund managers see an AI bubble, and Andrew Ross Sorkin says a crash will occur though timing is uncertain.
• Counterarguments frame the surge as a real industrial shift, with Justin Wolfers cautioning against confident bubble calls, Goldman Sachs judging valuations broadly defensible, and Jeff Bezos describing an “industrial bubble” that could still build lasting infrastructure.