Warnings that index funds have broken the stock market all imply a threshold: a share of the market at which price discovery fails. Nobody making the argument names it. Owen Lamont, writing in the Financial Analysts Journal, argues that no such number exists short of complete passive ownership, and that what actually determines whether prices stay informative is who is left doing the trading. His case, the strongest peer-reviewed research against it, and what the performance
Bubble warnings spiked in late 2025, then faded — but AI stock valuations haven't budged. New research analysing over 5,000 crashes reveals why that's significant: at genuine peaks, warnings are rare and sceptics are ignored. Widespread concern may actually signal safety.
Robin Powell
Jan 2710 min read
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