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
Investors are turning to AI hoping it will cut through the emotional noise and deliver clearer, more rational financial decisions. But two recent studies suggest these tools don't neutralise investor biases — they absorb them. And the more advanced the model, the worse the problem may get.
Robin Powell
Mar 107 min read
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