According to a research report by Morgan Stanley, investors may find it increasingly important to distinguish between periods when markets efficiently incorporate information and episodes when collective behavior amplifies mistakes. While consistently generating excess returns remains difficult, extreme sentiment, sharp price moves and elevated valuations could provide signals that the market's 'wisdom' is giving way to the 'madness' of crowds. The brokerage noted that markets generally do a good job of aggregating dispersed information through the interaction of buyers and sellers, making prices difficult to beat consistently.
The research identified a crucial difference between stock markets and prediction or betting markets. Unlike prediction markets, equities do not have a fixed date on which the correctness of a price can be conclusively established. Stock valuations depend on expectations for future cash flows, risk and investor behavior, leaving greater room for narratives and shifting sentiment to influence prices. Morgan Stanley identified three conditions that make crowds collectively intelligent: cognitive diversity, effective aggregation and appropriate incentives.
The report highlighted that the stock market is particularly vulnerable to a breakdown in diversity because investing is inherently social. Investors can begin responding to the same information in similar ways, while prices themselves become signals that influence subsequent decisions. Such correlated behavior can contribute to market booms and busts. The research also emphasized the importance of investor time horizons, with experiments showing that longer-horizon markets tended to converge towards fundamental value, while shorter-horizon settings were more prone to bubbles as participants extrapolated recent price trends.
For investors, the implication is not that markets should be routinely challenged, but that periods of unusually strong consensus deserve greater scrutiny. The report suggests that identifying when diversity is breaking down may offer a better route to understanding market extremes than simply assuming prices are either always right or always wrong. Strong sentiment, major market moves and extreme valuations can therefore serve as useful indicators of a potential crowding episode, according to Morgan Stanley.
