Sure, if enough people start believing the stock market is on the edge of a crash, their actions can cause it to crash. For the stock market is a social constru

Sure, if enough people start believing the stock market is on the edge of a crash, their actions can cause it to crash. For the stock market is a social construct: The decisions of buyers and sellers at every instant construct the market. Widespread fear can cause a crash. Coincidentally, Nobel prize winner Robert Shiller wrote a piece about this just last week: "People Fear a Market Crash More Than They Have in Years" (https://www.nytimes.com/2020/10/23/business/people-fear-a-market-crash-more-than-they-have-in-years.html https://www.nytimes.com/2020/10/23/business/people-fear-a-ma...). Quoting Shiller: > Consider what my Crash Confidence Index[a] is telling us. That measurement of sentiment about the safety of the stock market is based on this question: “What do you think is the probability of a catastrophic stock market crash in the U.S., like that of Oct. 28, 1929, or Oct. 19, 1987, in the next six months, including the case that a crash occurred in the other countries and spreads to the U. S.?” The index is a rolling six-month average of the percentage of monthly respondents who think that the probability of such a major crash is less than 10 percent. In August, the percentage of individual investors with that level of confidence in the market hit a record low, 13 percent. The most recent reading in September, 15 percent, was still extremely low. [a] https://som.yale.edu/faculty-research-centers/centers-initiatives/international-center-for-finance/data/stock-market-confidence-indices/united-states-stock-market-confidence-indices https://som.yale.edu/faculty-research-centers/centers-initia...