The occurrence of stock market bubbles and crashes is often cited as evidence against the efficient market hypothesis. It is argued that new information is rarely, if ever, capable of explaining the sudden and dramatic share price movements observed during bubbles and crashes. Samuelson (1998) distinguished between micro efficiency and macro efficiency. Samuelson took the view that major stock markets are micro efficient in the sense that stocks are (nearly) correctly priced relative to each other, whereas the stock markets are macro inefficient. Macro inefficiency means that prices, at the aggregate level, can deviate from fair values over time. Jung and Shiller (2002) concurred with Samuelson’s view and suggested that waves of over- and
A third level is to choose the stocks that you believe that others will expect the average investor to select. A fourth stage might involve choosing stocks that you believe that others will expect the average investor to see as most popular amongst investors. In other words, the beauty contest view sees investors as indulging in levels of second-guessing other investors. Even if every investor believes that a stock market crash is coming they may not sell stocks. They may even continue to buy.They may plan to sell just before others sell. In this way they expect to maximise their profits from the rising market. The result is that markets continue to rise beyond what the vast majority of investors would consider to be the values consistent with economic fundamentals. It is interesting to note that Shiller’s survey following the 1987 crash (Shiller 1987) found that 84% of institutional investors and 72% of private investors said that they had believed that the market was overpriced just before the crash. Shiller suggested that people did not realise how many others shared their views that the market was overpriced.
SOCIAL AND PSYCHOLOGICAL FACTORS
As Hirshleifer (2001) points out, people have a tendency to conform to the judgements and behaviours of others. People may follow others without any apparent reason. Such behaviour results in a form of herding, which helps to explain the development of bubbles