Jones believed that investor emotions created trends in stock prices. A rise in the stock market generates investor optimism, which in turn generates a further rise in the market, which generates further optimism, and so on; and this feedback loop drives stock prices up, creating a trend that can be followed profitably. The trick is to bail out at the moment when the psychology turns around—when the feedback loop has driven prices to an unsustainable level, and greed turns to fear, and there is a reversal of the pendulum.
