Go with the flowÉ
The momentum story has power because it can be a self-fulfilling
prophecy If investors buy into the momentum story and buy stocks that have gone
up in the past, these stocks will go up further. The momentum can continue as
long as you can new investors are attracted to the stock, pushing up demand and
prices. Thus, the strongest argument for momentum is herd behavior. In general,
there are three reasons given for why investors may indulge in this herd
behavior and why you should be able to take advantage of it.
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Investors learn slowly: If investors are slow to assess the effects of new information on
stock prices, you can see sustained up or down movements in stock prices after
news comes out about the stock Ð up movements after good news and down
movements after bad news. The investors who are quickest at assessing the
effect of information will profit as investors who are slower at assessing
impact gradually come on board.
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Investors learn by watching other investors: Some investors learn by watching other investors
trade rather than by analyzing fundamentals. If you accept this view of the
world, sustained price increases accompanied by high trading volume will
attract new investors to a stock.
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Investors weight the recent past much more than they
should: Psychologists have uncovered fairly
strong evidence that human beings tend to weight recent information far more
than they should and old information far less than they should. In other words,
a positive news announcement by a company can lead to a disproportionately
large increase in its stock price as investors react to the announcement.
Momentum stories almost invariably are accompanied with a sense of urgency. You need to get on the momentum bus or it will leave, you are told.