For the individual investor it is usually more important to be nimble and reactionary in bearish markets. Actually this could be true and necessary in any market. The larger institutional investors move stocks by trading millions of shares at at time. You can get an idea of what stocks are in favor by watching for large or unusual increases or decreases in volume. The volume is a measurement of number of shares traded and can be seen on most stock charts. The reason being nimble is so important is that often you don't know the institutional investors are buying until they have already made the trade. If they big guys are buying you want to jump on board and ride the wave and noticing volume spikes is one way to catch a ride at times.
Investors business daily also is a good source that monitors extreme volume changes. Of course this isn't always a perfect way to tell what stocks are going to move because thinly traded stocks could show a large increase or decrease with only a small number of institutional investors buying or selling. Therefore it may not lead to a strong run in either direction. The more you pay attention to volume and trade trends you will start to get an idea and usually the stock will start showing a strong trend line.
