      While oil prices will typically react immediately to an outbreak ofwar in the Middle East, it may be minutes, hours, days, or weeks before oiland airline stocks exhibit a price reaction to this news. Similarly, thetime frame in which oil stocks react to this news will vary from the timeframe in which airline stocks will react. The magnitude and severity of thenews will determine how quickly related securities exhibit price reactions.Therefore, a trader not only needs to know the correlation coefficientbetween different stocks, he or she also needs to know the time frame inwhich the different securities will react.