These are just two examples of the many studies that have found flaws in weak-form
market efficiency. It therefore stands to reason that the notion of being able to predict future price movements by examining past movements would be of great interest to an investor. The
study of past price movements is known as technical analysis. Technical analysis can be formally
defined as "the study of market action, primarily through the use of charts, for the purpose of
forecasting future price trends. The term market action includes the three principal sources of
information available to the technician - price, volume, and open interest" (Murphy 1999).