When someone decides to invest, he's taking a decision of making his savings productive. In this sense, it is important to understand the forces that take place in the capital market, specially the forces that interact in the stock market in order to understand why sometimes the values prices rise or decline, acording to the tendencies that manifest during one or different market sessions.

The stock market follows the principles and foundation constituted in the Free Market; which are the free Offer and Demand......

In essence, the consumers always buy goods and services, causing an increase in the demand curve, making it move its position to the right, from D to D1, as shown in the graph, increasing in consecuence the price of the good from P-E to P-E´. The same happens in the capital market. While offer orders and bid orders are being positioned in the Book of Orders of the quotes window of the respective transaction system, the tendency of each value for the day can be observed and in consequence, the market tendency through the respective indices of the exchange (General Index, Financial Index and Industrial Index).

In the same manner, a decline in the value price can be the result of an increase in the number of offerings, through numerous selling orders placed in the Orders Book, also reflected on the quotes windows fo the transactions system.

It's obvious that the increase in the offer or bid orders volume during a Market Session is consequence of a series of elements or aditional variables that must be also analized.