When Microsoft tried to acquire Yahoo, Yahoo share was rising to $ 30. Microsoft had offering $ 31 for a Yahoo share (stock). This offer was better than market value stock that day. This situation made Yahoo stockholder happy, they could sell their stock with best price. The stockholder will get profit from higher stock price. Microsoft has desire to wide their search engine business. Actually, they are of msn.com. A few months ago, they had opened bing.com for expanding market.

Why Yahoo stock price can raise? On the other hand, maybe someday Yahoo stock will turn down. Economic sciences can explain this phenomenon easily. Ceteris paribus, high demand makes the price of a commodity rise up. Stock price may rise or down because of  supply-demand force. When demand is so high meanwhile supply is low, stock price will rise and reverse.

When Microsoft try to acquisition Yahoo, Investor suddenly look for Yahoo stock so that the demand high. Automatically, Yahoo price will rise. Why investors interesting find Yahoo Stock? Investor believes that Yahoo stock will rise to $ 40 after Microsoft success to acquisition Yahoo.

Story of Microsoft acquisition plan above show us that good news will pull investor to buy that stock.  Other information public that may raise stock price is dividend announcement. Every dividend announcement almost can be sure the stock price will rise.

Every year public company has obligation to report their financial company report to public. Investor may interest to buy the stock of company that has good performance. Good company depict with it earning.  It can grow their earning year to year.

Conversely, bad company does not give good signal to investor. Investor may rethink to invest in bad stock. They sell their stock as soon as possible. They do not want suffer financial loss over many times. Supply side on bad stock will increase because there is a little or no one buys it. Stock price will go down soon. 

We may conclude that demand and supply influence share price. Demand and supply force is dependent by some factors. Both demand and supply affected by information, news, and rumor. Investor should notice any information about a company. Sometimes, investor must careful that provided information in public is not always true. Wrong information may astray investor. For example, Company XYZ announced that reached profit over two times last month. Now, company XYZ bankrupt because they cannot pay the debt. Company XYZ must manipulate their financial report.