More Buyers Than Sellers

• It sounds simple, but the reason that any stock goes up in value, regardless of other factors, is that there are more buyers than sellers. You can only buy stock that is available for sale, and if there is a limited amount of stock for sale, you might get shut out. To own the stock, you have to be willing to pay an amount that will persuade a stock owner to become a seller. Thus, you, and other buyers like you, are driving up the price of the stock.
  
  

Falling Interest Rates

• When interest rates fall, they make stocks more valuable. Lower interest rates mean lower interest costs for companies, and subsequently higher profits. Lower interest rates also mean that inflation is falling. As inflation increases a company's cost of operation, falling inflation can equal higher profits.
  
  

Low Rates on Bonds

• Bonds are a type of security that pays a fixed interest rate that is generally higher than the dividend rate that stocks pay. When bonds pay high rates of interest, they are more attractive investments, and some of the money that may have otherwise gone into stocks goes into bonds. When fewer investors buy stocks, stock prices tend to fall. Conversely, when interest rates on bonds are low, they aren't as attractive an alternative to stocks, and money tends to flow out of bonds and into stocks. Thus, low interest rates on bonds tend to result in increasing stock prices.
  
  

Raised Analyst Expectations

• As many investors don't have time to do a lot of their own stock research, they rely on professional stock analysts to do the research for them. If a well-known stock analyst changes his opinion on a stock from negative to positive, or makes other positive comments regarding a stock, many investors tend to follow the analyst's recommendation and buy the stock, thereby increasing the price.
  
  

Surprisingly Good Company Performance

• Stocks are generally priced based on the expected future performance of the underlying business. When a company announces surprisingly good earnings news, or makes any corporate announcement that is unexpectedly favorable, investors tend to flock to the stock, driving up the price.