Whenever a company decides to pay out some of its profits (normally in the form of a dividend) this comes on top of any growth in the share price and it could therefore increase your returns even further. Not all companies pay dividends, however, as many prefer to reinvest their profits and aim for further growth potentially increasing the share price further.

Of course, there is the other side of the coin. Companies that are having difficulties are likely to see their share price fall, which could reduce the value of your holding potentially leaving you with less than you invested. There are also times when the majority of companies rise or fall in value, seemingly regardless of their individual merits. Shares in aggregate are sensitive to general economic conditions in a country or a region.

Significant world events can affect the market as a whole, or have an impact on individual sectors. For example, when Hurricane Katrina hit oil refineries in the Gulf of Mexico it had an immediate effect on oil companies, but there were also implications for businesses that rely on oil and fuel, such as airlines.