Banks are in the business of taking on risk in order to generate a profit. When a bank underwrites a loan to a customer, there is the risk that that customer will not pay them back. In addition, there is the risk that the financial security the bank owns and shows on its balance sheet, such as a stock or a bond might be sold for less than expected or may not be able to be sold at all. There are other risks, such as the risk that a computer system is hacked and sensitive information is stolen. These examples illustrate that risks can be defined as uncertainty to a future expected outcome. These outcomes could be better or worse, either as upside as well as downside risk. If a bank knew with certainty which customers will default in the future, or exactly how much they will be able to sell a financial asset for in the future or what IT security systems will successfully defend against hackers, then a bank would have certainty about future outcomes and therefore have zero risk. Risk is also a function of the likelihood of a future occurring, what the magnitude of its impact might be, and the consequence for the bank of that event occurring.