Risk, in simple terms, refers to the possibility that the actual outcome that is achieved is different from the outcome that is expected. Though some bit of deviation from the expected is always expected in the actual values and the predicted, the occurrence of significant differences can create problems as it would render the process of decision making inefficient. This is because decisions are arrived at, after inputting the estimates into the decision making process, so as to determine the expected outcome. Though risk pertains to both positive as well as negative deviations from the expected value, in the field of finance, the downside risk (i.e. the risk that the actual outcome would be significantly lesser than the expected outcome) is of much more importance and concern. In the field of finance, risk pertains to the cash flows variability of a project. Risk is accounted by measuring the variance of returns and to account for the negative deviations more specifically, several measures like downside deviation; Value at Risk (VaR), etc have been introduced.