Risk refers to the degree of variability in investment returns that an individual is willing to withstand. It is the chance that an investment's actual return will be different than expected. Every investment carries some level of risk, and investors must establish their own measure of risk tolerance.
An investor with a high risk tolerance is likely to invest in securities, such as stocks in startup companies, and is willing to accept the possibility that the value of his/her portfolio will decline, at least in the short-term. An investor with a low risk tolerance, on the other hand, tends to invest predominantly in stable stocks and/or highly-graded bonds. One's risk tolerance is subjective and may vary according to age, needs, goals, and even personal dispositions.