Volatility

(1) The degree of price fluctuation for a given asset, rate, or index. Usually expressed as a variance or standard deviation. (Refer to beta)  (2) The sharp price movement of a security, commodity, or a market within a specified time period. A measure of the volatility of a stock or mutual fund relative to the overall market is beta. Thus, a mutual fund with a beta of 0.5 is half as volatile as the movement of the Standard & Poor's 500 index, while a fund with beta of 1.5 is 50 percent more volatile. Generally, a stock or mutual fund with a high beta is said to have more risk than one with a low beta, since there's an increased risk that the price of the security will have fallen when an investor wants to sell.