Volatility

Volatility is a measurement of change in price over a given period. It is usually expressed as a percentage and computed as the annualized standard deviation of the percentage change in daily price.

The more volatile a stock or market, the more money an investor can gain (or lose!) in a short time.

In referring to mutual funds, volatility (Standard Deviation for Mutual Funds) is the measure of the degree to which a fund's return varies from the average of all similar funds on a month-to-month basis over several years.