The price movement that is experienced by a security, commodity, or market, usually rising and falling sharply within a short period of time. However, variability may not always imply sharp rises or drops in an asset price. At times, variability may be stable or flat, and nevertheless a state of variability is still considered in existence.

In general, variability refers to sharp movement in prices or rates due to specific factors, individually or combined, such as high market risk, paradigm shifts in market fundamentals within a short period, and so on.

If variability (or volatility) is related to the broad market (i.e., relative volatility), a measure known as beta is used. Beta constitutes the relative variability of a tradable asset (e.g., a stock) to the overall market.

Variability reflects the degree of variation of a trading price series over time, as measured by the standard deviation (SD) of logarithmic returns. It may take many guises including historical volatility, forward volatility, expected volatility, etc.