Volatility

The degree of price variation in a security or market over time, typically measured by the standard deviation of returns or by implied volatility derived from options prices.

Volatility is the statistical measure of how much an asset's price fluctuates. Historical volatility calculates the standard deviation of actual past price returns over a defined lookback period. Implied volatility, derived from options prices, reflects the market's forward-looking expectation of future price movement. Both are expressed as annualized percentages — a stock with 30% annual volatility has historically moved roughly ±30% over a year.

Volatility is the core input to options pricing models like Black-Scholes. Higher volatility makes options more expensive because there's a greater chance the underlying will move far enough to make the option valuable. Traders who believe future volatility will exceed what the market has priced in buy options (go long volatility); those who believe it will be lower sell options (go short volatility).

For long-term investors, volatility is often confused with risk, but they are distinct concepts. Volatility measures price fluctuation; risk measures the probability of permanent capital loss. A stock that drops 30% then recovers is highly volatile but may pose little actual risk to an investor with a 10-year horizon. That said, high volatility increases the probability of behavioral errors — panic selling near bottoms — which is a very real practical risk for many investors.

This definition is for informational and educational purposes only. Nothing on Finance Compass constitutes financial, investment, or trading advice. Always conduct your own research and consult a qualified professional before making financial decisions.