Implied Volatility

Implied volatility, usually shortened to IV, is a number that expresses how much price movement the options market expects from a stock or other asset over a given period. It is not a forecast of direction — it says nothing about whether a stock will go up or down — only about how much it might swing, either way.

The number comes from working backward through an options pricing model, such as Black-Scholes. Options have a price, and that price is built from known inputs like the stock price, the strike price, time until expiration, and interest rates, plus one unknown: expected future volatility. Plug in the option's actual market price and solve for that missing input, and what pops out is the implied volatility. In practice, traders don't do this by hand; trading platforms calculate and display it, typically as an annualized percentage.

The nuance that trips people up is the word "implied." IV is not a measurement of how much the stock has actually been moving (that's historical or realized volatility, which is calculated directly from past price data). IV is instead a reflection of what option buyers and sellers are currently willing to pay, which bakes in their collective expectation of future movement. If demand for options rises — often around earnings, Fed announcements, or other known events — option prices rise, and IV rises with them, even if the stock hasn't moved yet.

IV also isn't a single fixed number for a stock; it varies by strike price and expiration date, a pattern often called the volatility "smile" or "skew." A quoted IV figure is usually for a specific option or an average across several, so comparing IV across different stocks or different option contracts should be done carefully.