Volatility comes in two flavors, and mixing them up is common. Historical volatility looks backward at how much a stock has moved. Implied volatility looks forward at how much the market expects it to move. The gap between them is where sellers find an edge.
Think of driving a car. Historical volatility is the rearview mirror, the road you have already driven. Implied volatility is the windshield, the market’s guess about the road ahead.
The rearview mirror: historical volatility
Historical volatility measures how much a stock has actually bounced around over some past period. It is a fact, calculated from real price history. Like a rearview mirror, it tells you exactly what the road behind you was like, smooth or bumpy, but it cannot see what is coming.
The windshield: implied volatility
Implied volatility is baked into option prices right now. It is the market’s forecast of how bumpy the road ahead will be, before earnings, news, or anything else on the horizon. When traders expect turbulence, implied volatility rises and options get more expensive. When they expect calm, it falls.
Where the edge lives
Sellers care most about the gap between the two. When implied volatility sits well above what the stock has actually been doing, the market may be overpaying for fear, and selling options into that can be an edge. When implied volatility is unusually low, premiums are thin and selling is less rewarding. Comparing the windshield to the mirror is how sellers judge whether premium is rich or cheap.
A quick example
Suppose a stock has quietly drifted a percent or two a week for months, so its historical volatility is low. Then earnings approach and implied volatility spikes: the windshield suddenly shows a storm the rearview mirror never had. If you believe the move will be smaller than the market fears, that gap is your opening. You sell the inflated premium and, once the event passes and implied volatility falls back toward the calm history, the option deflates in your favor.
A quick way to read the gap
You do not need to compute anything by hand. Many platforms show an implied volatility “rank” or “percentile,” which places today’s implied volatility against the stock’s own past year. High in that range means options are richly priced relative to normal, a friendlier time to sell. Low means they are cheap, a poorer time to sell and sometimes a better time to buy. It is the mirror-versus-windshield comparison, done for you.
A simple habit: before selling, ask whether implied volatility is high or low compared with the stock’s own history. Selling rich volatility and letting it fall back toward normal is one of the steadiest edges a seller has.
- Historical volatility is the rearview mirror: how much the stock has actually moved.
- Implied volatility is the windshield: how much the market expects it to move next.
- Sellers find an edge when implied volatility is rich compared with the stock’s own history.
This article is educational and is not investment advice. Options involve risk, including the possible loss of principal. Examples and premiums shown are illustrative and change with the market. Practice with paper trading before committing real money.