Implied Volatility Explained: What IV Tells You and What It Does Not
What implied volatility actually measures, why it differs across strikes, how it moves around events, and the difference between IV being high and options being expensive.
Arthalab10 min read
Implied volatility is the option's price, restated as a volatility number. It is obtained by running a pricing model backwards: given what the option actually trades at, what volatility would the model need to assume to produce that price?
That definition matters because it determines what IV can and cannot tell you. It is a restatement, not a forecast — and most of the confusion around it comes from treating it as the second thing.
Why express price as volatility at all
A premium of 90 points means nothing on its own. Is that expensive? It depends on the strike, the time to expiry and how much the index actually moves.
IV strips those out. By converting price into a volatility figure, it becomes possible to compare a near-expiry at-the-money option against a far-dated out-of-the-money one on a common footing. That comparability is the entire reason the measure exists.
What high IV actually means
High IV means options are priced for large movement. It does not mean they are overpriced, and it does not mean a large move is coming — it means the market is charging for the possibility of one.
Sometimes that charge turns out to be too high and sellers profit. Sometimes the move arrives and buyers profit. IV being high tells you which way the market is leaning, not which side will be right.
The misreading to avoid
This is the single most common misreading in options content. Selling into high IV is presented as an edge, when it is better described as being paid more to take more risk. Whether that is a good trade depends on whether the premium exceeds the eventual movement, which IV cannot tell you in advance.
Why IV differs across strikes
If the model behind IV were a complete description of reality, every strike in an expiry would show the same IV. They do not, and the pattern is consistent enough to have a name.
Out-of-the-money options — particularly puts — typically show higher IV than at-the-money ones. The shape is called skew, and it reflects persistent demand for protection against large downward moves.
Skew is not an opportunity you spotted
This is normal and well known. Finding that a far out-of-the-money put has higher IV than the at-the-money option is not a mispricing you have discovered; it is the structure of the market you are trading in.
IV and events
IV rises ahead of scheduled events — policy announcements, major results, anything with a known date and an unknown outcome. The market prices the uncertainty in advance.
After the event resolves, IV typically falls sharply, often regardless of which way the outcome went. This fall is commonly called IV crush, and it has specific consequences for both sides.
Position
What IV crush does
Net effect
Long options
Reduces option value
Can lose even if direction was right
Short options
Reduces option value
Gains, independent of direction
The top row describes a genuinely frustrating experience: buying options before an event, being correct about direction, and still losing because the collapse in IV outweighed the move.
Why selling into events cuts both ways
The bottom row is why selling into events is attractive and also why it is dangerous. You profit from the crush, but you carry the event risk to get there, and the move that arrives can exceed what the elevated premium compensated for.
Is IV high right now? The question IV cannot answer
A single IV reading has no context. 14 is high in one regime and low in another, and the number alone does not say which.
What gives it meaning is comparison — against the same instrument's own recent range, or against how much the index has actually been moving. Traders use various measures for this; the common idea is that IV becomes informative only relative to something.
The comparison that actually matters
The comparison that matters most for a seller is between implied and realised movement. If options are consistently priced for more movement than subsequently occurs, selling has been profitable in that period. If not, it has not. That relationship is measurable after the fact and not predictable before it.
Implied against realised volatility
The comparison that gives IV meaning is against what the index actually did, rather than against its own past readings alone.
Implied volatility is what the market charged for expected movement. Realised volatility is how much movement actually occurred. The gap between them, over a period, is roughly what an option seller was paid or overpaid for.
Relationship over a period
Who it favoured
Implied consistently above realised
Sellers — options were priced for more movement than occurred
Implied consistently below realised
Buyers — movement exceeded what was priced
Roughly equal
Neither, before costs
Why this is history, not a signal
This relationship is measurable after the fact and not predictable before it. A long stretch where implied exceeded realised does not entitle you to the next one, and treating it as a standing edge is how option sellers end up over-sized before a regime change.
A common misreading worth naming
Content in this space frequently frames high IV as an opportunity to sell and low IV as an opportunity to buy. Stated that plainly, the logic does not hold.
If high IV reliably meant overpriced options, selling into it would be a free edge and the pricing would adjust until it was not. The persistence of elevated IV before events is the market charging for genuine uncertainty, not a repeated error.
What is actually true
What is true is narrower and more useful: selling into high IV pays more per unit of risk taken, and whether that compensation is adequate is decided by what the index subsequently does. That is a trade with a known payment and an unknown outcome, which is a different thing from an edge.
IV and your position
Your exposure to IV is vega, and the sign depends on which side you are on. The Greeks guide covers this in detail; the practical summary is short.
Option sellers are short vega. A volatility rise hurts, independent of direction, and usually raises margin at the same moment.
Option buyers are long vega. A volatility fall hurts, which is why being right on direction is not always enough.
Multi-leg structures net out. A condor's bought legs offset part of the short vega from its sold legs.
Using IV in strike selection
IV has a direct practical use that avoids all the forecasting questions: adaptive strike selection.
A strike rule based on a target premium automatically moves further out when IV rises, because the strike paying that premium is further away. The range widens exactly when the market expects wider movement, without you deciding anything.
A fixed-distance rule does the opposite — the same offset is a large move in a quiet market and a small one in an active market. For a strangle in particular, this difference substantially changes how the strategy behaves across regimes.
1
Decide what you want held constant
Premium collected, or distance from the money. You cannot hold both.
2
Pick the matching strike rule
Premium-based adapts to volatility; offset-based adapts to price.
3
Backtest across a varied period
The difference between the two rules only shows up across changing regimes.
4
Check behaviour in the high-IV stretch specifically
That is where the rules diverge most and where the losses concentrate.
What IV will not do for you
Predict direction. It is symmetric; it says nothing about which way.
Predict magnitude. It states what is priced, not what will occur.
Tell you an option is cheap. Only comparison against context does that.
Warn you before a surprise. Unscheduled events are, by definition, not priced in advance.
The short version
IV is the price restated as volatility — a unit change, not extra information
High IV means priced for movement, not overpriced and not a forecast
Skew across strikes is normal structure, not a mispricing you found
IV crush after events can beat a correct directional view
Sellers are short vega; rising IV means losing and higher margin together
Premium-based strike rules adapt to IV automatically; fixed offsets do not
IV is visible per strike on the option chain. Reading the chain covers where it sits alongside OI, volume and the spread.
Frequently asked questions
Implied is what the market charged for expected movement. Realised is how much movement actually occurred. The gap between them over a period is roughly what an option seller was paid or overpaid for.
No. That relationship is measurable after the fact and not predictable before it. Treating a past stretch as a standing edge is how sellers end up over-sized ahead of a regime change.
Low IV means options are priced for little movement. Whether that is cheap depends on what the index then does, which IV does not tell you. The framing of low IV as an automatic buying opportunity does not hold.
No. Out-of-the-money options, particularly puts, typically carry higher IV. That pattern is called skew and reflects persistent demand for protection rather than a mispricing.
The option's market price, restated as a volatility number by running a pricing model backwards. It is a unit conversion rather than new information.
No. It means the market is pricing for the possibility of one. Sometimes that pricing is too high and sellers profit; sometimes the move arrives. IV does not say which.
High IV pays you more and asks you to carry more risk. Whether that is a good trade depends on whether the premium exceeds the eventual movement, which is not knowable in advance.
The sharp fall in implied volatility after a scheduled event resolves. It reduces option values regardless of direction, which helps sellers and can cause buyers to lose even when right about direction.
Persistent demand for protection against large moves means out-of-the-money options, particularly puts, typically price higher. The pattern is called skew and it is normal market structure.
Not on its own. It becomes informative only relative to something — the instrument's own recent range, or how much the index has actually been moving.
For an option seller, rising IV typically raises the margin requirement at the same time as it produces a loss on the position. The two arrive together, which is why headroom matters.
Yes, indirectly. A premium-based strike rule moves further out when IV rises, because the strike paying your target premium is further away. That adapts the range to conditions without you deciding anything.
No. It is symmetric and says nothing about which way the index will move.
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