Implied Volatility and Skew: Why Puts Cost More Than Calls

Two options sit the same distance from spot. Same expiry, same width, and still they will not cost the same. The put is usually dearer.

That gap is the market telling you how equities actually move, and reading it properly is most of what separates a trader who uses options deliberately from one who buys calls and hopes something happens.

What implied volatility is

Nobody forecasts implied volatility. It gets solved backwards, out of prices that already exist.

Take what an option is trading at, push it into a pricing model, and ask which volatility assumption would make the model spit out that exact price. The answer is the implied volatility. It is the market’s collective expectation of movement, pulled out of nothing more than what people are actually willing to pay for the contract today, which is why it can move sharply on a day when nobody’s forecast of the future has changed at all.

Two things follow immediately. IV carries demand inside it as well as expected movement, so a wave of hedging buys pushes IV higher whether or not the stock itself gets any wilder. And IV has no direction at all: it sizes the expected move and says nothing whatever about which way it runs.

Skew: the shape of the curve

Plot IV against strike. In equities the line runs downhill from low strikes to high ones, so downside puts carry fatter IV than the calls sitting an equal distance above.

Two reasons, and they reinforce each other. Equities genuinely fall faster than they climb: advances grind upward, declines arrive all at once and in correlation, and the return distribution has a fatter left tail that the skew prices correctly. Then there is demand, which is structural and one-sided. Institutions with long books buy puts continuously, as insurance, whatever their view happens to be. No natural buyer of upside calls exists at anything like that size. Persistent demand meeting limited supply keeps put IV elevated.

The volatility smile is the related shape. It turns up in currencies and some commodities, where both tails carry elevated IV. Equity indices show a smirk, with the elevation on the downside only, and the shape of the curve tells you what the market is afraid of in that particular asset.

Term structure

IV varies across expiries too.

Contango is the normal state, with longer-dated options carrying higher IV than short-dated ones, for the simple reason that more can happen over more time, and that extra window of possibility has to be paid for by whoever wants it. Backwardation is the inversion: short-dated IV above long-dated. It shows up when something specific is coming, an earnings release, a court decision, an election. The near contract prices the event while the far one carries on as though nothing were scheduled at all, and the gap between the two is the market stating, in the only language available to it, how much of the coming move it expects to be spent inside the next few sessions.

The inversion is worth reading on its own. It says the market has found a specific near-term worry. It also shows you exactly where the premium has concentrated.

IV rank: the number that makes IV usable

A raw IV of 45% tells you nothing on its own. Historically calm for a biotech. Extreme for a utility.

IV rank fixes that by placing current IV inside its own trailing one-year range, 0 to 100.

IV rank	What it usually implies
Above 70	Options expensive against their own history; favours selling premium
30–70	Unremarkable
Below 30	Options cheap against history; favours buying premium

That comparison is why IV rank is the most practical volatility metric going. An absolute number becomes a relative one, and relative is the only form in which a market number ever tells you very much.

Earnings and IV crush

The clearest application of all this. Also the one that costs beginners most.

Ahead of a scheduled release, IV on near-dated contracts climbs hard. The uncertainty is genuine and the market prices it. Then the release lands. The uncertainty evaporates. IV collapses inside minutes, regardless of what the numbers actually said.

Here is where people get caught. The company beats, the stock rises 6%, and the call bought the previous afternoon is worth less than it cost, because the gain in intrinsic value was smaller than the loss from the volatility collapse.

What skew tells you that price doesn’t

Skew is a positioning signal as well as a pricing feature. When put IV climbs sharply against call IV, institutions are paying up for protection, and that tells you something about how the market is positioned which the index level by itself will never show you.

Steepening skew during a rally carries the same message as narrowing breadth: the advance is being hedged even as it runs, and the people doing the hedging are the ones with the most at stake. Neither one times a turn. What both do is tell you how much risk the market is carrying.

The practical takeaways

1. Compare options on implied volatility and on IV rank. Price by itself tells you little.
2. Check term structure before any dated trade. Inversion means an event is priced in.
3. High IV rank favours selling premium and low IV rank favours buying it. Treat that as a starting bias. The setup still has to stand up on its own merits.
4. Assume the expected move is already in the premium. Your bet is on a move larger than the one priced, which is a harder thing to get right than direction alone.
5. Skew makes spreads asymmetric. A put spread and a call spread of identical width carry different credit. They carry different risk too.

Read how options work for the fundamentals underneath all of this, and options strategies ranked by risk for which structures suit which volatility environment. Model the payoff of whatever you settle on with the options profit calculator.