Implied volatility is not a weather report from the stock. It is a number a model backs out of an option’s price. Premium in. Strike, spot, time, rates. Solve for the vol that makes the model match the market. That vol is IV.
People search “what is IV” because every chain quotes it and almost nobody says what the quote *is*. It is not “how much the stock will move.” It is “how much movement this contract is *charging for*.” High IV means rich premium for a given strike and expiry. Low IV means cheap premium. Neither sentence says up or down.
This page is the number. Volatility smile is that number plotted by strike. VIX is a 30-day *basket* of SPX options turned into an index. Three related maps. Don’t mash them. If you want the live smile, open Gamma and hit Volatility smile.
Price first, or IV is magic
An option has a market price. Bid, ask, last — pick a mark, live with the mess. A pricing model (Black-Scholes and cousins) needs a volatility input to spit out a theoretical price. Run it backwards: which volatility makes theory equal the mark? That’s implied vol. One number per contract, usually quoted as an annualized percent.
If every strike had the same IV, the smile would be a flat line. It isn’t. OTM puts on SPY usually print richer IV than OTM calls. That’s skew: crash insurance is bid. The model assumed a single vol. The market didn’t. 1987 and every crash since said no.
IV is not realized volatility. Realized (or historical) vol is measured from prices that already printed — a standard deviation of returns, annualized. Backward-looking. A fact about the tape. IV is forward-looking only in the weak sense that it is *embedded in prices people are paying now*. It can be wrong tomorrow. It is often higher than what later realizes. That gap is a risk premium story, not a “sell premium” order. We are not writing that playbook.
A 20% IV on a 30-day option is a *rough* annualized one-standard-deviation scale. People translate it into an “expected move” over the life of the contract with a square-root-of-time napkin. Useful as a *priced* range. Not a promise the stock will sit inside it. Not a GEX wall.
IV also smears gamma. Higher vol fattens the tails of the model, so delta (and gamma) spread across more strikes. A vol crush after earnings can kill gamma on the same open interest. Contracts didn’t vanish. The bend did. GEX moves. Max pain, which ignores gamma, doesn’t. Different toys.
IV crush, events, and 0DTE
Before a binary — earnings, FOMC, CPI — people bid options. IV goes up because the *price* went up. After the number, the uncertainty is (partly) gone. Premium falls even if the stock did what you wanted. That’s IV crush. Vega did the damage. Direction can still save or kill you. Both can be true in the same minute.
On 0DTE the crush can happen before the cash open. Vega is small when almost no time is left; gamma is huge. A same-day smile is a weather vane. A monthly smile is slower. Don’t read a leap’s IV as today’s tape.
IV rank / IV percentile — where today’s IV sits versus its own history — is a *relative* ruler. Useful. Abused. “IVR is 20 so buy premium” is still a playbook. Rank does not tell you the event is mispriced. It tells you this ticker’s options are cheap versus *this ticker’s* recent options. Different sentence.
IV vs VIX vs GEX vs smile
Contract IV is one option: that strike, that expiry, that ticker.
Smile is many of those, plotted against strike, one line per expiry. That’s the widget on our tab.
VIX is not “SPY IV.” It is a Cboe index from a strip of SPX options, aimed at about 30 days. Magnitude of expected S&P move, not direction. You cannot read NVDA’s chain off VIX. You cannot price 0DTE off VIX. What the VIX is.
GEX is not IV. GEX stacks modeled dealer gamma from listed OI. Smile is what options *cost* in vol terms. A steep put wing can sit next to a quiet GEX put wall, or next to a violent one. Look at both. Don’t infer one from the other.
Put/call ratio is a count of contracts, not a vol. Heavy put volume can print at calm IV. Steep smile can print with a boring PCR. Put/call ratio.
What IV is not
It is not a direction. High IV is not bearish. Low IV is not bullish. Sign of the *move* is a different question.
It is not vega. Vega is how the option’s *price* changes when IV changes. IV is the input. Vega is the sensitivity. Related. Not the same Greek.
It is not a trading signal. “IV is high, sell the straddle” is a YouTube title. This page is a definition.
It is not GEX, not a call wall, not max pain. Those are other maps.
How this shows up on our Gamma tab
You don’t get a per-contract IV ladder as the main view. You get Volatility smile: IV % on the Y-axis, strikes on the X, one colored line per selected expiry, dotted spot. OTM puts below spot, OTM calls above — that’s the hint on the tab.
The GEX profile is the other chart. Cyan and red are gamma, not vol. Don’t mash the Y-axes.
Guests see a delayed snapshot. IV on 0DTE moves fast. Delay matters. If smile is unavailable, the tab says so. Don’t invent a curve. A free account keeps a journal and one full report. Pro is unlimited tickers, not a secret surface.
Single names: IV can go feral around earnings. The Greek is still “vol backed out of price.” The smile can look like a circus. Read SPY and a biotech as different animals.
A short way to remember IV without a playbook
- IV is the vol a model needs to match the option’s price.
- It is not realized vol and not a forecast of direction.
- Smile is IV by strike. VIX is a 30-day SPX basket. GEX is gamma.
- Then stop.
If those four are boring, good. Boring is the point. You wanted the quote. You got the quote.
Also in this series: volatility smile and skew, what the VIX is, what GEX is, what gamma is, 0DTE.