ATM Implied Volatility
The implied volatility of at-the-money SPX options — reflects the market's real-time pricing of expected movement for the current session.
ATM (at-the-money) Implied Volatility is the volatility level implied by the price of SPX options with strikes closest to the current index level. While VIX measures 30-day expected volatility, ATM IV for 0DTE options reflects the market's pricing of expected movement for just today's session.
0DTE ATM IV is uniquely informative because:
- ●It reprices continuously based on order flow and hedging demand
- ●It directly determines how expensive structures are to enter
- ●It reflects institutional positioning and expected catalysts
- ●It helps calibrate whether options are "cheap" or "expensive" relative to likely movement
SPXXL tracks ATM IV in real-time and compares it to:
- ●Historical ATM IV for the same session type
- ●Current VIX level (to detect IV skew)
- ●Realized intraday volatility (to detect over/under-pricing)
When ATM IV is high relative to historical: Options are expensive — favor selling (credit spreads, iron condors)
When ATM IV is low: Options are cheap — favor buying (debit spreads, butterflies)
The ATM IV level is displayed on SPXXL's dashboard and is a key input to the Close Zone projection width. Higher ATM IV = wider Close Zone band = wider structures needed.
Related Terms
The CBOE Volatility Index measuring expected 30-day SPX volatility — the market's "fear gauge" and key input to session classification.
The rate at which an option loses value as time passes — accelerates dramatically for 0DTE options as expiration approaches.
The aggregate gamma positioning of options market makers — determines how dealer hedging amplifies or dampens SPX price moves.
Options that expire on the same day they are traded — the fastest-growing segment of the options market with unique risk/reward characteristics.