Vega exposure (VEX)
Vega exposure is the aggregate sensitivity of an option book's value to a one-point change in implied volatility: the sum of open interest × vega × contract multiplier across strikes and expiries, optionally signed by a positioning assumption. The abbreviation VEX is also used by some vendors for vanna exposure, so the definition must be checked before comparing numbers.
Senzoukria · Glossary · Updated September 2026
At a glance
- Formula
- Σ OI × vega (per vol point) × multiplier
- Unit
- Dollars per volatility point
- Naming clash
- VEX means vega exposure in some tools, vanna exposure in others
Definition
Vega is the change in an option's value for a one-point change in implied volatility. Multiplying each series' vega by its open interest and the contract multiplier and summing gives the dollar amount by which the open-interest book would gain or lose if implied volatility moved by one point across the chain. Seen from the holders' side it is always positive, because long options have positive vega; a positioning convention can sign it from the dealer's side instead.
Worked example
A 30-day at-the-money option on an underlying at 100 with 20% implied volatility has a vega of 0.114 per point. With 10,000 contracts open and a multiplier of 100, the series carries 10,000 × 0.114 × 100 = 114,000 dollars of vega: a one-point rise in implied volatility raises the value of the open contracts by about that amount, and a one-point fall lowers it by the same.
- Long-dated series dominate vega exposure, since vega grows with the square root of time.
- Short-dated series dominate gamma exposure; the two aggregates describe different parts of the curve.
VEX: vega or vanna?
Vega exposure answers how much the book's value changes with volatility. Vanna exposure answers how much the book's delta changes with volatility, which is the amount a delta-neutral hedger would have to buy or sell. Both are abbreviated VEX in different products. They have different units, dollars of value per point against dollars of delta per point, and they can have different signs, so a VEX figure without a definition cannot be interpreted.
In Senzoukria
In the GEX overview, Total VEX means vega exposure. The tile, labelled per vol-pt, sums open interest × vega × 100 across every call and put of the loaded chain without a dealer sign, and reports that the field is not in the chain when the provider publishes no vega or no leg combines vega with open interest. Vanna exposure has its own tile, labelled in dollars of delta per vol-pt, and is available as a value on the Surface page, so the two quantities are never merged under one name.
Related
In the same section
- Velocity logic
- Vega
- Vertical spread
- Variation margin
- Visible range volume profile
- Variance swap
- VIX
- Volatility cone
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Frequently asked questions
- Does vega exposure tell me whether implied volatility will rise?
- No. It measures sensitivity, not direction. A large vega exposure means that a move in implied volatility, whichever way, changes the value of the open-interest book by a large amount.
- Why can vega exposure fall on a day with no new positions?
- Because vega itself changes: it shrinks as time passes, and it falls for strikes that move away from the money as spot moves. With open interest fixed until the next publication, those effects alone change the total.