What hedge change follows from +500 shares/vol point and a −2-point IV move?
Reveal the worked answer
Buy 1,000 shares.
The hedge offsets the −1,000 option-Delta change.
Dealer Logic · DL-08 · Core
Dealer Vanna
How can IV change the hedge without a spot move?
What you will learn and prerequisites
- Explain the mechanism in the lesson question.
- Reproduce the worked comparison and recognize its failure case.
Read first: Why dealers hedge
Vanna links Delta and implied volatility. A volatility change can alter directional exposure even while spot is quiet. Maintaining an old hedge can therefore leave a new residual Delta.
The direction is not determined by 'IV rose' or 'IV fell' alone; signed book Vanna is required.
Understand the mechanism
For a small parallel IV shift, dDelta≈Vanna×dIV, and the neutralizing hedge takes the opposite sign. A per-volatility-point number uses 25%→26% as +1; raw decimal Vanna uses +0.01.
Real surfaces often move nonparallel across strikes and expiries. One scalar can conceal materially different local changes.
Walk through the process
Declare the inventory sign, units and surface shock. Calculate the local change separately from Gamma and Charm. Then stress alternative skew and term-structure movements.
Do not generalize a buy-flow story from one assumed book to every volatility decline.
Evidence boundary
The arithmetic is original conditional teaching material, not a measurement of current dealer positions. The cited Cboe research is historical product-specific evidence, not a live inventory feed. Model outputs should remain distinguishable from observed market facts.
A worked example
Book Vanna is hypothetically +500 share-equivalents per vol point. IV falls from 25% to 23%, or −2 points. Option Delta changes by approximately −1,000 shares, so a neutralizing hedge buys 1,000.
If signed Vanna were −500, the same event would imply selling 1,000. The graph fixes the positive-Vanna case and varies the shock.
Open the calculation without leaving this lesson
Dealer Vanna—worked comparison
Vertical: Hedge change (shares)
Horizontal: IV change (vol points)
1. Fictional example
Read the graph as a data table
| IV change (vol points) | Fictional example |
|---|---|
| -2 | 1,000 |
| -1 | 500 |
| 0 | 0 |
| 1 | -500 |
| 2 | -1,000 |
What would invalidate the reading?
An unsigned Vanna narrative can predict the wrong direction. Mixing raw and point-scaled units creates a factor-of-100 error.
Check your understanding
Try the question before revealing its answer. These are reading checks, not trading certification or a site completion record.
What is the critical failure to avoid?
Reveal the worked answer
An unsigned Vanna narrative can predict the wrong direction. Mixing raw and point-scaled units creates a factor-of-100 error.
Explain this risk before treating the example as a decision rule. A correct calculation does not guarantee a favorable market outcome.
Return to the question: How can IV change the hedge without a spot move? State the observed facts, the assumptions and the failure condition separately.
Sources, assumptions and downloadable script
External references support definitions and conventions. Worked scenarios and prose are original. No current quotes or dealer inventory are claimed.
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