Vanna measures how an option’s delta changes when implied volatility moves (equivalently, how vega changes when price moves). It’s a second-order Greek — and because dealers must hedge it, it drives real flows in the market.

What vanna captures

Delta isn’t static — it shifts as conditions change. Vanna isolates one driver: volatility. When IV falls, the delta of a dealer’s options book changes, forcing them to re-hedge (buy or sell futures/shares) to stay neutral. That hedging is vanna flow, and it can push price independent of any news — see vanna flows explained.

Why it drives rallies

The classic pattern: markets calm down, IV drifts lower, and in a “short vanna” dealer regime that falling vol forces dealers to buy to stay hedged — a self-reinforcing vanna rally that can lift price with no fundamental catalyst. It’s a big reason markets often grind higher as fear fades (and why a post-event vol crush can spark a bounce).

Vanna is the hidden bridge between fear and price: when volatility drops, vanna hedging can quietly buy the market higher — no news required.

What it means for a scalper

You don’t compute vanna, but knowing it exists explains otherwise-puzzling drift, especially after volatility crushes and around OPEX. It’s part of the higher-order Greek picture that shapes the tape NoVo reads and maps. Related: charm, the time-based cousin of vanna.