Vanna exposure — VEX — measures how much dealer hedging is driven by implied volatility rather than price. Gamma tells you what happens when price moves. Vanna tells you what happens when volatility moves — even if price doesn't.
A market maker who sells you an option hedges it in the underlying. That hedge is sized to the option's delta — and delta is not a fixed number. It depends on where price is, how much time is left, and how much implied volatility is in the option.
Which means something easy to miss: if implied volatility changes and price does not move at all, the dealer's delta has still changed. Their hedge is now the wrong size. They have to fix it. That fix is a real order, in the real market.
Vanna is the Greek that measures exactly this: how much an option's delta moves when implied volatility moves. Vanna exposure (VEX) is the sum of that sensitivity across the whole dealer book — how much hedging flow gets forced into the tape per unit of volatility.
The setup that matters most is the one that is almost always in place. Investors buy downside protection, so dealers end up short puts in size, and they hedge that by being short the underlying.
Now let implied volatility fall — the market calms down, a feared event passes, the VIX bleeds lower. Those out-of-the-money puts become less likely to matter, and their deltas shrink toward zero. The dealer's short hedge is suddenly too big. To stay neutral, they have to buy the underlying back.
Nothing about price caused that buying. Falling volatility did. That is the vanna rally: the slow, mechanical grind higher that so often accompanies a bleeding VIX, and the reason a market can drift up all day on no news at all.
It runs in reverse too. Volatility spikes, put deltas swell, dealer hedges get too small, and they must sell into a falling market — one of the reasons selloffs feed themselves.
Gamma is what happens when price moves. Vanna is what happens when volatility moves. VEX shows how much hedging flow a shift in implied volatility will force into the market — and which way.
Dark Horse computes the day's net vanna exposure and plots it alongside the gamma and delta panels, so a change in implied volatility is visible as positioning pressure rather than something you have to infer from the VIX after the fact. Vanna exposure is included on the Complete tier, on any optionable US ticker.
One honest note, which we would rather state than bury: higher-order exposures like vanna are model-derived estimates. They depend on a pricing model and its assumptions in a way that first-order gamma does not. That is true of every provider who publishes them. Read VEX as positioning context, not as a precise number.
Not investment advice. For educational purposes only. Market maker positioning levels, not trade signals.