Vanna & Charm · Foundations

What Vanna & Charm Actually Are

Two second-order Greeks, two hidden hedging flows. Once you see how each one moves a dealer's delta, the quiet drifts and OPEX pins stop being mysterious.

Delta is what a dealer hedges. Gamma, vanna, and charm are the three things that change delta — and vanna and charm are the two that don't need price to move at all.

Vanna — delta's sensitivity to volatility

Vanna is the rate at which an option's delta changes as implied volatility changes (equivalently, how vega changes as spot moves). It matters because dealers carry large books of customer protection. When implied vol drops, the deltas on those positions shift, and to stay neutral the dealer must trade the underlying — typically buying as vol falls. No news, no price catalyst; just a volatility move forcing a hedge.

Charm — delta's sensitivity to time

Charm is the rate at which delta changes simply because time passes (delta decay). As an option ages toward expiration, an out-of-the-money strike's delta drifts toward zero and an in-the-money strike's toward one — and the dealer re-hedges as it does. Charm flow builds into expiration, and in a calm tape it's often gently supportive: part of the quiet upward drift markets show in the run-up to a big OPEX.

Why these are "the flows gamma misses"

Gamma needs price to move to generate a hedge. Vanna needs only a vol move; charm needs only the clock. So on a day when the index is flat but vol is sliding into a Friday expiration, gamma is silent while vanna and charm are actively buying. That's exactly when traders are most puzzled by a market that won't go down — and exactly what this tool is built to show.

Reading them by strike

Like gamma, vanna and charm are concentrated at particular strikes — driven by where the open interest sits. The tool maps net dealer vanna by strike and net dealer charm by strike so you can see which levels will generate the most hedging when vol moves or as expiration nears. The same standard sign convention applies: dealers assumed long call exposure and short put exposure.

Educational content from Nations Indexes. Vanna and charm exposures are regime heuristics estimated from open interest under a standard sign convention, not precise flow models. Nothing here is investment advice.