Dealer hedging is the buying and selling of the underlying stock that options market makers do to offset the directional risk of the options they hold. Because those hedges must be adjusted as price, time and volatility change, the resulting flows can at times hold a stock near a strike (pinning) or push it further in the direction it is already moving.
How it works
A market maker earns the bid/ask spread and aims to avoid betting on direction. After taking the other side of a customer's option trade, the dealer buys or sells enough shares to bring the position's net delta close to zero. This is delta hedging. The hedge does not stay correct for long, because delta changes:
- With price, at a rate set by gamma (see options Greeks).
- With implied volatility, an effect known as vanna.
- With time, an effect known as charm, which grows as expiry approaches.
Whether re-hedging stabilizes or destabilizes price depends on the sign of the dealer's gamma:
- Long gamma (dealers net long options): as the stock rises the book gets longer, so the dealer sells; as it falls, the dealer buys. Hedging leans against moves.
- Short gamma (dealers net short options): as the stock rises the book gets shorter, so the dealer buys; as it falls, the dealer sells. Hedging reinforces moves.
Pinning
When dealers are long a large amount of gamma at one strike, they sell as price rises above it and buy as it falls below it. In the final days before expiry, when gamma at that strike is at its highest, this two-way flow can hold price close to the strike. That is the pinning often seen around large open-interest strikes on monthly expiry.
Pushing
When dealers are short gamma, every move generates hedging in the same direction, which can extend it. A gamma squeeze is the extreme case: heavy call buying leaves dealers short calls, a rally forces them to buy shares, and that buying lifts the price further. The same dynamic can deepen a sell-off when dealers are short puts.
How to read it
- Regime first. Net gamma exposure and the gamma flip estimate whether hedging is more likely to dampen or amplify.
- Location. Large open-interest strikes, the call wall and put wall, show where hedging is heaviest.
- Calendar. Pinning is strongest in the last days before a large expiry. After expiry, those hedges are unwound and the picture can change quickly.
- Volatility direction. When implied volatility falls, for example after an event, the delta of out-of-the-money options shrinks and dealers adjust their hedges accordingly, which can move the stock even if nothing else changes.
Worked example (illustrative numbers)
A stock trades at $48. Customers buy 1,000 call contracts at the $50 strike, and a dealer sells them. Each call has a delta of 0.40, so the dealer is short the equivalent of 1,000 × 100 × 0.40 = 40,000 shares and buys 40,000 shares to hedge.
| Stock price | Call delta | Shares needed as hedge | Dealer action |
|---|---|---|---|
| $48 | 0.40 | 40,000 | Buys 40,000 (initial hedge) |
| $50 | 0.50 | 50,000 | Buys 10,000 more into the rally |
| $48 | 0.40 | 40,000 | Sells 10,000 into the decline |
Being short gamma, this dealer buys high and sells low, adding to each move. Had the dealer been long those calls, every step would reverse: selling 10,000 shares into the rally and buying them back on the decline, leaning against the move. Across thousands of strikes, the net of these flows is what gamma exposure tries to estimate.
Limitations and common mistakes
- Positioning is estimated. Public data does not show whether dealers are long or short at a given strike.
- Hedging is not mechanical. Dealers net exposures across many positions, hedge with futures or other options, and re-hedge at intervals rather than on every tick.
- Size is relative. In heavily traded large caps, hedging flows can be small compared with total volume.
- Pinning is a tendency. Many expiries end well away from the largest strike, especially around earnings or macro events.
- Not a directional forecast. Hedging describes how a move may unfold, not which way the next one will go.
In Clear Tape
The Options page is built around this question: where dealer hedging is likely to hold price and where it may push it, estimated from open interest across every listed contract. The free SPY, QQQ and IWM cards show the gamma regime, gamma flip and walls. Pro members get the same reading for any stock with listed options, with notes that describe the hedging regime in plain words, and a strategy builder that checks whether short strikes sit beyond the walls and how the gamma regime may affect the trade. Positioning is estimated (dealers long calls, short puts), and members see each session's closing data once the next session has opened. See pricing.
For educational purposes only. Not investment advice.