A gamma flip occurs when the collective gamma position of market makers and dealers shifts significantly, often from being net long gamma (positive gamma) to net short gamma (negative gamma), or the reverse. This transition has a notable impact on how market makers hedge their positions and, consequently, on market volatility and the behavior of options prices. When dealers are net long gamma, they typically need to buy underlying assets as prices fall and sell as prices rise, which can dampen volatility. Conversely, when they are net short gamma, they must buy as prices rise and sell as prices fall, potentially amplifying price movements.
This dynamic impacts how options prices react to changes in the underlying asset's price. For example, if a major index ETF, currently trading at $400, experiences a gamma flip from positive to negative at the $400 strike level, it means that many dealers are now short gamma around that price. As the ETF moves, for instance, a 1% drop from $400 to $396, dealers obligated to sell the underlying to hedge their short calls or buy underlying to hedge their short puts will execute these trades, potentially accelerating the downward move. This increased order flow from hedging can cause option premiums for out-of-the-money options to become more sensitive to movements in the underlying than they were before the flip, especially if the new short gamma position is substantial.
The critical point of a gamma flip often corresponds to significant open interest at particular strike prices, where a large number of options contracts are concentrated. As the underlying asset approaches or crosses these strikes, the collective gamma exposure of market participants changes, triggering this shift in hedging behavior. This altered hedging can create a reinforcing feedback loop, where initial price movements are exacerbated by dealer activity, leading to greater volatility and more pronounced changes in option values.
A gamma flip significantly impacts market makers by changing their collective gamma exposure. This forces them to adjust their delta hedging strategies, often amplifying price movements in the underlying asset.
A gamma flip often occurs when the underlying asset's price crosses specific strike prices where there is a large concentration of options contracts and significant open interest, altering collective gamma exposure.
When a gamma flip shifts to negative gamma, options premiums become more sensitive to underlying price movements. Conversely, a shift to positive gamma typically makes premiums less sensitive.
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