Gamma Squeeze
A gamma squeeze is a rapid, self-reinforcing surge in a stock price caused by market makers purchasing shares to hedge their delta exposure as call options move in-the-money, creating a feedback loop that accelerates the upward price movement.
Gamma squeezes became a widely known phenomenon in January 2021 when GameStop (GME) experienced a historic short squeeze combined with an options-driven gamma squeeze. The mechanics are rooted in the way market makers manage options risk. When a market maker sells call options, they are short gamma — meaning they must continuously buy shares as the stock rises to maintain a delta-neutral hedge. As the stock moves higher, the delta of the sold calls increases, requiring the market maker to buy more and more shares. This buying creates additional upward pressure on the stock price, which in turn forces more hedging purchases in a self-reinforcing cycle.
The intensity of a gamma squeeze is amplified when a large number of call options are concentrated near the current stock price — specifically when there is significant open interest in near-term, at-the-money or slightly out-of-the-money calls. As the stock rises through successive strike prices, market makers must hedge each layer of newly in-the-money calls. The combination of retail call buying, concentrated open interest, and dealer gamma creates the conditions for explosive upward moves.
The speed and severity of a gamma squeeze depends on several factors: the total open interest in near-dated call options, the current level of implied volatility, the liquidity of the stock (less liquid stocks are more susceptible), and the proportion of the float available for market makers to purchase. In the case of GameStop, an already elevated short interest meant that shares were scarce, further amplifying the dynamics.
From a risk management standpoint, gamma squeezes represent a serious hazard for traders who are short calls — particularly naked calls — in stocks with concentrated call open interest and volatile trading environments. The CBOE and SEC have studied gamma squeeze dynamics in the context of market stability, and the events of 2021 prompted regulatory discussions about transparency in options data and reporting requirements for large options positions.
For retail traders, gamma squeeze awareness matters both offensively and defensively. Recognizing the conditions that precede a squeeze — unusual call volume, rising open interest near at-the-money strikes, compressed float — can provide context for sudden price moves. Being short calls in a stock experiencing these conditions, however, presents extreme risk that defined-risk spreads can partially mitigate by capping the potential loss.