What is a Gamma Squeeze?
A gamma squeeze occurs when heavy call option buying forces market makers to buy increasing amounts of the underlying stock to hedge their exposure, creating a self-reinforcing cycle that drives the price sharply higher. Unlike a traditional short squeeze (where short sellers are forced to buy back shares), a gamma squeeze is driven by the mathematical requirements of options hedging. The two can occur simultaneously, creating explosive price moves.
The Mechanics Step by Step
To understand a gamma squeeze, follow the chain of events:
Step 1: Traders buy a large volume of out-of-the-money call options. Perhaps a stock is trading at $50, and call buyers are aggressively purchasing $60, $70, and $80 calls.
Step 2: Market makers who sell those calls must delta-hedge by buying shares. If a $60 call has a delta of 0.15, the market maker buys 15 shares per contract. For 10,000 contracts, that is 150,000 shares.
Step 3: As the stock price rises toward $60 (partly due to the market maker's share buying), the delta on those $60 calls increases. Delta might go from 0.15 to 0.40. The market maker must buy 250,000 more shares to maintain the hedge.
Step 4: This additional buying pushes the stock price higher, which increases the delta further. Higher delta requires more share purchases. A positive feedback loop has begun.
Step 5: As the stock approaches and passes $60, those calls become at-the-money or in-the-money with deltas approaching 0.80-1.00. The market maker now has to own nearly 100 shares per contract. If there were 10,000 contracts, that is close to 1,000,000 shares they need to hold. The buying pressure becomes enormous.
Step 6: With each strike the stock passes through, a new set of calls rapidly gains delta, triggering another wave of hedging purchases. The squeeze cascades from strike to strike.
The GameStop (GME) Case, and What the Evidence Actually Shows
GameStop in January 2021 is the episode everyone reaches for, and it is worth walking through carefully, because it is also the clearest example of how quickly the label gets applied to something else.
The popular account runs like the mechanism above: retail traders bought short-dated out-of-the-money GME calls, the market makers who sold them had to buy stock to hedge, and that hedging drove the price. GME did have extraordinary short interest, which the SEC put at 122.97% of float, the only stock its staff observed above 100% that month, and the stock did close at $347.51 on January 27 before touching an intraday high of $483.00 the next day.
What the record does not support is the gamma-squeeze attribution. In its October 2021 staff report, the SEC stated plainly that staff "did not find evidence of a gamma squeeze in GME during January 2021," and that the "data show that market-makers were buying, rather than writing, call options", the opposite of the dealer position the mechanism requires. Staff also found that the surge in options volume from individual customers was "mostly driven by an increase in the buying of put, rather than call, options," and that short covering was "a small fraction of overall buy volume."
That leaves GME as a useful illustration of the ingredients, concentrated call activity, extreme short interest, a small float, without being a confirmed instance of the mechanism. It is a good reminder that the visible inputs are not the same as evidence about dealer positioning, which is not published. For how the two mechanisms differ and how to tell which one you are watching, see gamma squeeze vs short squeeze.
Conditions for a Gamma Squeeze
Not every stock with heavy call buying experiences a gamma squeeze. Several conditions must align:
Low float: A limited number of shares available to trade makes it easier for hedging demand to overwhelm supply. Stocks with small floats or low average volume are more susceptible.
High short interest: Existing short positions add fuel. Short covering combines with hedging demand to create maximum buying pressure.
Concentrated OTM call interest: The squeeze is most powerful when large open interest exists at strikes progressively higher than the current price, creating a "staircase" of gamma that activates sequentially.
Momentum: The initial price move must be strong enough to start pushing calls from OTM toward ATM. Without this initial catalyst, the gamma ramp remains dormant.
Risks and Reversals
Gamma squeezes are not one-way streets. When the buying pressure subsides (call buyers take profits, stop buying, or are restricted), the reverse process begins. Market makers who were forced to buy at high prices now have too many shares as delta declines. They sell aggressively, and the unwind can be as violent as the move up, with the added asymmetry that a gamma unwind produces mechanical selling, where short covering merely stops producing buying. GME gave back most of its January gain within about a week, though for the reasons above the reversal should not be attributed to a gamma unwind either.
Trading gamma squeezes is extremely risky. The timing of entry and exit is critical, and the reversal can be sudden and severe. If you participate, use strict position sizing and accept that the move can reverse at any time.
SquawkFlow publishes gamma exposure computed from daily-settled Cboe open interest, with the settlement date attached, alongside unusual call activity. The gamma profile does not update from intraday options trades, so read it as where hedging pressure sat at the last settlement rather than as a running count of squeeze conditions forming.