The phrase 'gamma squeeze' got abused in the 2021 retail trading boom to the point that the underlying mechanic became invisible behind the meme. The mechanic is real and it matters. What follows is the gamma squeeze explained from the dealer-hedging side rather than the retail-hype side.
How dealers end up short gamma
When retail buys a flood of OTM calls, the market-maker on the other side is short those calls. To stay delta-neutral, the dealer hedges by buying stock equal to the call delta. As the stock rises, those calls move closer to in-the-money - their delta increases. The dealer has to buy more stock to stay hedged.
The feedback loop
More buying → stock up → call deltas up → more dealer buying → stock up further. The dynamic compounds. This is gamma squeeze: forced dealer buying mechanically pushing the stock higher because of their own short-gamma exposure. That is the gamma squeeze explained in a single loop - buying forces hedging, hedging forces more buying.
Why it ends violently
The squeeze accelerates into expiry as gamma peaks. After expiry, the dealer's short position is gone or rolled. The forced buying stops. The stock often gives back the squeeze move quickly because the demand was synthetic, not fundamental.
How to recognize a real squeeze setup
- Massive call volume concentrated in short-dated OTM strikes.
- Vol/OI above 10 on multiple strikes.
- Stock running into the expiry week without obvious news.
- Put/call ratio collapsing below 0.4 on the name.
Why it does not happen to most stocks
Mega-cap names have such liquid order books that even large call buying does not force noticeable dealer hedging. Squeezes happen in small/mid-caps where dealer hedging actually moves the underlying. The same retail flow that crushed GameStop would barely move SPY.
The honest take
Gamma squeezes happen but they are rarer than retail narrative suggests. Most 'squeeze candidates' on Reddit do not have the positioning structure to actually squeeze. Watch the options tape for confirmation, not the chart.
With the gamma squeeze explained mechanically, the useful next step is watching the positioning that precedes one. Gamma exposure shows where dealers currently sit, live options flow shows the call buying as it prints, and the Vol/OI ratio is the same measure the checklist above leans on.