TL;DR A gamma squeeze happens when heavy call-option buying forces the dealers who sold those options to keep buying the underlying stock as it rises — mechanical buying that feeds on itself.
The setup: someone has to take the other side
When you buy a call option (a bet the stock goes up), a market maker usually sells it to you. Market makers don't want to gamble on direction — they want to collect small spreads. So they immediately protect themselves: they buy some of the actual stock. If your call wins, their stock position covers what they owe you. This protection is called hedging.
How much stock they buy per option depends on how likely the option is to pay off. That sensitivity has a Greek name — delta — and the speed at which delta changes as the stock moves is gamma. That's the whole cast.
The squeeze mechanic
Now flood the market with call buying on one stock:
- Market makers sell the calls and buy stock to hedge.
- That buying nudges the price up.
- As the price rises toward the calls' strike prices, the options become more likely to pay off — so dealers must hedge more, buying more stock.
- Which pushes the price up further. Which raises the required hedge again.
The dealers aren't bullish. They're not even opinionated. They're a machine mechanically forced to buy into a rising market — and everyone watching the machine knows exactly which direction it must lean next.
Gamma squeeze vs short squeeze
They rhyme but differ: a short squeeze forces bearish traders to buy back stock they borrowed. A gamma squeeze forces neutral dealers to buy stock as a side effect of options math. In the famous 2021 meme-stock runs, both engines were widely believed to be running at once — which is why the moves were so violent.
The common mistake
Believing loading up on cheap short-dated calls reliably causes squeezes. The conditions are rare: it takes enormous, concentrated options volume on a stock with the right setup. Most of the time, buying far-out-of-the-money calls just donates your premium to the market maker — who thanks you and hedges accordingly.
Educational only — not investment advice. Options can lose 100% of what you put in, on schedule, by design.