The loop
A surge of call buying — especially out-of-the-money, short-dated calls — forces dealers to buy the underlying to stay hedged. That buying lifts price, which pushes those same calls toward the money, which raises their delta, which forces still more dealer buying. Unlike a short squeeze, driven by short sellers scrambling to cover, a gamma squeeze is driven entirely by dealer hedging mechanics — no one has to be wrong about direction for it to happen.
The loop is genuinely mechanical, not sentiment-driven: buy out-of-the-money calls, dealers buy the underlying, price rises, those calls migrate toward the money, their delta jumps, dealers buy more, and price rises again. Every step follows from the one before it; the only external input is the initial wave of call buying that starts the sequence.
Why it accelerates
Delta does not rise in a straight line as price approaches a strike — it accelerates, and options closest to expiration carry the most gamma of all. A given move in the underlying therefore forces a disproportionately large hedge the nearer that move gets to a heavily-held strike.
Large dealer inventory sitting on thin liquidity amplifies each of those hedges further, and rising price then attracts more buyers on its own — a self-reinforcing dynamic rather than a self-correcting one, at least until the loop runs out of fresh call buying to feed on.
Four stages
Call accumulation builds modest out-of-the-money gamma while price grinds quietly, largely unnoticed. Hedging kicks in next: dealers begin buying the underlying, producing a steady, low-volume lift that looks like nothing more than a firm bid.
Acceleration is the visible phase — options move from out-of-the-money to at-the-money, delta surges, and the market sees a rapid, high-volume breakout. What follows is either exhaustion or extension: fresh out-of-the-money call open interest extends the loop into a new range, while shrinking out-of-the-money gamma signals the loop is running out of fuel and reversal risk is rising.