TL;DR A short squeeze is a chain reaction where people who bet against a stock are forced to buy it back as it rises — and their buying pushes it higher, which forces more of them to buy.
First, the setup: short selling
To bet against a stock, a short seller borrows shares and sells them, hoping to buy them back later at a lower price and keep the difference. Their dream: the stock falls. Their nightmare: it rises — because eventually they must buy shares back to return them, whatever the price.
Key detail: when you buy a stock normally, the most you can lose is what you paid. When you short a stock, your loss has no ceiling. There's no upper limit on a stock price.
The squeeze
Now imagine a stock where a huge fraction of shares are sold short, and the price starts rising instead of falling. Every short seller is losing money. Some give up and buy back shares to close their position — but buying pushes the price up. That deeper pain forces more shorts to buy back. Which pushes it higher again.
It's a crowd stampeding toward one exit, and the act of exiting makes the fire bigger.
The famous example
GameStop, January 2021. Short interest was so extreme that more shares were sold short than were easily available to buy back. When retail buying pushed the price up, shorts had to chase shares in a rising market. The stock went from under $20 to an intraday peak near $483 in about two weeks. Some funds betting against it lost billions.
The common mistake
Assuming every heavily-shorted stock will squeeze. Most don't. High short interest usually means sophisticated investors see real problems — and most of the time, they're right and the stock just… goes down. Squeezes are rare, violent, and usually end with a crash back down that arrives faster than anyone posts about it.
Why you care
Squeezes explain some of the market's wildest days, and "short interest" is a number you'll see thrown around constantly. Now you know what the crowd is actually watching for.
Educational only — not investment advice. Chasing squeezes has vaporized at least as many accounts as it has made.