Explainers / Markets
What is a short squeeze?
In January 2021 GameStop's share price rose about 2,700% in three weeks. Here is the mechanism, and why the US regulator says a squeeze was only part of the story.
By Kinza Updated 29 September 2026 4 min read
Short selling in one paragraph
Normally you buy a share and hope it goes up. Short selling is the reverse. You borrow a share from someone who owns it, sell it today, and plan to buy it back later at a lower price to return it. If the price falls, you keep the difference. If the price rises, you lose, and there is no limit to how much: a share can only fall to zero, but it can rise without end.
Why that creates a squeeze
If a lot of people have shorted the same company and its price starts rising, every short seller is losing money at once. To get out, they have to buy the shares back. But buying pushes the price up further, which can force the next short seller to buy, which pushes the price up again. That loop is a short squeeze. It is a mechanism, not an opinion about what the company is worth.
What happened with GameStop
GameStop is a US video-game retailer. In January 2021, the shares that had been sold short added up to 122.97% of its shares available to trade. That can happen when the same shares are borrowed and sold more than once.
That month, investors on online forums, including Reddit’s WallStreetBets, talked the company up. Some argued it was undervalued. Others argued that the huge short interest made a squeeze possible. By 27 January nearly 900,000 separate accounts were trading GameStop in a single day, up from fewer than 10,000 at the start of the month.
From its lowest point on 8 January to its highest on 28 January, the share price rose about 2,700%. On 28 January several brokers restricted trading in the shares. By the end of the first week of February it had fallen more than 86% from that high, and by 19 February it was as low as $40.59. (Prices are as the SEC reported them in 2021.)
Was it really a short squeeze?
This is the interesting part. The SEC, the US regulator, looked at who was buying. It found that short sellers buying back shares did push the price up at times. But their buying was a small fraction of all the buying, and the price stayed high after its effect would have faded. The SEC’s conclusion: it was positive sentiment, not short sellers buying to cover, that kept the price up for weeks.
In the UK, the FCA put out a short statement on 29 January 2021. It warned that trading in very volatile shares can mean losing money fast, that those losses are unlikely to be covered by compensation, and that brokers may withdraw their services when trading is heavy and prices swing wildly.
What it tells you, and what it doesn’t
It tells you that prices are set by buying and selling, not by a company’s value, and that the two can come apart. It tells you that a famous story can be less simple than its headline: the SEC calls GameStop the most famous of the “meme stocks”, and even its rise was mostly not a short squeeze.
It does not tell you that you can do it again. Every share sold near the top was bought by someone at the top.
The analyst habit
When a share moves a lot, separate two questions. Has the business changed? Or has the crowd changed? They have different answers, and only one of them lasts.