American Airlines surges 50% after better-than-expected earnings, squeezing short sellers

American Airlines shares jumped by more than 55% in premarket trading on Thursday after posting a smaller-than-expected loss and higher sales than analysts projected.

The carrier is the most-shorted U.S. airline, according to FactSet, and the big move comes after explosive rallies in other heavily shorted stocks GameStop and AMC Entertainment Holdings. Short sellers are betting a stock will fall by selling the shares now with an agreement to buy them later when they think the price will drop — pocketing the profits.

Those stocks have shown up in “Wallstreetbets” Reddit chat room where a wave of at-home traders made the opposite bets on heavily shorted stocks, sending shares soaring and squeezing out short-selling hedge funds. Short positions are bets that stocks will fall, where an investor or trader sells a share in hopes of selling it back at a lower price and pocketing the difference.

The percentage of short interest in American Airlines shares far outpaces that of its competitors. Short interest in American was 25% of the company’s float, according to FactSet, compared with 14% of Spirit Airlines‘ and about 5% of United Airlines‘.

“We do not believe the move is fundamentally driven as American’s outlook is similar to others we have heard during this earnings cycle,” said Cowen & Co. airline analyst Helane Becker. “We believe the move is due to the de-risking going on in the market and American remains one of the most consensus short airlines in our coverage universe.”

She said American could use this rally for a stock offering.

-CNBC’s Yun Li contributed to this report.