bear squeeze
noun [ C ]
FINANCE, STOCK MARKET ukusa situation in which people who have an agreement to sell shares in the future at the present price, expect the price to go down and sell the shares believing that they can buy them back more cheaply before the date of the sale to the buyer. Instead the price rises and they must buy the shares back at a higher price, which forces the price even higher:
Traders reported a bear squeeze - when traders who have oversold a particular stock have to buy back shares to rebalance their portfolios.