By Liz Moyer
Investing.com -- GameStop Corp (NYSE:GME) tumbled 20% on Monday as the short squeeze appears to have run out of momentum.
Shares of the video game retailer spiked more than 400% last week as retail traders, many using the Robinhood mobile app and goading each other on a Reddit forum, pushed the shares higher to counter bearish bets by some hedge funds.
Trading continued to be extremely volatile. Before the market open, GameStop was up 18%.
Robinhood and other trading sites have restrictions on trading in GameStop and other highly volatile stocks, including AMC Entertainment Holdings Inc (NYSE:AMC), BlackBerry Ltd (NYSE:BB) and Express Inc (NYSE:EXPR).