GameStop and AMC shares surged again on Tuesday in a resurgence of the short squeeze phenomenon. GameStop jumped over 50%, and AMC was up nearly 60% in premarket trading. The rally was turbocharged by the return of Keith Gill, known as "Roaring Kitty," to social media, where he had previously driven interest in GameStop among retail traders. Both stocks saw heavy option trading volume on Monday, contributing to their gains, while other heavily shorted names like BlackBerry and Virgin Galactic also rose.