A GameStop location on 6th Avenue in New York on March 23, 2021.Shares of GameStop and AMC jumped around 40% in premarket trading on Tuesday, on track to extend gains after "Roaring Kitty," the man at the center of the meme stock craze, posted online for the first time in roughly three years.Shares of video game retailer GameStop traded 40% higher at 4:50 a.m. E.T., while movie exhibition company AMC rose over 38%.The market moves follow dramatic gains for the stocks at the start of the trading week. GameSt ...