Shares of GameStop and AMC Entertainment exploded Monday, up close to 80% and 50%, respectively, as Roaring Kitty, aka Keith Gill, the trader and Reddit celebrity who sparked the so-called meme stock revolution on Wall Street starting in early 2021, posted on X (formerly Twitter) for the first time in almost three years. Gill, a former marketer for Massachusetts Mutual Life Insurance, got the big screen treatment in Dumb Money, where he was played by Paul Dano. An investment advisor working at home during ...