The surprise social media return of the trader who helped ignite the meme stock frenzy in 2021 sent GameStop shares skyrocketing Monday. The surge had nothing to do with the troubled company’s fundamentals — and everything to do with a cartoon of a gamer that the trader, nicknamed Roaring Kitty, shared on X. GameStop shares surged 74% on Monday after the account run by Keith Gill shared a meme on X, marking its first post in three years. The shares skyrocketed by more than 110% earlier and were halted for volatility several times on Monday morning. Short sellers have seen...