Share of GameStop Corp. /zigman2/quotes/203755179/composite GME -1.12% swung to a gain 4.2% in morning trading, to add to recent sharp gains, as the so-called "meme" stock reversed an earlier loss of as much as 6.8% moments after the open. The stock, which have been volatile in recent weeks as investors on a Reddit subgroup have fueled trading in the videogame retailer, had rallied 18.3% on Monday, and soared 167.7% over the past four sessions, on the heels of a record monthly selloff of 68.7% in February. Fellow "meme" stock AMC Entertainment Holdings Inc. /zigman2/quotes/200235402/composite AMC -5.76% rose 1.5%, reversing an earlier loss of 3.1%. AMC's stock lost 39.6% in February. Over the past three months, GameStop's stock has rocketed 656.6% over the past three months and AMC shares have rallied 115.7%, while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.36% has gained 6.2%.