https://www.reuters.com/article/us-retail-trading-gamestop-gill/gamestop-stock-rallies-after-roaring-kitty-testifies-to-congress-idUSKBN2AI2LG >Shares of GameStop briefly reversed losses to trade as much as 4% higher on Thursday after Keith Gill, who helped drive a recent surge in the videogame retailer's stock, gave testimony in a congressional hearing.