The band of amateur day traders that interact with each other on the Reddit page WallStreetBets, encouraged whoever was listening to buy shares of the flailing GameStop, AMC, Macy’s and Koss stocks. Big investors, often in the form of hedge funds, frequently bet against struggling public companies using a process referred to as “shorting,” which allows investors to bet on the degree of misfortune a stock may experience and earn billions of dollars in profits as a result.