** Shares of videogame retailer GameStop GME.N rise 4% to $22 in premarket trade

** CEO Ryan Cohen purchases 500,000 shares of GME on Thursday

** Cohen now has a stake of 8.4% in GME as of April 3

** Last month, GME said its board has approved the addition of bitcoin as a treasury reserve asset

** Up to last close, GME has fallen 32% YTD; it jumped 78% last year

(Reporting by Zaheer Kachwala in Bengaluru)

((Zaheer.Kachwala@thomsonreuters.com))