Cheng Xin/Getty Images eBay has rejected GameStop's unsolicited $56 billion takeover bid , calling it "neither credible nor attractive," according to a letter from eBay chairman Paul Pressler seen by Bloomberg . That reaction may set in motion an attempt by GameStop to take the offer directly to eBay's shareholders or replace eBay's board with one favorable to its offer via proxy fight.  Last week, Gamestop offered $125 a share to purchase eBay, despite having a market value less than a quarter of eBay ($11 billion compared to $45 billion). The bid, consisting of half cash and half GameStop stock, represents a 20 percent premium over eBay's current stock price. GameStop plans to borrow $20 billion to help finance the acquisition but, when asked , CEO Ryan Cohen couldn't explain in detail where it would raise the additional capital required.  eBay said that it reviewed the offer thoroughly and expressed concerns about financing and debt related to the deal.…