The FTC, which enforces antitrust law, has already asked an in-house administrative judge to block the transaction on antitrust grounds in early December, arguing it would give Microsoft's Xbox exclusive access to Activision games, leaving Nintendo consoles and Sony Group Corp's PlayStation out in the cold. Microsoft's bid to acquire the "Call of Duty" videogame maker in a $69 billion deal was approved by the EU in May, but British competition authorities blocked the takeover in April. Shares in Microsoft closed up 1.5% Monday, while Activision fell 0.8%. "We welcome the opportunity to present our case in federal court," said Microsoft president Brad Smith in a statement. Activision did not comment. Microsoft has said the deal would benefit gamers and gaming companies alike, offering to sign a legally binding consent decree with the FTC to provide "Call of Duty" games to rivals including Sony for a decade.