NYSE Euronext said on Wednesday that it would return $550 million to shareholders and seek to grow its derivatives business after EU antitrust regulators blocked its planned merger with Deutsche Boerse. In a statement, the New York bourse said: " NYSE Euronext announced its intent to resume a $550 million share repurchase program following the termination of the merger agreement and after the release of its fourth quarter and 2011 year-end results on February 10."