NYSE Euronext chief executive Duncan Niederauer, a day after US authorities scuttled a rival bid for the Big Board operator, stepped up his effort to win over European regulators for the planned merger with Deutsche Börse.

Niederauer said in a message to staffers that he was wrapping up a second day of meetings with European officials and policy makers before continuing to Asia, acknowledging the antitrust and related hurdles that stand in the way of the agreed-to combination with the German exchange operator.