The board of NYSE Euronext issued a harsh rejection of the $11.3bn unsolicited takeover bid led by Nasdaq OMX, setting up a potentially awkward showdown between the Big Board and its own shareholders.

In a statement Sunday, NYSE Euronext called the bid by Nasdaq and partner IntercontinentalExchange "strategically unattractive" and entailing "unacceptable execution risk." The NYSE reaffirmed its commitment to a $9.7bn merger with Deutsche Börse announced in February, itself fraught with political and antitrust issues in both Europe and the US.