Dissident New York Stock Exchange seatholders have claimed that Citigroup's independent valuation of the exchange's proposed $6bn (€5.1bn) merger with electronic rival Archipelago is "sorely lacking for a number of key reasons."

Ten rebel seatholders, led by William Higgins, have submitted to the New York State supreme court, an analysis of Citigroup's valuation carried out by Willamette Management Associates, an independent advisory firm.