One of the largest shareholders in Euronext, the Children's Investment Fund Management, has threatened to derail the exchange's proposed merger with the New York Stock Exchange by demanding shareholders are allowed to vote on its preferred option of a merger with Deutsche Börse.

Christopher Hohn, TCI's manager, who was instrumental in a campaign to remove Deutsche Borse's chairman and chief executive following a disagreement over merger strategy last year, today made the demand to Jean-François Théodore, chairman and chief executive of Euronext, during a conference call to announce the exchange's financial results for the first half of the year.