John Thain, CEO of the New York Stock Exchange, has said he will not improve terms of its £10.7 billion merger with Euronext, despite noises from rival Deutsche Borse that its proposal was worth more.

The Times (London) reports: “Speaking to journalists in New York last night, and reported by AFP, Mr Thain said he noted continued moves by Deutsche Borse to lure Euronext away from the agreed merger but said he would not increase his offer price, whatever plan the German exchange came up with.”

Euronext said: “This first half of the year has been the best one ever for cash and derivatives markets and has created the conditions for all business lines to register an increase in their revenues. This strong performance has been achieved in spite of the impact of changes in the scope of consolidation.”

Euronext’s Chief Executive, Jean-Francois Theodore, and John Thain have said they are on course to complete their landmark merger during the first quarter of next year.

The rumblings continue. The Teutonic giant of Frankfurt, Deutsche Borse, is still insisting that its offer of cash and shares for Euronext, the pan-Continental stock exchange, is better than the New York Stock Exchange’s offer because of the rise in the German company’s share price.

However, Euronext, which has agreed to the American offer, insists it can’t keep changing its mind on the basis of day-to-day fluctuations in stock prices. It also points out that the NYSE bid is protected by the fact that 30 pc of it is in cash.

With the possibility of a merger between Euronext and Deutsche Borse again being discussed, the German exchange is saying it no longer contemplates a top position for Euronext’s Chief Executive, Jean-Francois Theodore.

‘You can’t want to give responsibility to someone who clearly wants to torpedo the operation,’ reports Agence France-Presse.

Earlier this week, Deutsche Borse put forward a modified merger offer, making some concessions to Euronext. But Euronext again flatly rejected the German group’s advances, says Forbes.

An unnamed supervisory board member told the German edition of the Financial Times that Theodore would not be nominated for the position as Chairman of the supervisory board.

“Deutsche Borse declined to comment on the future of Theodore within a merged group, with a spokesman only pointing out that the latest offer does not mention the Frenchman’s name. In May, the Frankfurt stock exchange had suggested appointing Theodore as head of the new group until 2008.”