Deutsche Börse yesterday hinted it could improve its proposal to merge with Euronext to stop the Paris exchange accepting a bid from the New York Stock Exchange.

Euronext this week snubbed an initial Börse approach in favour of the NYSE, leaving the German group with the stark choice of somehow nudging its main European rival into a deal or missing out on market consolidation.

Reto Francioni, Deutsche Börse chief executive, told shareholders at yesterday's annual meeting that the offer to Euronext shareholders, which Deutsche Börse says is worth €76.60 per share or €8.6 billion, would "stand until further notice".

But Mr Francioni said the Börse was not interested in buying "at any price" and stressed that a second-best "standalone option" would still allow it to "grow inorganically".

Mr Francioni repeated that a merger was the "most attractive solution" for both companies.Bankers in Frankfurt said Deutsche Börse had some room to change the terms of its proposal, whose merger ratio is currently based on the three-month weighted average of the share price of both stock exchanges.

At today's prices, Euronext shareholders would get less than the shares are worth, Börse shareholders more. To remedy this, one senior banker close to the deal suggested Deutsche Börse could use criteria "more favourable to Euronext" to determine the merger ratio. "A premium - but only a small one - is certainly possible," the banker said.

Deutsche Börse could offer Euronext's shareholders more of the potential synergies. But its room for manoeuvre is limited and the next step would be a straight takeover pitched directly at Euronext shareholders.

Euronext has rejected the first proposal because of the price. It argues Börse's offer is worth €58.73 a share or €6.6 billion, compared with the €68.34 a share or €7.7 billion proposed by the NYSE.

But advisers to Deutsche Börse say the German offer is worth €67.55 per share stripping out the cash.

Mr Francioni suggested Euronext was undervaluing Deutsche Börse's bid by simply using the past three months to calculate an average price when the period prior to signing a deal would in the end be crucial.