Nasdaq, the New York exchange, is not relying on a swift sale of its 31 per cent holding in the London Stock Exchange to fund its ambitions to buy OMX, the Baltic and Swedish operator, sources close to the company insist.

Market-watchers had assumed that the Americans put the stake up for auction last month to help to fund a bidding war for OMX with Borse Dubai. At Friday’s closing price the stake was worth £850 million (£420 million).

Dubai has tabled a $4 billion bid for OMX, trumping an early agreed offer between the Stockholm-based group and Nasdaq. This raises the prospect of an auction between the Americans and one of the world’s richest men, Sheikh Mohammed bin Rashid Al Maktoum, the Dubai monarch, who is trying to create a world financial centre. Nasdaq sources insist that the decision to sell out of the LSE, after a hostile Nasdaq offer failed in February, was taken independently of the OMX bid. “Bob [Greifeld, the Nasdaq chief executive] had decided to move on. He had believed for a long time that it was holding down his share price,” one said.

JPMorgan, the merchant bank handling the stake sale for Nasdaq, is not commenting on the progress of the auction, but it is understood that, while a number of initial approaches have been received, several of the names rumoured to be interested are wide of the mark.

These include the Australian Stock Exchange, which has ruled itself out, and Deutsche Börse, which failed in an earlier attempt to buy the LSE. Temasek, the Singaporean state investment vehicle that has a 2.1 per cent holding in Barclays Bank, is thought to be a contender. Qatar also reportedly approached Nasdaq about the sale.

If Nasdaq is not constrained financially by the sale of the LSE stake, Mr Greifeld has the option of waiting until the LSE completes its own €1.6 billion (£1 billion) purchase of Borsa Italiana in October. This dilutes its stake to a more manageable 22 per cent, which could be more easily passed on to a single buyer.

Under the rules as they stand in London, anyone buying 31 per cent would be forced to make an immediate bid for the LSE, and Nasdaq is more likely to sell a holding of less than 30 per cent if an early buyer emerges and hang on to the remaining rump of shares.

Alternatively, the holding could be broken up to go to several investors, a move that would be welcomed by Clara Furse, the LSE chief executive, and the rest of the board, who have vigorously defended their independence.

Dubai is bogged down in regulatory difficulties in Stockholm. There is a potential criminal investigation into its tactics in amassing a 28 per cent stake from various hedge funds, although Dubai has denied any wrongdoing.

The Swedish financial regulator has issued a slap across the wrist over the decision to acquire the stake before launching a full bid. Today, Sweden’s national Economic Crimes Bureau will decide whether it will investigate allegations of insider-dealing related to the OMX stake purchase.

In addition, Ian Hay Davision, the former Lloyd’s chief executive, who controversially was fired as regulator in Dubai in 2004 after complaining over alleged conflicts of interests, has said that he will share with the Swedish authorities his knowledge of business methods on the Dubai financial scene.

Mr Greifeld, therefore, has the option of waiting to see if the Dubai bid fails on regulatory grounds rather than engaging in a bidding war with Sheikh Maktoum.

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