Big money from the Middle East is still stalking the London Stock Exchange.

The Qartar Investment Authority, which is also preparing to buy J Sainsbury, the British supermarket chain, is said to be joining forces with three major Italian investors to take Nasdaq’s stake in the LSE, worth around £1billion ($2bn).

Nasdaq is selling its shareholding to increase its offer for Nordic exchange OMX, where it is in competition with another Gulf state, Dubai.

Nasdaq’s Robert Greifeld has put the American company’s substantial stake in the London Stock Exchange up for sale.

The move is thought to signal the end of the aggressive CEO’s ambitions to take over the LSE, while giving him extra leverage in his bid for the Scandinavian exchange group, OMX.

The sale would open the way for a higher offer on OMX, after the Dubai Financial Centre topped Nasdaq’s agreed bid last week.

Speculation is rife that a deal between Nasdaq and Dubai may be in the offing, which would leave the ambitious Gulf State with a major holding in the LSE and Greifeld with a clear run at OMX.

That would be yet another blistering headache for Clara Furse and her team in the City.

Investors in the London Stock Exchange have backed its bid to take over Borsa Italiana by a large majority. Some 78 percent of the shareholder base approved the deal, including Nasdaq, former hostile bidder for the LSE which holds 30 percent of the shares.

Chief Executive, Clara Furse said, “This value-creating deal also accelerates our shared vision to become the world’s capital market”.

The Borsa brings a welcome strength in derivatives and fixed-income trading to an often beleaguered London market that let slip the chance to buy Liffe five years ago. The deal will put the LSE in the Footsie 100 for the first time.

It will now be more difficult for any predator wishing to snap up the LSE in future. Nasdaq’s agreement may signal it now accepts that future bids are out of the question.

The long-awaited counterbid for the Scandinavian stock exchange group, OMX, by the Dubai International Financial Centre (DIFC) could be made this week.

Advisers, UBS and Goldman Sachs are said to be on standby for the event.

The new bid is expected to be up to 20 percent higher than rival Nasdaq’s agreed $3.7bn (£1.9bn) merger offer already on the table.

DIFC is understood to have amassed a stake in OMX of around 4 - 5 percent in the open market, which is below the 5 percent level where a bid must be declared under Swedish rules.

A Dubai director recently said that “the sky’s the limit” for its international investment ambitions.