Bob Greifeld has suddenly become less hostile.

The Nasdaq OMX Group's (NDAQ) famously pugnacious chief executive, who has made a name for himself launching unsuccessful hostile attacks to buy rival exchanges, including most recently one on the New York Stock Exchange (NYX), has all but ruled out launching a hostile bid as he eyes his next acquisition, the London Stock Exchange, people close to the exchange tell the FOX Business Network.

Instead, Greifeld's troops have attempted to reach out to officials at the LSE in order to mend fences over the Nasdaqs 2007 attempted hostile takeover of the London exchange before the start of official merger talks, according to one person with direct knowledge of the matter. 

Top executives at the LSE, including its CEO, Xavier Rolet, are said to be bitter over the Nasdaqs 2007 bid, which if successful would have replaced the LSE management with Greifeld and his team to run the combined entity. The bid was ultimately rejected by LSE shareholders.

Theres not a lot of trust for Greifeld in London, said a senior Wall Street executive who has had extensive dealings with both Greifeld and Rolet. Thats why Greifeld is reaching out -- he knows he has work to do getting them to the table.

The kinder, gentler Greifeld underscores the difficult competitive position of the Nasdaq in the aftermath of its failed attempt to take over the NYSE and break up its planned merger with Germanys Deutsche Borse. The Nasdaq teamed up with the Intercontinental Exchange (ICE) to mount a hostile bid for the NYSE, but was forced to walk away after U.S. regulatory officials said the deal would violate anti-trust law since the Nasdaq and the NYSE are the worlds largest stock markets. 

Meanwhile, NYSE shareholders approved the Deutsche Borse merger Thursday, and are now looking for regulatory approval for a deal that would create the worlds largest stock market.

As first reported by the FOX Business Network, Greifeld is planning to approach the LSE about a possible merger, but in order to do so he first needs the LSE and Rolet to be a participant in any possible deal. Though the combination of the Nasdaq and the LSE makes strategic sense, particularly given the changing competitive landscape, its unclear if Rolet wants to do business with Greifeld for the simple reason that Greifeld has a reputation for not wanting to share power.

For that reason, Greifelds troops have been trying to soften their CEOs image with the executives of the London Stock Exchange. One scenario that might be broached under a merger agreement: Greifeld would take the CEO post, while Rolet would become chairman, according to people close to the Nasdaq.

But that might not work either. The people in London would want Greifeld out is my feeling, said the Wall Street executive. They know him all too well and they think their exchange ought to be run out of London, not New York.

Spokesmen for the Nasdaq and LSE declined comment.

Charles Gasparino joined FOX Business Network (FBN) in February 2010 as Senior Correspondent.