Quinn Financial Services, the insurance and investment arm of Mr Seán Quinn's Fermanagh-based Quinn Group, has emerged as the new institutional backer of stockbroker NCB.

The deal will see Quinn Financial Services take an estimated 20 per cent stake in NCB, thus replacing Mr Dermot Desmond's IIU as the broker's "strategic investor". IIU took a temporary holding in NCB in August, when the broker was sold by Ulster Bank to members of its management team and corporate finance house Key Capital for €20 million.

It was made clear at that time that Mr Desmond, who founded NCB in 1981, would exit the company as soon as a new institutional backer could be found.

It is understood that he will not realise a profit on the latest arrangement, which remains subject to regulatory approval.

Quinn Financial Services is believed to have competed with two international institutions for the NCB stake, with Alchemy previously mentioned as an interested party.

A spokesman for Quinn Group said the company saw the potential for "long-term linkages" with NCB, citing the potential for the two companies to collaborate in areas such as product launches.

It is known that Mr Quinn is keen to grow his financial services interests, which comprise insurance firm Quinn Direct and investment company Quinn Life.

The spokesman said Quinn Group's chief executive, Mr Liam McCaffrey, would take a non-executive seat on NCB's board.

In a joint statement, both NCB chief executive Mr Conor O'Kelly and Mr Quinn declared themselves "delighted" with their new connection. The two parties have in the past maintained a long professional relationship, with NCB acting as adviser to Mr Quinn on a number of corporate finance and stockbroking transactions.

Mr O'Kelly described Mr Quinn as "a brilliant entrepreneur" and "long-term thinker".

"He wants to grow in financial services and we're a financial services business that wants to grow as well," he said.

Acknowledging that Mr Quinn may not be very well known in the international financial world, Mr O'Kelly said he would nonetheless be considered powerful. He referred to the "financial muscle and business acumen" that the Fermanagh entrepreneur would bring to NCB.

Quinn Group, which is also active in cement, concrete, glass, hotels and bars, is one of Ireland's largest privately owned companies. The company indicated yesterday that it would realise a pre-tax profit of more than €150 million this year, with turnover on track to exceed €650 million.

Mr Quinn said he expected his company's investment in NCB to be "mutually rewarding", adding that he held the broker's management team in very high regard.

The arrangement brings to an end a period of uncertainty for NCB, which was on the cusp of being sold twice before the August buyout was concluded.

This deal was approved by the Irish Financial Services Regulatory Authority last week.