Glen Dimplex has said that Mr Lochlann Quinn's sale of his entire shareholding in the business for an estimated €200 million will have no impact on the company.
Mr Quinn (65) remains as deputy chairman of the group, which is one of the world's biggest manufacturers of heating and domestic appliances under brand names such as Morphy Richards and Belling.
Glen Dimplex chief executive Mr Seán O'Driscoll said Mr Quinn had sold his 26 per cent stake to the firm's founder, Mr Martin Naughton, "some time ago" and that its directors and key clients had been informed.
"We had been working towards this exit for a long time. Lochlann had stepped back from the business over the past five or six years," he said.
"While he is no longer a shareholder, his contribution to the group will not change."
Mr Naughton now owns 100 per cent of the business, which is worth up to €900 million.
Mr O'Driscoll said the group had new structures in place to cope with the departure of Mr Quinn.
None of Mr Quinn's family were involved in Glen Dimplex. Mr Naughton's son, Niall, is a director and has held a number of positions within the group over the past 11 years.
Mr Naughton founded Glen Electric in 1973 in Newry and acquired Dimplex in the UK three years later. He invited Mr Quinn, who was a partner at accountants Arthur Andersen, to join the firm in 1979 when he became a shareholder.
The business now has more than 22 companies generating sales of more than €1.5 billion.
It employs some 8,500 staff in plants from Dunleer, Co Louth to Shenyang in China. In recent years, Mr Quinn held the post of chairman of AIB and he is currently chairman of the National Gallery of Ireland.
Mr Quinn and Mr Naughton are both investors in Dublin's Merrion Hotel and Patrick Guilbaud's restaurant, which is in the hotel.
Mr Quinn has made no comment on what he planned to do with the proceeds of the sale but stressed that the change of ownership had been "completely amicable".
He added that shareholdings "evolve over time".
Three years ago, he paid €38 million for the vineyard Chateau de Fieuzal in Bordeaux. He has also invested substantially in property and art.
Glen Dimplex is a privately owned company and its ownership is held through an Isle of Man registered company, Kilkee Investments. Few financial details are available.
Mr O'Driscoll said that, while there was a view that Glen Dimplex was run by one or two people, it had a broad management team.
"Lochlann's role is strategic and not directly hands on. He will continue to work with Martin Naughton and myself," Mr O'Driscoll added.
