A major Belfast construction materials business, Lagan Group, has been sold for £455m (€526m).
UK construction giant Breedon Group has acquired a suite of businesses owned by Kevin Lagan.
Mr Lagan's other key business - Lagan Homes - is not part of the deal.
By acquiring Lagan Group, Breedon, already one of the UK's largest construction materials groups, will take over Whitemountain, Lagan Cement, Lagan Brick, Lagan Asphalt and Welsh Slate.
The Lagan Group's combined earnings in 2017 amounted to £55m (€63m).
The combination of Breedon and Lagan's materials interests will create a workforce of around 3,000 and turnover of more than £900m (€1.04bn).
Mr Lagan, who has driven the growth of his business for 40 years, said: "Our committed and passionate staff at Lagan Group have contributed significantly to the development and growth of the business, differentiating us from our competition in all of the markets in which we operate.
"I'd like to thank the staff for the role they have played in the growth of Lagan Group, and I wish them every success as they enter an exciting new chapter with Breedon, who I am confident will build on that success, supporting the development of the business in the years ahead".
Mr Lagan said he intended to pursue a managed growth strategy with his retained interests, Lagan Homes and FastHouse businesses.
Breedon's executive chairman, Peter Tom, said: "We are delighted to have completed our largest acquisition to date and particularly pleased that it has been so strongly supported by our shareholders.
"Over the last eight years we have pursued a successful buy-and-build strategy which has established Breedon as the largest independent construction materials business in the UK and the acquisition of Lagan is another strategic step for us.
"We believe it has the potential to add significantly to the group's performance and prospects, and we are looking forward to working with our new colleagues to deliver further value for our investors."
The Lagan brand was established by Mr Lagan's father, Peter, in 1960 when he opened his first quarry.
Kevin and his brother, Michael, then took over the reins and built a huge business empire. They later went their separate ways, dividing the assets between them.
The acquisition of Kevin Lagan's Lagan Group comes weeks after it was announced that four firms within Michael Lagan's Lagan Construction Group had gone into administration, putting 200 jobs at risk.