Highlands-based Tulloch Construction has been sold for £31.3m to development services company Rok plc.
Tulloch Construction employs more than 800 staff
Rok notified the Stock Exchange that it has agreed to acquire the construction arm of Tulloch Ltd. The parent company is not part of the acquisition.
Tulloch's 875 staff working from offices in Inverness, Thurso, Glasgow, Edinburgh, Tain, Elgin, Oban, Nairn and Fort William will transfer to Rok.
It first began as a small building firm in Nairn, near Inverness, in 1925.
Rok's registered office is in Exeter.
A press release issued on Tulloch's behalf said the sale was expected to be completed early next week.
The deal will see the construction, civil engineering and building services divisions transfer to Rok.
Tulloch Ltd will retain ownership of Tulloch Homes which has 170 employees and a £60m turnover.
David Sutherland, chairman of Tulloch Construction, will join the Rok board as a non executive director.
He said the firm had previously considered a market flotation.
Mr Sutherland added: "This deal with Rok, however, is a much better option for the employees and customers of Tulloch Construction."
In May, Tulloch Construct began work on three new primary schools for the Highlands. It has a £22m contract to build primaries in Cawdor, near Nairn, and Culbokie and Cullicudden in the Black Isle.
Tulloch will also be building a new secondary school in Kinlochleven as part of the Alpha Schools private public partnership programme.