Lagan boss Kevin Lagan and Mivan’s founder Ivan McCabrey were reported to be in talks about the benefits late last year.
But the two have failed to reach agreement and a deal is no longer on the cards, a source told the Enquirer.
Both firms have earned reputations for developing strong international business in their own fields of expertise over the years.
Belfast-based Lagan Group has interests in quarrying, cement, building materials, house building and civil engineering.
Mivan made its name in the international contracting arena on high-end projects, often in the Middle East, but has struggled in recent years after some overseas property investments backfired.
More recently Mivan has been concentrating on fit-out jobs in the UK and Lagan has also expanded its presence in England.
A merger looked on the cards because Mivan would bring a new specialism to the Lagan Group and would benefit from its greater financial firepower.