All 1,400 jobs at Wrightbus in Ballymena are at risk as the company could be plunged into administration as early as next week.
The bus-making company has been in talks with potential buyers for a number of weeks, after confirming that it was facing financial difficulties.
However, it is understood that all previously interested bidders have pulled out of the process.
Wrightbus was founded back in 1946 and has grown to employ around 1,400 people, making it one of Northern Ireland’s biggest privately-owned employers.
It is also one of the last major employers in the Ballymena area of Co Antrim, following a spate of closures in recent years.
The losses of the likes of building giant Patton, tobacco company JTI Gallaher, and tyre manufacturer Michelin have hit the town hard.