The firm employs 1,800 people across the region
One of the leading employers in Northern Ireland is to let go up to 250 people.
Caterpillar is the world's largest manufacturer of heavy construction equipment, and employs 1,800 people across the North.
It is looking at closing the Monkstown facility near Belfast - and the consolidation of operations at two other sites in the city.
It would affect those working in production, support and management roles at the firm.
The company says its been hit by a global downturn in mining and oil exploration, which has reduced demand for its products.
East Antrim DUP MLA Alastair Ross has expressed his disappointment at the news.
"Clearly this is another difficult day for the Caterpillar workforce, particularly those in the Monkstown plant with significant job losses of up to 250 employees.
"Caterpillar have dramatically reduced their workforce globally as a result of falling demand in important markets such as China and South America, and this has had an impact on the Northern Ireland plants.
"Whilst it will be of little comfort to those who have lost their job today, it is important that the other two sites in Larne and Belfast are staying as part of their restructuring plans and can hopefully work to attract new production lines in the future."
These workers say they are devastated.
While Davy Thompson from the union Unite says there will be knock-on effects.