Yellow Corp. trailers sit at a terminal in Florida on Friday.
New York CNN  — 

Yellow Corp., a 99-year-old trucking company that was once a dominant player in its field, halted operations Sunday and will lay off all 30,000 of its workers.

The unionized company has been in a battle with the Teamsters union, which represents about 22,000 drivers and dock workers at the company. Just a week ago the union canceled a threatened strike that had been prompted by the company failing to contribute to its pension and health insurance plans. The union granted the company an extra month to make the required payments.

But by midweek last week, the company had stopped picking up freight from its customers and was making deliveries only of freight already in its system, according to both the union and Satish Jindel, a trucking industry consultant.