plant closing is loosely defined. I worked at a bank that closed a division, and the division closing fell under the WARN Act.

Only if it's part of a "plant closing."

I am currently awaiting a 60 day notice, as 80% of the company is being laid off. Our parent company recently laid off a number of folks who only got 30 as the company is eliminating a large portion of the company.

A place that I worked at two years ago laid off 2/3 of the company just 49 days after I'd joined. They weren't as brain dead as the federal legislature so they simply framed it as temporary for five months which falls under the requirements of "WARN."