The troubled Ann Arbor, Mich., bookseller could file for Chapter 11 bankruptcy-protection as soon as Monday or Tuesday, paving the way for hundreds of store closings and thousands of job losses, said people familiar with the matter.

Borders has abandoned efforts to refinance its debts, and is preparing bankruptcy papers and seeking financing agreements that would keep it operating during the Chapter 11 restructuring process, the people said. Its shares tumbled 33% to 25 cents apiece in 4 p.m. New York Stock Exchange trading after The Wall Street Journal reported its plans.

"Borders is not prepared at this time to report on the course of action it will pursue," Borders said in a statement.