The Wall Street Journal warned in an editorial Monday that Americans should brace themselves for "a very rough Monday."
In a statement released after midnight, Lehman Brothers said it intended to file for bankruptcy "in order to protect its assets and maximize value."
The financial firm said the filing was authorized by its board of directors and will occur at the United States Bankruptcy Court for the Southern District of New York late in the day.
"Customers of Lehman Brothers, including customers of its wholly-owned subsidiary, Neuberger Berman Holdings LLC, may continue to trade or take other actions with respect to their accounts," the statement said.
The beleaguered Wall Street firm lost an estimated 3.9 billion dollars (2.7 billion euros) in its fiscal third quarter amid fresh writedowns on mortgage assets.
The bankruptcy announcement came after a last-ditch effort to find a buyer for the troubled investment bank collapsed Sunday.
A London source at British bank Barcla