Lehman Brothers, burdened by $60 billion in soured real-estate holdings, filed a Chapter 11 bankruptcy petition in U.S. Bankruptcy Court after attempts to rescue the 158-year-old firm failed. Bank of America Corp. said it is snapping up Merrill Lynch & Co. Inc. in a $50 billion all-stock transaction.

The demise of the independent Wall Street institutions came as shock waves from the 14-month-old credit crisis roiled the U.S. financial system six months after the collapse of Bear Stearns.

The world's largest insurance company, American International Group Inc., also was forced into a restructuring. ...