from bbc: Wall Street bank Lehman Brothers has filed for chapter 11 bankruptcy protection after emergency talks to find a buyer failed. Confidence in the 150-year-old investment bank – the fourth largest in the US – crumbled last week amid growing concerns that its large portfolio of mortgage-backed assets was worth far less than it was originally valued. During the past year Lehman reported billion-dollar losses and saw its share price plummet more than 95%.