When Bear Stearns was rescued by JPMorgan Chase in March, bankers and regulators believed they had stopped the financial crisis from engulfing the rest of Wall Street. Exactly six months later, however, senior executives at Lehman Brothers are preparing for another frantic weekend of negotiations designed to stave off the investment bank’s collapse.

On Friday, at least two bidders were examining the possibility of mounting a bid for all or part of Lehman. Bank of America, the giant US lender, has teamed up with JC Flowers & Co, the financial investor, and China Investment Co, China’s sovereign wealth fund, to consider a bid. Barclays, the UK bank, was also interested.