Merrill Lynch on Monday rushed into an agreement to be acquired by Bank of America for $50bn in a sign that the crisis gripping Lehman Brothers is forcing rival investment banks to seek partners to avoid suffering the same fate.

In a dramatic U-turn on Sunday, BofA entered discussions with Merrill after pulling out of the bidding for Lehman, partly prompted by the US government’s refusal to supply financial help for a Lehman takeover.