FT.com – When Merrill Lynch, the US bank, announced 10 days ago that it was taking $8bn-worth of losses on mortgage-related securities, bankers and regulators around the world reeled in shock. For the writedown was twice the size of the losses that Merrill had forecast just a two and a half weeks earlier – a “staggering” multi-billion dollar gap, as Standard and Poor’s, the US credit rating agency, observed.