“Under-promise, then over-deliver” is usually a pretty good rule to follow in a banking career. For Stefan Hoops, though, the rule being followed seems to be more like “over-promise massively, in an interview with the Financial Times”. The 39 year-old head of Deutsche Bank’s transaction banking business seems to be saying not only that he will be able to keep revenue losses under control in the event of a merger with Commerzbank, but that there will be none at all. This is pretty ambitious stuff. Most bank mergers, particularly in corporate and investment banking, tend to create “negative synergies”.