The $300bn-odd question remains: what are normalised earnings for banks post-meltdown? The most important factor is underlying profitability. But a close second is the extent to which regulators clamp down on the sector. Yesterday, Citigroup's results were supposed to shed light on the former. And that bank shares stabilised after Friday's mauling suggests investors reckon the Securities and Exchange Commission's charges against Goldman Sachs will not spread.

The problem with estimating a bank's core earnings power is that they are still giving off mixed signals. At Citi, securities and banking revenues were up by a half versus last quarter, but were down 19 per cent year-on-year. What is more, higher net revenue marks to the tune of over a billion dollars, plus lower credit costs and expenses, helped the bottom line. Citi's cost discipline should be applauded, but will banks go on a spending binge again if the good times keep rolling?

Nor is it certain these are such good times. Citi had virtually no asset growth to speak of and average loans and deposits declined. Mortgage volumes are also down. Consumer banking revenues in the supposedly hot Asian and Latin American markets were flat compared with the prior quarter and while overall credit trends were improving, losses remained elevated. Citi, with its consumer bias, is particularly exposed to another leg down in the global economy.