Few public figures have been lucky enough to enjoy the sort of reputation that has attached to Robert Rubin.

When he was US Treasury Secretary under President Clinton, the former Goldman Sachs chief was widely credited with an unmatched economic wisdom and a managerial financial genius that made him, in the eye of most pundits, a cross between John Maynard Keynes and JP Morgan.

In the space of six short years in Washington in the 1990s, it was generally agreed that he had balanced the federal budget, restored faith in the dollar, saved Mexico from financial collapse, rescued Asia from the regional economic crisis that threatened to overwhelm it, and steered the world through the last great global financial panic when Russia defaulted and a flashy US investment institution failed in 1998. If the sun shone on the global economy in that happy period, it did so only because Mr Rubin bent its rays in the right direction.

True, he had to share the credit for many of those triumphs with Alan Greenspan, the Chairman of the Federal Reserve at the time.

But history has been less kind to the old central banker than it has been to Mr Rubin. Mr Greenspan now travels the world explaining to sceptical audiences that he is not really responsible for the succession of financial bubbles that followed the two men’s co-dominion over the world economy. Mr Rubin’s standing, meanwhile, is so pristine that, like Charles de Gaulle at Colombey-les-deux-Églises, he is begged, one last time, to come to the aid of a world that can’t manage without him.

His appointment at the weekend as chairman of Citigroup, the vast, unwieldy issue of Sandy Weill’s ambition and now the object of much of the world’s current financial alarm, is filled with such irony. Mr Rubin has been partly responsible for running Citigroup all through the period in which the bank has got itself into so much trouble in the US sub-prime mortgage market.

He doesn’t share the burden of fault that Chuck Prince, the ousted chairman and chief executive carries, but he is hardly without blame. And yet, here he is again, the repository of hope for worried markets.

He has spent much of the past seven years publicly bewailing the fragile state of the US economy and fretting about the unsustainability of the various financial booms. And yet, here he is again, (tens of millions of dollars personally richer) given the task of restoring faith in the American banking system.

To be fair, his main job, presumably, will be to find a successor to Mr Prince as chief executive and then retire gracefully from the scene. But his arrival back in the limelight is a timely reminder of what is supposed to be the central role that the financial system plays in the health of the economy.

Mr Prince’s departure brings to two in a week the number of chief executives ousted at large US financial institutions. Last week it was Stan O’Neal at Merrill Lynch. To paraphrase Oscar Wilde, to lose one chief executive may be considered a misfortune, to lose two looks like carelessness. And yet America as a whole seems unchastened by the experience.

The oddest conundrum for global investors these days remains the apparent invulnerability of the US economy to the disasters playing out in its financial sector. Between them Citigroup and Merrill Lynch have now reported losses of about $20 billion on their investments in asset-backed securities.

Behemoths though they may be, these figures cannot be more than the tip of a nasty iceberg of losses across America’s financial system.

And yet the much-feared contagion from Wall Street to Main Street still seems illusory. Even as we have watched the traumas unfold in New York in the past week, we have had further encouraging evidence that the economy remains buoyant. Gross domestic product in the third quarter – the period when the financial ball really started to unravel – was remarkably robust. And the first set of data from the fourth quarter – led by last week’s employment report for October – showed, if anything, a slight acceleration. The economy added 166,000 jobs last month, the best figure in six months. Yesterday, the Institute for Supply Management said its service sector purchasing managers’ index for October was up from a month earlier.

What to make of this continued divergence between the financial world and what some commentators call the real world?

The view of some in the markets is one of simple disbelief. They don’t trust the Government’s numbers – especially the employment report, which has been subject to large revisions in the past. They think we will learn soon that things are much worse than they look.

Others think the present may be OK, but it is the future they worry about. The housing market will eventually drag down consumers; the credit crunch will eventually crimp all borrowers.

For this group of worriers, we are entering a kind of apocalyptic moment, with markets offering almost iconic numerical significance – the $2 pound, closing in on the $1.50 euro, $100 oil and $1,000 gold. It all signals, if not the End of Times, then at least a much larger economic crisis still to unfold.

Then there is a third group – the muddling-through crowd. They continue to think that, despite everything, the fundamentals of the modern US economy really are sound; inflation is under control; global demand is booming; wages are growing, and all will be able to withstand the current nastiness.

Whether they are right or wrong, it is the people in this third group that still seem to have the ear of investors.

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