There is nothing like a triple whammy to unsettle the stock market. In its latest upward run it has taken individual pieces of bad news in its stride, with no perceptible thought for the ominous build-up of events in Iran.

First, there was Alan Greenspan. In the years he was running the Fed, Greenspan took care to talk in riddles. On the one occasion that he strayed from his customary delphic script with the words "irrational exuberance" Wall Street barely blinked. Greenspan was right, but that was three years and a thousand tech-share fortunes later.

Now the great oracle, free from the constraints of office, has come straight out with the "R" word. "When you get this far away from a recession" he declared, "invariably forces build up for the next recession, and indeed we are beginning to see that sign, for example, in the US profit margins have begun to stabilise, which is an early sign we are in the later stages of a cycle".

Greenspan was his old imprecise self when it came to timing. Indeed, he made it clear he was not talking about the troubles of the American housing market, which he thinks may be past the worst. But he still let slip the phrase "Yes, it is possible we can get a recession in the latter months of 2007" – then started to discount its likelihood. By itself that would not have inflicted a triple-digit fall on the Footsie. A growing number of US company results falling short of the analysts' consensus has been noted on this side of the pond, by Mike Lenhoff at Gerrard for one.

But it bothered nobody. It has not been happening here. If anything, the problem has been banks making too much money and bringing the wrath of the Office of Fair Trading on their heads.

Until yesterday the market took that prospect in its stride – though it would have been happier if Lloyds TSB had raised its dividend.

But now the curse of the Internet has struck with two million e-mail "signatures" denouncing bank charges – and with it the cheerful suggestion that the banks may be forced to refund zillions of "illegal" charges, levied on people who over-cooked their overdrafts for years past. It is no longer just a question of a rap over the knuckles from the OFT and being told not to do it again.

Barclays' John Varley, flush with the spoils of successful expansion overseas and in investment banking, shrugged the prospect aside, all but promising not to retaliate by charging well-organised customers who stick to their overdraft limits. Other banks, more exposed than Barclays to this sort of thing, will hesitate to hand Mr Varley a competitive advantage by levying current account charges when he does not. So it is bank shareholders who stand to take it in the chin.

Similarly with the third blow, talk of a South African windfall tax on mining. On its own mining. But mining shares tend to give the 100-share Footsie its direction nowadays.

Three quite different ways, it was a bad news day. Remember, though, the elephant in the room is Iran.