You never know the minute with the stock exchange.

One day shares are a ba' hair (to use a technical financial term) away from their highest level ever. Next day they suffer the biggest fall since the last time Google filled in a tax form.

It used to be that ordinary folk could just ignore the stock market. Then some bright spark decided that no news bulletin was complete without telling us what the FTSE was doing. That's FTSE as in foot, foot footsie goodbye.

Now with endless hours of TV rolling news time to fill, we have to kept abreast with foreign stock exchanges. The French index is Cac even when it performs well. Spain acts the goat with the Ibex. The US has the Nasdaq, which is also a motor race. You will be familiar with far eastern indices such as the Nikkei, Hang Seng and Hong Kong Phooey.

There are many excuses for stock market collapses. Such as bad news about US factory gate prices. Tell me how recession can be sparked off by the cost of a factory gate.

This week's plunge was caused by concern over "stimulus taper". Worry that the US Federal Bank might curtail quantitative easing, also known as Fed-Ex-Lax for economic constipation.

Apparently it was all those extra printed dollars swilling about the world that put stock prices up in the first place. Some say shares are down because of gravity. What goes up must come down, although wages that go down may not come back up.

There is anxiety about the Chinese economy. The workforce is no longer satisfied with a salary of a bowl of rice. They want Louis Vuitton luggage and Rolex watches. Genuine ones, not the fakes from their own factories.

The real reason for the fall, as ever, is share dealers taking profits. Most of this will be spent on merchant bank bonuses and lunches of sea bass and Bollinger. What's left may find its way into your pension fund.

The main thing is don't worry. Not even if folk take headers out of tall buildings in the City of London. But if stockbrokers appear on window ledges in the Frankfurt financial district it may be time to get the money out from underneath the bed and invest in tinned food.

More seriously, havoc in Japan has led to fears of a return of old jokes about the Origami Bank folding, Karaoke going for a song and Kamikaze crashing. Not to mention the relative newcomer Sudoku Bank being unable to make the numbers work.

tom shields Boom and bust

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