Your essential companion to this week's big event

What are they?

Bearers of bad tidings.

Why are they in the news?

Sightings have increased in recent weeks. Most City professionals view them as pests, so an eradication plan is under way. One bear who broke cover this week, Tony Dye, head of fund management at PDFM, was caught early and may now be forced to turn into a bull.

That's so cruel! Have they not heard of BSE?

You're missing the point. Bears think the market will fall. A bull is a much more acceptable creature to be in the City, because it believes the market will continue to rise, and is better at persuading investors to part with their cash. "Super-bear" Robin Aspinall, formerly chief economist at Panmure Gordon and now chief European strategist at National Australia Bank, sympathises with Dye. "It's very lonely being a bear," he says. "Even if you're right, everyone hates you for it."

Where do bears and bulls come from?

These terms became Square Mile slang for market pessimists and optimists during the 19th century, possibly derived from the bullrings and bear pits in Southwark which were then frequented by traders after work. In 1894 Charles Dow (as in the Dow Jones index) defined a "bull" market as one which rose for at least two years. A big enough "correction" and it became a "bear" market.

So what can we do about these bears?

According to the Canadian Tourist Board, if a bear approaches you, "talk softly so it knows who you are". Your next move depends on the type of bear. If it's a grizzly, climb a tree. If it's a market bear, go liquid. Sell the lot, then put your cash under the bed or in the building society.

Isn't this what Tony "the bear" Dye has just done?

Yes, up to a point. His fund now has pounds 7bn in cash, out of the pounds 50bn PDFM has under management. It may not sound like much - after all, the majority of the fund's money is still in shares - but if he were behaving like a good bull, he would only have around pounds 3bn in readies.

Won't selling up make me a bear too?

That's why bears are so dangerous. Once loose, they breed fast.

I'm worried.

So is the market.