The volatility of the market was heightened by rumours sweeping dealing rooms, including a suggestion that Marks & Spencer is being eyed up for a takeover - perhaps even by former bidder Sir Philip Green. Elsewhere, house builder Persimmon said it was cutting more than 1,000 jobs because of the housing crisis and shares in struggling mortgage lender Bradford & Bingley were declared "worthless" by a firm of City brokers. At its worst point today the Footsie had fallen 20 per cent since its last peak in October - the usual definition of a bear market. The previous bear market lasted from autumn 2000 to spring 2003 when share values halved.