Another day and more profit warnings and grim news from the TMTs and other stocks on both sides of the Atlantic continued to drain much of what confidence remained in a London market still reeling from the `Marconi effect' yesterday.

And as well as having to cope with the ever-growing list of dismal corporate news, the London market was facing some worryingly weak economic data showing industrial production in May down 0.9 per cent, compared with a consensus forecast of plus 0.2 per cent.

That news was greeted with dismay in the market, pointing to growing downside pressure on manufacturing, while the services industries continue to expand, house prices are rising by almost 10 per cent, year-on-year, and retail sales improve.

The FTSE 100 index posted its fourth consecutive decline yesterday, finishing the day a net 70.4, or 1.3 per cent, off at 5,479.2, having been down 105.7 at a low for the day of 5,443.9.

But once again the biggest casualty of the main indices was the Techmark 100 which plummeted another 46.09, or 2.9 per cent, to a record low of 1,554.69.

The FTSE 100 losers list was filled with TMT stocks plus a sprinkling of banks, the latter weakened by a return of fears that any big corporate failures would inevitably impact on them.

But as was the case all week, it was the techs and telecoms that bore the real brunt of selling in the wake of the shock profits warnings and the impact of the prolonged suspension of trading in Marconi shares on Wednesday.

Marconi's pain was extended yesterday, the company's shares sliding below the 100p level to hit 96p at one stage, before rallying to close a net 7 per cent lower.

Other substantial casualties in the TMTs included Colt Telecom, Sage Group, Misys and ARM Holdings.