A ROLLER-coaster ride for blue-chip shares shuddered to a halt yesterday with the London market in rare positive territory.

The FTSE 100 Index closed 27.4 points ahead at 4021.9, the first time it has finished on the front foot since July 5.

It follows Monday's 229.6-point slide, which took the top flight to levels not seen since December 1996.

But the session was a bumpy one, with the FTSE 100 at one point surging ahead only to slump heavily back into the red.

Tom Hougaard, trader at financial bookies City Index, said: ''It was a day of absolutely phenomenal volatility. There's a huge tug of war going on between the bulls and bears right now."

London's close came amid a mixed session in the US.

Wall Street had initially tumbled on opening, but generally positive comments by US Federal Reserve chairman Alan Greenspan helped steady nerves.

Delivering his six-month report on the economy, Mr Greenspan told Congress the US economy was on the road to full recovery.

He said it was feeling the effects of last year's recession and the fallout from investors' loss of confidence in corporate America, but his tone was more upbeat and reassuring than earlier in the year.

The Dow Jones Industrial Average had failed to move into positive territory by London's close, but earlier losses were curtailed.

Vinay Bedi, asset management director at Newcastle stockbrokers Wise Speke, said the turbulence of the stock market could affect many people in many ways.

He said: "Share prices affect pensions, insurance companies and direct investors to varying degrees.

"They can affect the company director and the employee with shares and share options.

"They can affect the company that wants to float on the markets and raise money, they can affect investment levels and therefore future employment prospects."

Mr Bedi said there could be a knock-on impact on consumer spending and a big impact on those pending retirement. He said if shares continued to slide "it might not hit your pocket now, but it will at some point to some degree in the future. When the economy has less money circulating around it affects us all, shareholders or not.