The prospect of the FTSE 100 index, London's premier benchmark, finishing the week with a gain looked a forlorn hope on Wednesday afternoon.

Shortly after Wall Street opened on that day, the Dow Jones Industrial Average plunged over 400 points, back below the 10,000 level, and sent the Footsie close to 6,000 in the process.

But sentiment rapidly recovered from that slide, induced by an alarming set of results from IBM and higher-than-expected inflation figures. The Dow followed up Thursday's 167-point leap with a slightly twitchy performance but nevertheless showed a modest rise as London closed yesterday.

Even more impressive, however, was the tech-laden Nasdaq Composite, which followed a 247-point gain on Thursday with a drive back through the 3,500 level in early trading yesterday.

And it was a power-packed performance by the recently heavily sold TMT sectors that provided the impetus for the strong showing by the FTSE 100 yesterday.

The 100 index, while never totally convincing, finished the session a comfortable 57.4 higher at 6,276.3, re-establishing itself in the middle of the 6,000 to 6,800 range that it has been locked into for much of the last couple of years.

At its best, during the morning session and as the Nasdaq's overnight influence was at its height, the 100 index came within 5.5 points of reaching 6,300.

A mid-session wobble, triggered by fears of a downside reaction on Wall Street and hints of a sell-side programme trade, saw the 100 index give up all its early gains and post a modest 8.6 decline at worst, before the market regained its confidence and resumed the upward path.

The other FTSE indices were always in positive territory and did not experience the midday wobble that hit the top 100 stocks.

The FTSE 250 closed 67.3 higher at 6,502.0, a couple of points away from its best of the day, while the FTSE SmallCap pushed up 33.8 to 3,258.4.

Best of the indices bunch, however, was the Techmark 100, which rushed up 122.8 or 3.7 per cent to 3,450.54.

Another bull point behind Wall Street's surge was the speech by Mr Alan Greenspan, chairman of the US Federal Reserve, delivered at the Cato Institute in Washington. Mr Greenspan said the US economy had suffered little damage so far from the sharp rise in oil prices over the past year.