The new later opening of the London market's electronic trading system - SETS - was said by dealers to have made little or no difference to the market yesterday.

The change, which saw the market kick off at 9.00 a.m. compared with the old 8.30 a.m. start, was made to try to eradicate the unrepresentative prices so common at the start and finish of trading since SETS was introduced last year.

There were no apparent uncommercial prices yesterday, unlike last week when three of the biggest moves by FTSE 100 constituents on Thursday and Friday - Safeway, Thames Water and Severn Trent - were triggered by so-called "rogue trades".

The change in opening time was one of the few talking points during a day of painfully thin trading which saw an early upward move to a new intra-day record give way to small flurries of profit-taking. Just before the close, however, the market rallied sufficiently to leave the FTSE 100 index marginally higher and at another closing high.

The early bout of jitters came ahead of the twice-yearly Humphrey Hawkins address by Alan Greenspan, chairman of the US Federal Reserve, to the US Senate's banking committee, during which he will outline prospects for the US economy and monetary policy.

With Wall Street slipping back in early trading after last week's sharp gains, London struggled to build on its recent big gains, which had seen the FTSE 100 hit new intra-day and closing highs last Friday. The Dow Jones Industrial Average opened on a dull note and fell away quickly to post a 50-point decline about an hour after London closed its trading books.

The FTSE 100 finished the session a net 5.0 firmer at 6,179.0. At its best, during the first half-hour of trading, the index had nudged up to an intra-day peak of 6,183.7.

"After last week's performance, it was always likely that the market would take a breather ahead of Greenspan's speech. That has the capacity to turn everything upside down," said one marketmaker. He added that the market would have to cope with increased volatility as the interim results season got underway, at the same time as the onset of the holiday season which will see trading desks undermanned.

The best individual performance in the FTSE 100 came from Enterprise Oil, with rumours about "tenuous takeover stories".

Turnover at 6.00 p.m. was a miserable 580.1m shares, with non-FTSE 100 stocks accounting for 57 per cent.