Britain's top share index retreated from an earlier five-year high on Tuesday to trade lower as shares in BT Group extended their fall, rattled by a broadband competition threat from Carphone Warehouse.
A fall in shares of Scottish & Newcastle also helped erode an earlier rise after the brewer said it was raising cash through a share placing to fund its proposed acquisition of the Foster's brand in Europe.
Dealers said the move, interpreted by some as a defence strategy, might ward off potential predators.
"It is a poison pill (to deter a bid)," said a trader. "All those people who were thinking it was just around the corner will now be thinking it probably isn't."
By 0944 GMT the FTSE 100 benchmark share index was down 8.4 points, or 0.1 percent, at 6,058.7, retreating from an earlier high at 6,092.5, its best intraday level since February 2001.
Dealers said a recent rise by the top index to new five-year highs warranted some consolidation, but added that the general tone of the market remained buoyant.
Citigroup strategists raised their year-end forecasts for the FTSE 100 index to 6,400 points from 6,100, saying that valuations continued to look attractive, though concerns over whether the credit cycle may soon turn posed a risk to this forecast.
Xstrata, Rio Tinto and BHP Billiton each added around 2 percent to carry on a strong performance by Australian-listed miners overnight.
Marks & Spencer was the top FTSE 100 gainer as it bucked a lacklustre trend in the retail sector with forecast-smashing results. Its shares were up 3.6 percent at 585 pence, also helped by several analysts' upgrades.
But the wider sector was in gloomy spirits after British retail sales data showed a fall on the year. Shares in Next, GUS, DSG International and MFI were all lower.
Insurer Prudential eased 1.5 percent as take-over speculation, the main driver of Prudential's share price in recent weeks, was knocked by news that France's AXA was not interested in the UK company.
BT Group was another notable faller, shedding 2.6 percent after mobile phone seller Carphone Warehouse said it would become the first company to offer British customers free broadband.
"Carphone Warehouse's new broadband offer today has thrown down the gauntlet to the other fixed-wire operators in the UK," said Nomura analyst Chris Alliott.
"Whilst CPW will likely have to manage subscribers' expectations, this offer clearly ups the ante in the UK broadband market and adds to the competitive pressures on BT."