Weakness in miners and financials dragged Britain's top share index 0.9 percent lower by midday on Friday, as weak data this week increased investors' concerns, denting risky assets ahead of U.S. non-farm payrolls data.
At 1026 GMT, the FTSE 100 .FTSE was down 43.03 points at 5,004.78, on track to post the fourth session of losses after ending at a two-week closing low on Thursday.
Banks, which have been at the heart of the financial crisis, were among the big sector fallers, as investors plumped for less risky plays. Barclays (BARC.L), HSBC HSBC.L, Lloyds Banking Group (LLOY.L), Royal Bank of Scotland (RBS.L) and Standard Chartered (STAN.L) lost 0.8 to 4.7 percent.
The FTSE 100 has had a wobbly start to the fourth quarter of the year, having recorded its best gains since the index's inception in 1984 in the three months to September.
(The losses) are partly a reaction to the extent of the gains through the third quarter, said Grahame Exton, fund manager at Tilney Investment Management.
(The weak U.S. data from Thursday) is confirming doubts that improvements in underlying economies may not be supportive, he said, referring to weaker-than-expected U.S. manufacturing growth data on Thursday.
All eyes will be on U.S. non-farm payrolls data at 1230 GMT, with economists predicting a loss of 180,000 jobs in the month, compared with 216,000 jobs shed in August, while the unemployment rate is seen at 9.8 percent, up from 9.7 percent previously.
Miners were in the doldrums as demand worries put pressure on metal prices. Kazakhmys (KAZ.L), Lonmin (LMI.L), Rio Tinto (RIO.L) and Vedanta Resources (VED.L) shed 2.1 to 4.8 percent.
Xstrata (XTA.L) fell 4.1 percent as UK regulators said it must make a formal takeover bid for rival miner Anglo American (AAL.L), down 0.3 percent, by Oct. 20 or walk away for six months as Anglo again rejected a merger.
Investors took the opportunity to book profits on the life insurance sector, which has seen much interest recently on the back of continued M&A speculation.
Legal and General (LGEN.L), which is widely perceived to be on the bid radar for either Resolution (RSL.L) or an Australian firm, fell 4.3 percent.
L&G's shares have risen 26 percent since Monday. Goldman Sachs removed the stock from its Conviction Buy list on Friday.
Prudential (PRU.L), Standard Life (SL.L), Aviva (AV.L), and Friends Provident (FP.L) dropped 0.8 to 2.2 percent.
Economic data from the UK painted a mixed picture on Friday, with weakening construction activity overshadowing signs of a stabilising housing sector.
British construction activity contracted at a faster pace in September than in August, with the Chartered Institute of Purchasing and Supply/Markit construction PMI index falling to 46.7 in September from 47.7 in August.
Meanwhile, British house prices rose for a fifth straight month in September and was flat year-on-year, the Nationwide Building Society said.
On the upside, brokers' recommendations helped several stocks outperform the wider index. Fund manager Schroders (SDR.L) gained 1.6 percent, after an upgrade to buy from neutral.
Within the sector, hedge fund manager Man Group (EMG.L) and interdealer broker Icap (IAP.L) rose 0.5 and 1.2 percent.
SABMiller (SAB.L) rose 1.4 percent, drawing strength from a positive comment from Cazenove, which repeated its outperform rating on the brewer