Blue chip shares slipped in afternoon trading led by Royal Bank of Scotland (RBS) which posted another quarter of heavy losses.
RBS reported a £469m ($571m) loss for the three months to September as it continues to face a series of litigation and restructuring charges.
The bank's third-quarter loss compares with a profit of £952m in the same quarter a year ago, but is more than twice the £231m analysts had forecast.
It suffered a number of charges including a £425m of conduct and litigation costs and £301m of restructuring charges at Williams & Glyn, a network of around 300 banks it has been trying to sell for several years.
The FTSE 100 Index fell 16.2 points to 6970.4, as traders reacted to results from the Edinburgh-based lender that is 73%-owned by British taxpayers and has not made an annual profit since 2007.
Richard Hunter, head of equities at Wilson King Investment Management, said: "RBS has yet to emerge from the weight of misconduct fines, restructuring costs, the distraction of the sale of the Williams & Glyn unit, the spectre of the Government stake and the lack of a dividend payment."
The bank's shares were the biggest faller in the top flight, down 4.3p to 192.1p.
In afternoon trading the biggest risers in the FTSE 100 Index were International Airlines Group (+21.8p to 435.3p), Next (+118p to 4924p), Pearson (+17.5p to 760.5p), Sainsbury's (+5.6p to 249.6p) and Whitbread (+81p to 3612p).
The biggest fallers in the FTSE 100 Index were Royal Bank of Scotland (-4.3p to 192.1p), Dixons Carphone (-6p to 309.6p), Admiral Group (-28p to 1897p), BP (-6.6p to 487p) and HSBC Holdings (-7.7p to 619.8p).
In afternoon trading the biggest risers in the FTSE 250 Index were Elementis (+19.3p to 233.8p), Electrocomponents (+16p to 380.2p), Hastings Group (+6.8p to 216.8p), Just Eat (+13.5p to 520p) and Galliford Try (+23p to 1233p).
The biggest fallers in the FTSE 250 Index were Berendsen (-40p to 990p), Amec Foster Wheeler (-16.1p to 449.8p), Unite Group (-20p to 562p), Entertainment One (-7.3p to 229p) and Softcat (-9.8p to 321.6p).