The London market was on the back foot in afternoon trading after a rogue poll put Donald Trump in the lead with less than a week to go to the US Presidential elections.
A single poll for ABC News and the Washington Post, put the Republican nominee one percentage point ahead of Democrat Hillary Clinton, at 46% to 45%.
The FTSE was 27.2 points down at 6890, after Asian markets slumped in reaction to the poll leading European stocks to also open lower.
IG market analyst Joshua Mahony said: "Global stock markets are lower this morning, as US election fears dominate, despite a week's worth of top tier data to contend with."
Established housebuilder Persimmon said home sales were buoyant with confidence high among buyers regardless of the country's Brexit vote.
The group said its private sales rate was 19% ahead of last year, in a trading update that covers its third quarter period from the start of July to the start of November. Shares lifted 21p to 1758p.
In afternoon trading the biggest risers in the FTSE 100 Index were Next (+182p to 4992p), Associated British Foods (+74p to 2549p), EasyJet (+23.5p to 964p), Fresnillo (+27p to 1745p) and Randgold Resources (+110p to 7505p).
The biggest fallers in the FTSE 100 Index were Standard Chartered (-23.7p to 649.6p), 3i Group (-15p to 651.5p), Glencore (-4.3p to 242.2p), Ashtead Group (-21p to 1238p) and Tesco (-3.4p to 210p).
In afternoon trading the biggest risers in the FTSE 250 Index were G4S (+19.4p to 240p), Sports Direct International (+13.1p to 289.4p), NCC Group (+7.8p to 202p), Smurfit Kappa Group (+61 to 1821p) and BTG (12.5p to 634p).
The biggest fallers in the FTSE 250 Index were JD Wetherspoon (-53.5p to 834.5p), Hunting (-23p to 467.6p), Tullow Oil (-11p to 254p), Just Eat (-20.5p to 540.5p) and Henderson Group (-7.8p to 222.1p).