The FTSE 100 stock index slipped on 7 May as Britons cast their votes on the country's next government, with the two major parties running neck and neck in the last polls ahead of the election.
The market was pulled down by supermarket giant Morrisons, whose share price fell 6.5% as it reported worrying sales trends for 2015.
The supermarket saw sales decline 2.9% in the first three months of the year, in a decline that many analysts had predicted.
Stocks in mining companies also suffered amid uncertainty over the outcome of the UK election, while falling crude oil prices weighed on oil majors' stocks.
Meanwhile, budget airline easyJet and IAG fared well on the back of traffic growth in April but that was not enough to stop the index from sliding into negative territory.
Overall the FTSE 100 fell 47 points (-0.67%) to finish on 6,886.95.
FTSE 100 biggest risers
Carnival plc +108.00 (+3.72%) 3,011.00
SABMiller plc +124.50 (+3.65%) 3,531.00
Aberdeen Asset Management +14.20 (+3.29%) 445.30
International Consolidated Airlines Group SA +17.00 (+3.12%) 562.00
easyJet plc +48.00 (+2.71%) 1,821.00
FTSE 100 biggest fallers
Morrison (WM) Supermarkets -12.40 (-6.55%) 176.90
GlaxoSmithKline plc -67.50 (-4.46%) 1,447.00
Anglo American -46.50 (-3.86%) 1,107.00
BHP Billiton plc -56.50 (-3.54%) 1,538.50
Admiral Group -54.00 (-3.48%) 1,496.00