The FTSE slid lower to 7,526 despite rising commodity prices as weaker utility stocks offset a rally in miners.
National Grid (NG.) and United Utilities (UU.) retreated by up to 1.7%. Brent crude oil jumped 0.8% higher to $57.65 per barrel and copper surged 3.4% to $3.23 per pound.
Miners were among the winners, with Antofagasta (ANTO) taking the lead, up 2.8% to £10.38. BHP Billiton (BLT) and Glencore (GLEN) chased its peer higher, rising 1.6% and 2.1%, respectively.
A rally in banking and financial stocks helped the US stock markets gain positive momentum ahead of new earnings reports this week.
The Nasdaq opened 0.2% higher at 6,618 on Monday.
MID AND LARGE CAP RISERS AND FALLERS
Woundcare specialist ConvaTec (CTEC) plummeted 27.7% to 202p after reducing full year revenue forecasts due to ongoing supply disruptions.
The company said its performance was severely impacted by supply issues in its advanced wound and ostomy care divisions, as well as a lower-than-anticipated sales contribution from new products.
Shares in GlaxoSmithKline (GSK) were flat at £15.19 despite the approval of its vaccine Shingrix in Canada for the prevention of shingles in people over the age of 50.
Electronic trading firm NEX (NXG) was resilient at 658.9p following divisional CEO Jenny Knott's decision to stand down after a recent profit warning.
In the mining sector, Polymetal International (POLY) was broadly unmoved at 895p despite a 26% rise in third-quarter output, driven by an expansion of processing capacity in Russia.
SMALL CAP RISERS AND FALLERS
Oil and gas production firm Zenith Energy (ZEN) said recent production tests at C-21 well in Azerbaijan revealed a stabilised flow rate of approximately 50 barrels of oil per day. The stock surged 13.3% to 0.1p on the news.
A subsidiary of Allied Minds (ALM), Spin Transfer Technologies, signed a deal for a collaborative engineering program with Tokyo Electron, causing the share price to rise 5% to 173p.
Investors were worried about further financial pressures at Interserve (IRV) after it announced it is in ongoing discussion with its lenders, prompting the shares to slump 10.6% to 99p.
It was a bad start to the week for waste specialist Augean (AUG) thanks to a management shake-up to cut costs and profit warning for both 2017 and 2018. Augean blamed weaker trading and further uncertainty over its tax status for the underwhelming trading. The stock fell 6.2% to 25.5p.
Shares in banknote authentication company Spectra Systems (SPSY) went in the opposite direction, up 9% to 88.8p thanks to news that profit will significantly exceed profit expectations. This was due to royalties from printed notes containing its materials reaching a record level in 2017.
Meat packing group Hilton Food (HFD) announced it would proceed with expansion plans in New Zealand through a $54m investment in new processing facilities, but this failed to boost the stock at 773p.
Low & Bonar (LWB) warned the expected improvement in financial performance and anticipated material reduction in inventory level in the second half of the year would not be achieved. The performance materials group blamed challenging market conditions in its civil engineering business and subdued demand, prompting the shares to fall 15.7% to 67.2p.