The FTSE 100 fell 0.6% to 7,326.36 by midday with the market reeling from geo-political tensions in the Middle East and weak Chinese industrial production data.
Construction firm Kier dropped 19.6% on reports it was planning to sell its housebuilding unit for a beaten down price.
LARGE AND MID CAP RISERS AND FALLERS
Media firm Ascential fell 3.1% despite saying first half results were in line with expectations.
Guarantor loans firm Amigo's chief executive Glen Crawford stepped down due to ill health. Shares in the company fall 2.1%. Hamish Paton, the former CEO of Brighthouse, is due to take over but has not yet gained regulatory approval.
SMALL CAP RISERS AND FALLERS
Recruitment firm SThree gained 3% on reporting a 9% rise in first-half net fees, as strength in its contract business more than offset weakness in permanent placements.
Frontier Smart Tech jumped 16.9% on new that it received a preliminary approach 'from a credible, industry player' potentially rivaling Science Group's bid for the digital radio company. Science Group rose 0.9%.
Clean water technology company Mycelx Technologies tumbled 49% after it downgraded its annual guidance, citing delayed project bids.
Customer relationship management software provider Cerillion rallied 11.7% as it secured a contract worth an initial £5.1m from the Danish telecom and utility SE Group.
Bioplastics and radio frequency business Biome Technologies jumped 5.8% on announcing that it expected to receive revenues 'immediately' following the commercial production of its new heat-stable material in the US.
Luxury furniture retailer Walker Greenbank gained 0.3% as it reported weaker sales in the US and continued challenging conditions in the UK.
Advertising technology company Taptica International gained 14.2% as it approved a further share buyback programme worth up to $10m.
Investment company St Peter Port Capital dropped 21% after its annual net asset value slumped 17% owing to asset writedowns.
Logistics group Wincanton said it had secured a contract from supermarket chain Morrisons to provide transportation services from three distribution centres to its stores. Its shares dipped 0.8%.