StockMarketWire.com - UK stocks tumbled 8.2% at the open on Monday after a decision by Saudi Arabia to slash oil prices even as the coronavirus was crimping demand sent oil stocks plummeting.

At 0819, the benchmark FTSE 100 index had plunged 535.92 points to 5,926.63.

Oil companies were among the biggest losers, with Shell and BP down a whopping 22% and 20%, respectively.

Oil prices fell by more than a quarter as Saudi Arabia cut export oil prices and pledged to keep the production taps flowing after Russia refused to make output cuts.

The decision came while a widening spread of the coronavirus threatens to tip the global economy into recession, sapping demand for energy.

Supermarket giant Tesco fell 3.7% to 231.7p, even as it agreed to sell its Thai and Malaysian assets to Bangkok-based CP for $10.6bn (£8.2bn) and pledged to return £5bn of the proceeds to shareholders.

Outsourced services company Serco slipped 7.2% to 135.3p despite it winning a contract extension worth about A$730m (£370m) to provide support services to Fiona Stanley hospital in Perth, Australia.

Engineering company Wood Group, which offers services to the oil sector, sank 23% to 249p, even as it closed out a deal to sell its nuclear assets to Jacobs for £250m.

Life science research tools provider Abcam lost 8.4% to £11.54 after it reported a fall in profit, as a ramp-up in investments weighed on margins.

The company also said it was reviewing its dividend as it eyed investment opportunities as a potentially better way of deploying capital.

Shipping services provider Clarkson weakened 3.4% to £23.05, as it warned the coronavirus would hurt its performance in the first half of 2020.

Clarkson also booked a steep fall in annual profit amid a rise in costs following its acquisition of RS Platou and weakness in its financial business.

Distribution and services group Bunzl fell 6.9% to £17.8492 on announcing that it had acquired safety wear company Bodyguard Workwear, for an undisclosed sum.

Insurance company Phoenix reversed 3.6% to 659.4p, having announced that its finance director Jim McConville would stand down in May after having spent eight years with the company.

McConville, who was also in charge of the company's Scottish operations, would be replaced on 15 May by current deputy finance director Rakesh Thakrar.

Middle East and Africa focused Payments technology company Network International dropped 9.7% to 482p, despite it booking a 14% rise in annual profit buoyed by higher transaction volumes.

Oil company Serica Energy dropped 9.3% to 80p, even as it got production restarted back at the Bruce platform in the North Sea earlier than it had originally hoped following a technical issue.

Mass spectrometry developer Microsaic Systems slumped 30% to 0.7p, as it posted a full-year loss and said sales had slowed in the new year thanks to the coronavirus.

Waste management company Renewi shed 3.1% to 34p, having appointed Ben Verwaayen as its new chairman, to replace Colin Matthews from the beginning of April.

Verwaayen had been chief executive of companies including Alcatel-Lucent and and BT.

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