Oil majors BP and Shell have jumped towards the top of the FTSE 100, after the oil price reached a four-year high ahead of US sanctions on Iranian crude exports.
Oil stocks were in demand as the price of Brent crude rose to $81.86 a barrel, a four-year high, amid signs of reluctance from the Opec cartel of oil producing nations to counter the Iranian sanctions by increasing supply.
US president Donald Trump on Friday called on Opec to act. 'We protect the countries of the Middle East, they would not be safe for very long without us, and yet they continue to push for higher and higher oil prices,' he said on Twitter.
'We will remember. The Opec monopoly must get prices down now!'
But Opec and Russia, the biggest oil producer outside the cartel, rebuffed Trump. 'I do not influence prices,' Saudi Arabia's energy minister Khalid al-Falih said on Monday, according to Reuters, while Russian energy minister Alexander Novak said there was no need for an immediate increase in output.
'Following for years of collapsing international capital spend, Trump's removal of the world's fifth largest oil producer, Iran, from the market, with sanctions to be fully implemented in November, was never going to end well,' he said.
'We believe the combination of tight supply, healthy demand, falling global inventories, down from already under-stored levels, and anaemic spare capacity helps support an oil price which could end the year above $90.'
Next (NXT) meanwhile rose to the top of the FTSE 100, up 8.1% at £55.38, after the clothing retailer raised full-year profit guidance following better-then-expected trading over the last two months.
'Next is having a pretty good year, despite declining high street footfall, though the jury's still out on whether it's the balmy summer weather that's prompted its robust performance,' said Laith Khalaf, senior analyst at Hargreaves Lansdown.
Next is a high conviction holding for a number of UK-focused fund managers. Luke Chappell holds 5.9% of his £18 million BlackRock UK Focus fund, while James Goldstone has a 3% position in both his £302 million Keystone (KIT) and £77 million Invesco Perpetual Select UK (IVPU) investment trusts.
His colleague at Invesco Perpetual, Mark Barnett, holds 2.7% of his £1.7 billion Edinburgh (EDIN) investment trust, 2.4% of his £8.9 billion Invesco Perpetual High Income and 2.3% of his £4.1 billion Invesco Perpetual Income funds in the shares.
Neil Woodford, who had been a big backer of Next, sold his stake in February.
Among 'small-cap' stocks, Low & Bonar (LWB) tumbled 21.7% to 40.2p after the construction materials maker issued a profit warning.
CMC Markets (CMCX) was down 10.4% at 148.2p as the online trading firm said tighter European regulation would hit income.