RDSA.L Share News (RDSA)

A sharp drop in the price of Brent crude to below $80 a barrel sent oil stocks lower on Thursday, with oil prices now at their lowest levels in over four years.Tullow Oil was among the worst performers as a string of brokerages cut their target prices for the stock.'Big Oil' group Royal Dutch Shell, however, was also providing a big drag on the sector's average performance with shares automatically lower after the stock went ex-dividend.Brent futures for December delivery were around 1.6% lower at $79.09 a barrel, a level not seen since September 2010.Ongoing concerns that the Organization of Petroleum Exporting Countries (OPEC) will not act to curb a supply glut at its summit at the end of the month were continuing to drive the price of oil lower.Government data in the States was also expected to show that US crude stockpiles rose for a sixth consecutive week.Meanwhile, worries about demand added the downwards pressure after figures from China released overnight showed that increases in industrial production, retail sales and fixed-asset investment all eased in October. Chinese leaders have also apparently discussed lowering their 2015 growth target for gross domestic product below 7.5%, according to reports.Tullow was losing 3% of its market value in afternoon trade in London after analysts at Westhouse Securities, Credit Suisse and Deutsche Bank all lowered its target prices for the stock.The downgrades came after the oil explorer said that it would be cutting its exploration budget for 2015 substantially in light of the weaker oil price, reduced commercial success from offshore drilling, and failure to find a farm-out partner for the TEN development offshore Ghana.Others in the sector such as BP, BG Group, Afren, Ophir Energy, Premier Oil and Genel Energy were also trading firmly in the red.Top performing sectors so far todaySoftware & Computer Services 1,158.61 +1.52%Tobacco 42,182.12 +1.52%Forestry & Paper 11,514.58 +1.33%Personal Goods 24,115.03 +1.29%Mobile Telecommunications 5,042.67 +1.25%Bottom performing sectors so far todayOil Equipment, Services & Distribution 21,362.42 -1.75%Oil & Gas Producers 7,489.63 -1.62%General Industrials 3,921.05 -1.19%Aerospace and Defence 4,599.62 -0.35%Insurance (non-life) 1,847.71 -0.04%