Food retail stocks slumped as Oriel Securities downgraded Tesco after the supermarket chain launched 200m pounds of price cuts and said it was stepping up its store revamp programme.Oriel, which reduced Tesco from a 'buy' to an 'add' last October, lowered its recommendation again to 'hold' with a 325p target price.Industrial metals and mining shares also declined as the price of copper dropped on the London Metal Exchange amid recent weakness in the Chinese yuan. On the upswing, Weir Group led engineering stocks higher after saying it expects to return to growth this year and raising its full-year dividend by 11% to 33.2p per share.The company, which supplies equipment to the oil and gas industry, reported a drop in revenues and profits in 2013, but sees an improvement this year on higher upstream spending by customers. Technology hardware and equipment stocks, including chipmaker ARM Holdings, gained after the latest gadgets were unveiled at the Barcelona Mobile World Congress.Samsung was among the companies to reveal its new devices, which included the Galaxy S5 smartphone, at the four-day event which wraps up tomorrow. Top performing sectors so far todayIndustrial Engineering 10,888.88 +1.86%Technology Hardware & Equipment 1,191.37 +0.93%Tobacco 36,373.59 +0.47%Automobiles & Parts 9,644.52 +0.44%Industrial Transportation 3,394.24 +0.44%Bottom performing sectors so far todayFood & Drug Retailers 4,324.20 -2.52%Industrial Metals & Mining 1,033.76 -2.03%Construction & Materials 4,851.64 -1.54%Real Estate Investment & Services 2,957.20 -1.46%Aerospace and Defence 4,640.76 -1.43%RD