Telecoms titan BT Group was dragging the fixed line telecommunications sector lower after a downgrade from JP Morgan Cazenove today.The US broker cut its rating from overweight to neutral saying it may struggle to grow revenues in 2012. Despite this, it still expects the firm to do well in the long-term and raise its dividend payments "substainably over time". Sector peers Cable & Wireless Communications, Inmarsat and Avanti were all trading lower. Elsewhere, high-tech tool manufacturer Oxford Instruments gave the electronic and electrical equipment sector a boost after it said it expects full-year profits to come in at the top end of analysts' forecasts. In a trading update the firm said it continued to make good progress in line with its "14 Cubed" objectives - targeting compound revenue growth of 14% and a target return on sales of 14% by 2014. In November Oxford announced first-half pre-tax profits fell to £12.5m from £13.2m the year before but predicted an improved second half. Sector peers Domino Printing and Andor Technology followed the stock higher. Top performing sectors so far todayIndustrial Transportation 2,493.97 +2.33%Electronic & Electrical Equipment 3,273.72 +2.28%General Industrials 3,177.27 +1.69%Industrial Engineering 7,458.91 +1.68%Household Goods & Home Construction 7,044.53 +1.48%Bottom performing sectors so far todayFixed Line Telecommunications 2,430.54 -2.09%Forestry & Paper 5,848.85 -1.18%Food Producers & Processors 5,401.38 -0.16%Real Estate Investment & Services 1,603.51 -0.09%Tobacco 35,962.28 -0.09%NR