Retailers are on the back foot after Next kicked off the stream of Christmas trading updates by increasing full-year profit forecasts but saying it was cautious on prospects for 2010.Next's fellow clothing retailer Marks & Spencer, which is due to update tomorrow, is another faller. Other notable fallers include JJB Sports and Curry's and PC World owner DSG.RBS adds to the strong gains it posted yesterday, helping to lift the banking sector higher. Barclays is another riser, boosted by comments from Deutsche Bank, which says the bank offers both growth and recovery potential.Top performing sectors so far todayBanks 5,001.65 +2.78%Industrial Metals 5,247.54 +2.16%Construction & Materials 3,444.01 +1.97%Life Insurance 3,988.40 +1.62%Forestry & Paper 3,775.36 +1.56%Bottom performing sectors so far todayBeverages 8,124.40 -1.63%Pharmaceuticals & Biotechnology 8,890.89 -1.63%Food Producers & Processors 4,871.60 -1.58%General Retailers 1,776.87 -1.58%General Industrials 2,260.50 -1.21%