Centrica was the top riser on Wednesday after the energy company said it would sell its Texas gas-fired power stations to Blackstone for 685m dollars and use the proceeds to extend its share buyback programme.Chipmaker ARM Holdings gained after Dixons Retail posted sales growth driven by tablet computers. Rexam rallied, buoyed by an upbeat note on the sector from Bank of America Merrill Lynch. Supermarket retailers, including Sainsbury's, Mark & Spencer and Tesco, tumbled after a survey from market researcher Kantar Worldpanel showed that more than half of Britain's households shopped at German discount grocers Aldi or Lidl over the past 12 weeks.M&S was also hurt by a ratings downgrade by UBS from 'buy' to 'neutral'.RSA Insurance Group declined after the company revealed today that Ameriprise Financial took its stake in RSA below the 5% threshold last Friday.GlaxoSmithKline dropped on news the drug giant is launching a shake-up of its sales and marketing incentives as Chinese officials continue a probe into bribery allegations.FTSE 100 - RisersCentrica (CNA) 332.30p +2.85%ARM Holdings (ARM) 1,014.00p +2.11%Travis Perkins (TPK) 1,764.00p +1.85%Wolseley (WOS) 3,275.00p +1.83%Reckitt Benckiser Group (RB.) 4,634.00p +1.65%Rexam (REX) 496.00p +1.62%Standard Chartered (STAN) 1,323.50p +1.53%Associated British Foods (ABF) 2,335.00p +1.52%William Hill (WMH) 376.50p +1.48%Coca-Cola HBC AG (CDI) (CCH) 1,654.00p +1.35%FTSE 100 - FallersSainsbury (J) (SBRY) 367.50p -2.93%Marks & Spencer Group (MKS) 441.30p -2.43%United Utilities Group (UU.) 653.50p -2.17%RSA Insurance Group (RSA) 90.85p -1.68%Tesco (TSCO) 319.15p -1.65%Burberry Group (BRBY) 1,432.00p -1.38%GlaxoSmithKline (GSK) 1,546.00p -1.28%Petrofac Ltd. (PFC) 1,096.00p -1.26%Aggreko (AGK) 1,623.00p -0.98%Morrison (Wm) Supermarkets (MRW) 254.40p -0.90%RD