Supermarkets stocks were registering losses on Tuesday afternoon after a report from Kantar Worldpanel revealed that over half the UK shopped in either Aldi or Lidl during the 12 weeks to December 8th for the first time in history. The panel found that all of the Big Four grocers and with the Co-operative all lost market share during the period, causing the share prices of Sainsbury, Tesco and Morrison to fall before the close.Motor insurer Admiral declined after the Competition Commission said that car insurance in the UK was too high and that drivers were footing the bill for unnecessary costs incurred during the claims process following an accident. The competition watchdog is said to be planning new measure to reform the market.General insurer RSA Insurance was making gains but continues to trade well below levels seen last week after Friday's profit warning and resignation of its Chief Executive. Subsequently, S&P downgraded its credit rating on the stock on Monday to 'A-' with a 'Developing Outlook', having already downgraded last week, while Fitch cut its outlook to 'Rating Watch Negative'.Mining stocks were broadly higher with Antofagasta, Rio Tinto and Glencore Xstrata among the best performers.Barclays fell after calling for the US courts to block energy regulators from collecting $488m of fines for electricity trading market manipulation. Pharmaceuticals group GlaxoSmithKline declined early on after Deutsche Bank downgraded the stock to 'hold'.FTSE 100 - RisersRSA Insurance Group (RSA) 92.10p +2.22%Mondi (MNDI) 963.50p +1.90%Sage Group (SGE) 381.50p +1.73%Persimmon (PSN) 1,160.00p +1.40%Sports Direct International (SPD) 712.00p +1.35%Antofagasta (ANTO) 778.00p +1.30%Rio Tinto (RIO) 3,258.00p +1.23%Glencore Xstrata (GLEN) 309.10p +1.21%Reed Elsevier (REL) 868.50p +1.11%Carnival (CCL) 2,213.00p +1.05%FTSE 100 - FallersSainsbury (J) (SBRY) 378.60p -4.27%Petrofac Ltd. (PFC) 1,115.00p -3.30%Morrison (Wm) Supermarkets (MRW) 257.20p -2.72%Admiral Group (ADM) 1,229.00p -2.54%Tesco (TSCO) 325.05p -1.80%Vedanta Resources (VED) 785.00p -1.51%BP (BP.) 466.45p -1.43%Burberry Group (BRBY) 1,449.00p -1.43%Tate & Lyle (TATE) 774.00p -1.40%Marks & Spencer Group (MKS) 451.70p -1.38%BC