Supermarket stocks were under pressure on Friday, with Tesco in particular pulling back after a 15% surge the previous session, following the announcement of its turnaround plan and resilient Christmas sales. Dampening Tesco's shares was the news that ratings agency Moody's had cut the UK grocer's debt to 'junk', saying that measures announced on Thursday to revive the struggling business "will take time to implement". Analysts said that Tesco's "financial profile is likely to remain leveraged beyond what we consider to be commensurate with an investment-grade profile".Shares in rivals Sainsbury and Morrison were also in reverse after rallying strongly on Thursday.Housebuilders Barratt Developments and Taylor Wimpey were significantly lower, as analysts at Jefferies downgraded their ratings on stocks across the sector.Mining stocks were also trading lower on markets, with Fresnillo shares performing badly.Meanwhile insurers Friends Life Group, Aviva and Admiral Group were among the risers. High equity exposure over Thursday and Friday is thought to have boosted their portfolio values in the UK, Europe and the US. FTSE 100 - RisersFriends Life Group Limited (FLG) 373.00p +2.16%Aviva (AV.) 493.30p +2.09%Johnson Matthey (JMAT) 3,520.00p +1.85%ITV (ITV) 213.10p +1.72%Pearson (PSON) 1,182.00p +1.63%Ashtead Group (AHT) 1,148.00p +1.50%Intertek Group (ITRK) 2,461.00p +1.28%Shire Plc (SHP) 4,738.00p +1.11%easyJet (EZJ) 1,634.00p +1.11%Admiral Group (ADM) 1,351.00p +1.05%FTSE 100 - FallersBarratt Developments (BDEV) 426.40p -6.22%Taylor Wimpey (TW.) 125.20p -5.72%Persimmon (PSN) 1,456.00p -5.39%Morrison (Wm) Supermarkets (MRW) 177.20p -4.06%Sainsbury (J) (SBRY) 242.70p -3.84%Standard Chartered (STAN) 941.20p -3.04%Babcock International Group (BAB) 1,036.00p -2.81%Royal Bank of Scotland Group (RBS) 367.30p -2.75%Barclays (BARC) 230.55p -2.74%Tesco (TSCO) 203.90p -2.56%