African Barrick Gold was a heavy faller today after Chief Operating Officer (COO) Marco Zolezzi resigned with immediate effect. Zolezzi, who has been COO since September 2010, is leaving to pursue other interests. Gold mining peer Polymetal was also lower as gold prices fluctuated at a three-week low. Goldman Sachs today estimated that bullion prices will decline into 2014 as the Federal Reserve scales back its stimulus programme. It said that the next's policy meeting later this month "could prove the catalyse to push gold prices lower".House-builder Barratt Developments was also lower, despite the fact it delivered a strong set of annual results, as the housing market recovery starts to spread beyond London, and said the new financial year had started on a strong footing.Meanwhile, Perform Group was a high riser after JP Morgan Cazenove upped its target price on the stock from 1,407p to 1,520p, and reiterated its neutral rating. FTSE 250 - RisersPerform Group (PER) 550.00p +4.27%Premier Farnell (PFL) 236.50p +3.55%888 Holdings (888) 154.50p +3.34%Imagination Technologies Group (IMG) 312.10p +3.34%UBM (UBM) 746.50p +2.61%Carillion (CLLN) 319.30p +2.57%FirstGroup (FGP) 124.30p +2.47%Ocado Group (OCDO) 373.20p +2.25%Electrocomponents (ECM) 283.00p +2.13%Ferrexpo (FXPO) 190.90p +2.09%FTSE 250 - FallersAfrican Barrick Gold (ABG) 156.50p -5.95%Polymetal International (POLY) 730.50p -3.37%Barratt Developments (BDEV) 323.20p -2.74%International Public Partnerships Ltd. (INPP) 124.00p -2.67%Bwin.party Digital Entertainment (BPTY) 112.70p -2.51%Temple Bar Inv Trust (TMPL) 1,194.00p -2.21%Unite Group (UTG) 356.50p -1.95%Synthomer (SYNT) 244.70p -1.81%Howden Joinery Group (HWDN) 291.00p -1.69%Moneysupermarket.com Group (MONY) 165.70p -1.66%NR