Internet and catalogue home shopping firm N Brown topped the risers list on Tuesday afternoon, gaining 13 per cent after beating forecasts in the first half.The company reported that revenue in the 26 weeks to September 1st came in at £379.3m, up 4.3% on the year and ahead of the consensus estimate of £371.7m. Meanwhile, profit before tax and fair value adjustments fell by 4.5% to £42.0m, still ahead of the £40.6m forecast.Chip group Imagination Technologies was also a high riser after both Liberum Capital and Numis upgraded their ratings on the stock.Oil group Ophir Energy was the worst performer of the day after Deutsche Bank downgraded the stock to 'sell' and cut its price target from 565p to 505p.High Street betting firm William Hill gained after agreeing on a revised and increased possible offer with GVC for Sportingbet.Thermal processing services provider Bodycote was in demand after buying US-based Carolina Commercial Heat Treating from Bluewater Thermal Solutions for $68m. The company also said it was trading line with expectations in the most recent quarter.UK housebuilder Bellway was also a high riser after delivering a solid increase in full-year pre-tax profit, helped by a strong performance in London, and said reservations since July 31st have remained in line with expectations. Gold miner Petropavlovsk rose after saying it was on track to achieve its full-year production target of at least 700,000oz. FTSE 250 - RisersBrown (N.) Group (BWNG) 305.00p +13.09%Imagination Technologies Group (IMG) 477.70p +7.59%Perform Group (PER) 426.70p +6.67%Paragon Group Of Companies (PAG) 237.40p +6.46%William Hill (WMH) 341.10p +4.63%Bodycote (BOY) 359.80p +4.26%Kenmare Resources (KMR) 39.19p +4.15%Persimmon (PSN) 777.50p +4.15%Workspace Group (WKP) 293.60p +4.04%Berkeley Group Holdings (The) (BKG) 1,483.00p +3.85%FTSE 250 - FallersOphir Energy (OPHR) 577.50p -3.67%Carpetright (CPR) 690.00p -1.36%Savills (SVS) 403.10p -1.20%Talvivaara Mining Company (TALV) 133.80p -1.18%Stobart Group Ltd. (STOB) 117.30p -1.10%Rathbone Brothers (RAT) 1,324.00p -1.05%Inchcape (INCH) 355.20p -0.73%Greggs (GRG) 487.40p -0.69%Invensys (ISYS) 224.80p -0.66%Diploma (DPLM) 451.80p -0.66%BC