Shares in energy group Drax sank over 8% on Thursday after a UK court said one of its power-generating units wasn't eligible for a government incentive. Drax said the ruling meant the second unit conversion at its power station is "no longer eligible for an investment contract" that pays guaranteed electricity prices for 15 years.Investment group Henderson dropped nearly 7% after first-half results failed to meet the market's expectations. Assets under management fell nearly 6% over the second quarter as improvements in retail were offset by falls in the institutional business.In contrast, UK-based defence company Cobham impressed after beating estimates with a 6% rise in first-half pre-tax profits. Revenues fell 3% but were in line with forecasts, which Investec said will "likely reassure the bulls after a number of slip-ups in recent years".Boiler and pipeline control valve maker Spirax-Sarco Engineering was in demand after saying that organic growth of 4% in the first half was driven by gains across all business segments, though currency movements hit reported results.Meanwhile, estate agency and consultancy group Savills impressed with a 16% rise in underlying pre-tax profit to £30.1m in the first half, helped by the strength of key transactional markets in the UK and a recovery in Continental Europe.FTSE 250 - RisersElementis (ELM) 278.40p +5.29%Cobham (COB) 299.00p +4.18%Smith (DS) (SMDS) 270.40p +4.16%Savills (SVS) 594.50p +3.48%Euromoney Institutional Investor (ERM) 1,060.00p +3.41%Victrex plc (VCT) 1,645.00p +3.39%Spirax-Sarco Engineering (SPX) 2,777.00p +3.16%Alent (ALNT) 347.40p +3.09%Domino's Pizza Group (DOM) 566.00p +2.91%Fenner (FENR) 336.90p +2.74%FTSE 250 - FallersDrax Group (DRX) 650.50p -8.38%Henderson Group (HGG) 225.70p -6.54%Xaar (XAR) 545.00p -4.30%ITE Group (ITE) 193.00p -3.50%Stock Spirits Group (STCK) 300.40p -2.63%COLT Group SA (COLT) 132.60p -2.43%Supergroup (SGP) 1,019.00p -2.21%Petra Diamonds Ltd.(DI) (PDL) 191.20p -1.95%Fisher (James) & Sons (FSJ) 1,374.00p -1.79%Kazakhmys (KAZ) 309.40p -1.78%BC