Tranpsort group National Express was a high riser after cheering investors with news of cost savings and an increased total dividend for 2012. Howden Joinery beefed up annual earnings and underlined its confidence in future trading with a six-fold increase in its full-year dividend. Howden, whose products are predominantly sold to small local builders for installation in public and private housing, said group revenue rose to £887.1m from £853.8m in 2011. Meanwhile, Spirent Communications shares plunged Thursday after the company reported flat 2012 revenues and a fall in pre-tax profits. The UK-based telecommunications company posted revenues of $472.4m for the year, compared to $470.5m in 2011, as a result of a 29% drop in service assurance. FTSE 250 - RisersHowden Joinery Group (HWDN) 214.80p +12.82%National Express Group (NEX) 217.90p +11.57%COLT Group SA (COLT) 133.00p +7.69%Capital & Counties Properties (CAPC) 265.40p +5.15%Domino's Pizza Group (DOM) 542.00p +4.43%Derwent London (DLN) 2,207.00p +3.66%Fenner (FENR) 428.40p +3.38%CSR (CSR) 462.10p +3.31%Henderson Group (HGG) 158.80p +3.18%Dixons Retail (DXNS) 27.36p +2.93%FTSE 250 - FallersSpirent Communications (SPT) 154.70p -6.69%Ferrexpo (FXPO) 227.70p -5.36%Kier Group (KIE) 1,281.00p -4.83%Petropavlovsk (POG) 299.00p -2.67%Centamin (DI) (CEY) 53.60p -2.55%Man Group (EMG) 100.60p -2.33%African Barrick Gold (ABG) 262.30p -2.13%Chemring Group (CHG) 276.60p -2.12%JPMorgan Indian Inv Trust (JII) 387.70p -2.05%Afren (AFR) 140.20p -2.03%NR