Computer graphics chip specialist Imagination Technologies leapt after it said strong momentum in the first half has continued and it expects full year results to achieve good growth. Polymers firm Fenner has reported a strong trading period for the six months ended February 29th 2012, with operating profit for the half year 'significantly' ahead of the comparable period last year. At the opposite end of the FTSE 250 leader-board, Logica was a heavy faller after Morgan Stanley downgraded its rating on the business and technology service company from overweight to equal weight. FTSE 250 - RisersPerform Group (PER) 293.00p +7.68%Imagination Technologies Group (IMG) 646.50p +7.48%Fenner (FENR) 492.30p +7.09%Inmarsat (ISAT) 490.90p +6.42%Supergroup (SGP) 554.50p +6.23%Heritage Oil (HOIL) 169.10p +5.95%Spirax-Sarco Engineering (SPX) 2,124.00p +5.67%Balfour Beatty (BBY) 280.30p +5.57%Hunting (HTG) 846.00p +5.42%International Personal Finance (IPF) 256.90p +5.07%FTSE 250 - FallersGenus (GNS) 1,287.00p -2.20%Logica (LOG) 87.75p -1.63%Phoenix Group Holdings (DI) (PHNX) 547.00p -1.62%Moneysupermarket.com Group (MONY) 125.20p -1.42%Go-Ahead Group (GOG) 1,265.00p -1.40%SDL (SDL) 702.00p -1.40%Bumi (BUMI) 736.50p -1.27%FirstGroup (FGP) 283.80p -1.08%Home Retail Group (HOME) 102.20p -0.97%Shanks Group (SKS) 102.60p -0.87%