Oil and gas company Afren was extending gains after impressing the market on Monday with record results. Its share price spiked higher on the back of an enormous rise in trading volumes. The African-focused group earlier this week reported strong production and financial performance following exploration success in Nigeria and the Kurdistan region of Iraq. Following close behind was Bumi despite the bad press surrounding the company as co-founder Nat Rothschild continued to butt heads with the board and the Bakrie family. On the fallers list, Redrow led the race after JP Morgan Cazenove downgraded the housebuilder from 'neutral' to 'underweight', thought it did increase the target price from 159p to 172p.Galliford Try came in second following news it was dropped at the last minute from a £20m contract to refurbish the National Indoor Arena in Birmingham. FTSE 250 - RisersAfren (AFR) 150.80p +8.33%Bumi (BUMI) 339.20p +4.53%Stobart Group Ltd. (STOB) 100.40p +3.29%EnQuest (ENQ) 128.20p +3.05%Hikma Pharmaceuticals (HIK) 798.50p +2.18%RPC Group (RPC) 415.00p +2.09%Domino Printing Sciences (DNO) 634.00p +2.09%Daejan Holdings (DJAN) 3,038.00p +2.05%London & Stamford Property (LSP) 110.00p +1.95%Betfair Group (BET) 684.00p +1.94%FTSE 250 - FallersRedrow (RDW) 184.60p -4.00%Galliford Try (GFRD) 783.00p -3.93%TalkTalk Telecom Group (TALK) 231.70p -3.78%Barratt Developments (BDEV) 218.50p -3.57%Taylor Wimpey (TW.) 70.65p -3.55%Man Group (EMG) 93.20p -3.32%F&C Asset Management (FCAM) 105.50p -3.12%Big Yellow Group (BYG) 370.00p -3.12%Carillion (CLLN) 307.80p -2.99%Grainger (GRI) 125.00p -2.95%