Africa-focused oil explorer Ophir Energy saw its share price surge on Thursday after the company announced that it is selling its 20 per cent interest in Tanzanian Blocks 1, 3 and 4 to Pavilion Energy for 1.28bn dollars. Heading the other way was Serco which tumbled as the service company warned profits would be hit by contract delays with the UK government and currency movements.Digital sports media firm Perform was also a heavy faller after warning that full-year earnings would be £4m lower than previous forecasts due to a weak performance of Technology and Production in the second half.Fashion retailer Ted Baker gained after strong growth in wholesale and retail sales lifted third-quarter revenues.In the absence of any major catastrophe losses in the third quarter, insurance group Amlin said it now expects to deliver an above-target return on equity for 2013, causing shares to rise.Set-top box maker Pace declined after revenues in the third quarter came in lower than last year's, though this was as expected.FTSE 250 - RisersOphir Energy (OPHR) 366.30p +11.30%Xaar (XAR) 1,019.00p +7.77%Ted Baker (TED) 1,898.00p +6.03%Amlin (AML) 457.00p +5.84%Booker Group (BOK) 157.80p +4.85%NMC Health (NMC) 361.80p +4.48%Renishaw (RSW) 1,828.00p +4.22%SIG (SHI) 213.10p +3.55%Redrow (RDW) 274.20p +3.12%Partnership Assurance Group (PA.) 334.80p +3.02%FTSE 250 - FallersSerco Group (SRP) 418.60p -16.94%Perform Group (PER) 455.10p -15.72%Phoenix Group Holdings (DI) (PHNX) 714.50p -8.04%Pace (PIC) 290.10p -5.01%BBA Aviation (BBA) 319.70p -4.40%Bank of Georgia Holdings (BGEO) 2,068.00p -4.30%3i Group (III) 355.20p -4.21%Thomas Cook Group (TCG) 139.60p -2.92%Ladbrokes (LAD) 181.90p -2.62%Galliford Try (GFRD) 1,092.00p -2.15%BC