Kazakhstan-focused copper miner Kazakhmys surged after Kazakhstan's central bank devalued the local currency, the tenge, by 19 per cent. This, analysts at Investec said, will lead to a 10 per cent reduction in costs for Kazakhmys, given that around half of its costs are tenge-denominated. However, the broker warned that the move could lead to high inflation in the coming years.Debenhams and Home Retail rose strongly in line with their fellow retailers after the UK retail sector registered healthy growth in January, according to figures released this morning by British Retail Consortium (BRC), which showed that like-for-like retail sales rose by 3.9% last month. JD Sports Fashion was a notable decliner given today's positive non-food retail data, and particularly given the significant rise seen by sector peer Sports Direct. Halma was lower after it failed to impress with its interim management statement, despite reporting revenue growth in all regions and all sectors since the end of September, although the Medical sector did make slower progress. Investec lowered its target price on the stock from 730p to 715p. FTSE 250 - RisersKazakhmys (KAZ) 212.90p +20.28%Essar Energy (ESSR) 62.15p +9.90%Imagination Technologies Group (IMG) 183.50p +6.75%Ferrexpo (FXPO) 165.90p +4.67%Centamin (DI) (CEY) 49.72p +4.43%Debenhams (DEB) 77.00p +4.19%Home Retail Group (HOME) 188.10p +4.04%Victrex plc (VCT) 1,945.00p +3.73%TalkTalk Telecom Group (TALK) 308.90p +3.62%FirstGroup (FGP) 135.90p +3.35%FTSE 250 - FallersJD Sports Fashion (JD.) 1,410.00p -4.73%Rank Group (RNK) 142.00p -3.47%NMC Health (NMC) 457.00p -2.77%Perform Group (PER) 220.00p -2.22%UDG Healthcare Public Limited Company (UDG) 329.30p -2.11%Devro (DVO) 311.30p -2.11%Laird (LRD) 305.90p -2.02%Greencore Group (GNC) 250.00p -1.88%Halma (HLMA) 582.50p -1.85%Cranswick (CWK) 1,292.00p -1.52%NR