Shares in Serco plunged after the group issued a profit warning in which it predicted that 2014 profits would fall as much as 20 per cent short of the 277m pounds that the market had expected. The support services group said it now expected 2013 revenue to fall by a mid-single digit percentage. However, Serco also said the government had given the thumbs-up to the corporate renewal plan it launched following allegations that it had overcharged for tagging offenders. Platinum producer Lonmin was also a heavy faller after it warned it would have to reassess its guidance for the year following a mining strike in South Africa which has hurt production. However, it wasn't all bad news as the company also reported that refined production rose by 45% to 196,246 saleable ounces in the first quarter compared to the previous year. Fellow miner African Barrick Gold tracked the price of gold lower. Meanwhile, Renishaw gained despite posting a decline in both revenue and profit in the first half after it said it is expecting an improvement in trading activities and revenue in the second half. It also reported that it experienced strong demand for its 3D additive manufacturing, measurement automation, encoder and spectroscopy products. Strong demand for pork products fuelled Cranswick's third-quarter revenue, pushing the stock firmly higher. FTSE 250 - RisersRank Group (RNK) 136.90p +6.95%Renishaw (RSW) 1,880.00p +4.50%Homeserve (HSV) 325.00p +4.43%Carphone Warehouse Group (CPW) 299.10p +4.14%Cranswick (CWK) 1,294.00p +4.10%RPC Group (RPC) 599.50p +3.90%PayPoint (PAY) 1,125.00p +3.78%FirstGroup (FGP) 134.30p +3.47%Ocado Group (OCDO) 527.50p +3.33%Dunelm Group (DNLM) 940.00p +3.30%FTSE 250 - FallersSerco Group (SRP) 431.70p -15.27%Lonmin (LMI) 313.90p -4.42%Kazakhmys (KAZ) 172.20p -3.80%African Barrick Gold (ABG) 215.90p -2.75%TalkTalk Telecom Group (TALK) 314.10p -2.06%Evraz (EVR) 87.10p -1.97%Aveva Group (AVV) 2,149.00p -1.96%Rotork (ROR) 2,518.00p -1.95%Carillion (CLLN) 342.40p -1.95%Tullett Prebon (TLPR) 332.60p -1.89%NR