Interserve was one of the day's strongest risers after Berenberg Bank stuck with its 'buy' rating on the stock.Precious metals group Lonmin has returned to full production earlier than expected following a lengthy strike by workers that sent its share price tumbling more than 40% in the year to date. The group has achieved steady production since August, thanks to earlier and stronger levels of employees returning to work than had been previously anticipated.Bus and train operator Firstgroup was lower after failing to keep its Scotrail franchise from April next year. The group has already lost its First Capital Connect London commuter franchise and failed in a bid to run London-Scotland sleeper trains.Deutsche Bank knocked Ferrexpo lower after reducing its target price to 286p from 300p.Soco International was dragged into the red thanks to Canaccord Genuity, which cut its target price on the stock from 400p to 380p.FTSE 250 - RisersMan Group (EMG) 119.70p +3.46%Interserve (IRV) 605.50p +2.98%Lonmin (LMI) 175.20p +2.76%Rexam (REX) 485.50p +1.85%Infinis Energy (INFI) 229.10p +1.82%Pets at Home Group (PETS) 175.50p +1.68%Just Retirement Group (JRG) 126.00p +1.61%COLT Group SA (COLT) 131.20p +1.47%Riverstone Energy Limited (RSE) 899.00p +1.35%Euromoney Institutional Investor (ERM) 1,010.00p +1.30%FTSE 250 - FallersSpirent Communications (SPT) 71.00p -7.91%Ferrexpo (FXPO) 96.65p -5.98%RPS Group (RPS) 232.70p -4.63%FirstGroup (FGP) 110.00p -4.43%SSP Group (SSPG) 239.00p -4.40%Vedanta Resources (VED) 901.00p -3.89%Balfour Beatty (BBY) 161.90p -3.86%Just Eat (JE.) 283.90p -3.80%Soco International (SIA) 356.00p -3.65%Ophir Energy (OPHR) 214.90p -3.55%