First-half earnings at energy services provider John Wood Group were flat but slightly better than the market was expecting, pushing shares higher on Tuesday. Revenues were up 10% at $3.8bn as the company benefitted from strong activity in the US shale sector.Amlin fell after Deutsche Bank cut its target price from 472p to 461p and reiterated a 'hold' recommendation.Petra Diamonds was retreating one day after it pleased investors with its production forecasts that predicted a rise of around 3% to 3.2m carats in the 12 months to 30 June 2015.Hochschild Mining was falling ahead of its quarterly earnings on Wednesday. Go-Ahead Group declined despite being short-listed by the UK government as a potential bidder for two railway franchises. FTSE 250 - RisersCSR (CSR) 584.00p +10.19%AO World (AO.) 214.80p +6.44%Supergroup (SGP) 1,134.00p +5.69%Ocado Group (OCDO) 371.70p +5.51%Wood Group (John) (WG.) 790.00p +5.12%Ophir Energy (OPHR) 225.20p +5.04%Countrywide (CWD) 528.00p +4.14%Evraz (EVR) 108.80p +3.62%Howden Joinery Group (HWDN) 355.80p +3.49%Afren (AFR) 108.90p +3.32%FTSE 250 - FallersAmlin (AML) 432.80p -3.52%Petra Diamonds Ltd.(DI) (PDL) 192.20p -3.51%Diploma (DPLM) 652.50p -3.33%Perform Group (PER) 207.10p -3.18%Hochschild Mining (HOC) 160.90p -2.31%Telecity Group (TCY) 777.50p -1.77%Go-Ahead Group (GOG) 2,206.00p -1.34%Fenner (FENR) 364.50p -1.17%Hiscox Ltd (CDI) (HSX) 639.50p -1.16%Grainger (GRI) 215.20p -1.15%NR