(ShareCast News) - The FTSE 250 was back in the red by mid-afternoon on Thursday, down 12.76 points (0.08%) to 16,268.22.Melrose Industries was the biggest faller after it returned around £2.4bn in cash back to shareholders. The company gave 240p for each share held after the £3.3bn disposal of its Elster business to Honeywell International in December.Shares in transport operator FirstGroup slid on Thursday after it lowered its operating profit guidance for the current financial year amid a challenging trading environment.In the three months to 26 December, revenue dropped 9.5% at constant currency. The company said this reflected changes to the rail franchise portfolio and the number of First Student operating days due to the timing of the school calendar.FirstGroup said that excluding these effects, which it had already warned about, revenues were up 0.9% at constant currency. It said progress on the transformation plans in the third quarter was mitigated by a challenging trading environment, with revenues in First Bus hit by lower-than-expected high street footfall due to exceptionally wet weather and flooding.Tullow Oil and Petrofac were big risers as oil prices began to rise towards $35 a barrel. At 1516 GMT, West Texas Intermediate was up 3.81% to $33.53 while Brent was up 3.32% to $34.20. Tullow was also the subject of speculation in one publication about whether it could be a takeover target.Kier Group was also up after it said full-year trading was in line with expectations, sending shares surging.The company said in a trading update on Thursday that the group's underlying performance has remained in line with management's expectations since its last trading update in November. It has also settled a number of final accounts and improved its working capital performance, which has left net debt ahead of expectations at £175m.FTSE 250 - RisersTullow Oil (TLW) 172.60p 12.88%Vedanta Resources (VED) 237.00p 11.06%Drax Group (DRX) 259.70p 10.70%Amec Foster Wheeler (AMFW) 417.30p 7.30%Wood Group (John) (WG.) 637.50p 5.81%Petrofac Ltd. (PFC) 793.00p 5.73%Kier Group (KIE) 1,277.00p 4.93%Mitchells & Butlers (MAB) 295.30p 4.20%Aggreko (AGK) 861.00p 4.05%Acacia Mining (ACA) 201.60p 3.86%FTSE 250 - FallersMelrose Industries (MRO) 286.70p -85.12%FirstGroup (FGP) 92.15p -9.92%CLS Holdings (CLI) 1,592.00p -4.96%Go-Ahead Group (GOG) 2,415.00p -4.32%Riverstone Energy Limited (RSE) 720.00p -4.00%Carillion (CLLN) 267.50p -3.57%Hastings Group Holdings (HSTG) 164.00p -3.47%PayPoint (PAY) 803.00p -3.25%Home Retail Group (HOME) 145.40p -2.81%Worldwide Healthcare Trust (WWH) 1,731.00p -2.42%