(Sharecast News) - London's FTSE 250 was up 1.64% at 18,270.15 in afternoon trade on Tuesday, with Computacenter and Electrocomponents leading the charge.IT services provider Computacenter was the top riser, followed closely by Electrocomponents which made gains as Jefferies upgraded the stock to 'buy' from 'hold' while UBS raising its own recommendation for the shares to 'buy' from 'neutral'.In parallel, Serco climbed after the company won an asylum accommodation and support services contract for the North West and the Midlands and East of England, with a total contract value estimated to be around £1.9bn over the ten-year term, adding £1.9bn to the group's order book.Luxury car manufacturer Aston Martin Lagonda jumped after reporting that it has put in place a number of measures to prepare for a potential 'no-deal' Brexit.Pub operator Greene King rallied as it posted a 10.9% jump in like-for-like sales over Christmas and the New Year and expressed confidence over the full year, while Rotork was also on the rise after being upgraded Bank of America Merrill Lynch.Building materials group SIG was the worst performer on the FTSE 250 after saying it expects profit for 2018 to drop on the back of lower trading revenue amid challenging market conditions.In a research note, analysts from Canaccord said: "The profit miss will be food for the bears and until there is further evidence of profit improvement and visibility over where earnings will trough, the shares are likely to remain under pressure despite the obvious potential."Finally, precious metals miners Centamin, Acacia Mining and Polymetal International were under pressure as gold prices backed-off amid the more upbeat investor attitude and corrective weakness after prices reached a six-month high last week.Market MoversFTSE 250 (MCX) 18,270.15 1.64%FTSE 250 - RisersComputacenter (CCC) 1,054.65p 8.50%Electrocomponents (ECM) 541.00p 7.98%Serco Group (SRP) 109.90p 7.64%Just Group (JUST) 100.74p 6.94%Aston Martin Lagonda Global Holdings (AML) 1,284.80p 6.13%Greene King (GNK) 585.00p 5.75%Playtech (PTEC) 433.00p 5.07%TI Fluid Systems (TIFS) 171.90p 4.95%Rotork (ROR) 262.10p 4.80%Rank Group (RNK) 149.00p 4.78%FTSE 250 - FallersSIG (SHI) 110.70p -5.06%Hikma Pharmaceuticals (HIK) 1,620.50p -3.97%Vivo Energy (VVO) 128.04p -3.86%Energean Oil & Gas (ENOG) 639.30p -1.65%Centamin (DI) (CEY) 119.20p -1.24%Acacia Mining (ACA) 197.65p -1.17%Grafton Group Units (GFTU) 689.50p -1.08%Polymetal International (POLY) 857.20p -1.06%Convatec Group (CTEC) 140.35p -0.99%Contour Global (GLO) 188.20p -0.90%