Building products group SIG leads the risers. The firm said it has seen exceptionally challenging conditions and disruption to trading caused by extreme weather conditions in a number of countries in the final weeks of the year, but does not expect full year underlying pre-tax profits to be less than current analysts' consensus expectations of £60m.Clothes retailer N Brown is the heaviest faller in the mid-cap index after the High & Mighty owner posted higher sales but lower gross margins.Recruiter Hays is also lower after some cautious comments from the broker Charles Stanley. 'In our view, the key concerns centre on the group's exposure to the UK economy - where the outlook is possibly less positive than international markets - as well as its exposure to the public and construction & property sectors - again where the prospects are less strong,' it says.FTSE 250 - RisersSIG (SHI) 126.20p +8.05%PV Crystalox Solar (PVCS) 69.80p +3.48%Moneysupermarket.com (MONY) 76.45p +3.17%BSS Group (BTSM) 286.60p +2.98%Daejan Holdings (DJAN) 2,925.00p +2.24%Galiform (GFRM) 89.50p +2.23%Grainger (GRI) 141.60p +2.09%Amlin (AML) 374.00p +2.02%Cranswick (CWK) 763.00p +1.87%easyJet (EZJ) 355.30p +1.75%FTSE 250 - FallersBrown (N.) Group (BWNG) 246.80p -4.16%Wellstream Holdings (WSM) 520.50p -2.71%Fidessa (FDSA) 1,241.00p -2.67%IG Group Holdings (IGG) 373.80p -2.33%Redrow (RDW) 138.20p -2.33%Northgate (NTG) 225.00p -2.17%SThree (STHR) 305.50p -2.15%Hochschild Mining (HOC) 343.20p -2.14%Tomkins (TOMK) 207.10p -1.99%Hays (HAS) 105.30p -1.86%