Strong financial and mining stocks helped to drive the top share index higher Wednesday, while M&A activity and company updates had some FTSE 250 constituents soaring.HSBC went well, helped by a "buy" recommendation from Barclays Capital, but fellow banks Standard Chartered and Barclays were also wanted, as were insurers Legal & General and Aviva as eurozone debt contagion fears recede.In corporate news, supermarket giant J Sainsbury had its best Christmas ever, with better than expected sales, a growing market share and a record number of customers despite the snow. Like for like sales excluding fuel rose 3.6% in the 14 weeks to 8 January, or 5.4% including petrol, while total sales grew 6% and 7.5% respectively. Shares in the supermarket giant fell, though.Fund manager Gartmore Group's ill-starred and brief stint as a publicly listed company is set to come to an end. The company's board has agreed to a £335.3m takeover by rival Henderson Group in a deal that values each Gartmore share at 92.1p. Shares in both companies soared. So have SuperGroup's. The trendy fashion retailer predicts top-end profits following its best ever Christmas, almost doubling retail sales during the nine weeks to 2 January. The shares are sharply higher. Centrica's appeal to have competition restrictions lifted from its Rough gas storage facility in the North Sea has been rejected by the Competition Commission.Conveyor belt maker Fenner, another strong performer today, has seen a sharp increase in first quarter profitability compared to the same period last year. Quality and safety services provider Intertek has paid $6.9m for American Analytical Chemistry Laboratories (AAC Labs), a business that provides laboratory-based food testing in the United States.Conveyor belt maker Fenner, another strong performer today, has seen a sharp increase in first quarter profitability compared to the same period last year. Bakery chain Greggs like-for-like sales rose 0.6% over the Christmas trading period while total sales climbed 3.5% as shoppers snapped up hot coffee and mince pies. Mail order was a tough business when the snow hit in December, but N Brown struggled through to lift like-for-like sales by 1.2%. "The extreme weather conditions eventually affected customers who were concerned whether their Christmas orders would be delivered on time," it said.The expected December pick-up in activity failed to materialise last year for parcels and mail group UK Mail. To make matters worse, the adverse weather conditions meant the company incurred additional costs to hold and deliver consignments.Investors also had a strong appetite for Restaurant Group, which owns the Garfunkel's, Chiquito and Frankie and Benny's chains. It expects full-year profits to be "just ahead" of the market consensus.Barratt Developments sold its homes for 6% more during the first half as the number of houses sold made up a bigger share of the total, although volume growth for the year will be "limited".FTSE 100 - RisersEurasian Natural Resources Corp. (ENRC) 1,125.00p +4.36%Vedanta Resources (VED) 2,514.00p +4.27%HSBC Holdings (HSBA) 715.00p +3.82%Kazakhmys (KAZ) 1,671.00p +3.66%Barclays (BARC) 302.60p +3.63%Anglo American (AAL) 3,396.50p +3.44%Old Mutual (OML) 130.80p +3.15%Aviva (AV.) 421.30p +3.13%Legal & General Group (LGEN) 109.00p +2.83%TUI Travel (TT.) 263.00p +2.57%FTSE 100 - FallersGKN (GKN) 230.90p -2.61%National Grid (NG.) 539.00p -2.27%Sainsbury (J) (SBRY) 382.00p -2.15%Burberry Group (BRBY) 1,118.00p -2.10%Intertek Group (ITRK) 1,837.00p -2.03%Man Group (EMG) 302.50p -2.01%Diageo (DGE) 1,212.00p -1.94%IMI (IMI) 910.50p -1.94%Centrica (CNA) 327.40p -1.71%Fresnillo (FRES) 1,533.00p -1.67%FTSE 250 - RisersSupergroup (SGP) 1,390.00p +19.42%Gartmore Group Ltd. (GRT) 103.00p +13.69%Moneysupermarket.com Group (MONY) 85.75p +10.86%Savills (SVS) 358.80p +10.40%Henderson Group (HGG) 151.00p +9.26%Fenner (FENR) 386.70p +9.02%Kenmare Resources (KMR) 32.64p +7.02%Restaurant Group (RTN) 293.40p +6.85%Croda International (CRDA) 1,625.00p +5.38%Elementis (ELM) 141.90p +5.11%FTSE 250 - FallersTelecity Group (TCY) 444.00p -4.48%Avis Europe (AVE) 214.90p -4.45%Devro (DVO) 240.50p -4.22%Cookson Group (CKSN) 650.00p -3.63%Ashtead Group (AHT) 170.00p -3.52%Soco International (SIA) 348.60p -3.43%Redrow (RDW) 127.00p -3.35%Amlin (AML) 380.40p -3.18%Sports Direct International (SPD) 169.60p -2.92%Renishaw (RSW) 1,305.00p -2.76%