The UK stock market staged a slight 'Santa rally' on Wednesday, with risk appetite increasing before Christmas on the back of a Greek ratings upgrade and a better-than-expected reading of German confidence."Santa has returned to the markets, bringing some much needed cheer before the Christmas break - traders are feeling risky as such," said market strategist Ishaq Siddiqi from ETX Capital.However, gains across Europe were pared by the close after US stocks opened mixed on Wall Street with worries over the 'fiscal cliff' resurfacing. The White House Communications Director Dan Pfeiffer said that President Barack Obama would veto any 'plan B' from House Speaker John Boehner."This is a concern to anyone relying on a deal being done by the end of the year," said market analyst Craig Erlam from Alpari. "The fact that Republicans are preparing a plan B suggests they are not willing to meet Obama in the middle on spending and tax issues. Obama's rejection of the plan therefore suggests going over the fiscal cliff is yet again a possibility. These negotiations are starting to become a bit of a rollercoaster ride and I'm sure there's going to be many more ups and downs between now and the end of the year."Nevertheless, providing a lift to the markets early on was last night's news that Standard & Poor's had upgraded its rating for Greece from 'selective default' to 'B-minus' to reflect "our view of the strong determination of Eurozone member states to preserve Greek membership", the ratings agency said. The yield on a 10-year Greek bond dropped to its lowest level since March 2011 this morning. Meanwhile, the IFO institute reported that the German business climate index improved to 102.4 in December, above the 101.4 reading the month before and ahead of the 102.0 forecasts. Meanwhile, while the current assessment survey missed estimates, the expectations survey provided a beat.In other news, the Bank of England's Monetary Policy Committee (MPC) voted eight-to-one in favour to keep its asset purchase programme at £375bn in this month's meeting. The MPC voted unanimously to keep the Bank Rate at 0.5%.FTSE 100: Financials, IAG and CRH lead the risersInsurance and banking stocks were performing well this afternoon after Credit Suisse upgraded its ratings on both sectors this morning.Lloyds was up after the Swiss broker raised its view on European banks to 'benchmark' from 'small underweight', saying that the stock looks "abnormally cheap" versus its peers. Banking groups RBS, Standard Chartered and Barclays were also in demand.Car insurer Admiral was also higher after Credit Suisse raised the insurance sector from 'benchmark' to 'overweight'. However, sector peers British American Tobacco and Imperial Tobacco were lower after the same broker downgraded the tobacco sector from 'benchmark' to 'underweight'.Airline group IAG was flying high on news that its subsidiary British Airways is set to launch a new route to the Chinese city of Chengdu.Building materials firm CRH was also gaining after a broker upgrade. Deutsche Bank raised its recommendation for the stock to 'buy' in spite of its still-subdued performance in European markets. "After having been severely penalised by its sizeable developed market exposure in 2012, our economic recovery expectations combined with high private construction exposure, high operating leverage and additional cost savings lead us to believe that the stock should re-rate strongly in 2013," analysts said. Distribution and outsourcing firm Bunzl fell sharply after buying McCordick Glove & Safety based near Toronto, Canada, and Atlas Health Care in Adelaide, Australia. The news comes as the group said that group revenue growth in 2012 is expected to be 6% at constant exchange rates. United Utilities was in the red after going ex-dividend, along with Burberry.FTSE 250: Vesuvius's shares price adjusts to de-mergerVesuvius, previously known as Cookson, was showing as the heaviest faller on the FTSE 250, down around 50% after the de-merger of its Performance Materials division to Alent became effective. Vesuvius now only consists mainly of Cookson's Engineered Ceramics division so the sharp drop in the share price was as expected this morning.Central Europe-focused hard coal and coke producer New World Resources continued to surge after the International Energy Agency (IEA) said yesterday that coal will come close to surpassing oil as the world's top energy source by 2017. Berendsen, the European textile maintenance company, edged higher after saying that trading continues to be in line with expectations and that it expects to report "good" year-on-year progress for 2012.Oil and gas producer Salamander Energy rose after it signed two new borrowing facilities together totalling $350m, designed to extend the maturity of the group's financing, simplify Salamander's borrowing structure and lower its cost of debt.FTSE 100 - RisersCRH (CRH) 1,224.00p +4.88%Admiral Group (ADM) 1,199.00p +4.53%Lloyds Banking Group (LLOY) 49.20p +4.37%International Consolidated Airlines Group SA (CDI) (IAG) 188.50p +4.32%Standard Chartered (STAN) 1,568.00p +3.57%Royal Bank of Scotland Group (RBS) 315.40p +3.38%Wolseley (WOS) 2,880.00p +3.00%Old Mutual (OML) 179.50p +2.51%Evraz (EVR) 278.40p +2.39%ARM Holdings (ARM) 775.00p +2.38%FTSE 100 - FallersBunzl (BNZL) 1,020.00p -4.32%British American Tobacco (BATS) 3,095.00p -2.55%Rio Tinto (RIO) 3,506.50p -1.72%United Utilities Group (UU.) 688.00p -1.64%Fresnillo (FRES) 1,911.00p -1.60%BAE Systems (BA.) 341.90p -1.19%Burberry Group (BRBY) 1,249.00p -0.95%Imperial Tobacco Group (IMT) 2,397.00p -0.87%BG Group (BG.) 1,023.00p -0.78%Randgold Resources Ltd. (RRS) 6,105.00p -0.73%FTSE 250 - RisersNew World Resources A Shares (NWR) 308.50p +6.38%SIG (SHI) 123.50p +5.65%Synthomer (SYNT) 192.30p +5.37%Diploma (DPLM) 527.00p +4.98%Regus (RGU) 104.90p +4.90%Dixons Retail (DXNS) 29.80p +4.89%Bwin.party Digital Entertainment (BPTY) 113.70p +4.89%Talvivaara Mining Company (TALV) 101.30p +4.87%William Hill (WMH) 350.50p +4.85%Petropavlovsk (POG) 361.80p +4.63%FTSE 250 - FallersVesuvius (VSVS) 324.00p -49.77%Telecity Group (TCY) 800.00p -4.19%Homeserve (HSV) 233.10p -3.48%JD Sports Fashion (JD.) 710.00p -2.67%Shanks Group (SKS) 83.30p -2.29%Halfords Group (HFD) 339.20p -2.11%Grainger (GRI) 117.40p -1.92%Hochschild Mining (HOC) 484.60p -1.90%Centamin (DI) (CEY) 41.46p -1.52%NMC Health (NMC) 172.40p -1.49%BC