Supermarkets are among the best performing stocks today following Chancellor George Osborne's announcement that VAT will rise to 20% from 17.5%. The measure could squeeze supermarkets' profits by forcing consumers to cut back on expenditure, but the rise will not come into effect until January 4 and there was no move to extend VAT to items that are currently exempted, such as food and children's clothing.Morrisons is the best performer in the retail sector, with fellow supermarkets Tesco and Sainsbury's also going well.Oil and mining stocks are having a bad as commodity prices fall back after rising yesterday following China's announcement that it will de-link its currency from the US dollar. Oil and metals have fallen.BP continues its decline today, and is joined lower by fellow oil giant BG Group. Among the large-cap miners, silver specialist Fresnillo is the heaviest faller.Top performing sectors so far todayFood & Drug Retailers 4,506.15 +1.40%General Retailers 1,629.59 +0.97%Real Estate Investment & Services 1,378.45 +0.65%Alternative Energy 5,449.20 +0.31%Tobacco 25,945.07 +0.30%Bottom performing sectors so far todayIndustrial Metals & Mining 5,657.76 -2.63%Oil & Gas Producers 6,684.33 -2.41%Mining 21,691.64 -2.39%Automobiles & Parts 3,088.58 -2.29%Life Insurance 3,578.49 -1.63%