The FTSE 100 opened higher on Wednesday morning, though gains were only slight as investors turned cautious ahead of a statement from the Federal Reserve, hoping for indications of when the central bank will begin to taper stimulus.Following the heavy sell-off in June, the strong rebound in markets in parallel with slowly improving US economic data suggests that traders are beginning to feel more comfortable with the idea that quantitative easing will not be around forever.The minutes of June's Federal Open Market Committee (FOMC) meeting are due out after UK markets close later this evening. Analysts now widely expect the FOMC to begin scaling back its asset purchase programme as soon as September."Friday's payrolls data was certainly better than expected and the resultant rise in bond yields did spook investors for a while, however it would appear that the prospects of improving economic data set against a background of gradually slowing asset purchases would appear to suggest that the market is slowly adjusting to this new dynamic," said Senior Market Analyst Michael Hewson from CMC Markets.Markets this morning were also digesting the news that ratings agency S&P has cut the sovereign rating for Italy by one notch from 'BBB+' to 'BBB' on the back of weakening economic prospects. "The rating action reflects our view of a further worsening of Italy's economic prospects coming on top of a decade of real growth averaging minus 0.04%," S&P said. FTSE 100: Burberry jumps after Q1 updateLuxury brand Burberry was a high riser this morning after saying that it was pleased with its first-quarter retail performance as underlying revenues rose 18%. "Spring/Summer 2013 was a standout season driven by innovative marketing, cohesive monthly fashion groups and exceptional execution from all corporate and regional teams," said Chief Executive Angela Ahrendts.Supermarket peers Morrison and Tesco were also providing a lift this morning, along with banking groups RBS and Lloyds.Mining giant Vedanta Resources was a heavy faller today after going ex-dividend, meaning that from today investors won't be able to get their hands on the company's latest payout. The stock was shrugging off a upgrade by Goldman Sachs to 'buy' this morning.However, the same broker has cut its target prices for a number of mining stocks this morning, saying that negative earnings momentum and limited free cash flow continue to take the shine off the sector, as well as lower growth in China and weaker copper prices. Goldman has cut its targets for Vedanta, Anglo American, Glencore Xstrata, Rio Tinto and BHP Billiton.Miners were also in the red on the back of disappointing trade figures from China. Exports and imports were both worse than expected, falling 3.1% and 0.7% year-on-year, respectively, in June, meaning that the trade surplus of $27.12bn was slightly under forecasts.FTSE 250: Halfords surges after strong Q1Car and bike parts retailer Halfords delivered a better than expected improvement in first-quarter sales, fuelled by strong demand for its cycling and car maintenance divisions. The stock was registering impressive gains early on.Heading the other way was Dechra Pharmaceuticals as investors gave a cool reaction to the proposed disposal of the businesses within its Services Segment as the company looks to focus on high-margin, specialist veterinary pharmaceuticals products.FTSE 100 - RisersBurberry Group (BRBY) 1,501.00p +4.24%Petrofac Ltd. (PFC) 1,311.00p +2.10%Morrison (Wm) Supermarkets (MRW) 282.40p +1.58%Tesco (TSCO) 348.80p +1.51%Aberdeen Asset Management (ADN) 405.30p +1.43%Persimmon (PSN) 1,289.00p +1.26%Reed Elsevier (REL) 797.50p +1.21%Barclays (BARC) 305.95p +1.19%Royal Bank of Scotland Group (RBS) 307.80p +1.12%Lloyds Banking Group (LLOY) 66.95p +0.90%FTSE 100 - FallersFresnillo (FRES) 913.00p -4.00%G4S (GFS) 224.50p -2.18%Johnson Matthey (JMAT) 2,779.00p -1.94%Randgold Resources Ltd. (RRS) 4,143.00p -1.66%Vedanta Resources (VED) 1,076.00p -1.65%Glencore Xstrata (GLEN) 260.70p -1.34%Intertek Group (ITRK) 3,065.00p -1.13%Aggreko (AGK) 1,784.00p -1.05%Serco Group (SRP) 675.50p -0.95%Antofagasta (ANTO) 810.00p -0.92%FTSE 250 - RisersHalfords Group (HFD) 347.80p +9.30%Barratt Developments (BDEV) 349.20p +1.84%Countrywide (CWD) 557.50p +1.36%Ashmore Group (ASHM) 354.50p +1.05%Schroder Asia Pacific Fund (SDP) 256.50p +0.98%Close Brothers Group (CBG) 1,053.00p +0.96%Synthomer (SYNT) 193.10p +0.94%Mondi (MNDI) 892.00p +0.85%Redrow (RDW) 251.60p +0.84%3i Group (III) 370.20p +0.82%FTSE 250 - FallersDechra Pharmaceuticals (DPH) 656.00p -12.01%Bwin.party Digital Entertainment (BPTY) 123.80p -5.13%ICAP (IAP) 381.00p -4.75%Hochschild Mining (HOC) 163.50p -3.82%Kazakhmys (KAZ) 252.20p -3.33%Menzies(John) (MNZS) 723.00p -3.08%Daejan Holdings (DJAN) 3,884.00p -2.90%Savills (SVS) 595.00p -2.86%Booker Group (BOK) 126.80p -2.69%Computacenter (CCC) 514.50p -2.56%