London open: Markets edge higher despite taper uncertainty

- Fed meeting in focus, decision due out after close- BoE minutes to be released this morning- M&S downgraded by UBS to 'neutral'- Oil stocks in focus after exploration updatestechMARK 2,701.33 +0.62%FTSE 100 6,512.99 +0.41%FTSE 250 15,387.21 +0.25%Markets opened slightly higher on Wednesday despite the impending conclusion of the Federal Reserve's latest policy meeting, which could see the central bank begin to scale back its stimulus programme as the economic recovery strengthens.The FTSE 100 was trading 0.4% higher at around 6,513 in early trading.However, given that a decision is not due out until after UK markets close this evening, gains on the FTSE 100 are likely to be limited as traders scale back risk appetite and position themselves amid the uncertainty."Will they? Won't they? Tapering is likely the only thing on most investors mind today ahead of the [Fed's] decision on whether to finally taper the unprecedented $85bnn monthly bond-buying scheme," said Alex Conroy, Financial Sales Trader at Spreadex."If the last few months are anything to go buy expect huge volatility today as investors attempt to get ahead of the Fed," he said.Markets will also be on the look out for the minutes of the latest Bank of England policy meeting which should shed further light on its decision this month to maintain interest rates at 0.5% and to leave its bond-buying programme unchanged at £375bn.If that wasn't enough, Wednesday will also see the release of the German IFO business climate survey, UK employment data and a host of housing data from the States.M&S hit by UBS downgradeHigh Street retailer Marks & Spencer was a heavy faller this morning after analysts at UBS cut their rating on the stock from 'buy' to 'neutral' and lowered their target price from 550p to 475p. In a review of the sector, the bank said raised concerns about margins given that promotional levels across the industry are up on last year.United Utilities Group was in the red after going ex-dividend, meaning that from today investors won't be able to get their hands on its latest payout. Grainger, Marston's, Berkeley Group, Greene King and Halfords also went ex-div today.Sainsbury was off shopping lists again today, along with fellow supermarket groups Tesco and Morrison, after a report from Kantar yesterday showed that over half the UK shopped in discounter grocery stores over the past 12 weeks. Deutsche Bank cut its target price for Sainsbury slightly this morning, keeping a 'hold' recommendation.Oilfield services firm Petrofac was trading lower this morning after a profit warning from French peer Technip.Oil major BP rose after making its first significant oil discovery in the Gulf of Mexico since 2009, in the Gila deepwater prospect 300 miles off New Orleans. Sector peer Tullow however was flat after saying that one of its wells offshore Côte d'Ivoire has turned up dry.Africa-focused oil and gas group Ophir Energy pleased investors after farming out a minority interest of its deepwater offshore blocks in Gabon in an effort to 'mitigate' exploration risk ahead of drilling.India-focused Essar Energy rose after an update about its improving debt situation, tapering capital expenditure and healthy current trading.FTSE 100 - RisersSmith & Nephew (SN.) 853.00p +2.16%Persimmon (PSN) 1,176.00p +1.82%Fresnillo (FRES) 739.50p +1.58%Rexam (REX) 495.00p +1.41%ARM Holdings (ARM) 1,007.00p +1.41%AstraZeneca (AZN) 3,584.00p +1.34%Vedanta Resources (VED) 795.50p +1.21%Kingfisher (KGF) 371.00p +1.15%Imperial Tobacco Group (IMT) 2,284.00p +1.15%Travis Perkins (TPK) 1,751.00p +1.10%FTSE 100 - FallersMarks & Spencer Group (MKS) 441.40p -2.41%Sainsbury (J) (SBRY) 369.80p -2.32%RSA Insurance Group (RSA) 90.95p -1.57%United Utilities Group (UU.) 658.00p -1.50%Tesco (TSCO) 321.10p -1.05%Petrofac Ltd. (PFC) 1,101.00p -0.81%Morrison (Wm) Supermarkets (MRW) 254.80p -0.74%Amec (AMEC) 1,041.00p -0.67%BG Group (BG.) 1,228.00p -0.53%Smiths Group (SMIN) 1,390.00p -0.43%FTSE 250 - RisersCarpetright (CPR) 555.00p +4.72%Alent (ALNT) 344.00p +3.06%Rank Group (RNK) 134.50p +2.59%Ophir Energy (OPHR) 313.70p +2.52%St. Modwen Properties (SMP) 368.80p +2.16%Supergroup (SGP) 1,349.00p +1.81%Bovis Homes Group (BVS) 768.50p +1.72%Taylor Wimpey (TW.) 108.30p +1.69%Cranswick (CWK) 1,157.00p +1.67%Bellway (BWY) 1,496.00p +1.63%FTSE 250 - FallersPerform Group (PER) 233.20p -4.58%Smith (DS) (SMDS) 317.00p -2.64%Wood Group (John) (WG.) 685.50p -2.42%Marston's (MARS) 144.00p -2.04%Centamin (DI) (CEY) 41.41p -1.87%Kenmare Resources (KMR) 19.00p -1.66%Dunelm Group (DNLM) 921.50p -1.55%Berkeley Group Holdings (The) (BKG) 2,477.00p -1.43%Ferrexpo (FXPO) 181.40p -1.41%Evraz (EVR) 97.90p -1.31%BC