Stock markets in the UK opened broadly flat on Thursday morning in spite of the Federal Reserve's stimulus announcement last night, as the focus turns back to the impending 'fiscal cliff'.While mining stocks more or less gained early on, FTSE 250 gold miner Centamin grabbed the headlines plunging by over a half after suspending operations.The Fed announced that it would reinstate a policy of 'quantitative easing' "initially at a pace of $45bn per month". It said it would keep its range of interest rates near zero as long as the unemployment rate remains above 6.5%, near-term inflation stays below 2.5% and longer-term inflation expectations continue to be well anchored."While no doubt the Fed did deliver and lived up to expectations last night [...] markets still turned lower on a combination of profit taking as much of the news from the Fed has already been priced in and investors are now quickly starting to shift their focus to the budget stalemate in Washington where the US going over the 'fiscal cliff' in less than three weeks time is still a real possibility," said Markus Huber, the head of German HNW trading at ETX Capital.In the press conference following the Fed decision, Chairman Ben Bernanke said: "We cannot offset the full impact of the fiscal cliff ? it's just too big." Nevertheless, he did add that he thought the 'cliff' would be averted.FTSE 100: Wood Group hit by mixed updateEnergy services giant Wood Group has said that it expects to deliver good growth this year, with overall conditions in energy markets remaining "favourable". However, shares fell early on after reporting mixed trading in its Upstream division.Natural gas company BG Group was out of favour after naming executive Chris Finlayson as its new CEO to replace Sir Frank Chapman, who is stepping down because of medical reasons.Rolls-Royce, the global power systems company, fell despite saying that it has been awarded a significant order to supply integrated power and propulsion systems for seven offshore drilling vessels for Brazilian oil company Petrobras. Mining stocks were performing well this morning with ENRC, Vedanta and Rio Tinto among the best performers. However, diversified resources giant BHP Billiton was bucking the trend after giving the green light for a $520m investment in its Longford Gas Conditioning Plant project in Australia, which is necessary to its production plans.Supermarket group Morrison was flat after appointing Trevor Strain as its new Finance Director, who will replace Richard Penncock who announced his resignation in June. Strain is currently the Finance Director of Corporate at the company.FTSE 250: Centamin plummets after suspending operationsEgypt-focused gold mining company Centamin saw shares drop around 60% this morning after suspending operations at its Sukari gold mine because diesel has stopped being supplied.Centamin stated that it had received a "retrospective claim" for LE403m (approximately $65m) from the Egyptian General Petroleum Corporation (EGPC) for diesel fuel supplied from December 2009 to January 2012. Centamin alleged that the claim was "illegal" and claimed that EGPC had refused to authorise future supply of diesel to the Sukari Gold Mine until the amount was paid. High Street retailer Sports Direct fell despite delivering significant growth across the board in the first with with revenue up 22.5%.Bus and train group National Express gained after saying it is on target to deliver full-year results in line with company expectations despite challenging conditions.FTSE 100 - RisersTullow Oil (TLW) 1,203.00p +1.78%British Land Co (BLND) 560.50p +0.81%SABMiller (SAB) 2,803.50p +0.52%Hargreaves Lansdown (HL.) 708.50p +0.50%Land Securities Group (LAND) 814.00p +0.49%Intertek Group (ITRK) 3,086.00p +0.46%Resolution Ltd. (RSL) 248.10p +0.45%Standard Chartered (STAN) 1,497.00p +0.34%Barclays (BARC) 253.40p +0.32%Royal Bank of Scotland Group (RBS) 302.20p +0.27%FTSE 100 - FallersEvraz (EVR) 257.70p -2.28%Wood Group (John) (WG.) 752.50p -2.08%Amec (AMEC) 1,022.00p -2.01%BG Group (BG.) 1,048.50p -1.55%Burberry Group (BRBY) 1,277.00p -1.47%AstraZeneca (AZN) 3,000.00p -1.40%Fresnillo (FRES) 1,938.00p -1.32%Reed Elsevier (REL) 634.50p -1.17%Polymetal International (POLY) 1,130.00p -1.14%Kazakhmys (KAZ) 749.00p -1.12%FTSE 250 - RisersCOLT Group SA (COLT) 99.00p +2.33%Synthomer (SYNT) 194.40p +2.32%Talvivaara Mining Company (TALV) 95.65p +2.30%Daejan Holdings (DJAN) 3,069.00p +2.30%African Barrick Gold (ABG) 423.00p +1.93%National Express Group (NEX) 183.60p +1.89%Grainger (GRI) 118.30p +1.89%Petra Diamonds Ltd.(DI) (PDL) 110.00p +1.85%Domino Printing Sciences (DNO) 580.50p +1.84%Michael Page International (MPI) 383.70p +1.64%FTSE 250 - FallersCentamin (DI) (CEY) 24.00p -54.46%JD Sports Fashion (JD.) 715.00p -3.18%Dignity (DTY) 1,033.00p -2.27%New World Resources A Shares (NWR) 271.20p -2.09%Kenmare Resources (KMR) 30.53p -2.05%Bumi (BUMI) 266.50p -1.59%Imagination Technologies Group (IMG) 419.00p -1.41%BTG (BTG) 344.80p -1.37%Euromoney Institutional Investor (ERM) 796.00p -1.36%Hunting (HTG) 806.00p -1.35%BC