London open: Markets hold at three-week high

- Markets flat ahead of ECB, US data- Antofagasta operations unaffected by Chile quake- Domino's, ASOS impress with resultstechMARK 2,788.47 +0.16%FTSE 100 6,650.51 -0.03%FTSE 250 16,413.15 +0.03%UK stocks were flat at a three-week high on Wednesday morning as investors paused for breath ahead of some key risk events towards the end of the week, including a policy decision from the European Central Bank (ECB) and the US non-farm payrolls report.The FTSE 100 was trading just 0.03% lower at 6,651 early on, after closing at 6,652.61 on Tuesday, its highest finish since March 11th."With pressure mounting on the ECB to finally put aside rhetoric and take some action on low inflation, possibly at this week's meeting, and an expectation that US jobs growth will shrug off those winter blues this Friday, the momentum remains with the bulls," said Jonathan Sudaria, a dealer at Capital Spreads.Expectations over some sort of monetary easing from the ECB have increased after data on Monday showed that consumer price inflation slowed to just 0.5% in March, down from 0.8% the previous month and below estimates. Analysts, however, are still divided on whether policymakers will inject more stimulus at Thursday's meeting.US economic data will be in focus today with the ADP Employment Report often seen as a rough indicator of Friday's official non-farm payrolls figure. Consensus forecasts are pointing to a 195,000 increase in ADP private-sector payrolls in March, up from 139,000 the previous month.Antofagasta gains despite Chile quakeMining stocks were on the rise this morning as metals prices gained across the board. Copper miner Antofagasta was among the best performers despite reports of an 8.2 magnitude earthquake in Chile, where the company is based. According to Reuters, the company has said that its copper operations were unharmed by the disaster.Resource peers Fresnillo and Anglo American were also making gains early on.Domino's Pizza rose after a 10% increase in like-for-like sales at its 725 UK stores in the first quarter, driven by improved weather and the success of its Winter Survival meal deal. Online fashion retailer ASOS was also higher after a 22% drop in first-half profits was not as bad as feared, while revenues jumped by 34%.GlaxoSmithKline declined after saying it was "disappointed" with having to call an end to its clinical trial for its treatment for non-small cell lung cancer after results failed to meet expectations.Al Noor Hospital, the Abu Dhabi-based medical facilities firm, continued to surge after announcing yesterday that all resolutions were approved by shareholders at its annual general meeting.Financial groups Aviva, Jardine Lloyds Thompson, Phoenix and Resolution were all trading lower after going ex-dividend. Other stocks on the FTSE 350 trading without the right to their latest payouts included Pearson, Tullow Oil, DS Smith, Wolseley, 888 Holdings, Next and Interserve.FTSE 100 - RisersAntofagasta (ANTO) 857.50p +2.14%Sports Direct International (SPD) 909.50p +1.90%International Consolidated Airlines Group SA (CDI) (IAG) 432.20p +1.81%Marks & Spencer Group (MKS) 468.10p +1.81%Fresnillo (FRES) 861.00p +1.77%Mondi (MNDI) 1,055.00p +1.34%Melrose Industries (MRO) 304.10p +1.20%ITV (ITV) 194.90p +1.14%Anglo American (AAL) 1,538.00p +1.08%Randgold Resources Ltd. (RRS) 4,562.00p +1.06%FTSE 100 - FallersPearson (PSON) 1,011.00p -3.16%Resolution Ltd. (RSL) 294.70p -2.96%Reckitt Benckiser Group (RB.) 4,829.00p -1.57%ARM Holdings (ARM) 1,035.00p -1.15%Hargreaves Lansdown (HL.) 1,436.00p -0.97%Morrison (Wm) Supermarkets (MRW) 208.80p -0.95%Intertek Group (ITRK) 3,031.00p -0.92%Diageo (DGE) 1,835.00p -0.89%Royal Dutch Shell 'A' (RDSA) 2,191.00p -0.84%Admiral Group (ADM) 1,417.00p -0.84%FTSE 250 - RisersIntermediate Capital Group (ICP) 450.70p +3.56%Amec (AMEC) 1,201.00p +2.56%Bank of Georgia Holdings (BGEO) 2,666.00p +2.15%AL Noor Hospitals Group (ANH) 1,186.00p +1.80%International Personal Finance (IPF) 538.50p +1.80%COLT Group SA (COLT) 152.20p +1.74%UDG Healthcare Public Limited Company (UDG) 365.00p +1.70%Daejan Holdings (DJAN) 4,900.00p +1.64%Spirax-Sarco Engineering (SPX) 2,974.00p +1.50%Kazakhmys (KAZ) 264.10p +1.46%FTSE 250 - FallersInterserve (IRV) 711.00p -4.56%Phoenix Group Holdings (DI) (PHNX) 662.00p -3.29%Supergroup (SGP) 1,697.00p -2.69%Evraz (EVR) 77.10p -2.53%John Laing Infrastructure Fund Ltd (JLIF) 115.70p -2.28%Infinis Energy (INFI) 238.40p -1.69%F&C Asset Management (FCAM) 119.80p -1.64%Bwin.party Digital Entertainment (BPTY) 125.10p -1.50%Jardine Lloyd Thompson Group (JLT) 1,027.00p -1.44%Domino Printing Sciences (DNO) 797.00p -1.30%BC