After falling to its worst level in over six weeks, London's FTSE 100 opened broadly flat on Friday morning with investors refraining from building positions ahead of the all-important US jobs report due out this afternoon.The Footsie finished 1.3% lower on Thursday at 6,336, its lowest level since April 22nd, as the recent pattern of market volatility continued in anticipation of the key 'risk event' later today, May's reading of non-farm payrolls by the Bureau of Labor Statistics. Many see this release as one of the determining factors in how the Federal Reserve's potential 'exit strategy' from stimulus will play out in the near future."Traders this morning are clearly quite apprehensive about the upcoming jobs report, adjusting their risk profiles accordingly given the mixed data signals this week from the US labour market," said Market Strategist Ishaq Siddiqi from ETX Capital. This comes after the much worse-than-expected fall in the unofficial ADP data on Wednesday and Thursday's in-line decline in jobless claims yesterday."A reading above 169k will surely escalate expectations that the Federal Reserve will unwind asset purchases in coming months, while a number sharply below would suggest otherwise. Today's figure for that reason will dominate headlines, influencing price-action until the Fed's next policy meeting this month," Siddiqi said.Markets will also still be reacting to yesterday's move by the European Central Bank (ECB) to slash growth forecasts for the region for this year. The ECB expects the single-currency economy to contract by 0.6% in 2013, worse than its previous -0.5% estimate.Meanwhile, the Bundesbank has cut German growth forecasts and sees risks to the downside as the Eurozone recession continues to weaken demand for German exports. The German central bank cut the growth forecast for this year to 0.3%, from the prior 0.4%. It also revised the 2014 growth estimate down to 1.5% from the prior 1.9%.FTSE 100: Aberdeen drops after BofA downgradeAsset management group Aberdeen was a heavy faller this morning after Bank of America Merrill Lynch downgraded its rating for the stock to 'underperform' and cut its target price from 475p to 410p.The broker said that Aberdeen's organic inflows could slow significantly from consensus expectations. "With the stock up around 20% year-to-date, the valuation premium to peers looks unwarranted."Chemicals group Johnson Matthey was also in the red this morning, pulling back after a strong rise yesterday. Citigroup, Deutsche Bank and Goldman have all raised their target prices for the stock this morning following Thursday's well-received full-year results.BG Group was lower despite the announcement that a third floating production, storage and offloading (FPSO) vessel has come on stream offshore Brazil in the pre-salt Santos Basin as it progresses with its development on the massive BM-S-11 block.Mining stocks were performing well this morning with ENRC, Fresnillo, Glencore Xstrata and Randgold among the best performers.FTSE 250: KCOM and Bellway impress early onTelecoms and internet communications provider KCOM Group was a high riser after upping its dividend by 10% as promised after a 3.1% rise in pre-tax profit. Sales however fell for a fifth year in a row, down 3.7%.Housebuilder Bellway advanced after saying that the second half has been "encouraging" so far with the government's 'Help to Buy' scheme boosting demand. Reservations averaged 160 per week between the start of February and the end of May, up an impressive 31% with the same period last year. Sector peers Persimmon and Taylor Wimpey rose in sympathy.FTSE 100 - RisersEurasian Natural Resources Corp. (ENRC) 249.50p +2.72%Fresnillo (FRES) 1,142.00p +2.42%Glencore Xstrata (GLEN) 317.20p +2.01%TUI Travel (TT.) 341.20p +1.85%BT Group (BT.A) 307.00p +1.76%Land Securities Group (LAND) 923.00p +1.65%Randgold Resources Ltd. (RRS) 5,070.00p +1.42%easyJet (EZJ) 1,199.00p +1.27%British Land Co (BLND) 588.00p +1.03%Hammerson (HMSO) 496.20p +0.87%FTSE 100 - FallersAberdeen Asset Management (ADN) 417.10p -1.35%Sainsbury (J) (SBRY) 359.50p -1.05%British American Tobacco (BATS) 3,465.00p -0.94%WPP (WPP) 1,090.00p -0.91%ARM Holdings (ARM) 870.50p -0.91%Meggitt (MGGT) 520.00p -0.86%Babcock International Group (BAB) 1,108.00p -0.81%Smiths Group (SMIN) 1,297.00p -0.77%Experian (EXPN) 1,173.00p -0.76%Melrose Industries (MRO) 249.30p -0.76%FTSE 250 - RisersNew World Resources A Shares (NWR) 101.00p +7.05%KCOM Group (KCOM) 81.50p +6.05%888 Holdings (888) 144.50p +3.21%Barratt Developments (BDEV) 315.40p +3.11%Bellway (BWY) 1,353.00p +2.89%Diploma (DPLM) 556.00p +2.77%Persimmon (PSN) 1,205.00p +2.64%Kazakhmys (KAZ) 324.20p +2.37%Taylor Wimpey (TW.) 95.35p +2.36%Spirent Communications (SPT) 127.20p +2.25%FTSE 250 - FallersPerform Group (PER) 582.50p -1.60%Imagination Technologies Group (IMG) 333.30p -1.59%Euromoney Institutional Investor (ERM) 943.00p -1.46%Henderson Group (HGG) 150.90p -1.44%Telecity Group (TCY) 957.50p -1.19%Home Retail Group (HOME) 152.70p -1.17%Elementis (ELM) 224.10p -1.10%Mitie Group (MTO) 247.30p -1.08%Centamin (DI) (CEY) 37.66p -1.00%Heritage Oil (HOIL) 139.00p -1.00%