London open: ASOS plummets as UK stocks fall ahead of ECB

techMARK 2,825.83 +0.11%FTSE 100 6,802.80 -0.23%FTSE 250 15,937.44 -0.31%A surprise profit warning from fast-growing fashion retailer ASOS and a cautious outlook from speciality chemicals firm Johnson Matthey sent UK stock markets lower on Thursday, as investors nerves were tested ahead of the pivotal European Central Bank (ECB) meeting this afternoon. Although the ECB is widely expected to unleash a host of new measures to battle deflationary pressures and boost growth across the single-currency region, risk appetite is likely to be kept in check given the potential for policymakers to disappoint. The FTSE 100 fell 0.2% to 6,803 in early trading. The index has not closed lower than this since May 20th."After this week's weak inflation numbers, market expectations of the ECB have likely risen, which we believe raises the bar for the ECB to impress the market with a package of measures," said Analyst Khrishnamoorthy Sooben from Barclays."While weak inflation prints increase the probability of quantitative easing (QE) somewhat, we still think the ECB will prefer to wait before embarking on QE and instead focus on rate cuts and credit easing tools in today's meeting."While the ECB will undoubtedly garner the most attention today, the Bank of England will also be watched as it reports its own monetary policy decision at noon, though analysts expect no change from UK policymakers just yet. The Bank Rate is forecast to be held at 0.5% with the size of the asset purchase programme unchanged at £375bn.Meanwhile, jobless claims data from the States will be analysed as markets gear up for the all-important US employment report tomorrow, which has the potential to spark some volatility across global financial markets. Jobless claims are expected to rise to 310,000 in the week ended May 31st, from 300,000 the week before which was the second-lowest reading since the financial crisis ended.ASOS plummets on profit warningShares in online fashion retailer ASOS plummeted as much as 40% after the company cut its margin guidance for the full year and blamed a strong pound for a slowdown in growth in the third quarter. The company said that because of a higher mix of UK and European sales, which have lower retail margins, together with increased promotions, its operating margin for the current financial year would be 4.5%, down from its previous forecast of 6.5%.The surprise trading statement saw shares in fellow retailers Next, Sports Direct, N Brown, SuperGroup and Primark owner Associated British Foods lower. boohoo.com, the online fashion group which floated in March, was down around 12%. Johnson Matthey, which makes catalytic converters for cars, reported higher sales and profits and hiked its dividend, but the share price fell as it warned that changes in a deal with a supplier and currency volatility would hit growth in 2014/15.Leading the upside was Smith & Nephew which jumped around 4% as M&A speculation continues to surround the medical devices manufacturer. US group Medtronic has become the latest party rumoured to be interested in the UK firm and is reportedly in the early stages of preparing an offer.The numbers of passengers flying with budget airline easyJet rose 7.9% in May compared to the same month last year, helping the stock higher early on.Lloyds Banking Group edged higher after saying that it is to sell a portfolio of UK commercial real estate loans to Promontoria Holding for £352m as part of its continued "non-core run-off portfolio asset reduction programme".UK residential property developer Bellway rose after saying that demand for new homes remains robust, buoyed by growing consumer confidence and a strong supply of mortgages. FTSE 100 - RisersSmith & Nephew (SN.) 1,110.00p +4.32%Admiral Group (ADM) 1,490.00p +1.22%Shire Plc (SHP) 3,546.00p +0.91%Meggitt (MGGT) 496.60p +0.51%Rolls-Royce Holdings (RR.) 1,067.00p +0.47%easyJet (EZJ) 1,598.00p +0.44%National Grid (NG.) 834.00p +0.42%United Utilities Group (UU.) 871.50p +0.40%Old Mutual (OML) 200.00p +0.40%Aviva (AV.) 528.00p +0.38%FTSE 100 - FallersPersimmon (PSN) 1,260.00p -5.41%Hargreaves Lansdown (HL.) 1,230.00p -1.91%Associated British Foods (ABF) 2,999.00p -1.61%Randgold Resources Ltd. (RRS) 4,314.00p -1.60%Fresnillo (FRES) 777.50p -1.58%Johnson Matthey (JMAT) 3,207.00p -1.57%Sports Direct International (SPD) 787.00p -1.50%Next (NXT) 6,560.00p -1.28%Carnival (CCL) 2,404.00p -1.07%Anglo American (AAL) 1,446.00p -1.03%FTSE 250 - RisersAL Noor Hospitals Group (ANH) 1,036.00p +2.98%Bellway (BWY) 1,430.00p +1.78%Genus (GNS) 1,059.00p +1.44%Worldwide Healthcare Trust (WWH) 1,304.00p +1.40%Perform Group (PER) 270.00p +1.39%Diploma (DPLM) 662.50p +1.07%Infinis Energy (INFI) 210.90p +1.01%Big Yellow Group (BYG) 497.30p +0.95%JPMorgan Emerging Markets Inv Trust (JMG) 560.00p +0.90%JD Sports Fashion (JD.) 1,640.00p +0.86%FTSE 250 - FallersSupergroup (SGP) 1,059.00p -4.59%Ocado Group (OCDO) 357.10p -3.51%Brown (N.) Group (BWNG) 458.20p -2.34%Morgan Advanced Materials (MGAM) 327.10p -2.07%Tullett Prebon (TLPR) 282.00p -1.88%Centamin (DI) (CEY) 60.75p -1.86%Lonmin (LMI) 249.10p -1.62%Unite Group (UTG) 415.80p -1.47%Moneysupermarket.com Group (MONY) 175.90p -1.46%Elementis (ELM) 284.30p -1.28%BC