London midday: Evraz leads fallers on the FTSE 100

- Investors in 'wait and see mode' ahead of ECB- Markets await pivotal US ISM data- Moody's lower EU outlook to 'negative'The FTSE 100 had slumped to its lowest levels of the day by Tuesday lunchtime as investors were cautious about building positions ahead of some pivotal US economic data this afternoon and a policy decision in Europe later this week."Overall, volumes remain thin, with no strong leads as the US was closed for a public holiday yesterday - investors here in Europe are sitting on their hands in a 'wait and see mode', as they don't want to get caught in the event of the European Central Bank [ECB] failing to deliver on a policy that would ease tensions in the debt markets," said ETX Capital market strategist Ishaq Siddiqi.ECB President Mario Draghi is widely expected to unveil plans on Thursday for buying sovereign debt in order to bring down bond yields in peripheral nations.Investors were also nervous about some manufacturing data due out Stateside this afternoon. The US ISM manufacturing index is expected to improve from 49.8 last month to 50.0, the level that separates expansion and contraction. A better-than-expected figure may ease the Federal Reserve's concerns about the economy, disrupting hopes that the central bank will launch another round of quantitative easing at its meeting next week. Meanwhile, credit ratings agency Moody's last night maintained the European Union's 'Aaa' rating but lowered its outlook for the region from 'stable' to 'negative' to reflect "the negative outlooks now assigned to the Aaa sovereign ratings of key contributors to the EU budget: Germany, France, the UK and the Netherlands, which together account for around 45% of the EU's budget revenue". FTSE 100: Blue chips hit by negative broker commentarySteel giant Evraz was among the worst performers of the day after Credit Suisse said that downward trend in iron ore and coal prices last week "goes in line with our view that risk for profitability of integrated producers and bulk miners (NLMK, Mechel, NWR, Kumba, Evraz, Severstal) is on the downside." The broker maintained a 'neutral' stance on Evraz today.Telecoms group Vodafone declined after being downgraded by Bernstein from 'outperform' to 'market perform' on the back of "an increasing number of negative risks".Real estate investment trust (REIT) Land Securities was a heavy faller after both JP Morgan Cazenove and UBS downgraded their ratings on the stock to 'neutral' this morning. UBS said that the Land Secs' valuation reflects "fair value after a strong run". UBS also cut its recommendation for REIT peers British Land and SEGRO today.Banking group Royal Bank of Scotland (RBS) was lower as the threat of a bruising legal battle with angry shareholders continues to hang over the company. Investec this morning lowered its recommendation on the shares from 'buy' to 'hold', saying that "after another modest rally, we throw in the towel". In contrast, oilfield services group Petrofac was performing well after Credit Suisse upped its rating from 'neutral' to 'outperform'. "We believe the stock has performed poorly on a lack of project awards over the summer period and elevated expectations for the IES business. We believe the next few months will be better: awards should step up, thanks to less instability in the Middle East, and the payoff of extensive marketing efforts in southeast Asia and amongst oil majors," the broker said.FTSE 250: Ashtead leads risers after upping guidanceHigh-flying plant hire firm Ashtead jumped after raising profits guidance again as its new financial year got off to a strong start. "Given this early stage of the recovery, we see further outperformance from re-rating as well as scope for further positive earnings surprises," said analyst Andrew Nussey from Peel Hunt. Veterinary pharmaceuticals firm Dechra rose after revealing growing sales across all its major brands and profits ahead of market forecasts for the full year to the end of June. Recycled packing company DS Smith was in demand after saying it was trading in line with market expectations and expected substantial year-on-year growth in earnings per share. Also on the rise was Old Speckled Hen brewer Greene King which shrugged off the Olympics and the poor weather to make a robust start to the financial year.FTSE 100 - RisersPetrofac Ltd. (PFC) 1,536.00p +1.32%Pennon Group (PNN) 741.00p +0.68%Capita (CPI) 726.00p +0.35%BT Group (BT.A) 223.10p +0.27%Schroders (SDR) 1,433.00p +0.07%Serco Group (SRP) 568.50p 0.00%Resolution Ltd. (RSL) 214.50p -0.05%Diageo (DGE) 1,750.00p -0.06%Morrison (Wm) Supermarkets (MRW) 278.00p -0.07%Reed Elsevier (REL) 598.00p -0.17%FTSE 100 - FallersEvraz (EVR) 220.50p -2.82%Land Securities Group (LAND) 775.50p -2.27%Vodafone Group (VOD) 179.05p -2.27%Xstrata (XTA) 926.00p -2.24%Rio Tinto (RIO) 2,735.00p -2.16%Burberry Group (BRBY) 1,326.00p -2.14%Standard Chartered (STAN) 1,361.00p -2.09%WPP (WPP) 805.00p -2.07%British American Tobacco (BATS) 3,265.00p -2.05%Aggreko (AGK) 2,290.00p -2.01%FTSE 250 - RisersAshtead Group (AHT) 314.60p +11.36%Heritage Oil (HOIL) 198.90p +4.63%Greene King (GNK) 583.50p +3.55%Smith (DS) (SMDS) 167.10p +3.15%Ophir Energy (OPHR) 603.00p +2.90%Dixons Retail (DXNS) 18.59p +2.71%Menzies(John) (MNZS) 626.50p +2.12%Hansteen Holdings (HSTN) 77.20p +1.78%Drax Group (DRX) 487.70p +1.75%SIG (SHI) 101.80p +1.70%FTSE 250 - FallersBumi (BUMI) 286.10p -5.64%Talvivaara Mining Company (TALV) 133.80p -4.43%Taylor Wimpey (TW.) 51.40p -3.47%Gem Diamonds Ltd. (DI) (GEMD) 160.30p -2.91%Genus (GNS) 1,336.00p -2.84%Fenner (FENR) 349.40p -2.84%Centamin (DI) (CEY) 81.20p -2.46%Bodycote (BOY) 346.30p -2.20%Domino's Pizza Group (DOM) 533.00p -2.20%Ruspetro (RPO) 123.40p -2.06%BC