London open: Stocks slip after IMF cuts growth forecasts

- IMF cuts global growth estimates- Q3 US earnings season to kick off this evening- Capita and Aggreko dented by broker downgradesUK stocks continued to fall on Tuesday morning following a steep drop the day before, as concerns about the global economy were fuelled by a downgrade to growth forecasts from the International Monetary Fund (IMF).The IMF has cut global economic growth forecasts for this year and next because "prospects have deteriorated further and risks increased". The IMF said: "The recovery has suffered new setbacks, and uncertainty weighs heavily on the outlook. Downside risks have increased and are considerable."According to its "World Economic Outlook", the IMF now expects the world economy to grow 3.3% in 2012 compared to the prior 3.5% July estimate and just 3.6% in 2013, down from the previous 3.9% forecast. Forecasts for the Eurozone, UK and emerging markets were all cut.Losses were seen in the US last night ahead of the start of the third-quarter earnings season as investors fretted about how a subdued global economy will affect corporate profits, while strong gains were seen on the Hang Seng in Asia . Finance ministers from the European Union are meeting in Luxembourg today to discuss the region's top issues ahead of a summit in Brussels in a couple of weeks. Eurozone ministers yesterday said that the €500bn European Stability Mechanism was operational.FTSE 100: Capita and Aggreko hit by downgradesOutsourcing company Capita was a heavy faller after Seymour Pierce downgraded its recommendation on the stock to 'hold'. Meanwhile, temporary power solutions provider Aggreko was hit by a ratings cut from HSBC to 'neutral'.In contrast, asset manager Schroders was given a lift by Morgan Stanley which upgraded the shares to 'equal weight' and lifted its target price from 1,535p to 1,665p.Rio Tinto was making gains this morning despite saying at an investor seminar: "The short-term macroeconomic outlook remains volatile. Economic growth in China is robust but moderating, and is slow and uneven in developed economies."Sector peer Vedanta was also higher despite seeing production and sales of iron ore from Goa fall in the second quarter as the government's ban on mining activities in the state starts to bite.Banking group Barclays was in the red after announcing to say that it is to acquire the deposits, mortgages and business assets of ING Direct UK from Dutch finance house ING.Defence group BAE Systems continues to register losses as opposition to its proposed merger with European aerospace giant EADS mounts. According to the Financial Times this morning, more than 30% of shareholders in BAE have expressed "significant concerns" with the deal.Power systems firm Rolls-Royce was in the red despite being awarded a $103.3m MissionCare contract by the US Department of Defense.FTSE 250: Hays impresses with first-quarter IMSIn spite of a mixed trading update, recruitment firm Hays jumped early on. The company said that markets were overall stable through the first quarter though group net fees fell by 1% year-on-year.Satellite communications services firm Inmarsat fell despite saying that trading in the third quarter remained consistent with trends in the second quarter and in line with full year expectations.Egypt-focused gold miner Centamin also disappointed after revealing that third-quarter production was 10% down on the record second quarter. Nevertheless, the group said it was on track to hit full-year output guidance.FTSE 100 - RisersSchroders (SDR) 1,555.00p +1.50%Vedanta Resources (VED) 1,080.00p +1.12%Rio Tinto (RIO) 3,015.50p +1.04%Marks & Spencer Group (MKS) 372.30p +0.76%Kazakhmys (KAZ) 731.50p +0.69%Hammerson (HMSO) 470.90p +0.68%Polymetal International (POLY) 1,155.00p +0.43%Fresnillo (FRES) 1,966.00p +0.41%Anglo American (AAL) 1,808.50p +0.33%Land Securities Group (LAND) 776.00p +0.32%FTSE 100 - FallersCapita (CPI) 745.50p -2.99%Aggreko (AGK) 2,256.00p -2.72%InterContinental Hotels Group (IHG) 1,619.00p -2.06%CRH (CRH) 1,164.00p -1.61%Croda International (CRDA) 2,259.00p -1.35%Serco Group (SRP) 588.00p -1.26%Amec (AMEC) 1,099.00p -1.26%Whitbread (WTB) 2,373.00p -1.17%BT Group (BT.A) 224.40p -1.10%GKN (GKN) 214.70p -1.01%FTSE 250 - RisersHays (HAS) 80.00p +6.38%Brown (N.) Group (BWNG) 284.20p +1.75%Mitchells & Butlers (MAB) 308.50p +1.65%Shanks Group (SKS) 81.85p +1.43%Murray Income Trust (MUT) 681.94p +1.18%St. Modwen Properties (SMP) 199.55p +1.09%Home Retail Group (HOME) 95.30p +1.06%Templeton Emerging Markets Inv Trust (TEM) 568.50p +0.98%Laird (LRD) 229.80p +0.92%Sports Direct International (SPD) 392.20p +0.85%FTSE 250 - FallersPerform Group (PER) 420.00p -3.67%Ruspetro (RPO) 101.00p -2.51%Carpetright (CPR) 643.00p -2.43%Renishaw (RSW) 1,733.00p -2.42%Berkeley Group Holdings (The) (BKG) 1,398.00p -2.31%Oxford Instruments (OXIG) 1,362.00p -2.01%Cookson Group (CKSN) 529.50p -1.76%Bovis Homes Group (BVS) 492.50p -1.60%Investec (INVP) 370.90p -1.51%Go-Ahead Group (GOG) 1,317.00p -1.50%BC