London midday: Mixed reception for deluge of updates

London's leading share index is uncertain today as the continuing stream of company updates gets a mixed reception.Kazakhstan-focused copper miner Kazakhmys is in demand after it said underlying profits were 24% ahead in the first half and revealed details of a $250m buy-back programme. The group said the contribution from sector peer ENRC, in which it owns a 26% stake, increased significantly over the year. ENRC, too, was among the best performers in the morning.FTSE 100 drinks giant Diageo was firmer after it posted a 2% increase in sales in the year ended 30 June, as strong growth in the emerging markets outweighed more subdued conditions in Europe.A 12% increase in sales saw FTSE 100 global engineering firm IMI, another big gainer today, top the £1bn revenue mark in the first half, enabling the group to up its dividend by 22%. Shares jumped higher.Aggreko, the high-flying supplier of temporary power and temperature control, rose after it upped its full-year profits guidance, despite profits easing 5% in the first half.Another in demand was Switzerland-based commodities trading house Glencore International, which announced earnings ahead of some expectations, on the back of a strong showing in the energy segment.A strong performance in its mining and power and process divisions, and increased activity in the UK North Sea, more than offset the anticipated reduction in activity levels within the oil sands and federal businesses of AMEC in the first half of 2011, but the shares are lowerBanking trioRBS, Barclays and Lloyds were also in demand.Mining behemoth Rio Tinto rose after it exercised its right to acquire more shares in Asia-Pacific focused miner Ivanhoe Mines, taking its stake up to 48.5% from 46.5% previously.Car insurer Admiral fell lower, extending losses from Wednesday when the firm disappointed with a worse-than-expected combined ratio.In the FTSE 250, strong demand for gadgets such as smartphones and flat screen TVs helped AZ Electronic Materials, a supplier speciality chemical materials to technological manufacturers, move into profit in the six months to 30 June. The shares are up more than 10%. Pre-tax profits totalled $60.9m for the period, against a loss of $290.8m for the same period the previous year, on revenues that soared to $391.8m from $320.7m. Russian gold miner Petropavlovsk's profits and revenues soared in the half year to 30 June as it benefitted from continuing strong demand for the precious metal as investors seek a haven amid economic uncertainty. The shares are higher.Turning to the mid-cap fallers, Premier Oil saw profits tumble in the first half of the year but maintained its production estimates. Pre-tax profits came in at £32.5m, down from £111.6m the previous year. Unlike Tullow, which cut its 2011 forecasts on Wednesday, Premier offered no surprises on the operational front, with production just shy of 37,000 barrels of oil equivalents per day (boepd) and full-year guidance maintained at 40-45,000 boed. FTSE 100 - RisersBarclays (BARC) 161.20p +7.75%IMI (IMI) 845.00p +7.57%Kazakhmys (KAZ) 1,016.00p +7.17%Diageo (DGE) 1,197.00p +7.07%Royal Bank of Scotland Group (RBS) 22.89p +4.66%GKN (GKN) 191.70p +4.47%Lloyds Banking Group (LLOY) 31.36p +4.13%International Power (IPR) 317.30p +3.25%Anglo American (AAL) 2,352.00p +2.84%BHP Billiton (BLT) 1,977.00p +2.30%FTSE 100 - FallersAdmiral Group (ADM) 1,259.00p -6.95%Shire Plc (SHP) 1,930.00p -4.08%Kingfisher (KGF) 224.30p -2.98%Marks & Spencer Group (MKS) 323.60p -2.18%Amec (AMEC) 896.00p -2.13%Man Group (EMG) 211.70p -2.04%Hargreaves Lansdown (HL.) 417.40p -1.88%Land Securities Group (LAND) 722.50p -1.83%Vodafone Group (VOD) 165.15p -1.70%Randgold Resources Ltd. (RRS) 6,310.00p -1.56%FTSE 250 - RisersAZ Electronic Materials SA (WI) (AZEM) 231.60p +9.76%Petropavlovsk (POG) 836.00p +6.36%Kenmare Resources (KMR) 44.51p +5.98%Perform Group (PER) 169.30p +5.81%Barratt Developments (BDEV) 75.15p +5.77%Taylor Wimpey (TW.) 31.17p +5.59%Rightmove (RMV) 1,202.00p +5.44%Persimmon (PSN) 429.50p +5.09%Soco International (SIA) 307.90p +4.76%Senior (SNR) 155.00p +4.31%FTSE 250 - FallersPremier Oil (PMO) 322.20p -7.94%Pace (PIC) 100.20p -3.75%SIG (SHI) 103.50p -2.82%Dunelm Group (DNLM) 427.90p -2.75%Exillon Energy (EXI) 289.70p -2.49%F&C Asset Management (FCAM) 66.45p -2.28%Catlin Group Ltd. (CGL) 356.70p -2.25%JKX Oil & Gas (JKX) 188.40p -1.88%Gem Diamonds Ltd. (DI) (GEMD) 194.70p -1.67%Halfords Group (HFD) 295.90p -1.66%