London midday: UK stocks pull back from two-month high

- Barclays, Aberdeen, AstraZeneca, Balfour Beatty fall- Ukraine tensions continue to rise- FTSE 100 pulls back from two-month high- UK services PMI beats forecaststechMARK 2,798.81 +0.15%FTSE 100 6,811.35 -0.16%FTSE 250 15,928.23 -0.02%Falls from Barclays, Aberdeen, AstraZeneca and Balfour Beatty pulled UK markets lower on Tuesday as investors returned to their desks in a cautious mood following the three-day weekend.Heightened tensions in Ukraine were also keeping risk appetite in check today after an army helicopter was shot down yesterday by pro-Russian activists near the city of Sloviansk. Deaths have been reported on both sides amid heavy fighting along the eastern border as Kiev continues its so-called 'anti-terrorist' operations.The FTSE 100, which was closed on Monday for a public holiday, was down 0.2% at 6,811 by midday after having closed at 6,822.42 on Friday, its highest finish since March 4th.Chris Beauchamp, Market Analyst at IG, said that it seemed as if the recent rally on the FTSE 100 "has run its course for now"."The big question now is whether we can sustain the move above 6,800, but it certainly feels as if markets had gotten a little ahead of themselves, especially in regards to Ukraine, where the situation seems to be worsening by the hour."Investors were largely overlooking upbeat UK economic data today which showed that growth in the services sector picked up faster than expected in April. Markit's UK services purchasing managers' index (PMI) rose from 57.6 to 58.7 last month, compared with the 57.8 forecast.Barclays, Aberdeen, AstraZeneca, Balfour BeattyBarclays was a heavy faller this morning, blaming a weak performance in its investment banking arm for a 5% decline in quarterly adjusted pre-tax profit to £1.7bn in the first quarter, although it said its retail and credit card operations did well.Banking peers Lloyds and RBS, which both beat market forecasts last week with their quarterly results, were also trading in the red this morning.Aberdeen Asset Management was lower after suffering net outflows of £8.8bn in a "demanding" six months to end-March. Assets under management fell 5% to £190.4bn during the period.Pharmaceutical giant AstraZeneca fell as speculation regarding a potential £63bn-plus takeover by US peer Pfizer continued to dominate headlines. According to the Financial Times, AstraZeneca has pressed Prime Minister David Cameron to remain neutral over Pfizer's offer, which was rejected by the board last week.Meanwhile, infrastructure services group Balfour Beatty sank sharply after Chief Executive Andrew McNaughton quit as the company warned on full-year profits. The group said pre-tax profits in 2014 were likely to come in between £145m-£160m, significantly lower than it forecast in March.Housing stocks were among the best performers of the morning with Persimmon, Barratt Developments, Travis Perkins and Bellway all making gains.Estate agent chain Countrywide rose after saying momentum in the later stages of 2013 continued into the first quarter of this year as the recovery in the residential property market continues.FTSE 100 - RisersPersimmon (PSN) 1,375.00p +3.62%Morrison (Wm) Supermarkets (MRW) 201.60p +2.75%Melrose Industries (MRO) 293.00p +2.63%easyJet (EZJ) 1,681.00p +2.44%Barratt Developments (BDEV) 383.60p +2.29%Ashtead Group (AHT) 891.00p +2.06%Pearson (PSON) 1,115.00p +1.92%Sainsbury (J) (SBRY) 327.00p +1.77%ARM Holdings (ARM) 901.00p +1.69%Whitbread (WTB) 4,132.00p +1.52%FTSE 100 - FallersAberdeen Asset Management (ADN) 418.00p -6.26%Barclays (BARC) 246.80p -4.53%Shire Plc (SHP) 3,375.00p -2.65%AstraZeneca (AZN) 4,687.50p -2.51%Coca-Cola HBC AG (CDI) (CCH) 1,444.00p -2.43%Centrica (CNA) 322.00p -2.07%Anglo American (AAL) 1,538.50p -1.69%Rio Tinto (RIO) 3,194.00p -1.63%SABMiller (SAB) 3,200.50p -1.58%BHP Billiton (BLT) 1,902.50p -1.48%FTSE 250 - RisersPace (PIC) 355.60p +5.52%Rentokil Initial (RTO) 125.70p +3.63%BTG (BTG) 563.50p +3.58%Perform Group (PER) 225.00p +3.21%AL Noor Hospitals Group (ANH) 1,032.00p +3.20%ITE Group (ITE) 230.50p +2.54%Northgate (NTG) 535.00p +2.49%Cable & Wireless Communications (CWC) 55.00p +2.33%Brewin Dolphin Holdings (BRW) 335.30p +2.23%Supergroup (SGP) 1,438.00p +2.20%FTSE 250 - FallersBalfour Beatty (BBY) 235.40p -17.63%African Barrick Gold (ABG) 230.50p -4.36%Fisher (James) & Sons (FSJ) 1,400.00p -3.11%Croda International (CRDA) 2,487.00p -3.04%Man Group (EMG) 97.25p -2.41%Just Retirement Group (JRG) 162.00p -2.35%Carillion (CLLN) 365.40p -2.30%Brown (N.) Group (BWNG) 455.40p -2.06%Lancashire Holdings Limited (LRE) 667.00p -1.98%Lonmin (LMI) 287.60p -1.71%Bc