London midday: Stocks pare gains ahead of ECB as BoE holds fire

- BoE leaves rates on hold- ECB speculation ramps up ahead of decision- Crimea votes to join Russia, referendum set for 10 days- Aviva, Aggreko and Schroders jump after resultstechMARK 2,894.33 -0.17%FTSE 100 6,784.24 +0.13%FTSE 250 16,663.49 +0.30%UK stocks had trimmed earlier gains by Thursday lunchtime as investors adopted a cautious stance in the face of central bank decisions from the Bank of England (BoE) and European Central Bank (ECB) and ongoing geopolitical developments in Ukraine.The FTSE 100 was trading 0.1% higher at 6,784 by the midday mark, pulling back after hitting a high of 6,806.62 early on.The BoE announced at noon that it had kept its monetary policy unchanged this month, as expected, leaving the Bank Rate at 0.5% and the size of its asset purchase programme at £375bn.While the UK policy decision came as little surprise to the markets, analysts have mixed opinions on whether the ECB will act this afternoon to quash rising deflationary risks in the Eurozone. Some expect that the ECB will keep its benchmark interest rate at the record low level of 0.25% in light of improving economic data and the small tick-up in consumer price inflation in February. However, others are anticipating a possible rate cut of around 15 basis points to 0.1% and a reduction in the deposit rate too."If the ECB were to cut today when inflation is edging higher it rather begs the question why they didn't act last month when inflation was falling. For this reason no action seems the most likely course of action given that there has been no material deterioration in any of the data since the last meeting," said Chief Market Analyst Michael Hewson from CMC Markets.However, comments from ECB President Mario Draghi earlier this week have ramped up speculation about some sort of action from policymakers today, after he said that inflation is "way below" the 2% target and risks becoming entrenched at low levels.The ongoing crisis in Ukraine continued to act as a backdrop for markets today as European Union leaders met for emergency talks to decide on their response to Russia's increased military presence in the Crimea region.Crimea, which has an ethnic Russian majority, today asked to join Russia after MPs agreed unanimously "to enter into the Russian Federation with the rights of a subject of the Russian Federation". A public referendum on the decision has been set for March 16th.Aviva, Aggreko and Schroders surgeShares in insurer Aviva soared after investors celebrated a better-than-expected set of 2013 results as its turnaround under Chief Executive Mark Wilson saw encouraging progress. Operating profits rose 6% year-on-year to £2,049m, some 3% ahead of the consensus estimate of £1,988m. Panmure Gordon was also providing a lift to the stock today, raising its rating from 'hold' to 'buy'.Temporary power group Aggreko jumped strongly after confirming that it would return £200m in capital to shareholders, outweighing the news that profits fell 8% last year.Schroders also surged after hiking its full-year dividend by 35% following a record year for the asset management group in 2013 as the company saw profits increase 41%.Results from engineering group IMI, however, failed to impress as the company reported a 3% increase in revenues from continuing operations. The company said it expects "modest" growth in the first half of 2014, but only when excluding the adverse impact of exchange rates.Aerospace and engine maker Rolls-Royce was trading in the red as sentiment was dampened by cautious comments from Citigroup, which said that ongoing concerns about "relatively aggressive accounting policies" may continue to limit upside for the stock.Legal & General was lower after Beaufort Securities lowered its rating on the stock to 'hold', while BSkyB was hit by a downgrade to 'neutral' by Westhouse.FTSE 100 - RisersAviva (AV.) 509.50p +9.31%Aggreko (AGK) 1,693.00p +7.63%Schroders (SDR) 2,674.00p +3.24%Fresnillo (FRES) 934.50p +2.35%Anglo American (AAL) 1,550.00p +1.97%Glencore Xstrata (GLEN) 338.50p +1.90%Aberdeen Asset Management (ADN) 388.80p +1.78%Lloyds Banking Group (LLOY) 81.91p +1.46%International Consolidated Airlines Group SA (CDI) (IAG) 448.70p +1.42%Ashtead Group (AHT) 948.00p +1.12%FTSE 100 - FallersIMI (IMI) 1,472.00p -4.91%Legal & General Group (LGEN) 231.30p -1.99%Meggitt (MGGT) 477.50p -1.87%British Sky Broadcasting Group (BSY) 927.00p -1.49%Rolls-Royce Holdings (RR.) 1,010.00p -1.46%United Utilities Group (UU.) 783.00p -1.26%Melrose Industries (MRO) 298.80p -1.19%Travis Perkins (TPK) 1,924.00p -1.08%Persimmon (PSN) 1,418.00p -1.05%Carnival (CCL) 2,371.00p -0.88%FTSE 250 - RisersEssar Energy (ESSR) 70.90p +5.58%Evraz (EVR) 66.45p +4.98%African Barrick Gold (ABG) 315.00p +4.41%Devro (DVO) 258.20p +4.32%Inmarsat (ISAT) 700.00p +3.86%RPS Group (RPS) 349.20p +3.62%Centamin (DI) (CEY) 57.95p +3.11%Lonmin (LMI) 302.70p +2.99%Henderson Group (HGG) 251.50p +2.86%Betfair Group (BET) 1,164.00p +2.83%FTSE 250 - FallersImagination Technologies Group (IMG) 173.80p -7.85%Balfour Beatty (BBY) 300.20p -6.60%Perform Group (PER) 275.90p -6.47%CSR (CSR) 766.50p -2.73%Pace (PIC) 463.10p -2.40%Unite Group (UTG) 442.10p -2.19%Oxford Instruments (OXIG) 1,352.00p -1.96%Daejan Holdings (DJAN) 4,862.00p -1.96%Computacenter (CCC) 677.50p -1.81%Euromoney Institutional Investor (ERM) 1,276.00p -1.47%BC